Essential Biology for Cambridge IGCSE® [2 ed.] 0198355149, 9780198355144

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Essential

Biology for Cambridge

®

IGCSE 2nd

Gareth

Williams

Richard

Fosbery

Series

Editor:

Lawrie

Ryan

Edition

Library;

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BIOLOGY

ATES/Science

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the

Contents

Introduction

Unit

1

1

Characteristics

of

living

Characteristics

1.2

Classication

Features

of

of

Vertebrates

1.5

Invertebrates

1.6

Ferns

1.7

Dichotomous

Starvation

7.5

Digestion

78

7.6

Teeth

80

living

organisms

7.7

Mouth,

7.8

Small

intestine

and

absorption

84

7.9

Large

intestine

and

intestinal

86

Unit

2

2.1

oesophagus

Structure

Different

2.4

Levels

owering

plants

keys

8

Plant

transport

Transport

Water

8.3

Transpiration

94

of

cells

8.4

Translocation

96

Practice

98

types

of

of

cell

organisation

Movement

Osmosis

Active

in

in

and

plant

out

of

cells

and

animal

cells

transport

Transport

24

9.1

Circulation

100

26

9.2

The

102

Chemical

9.3

Heart

9.4

Blood

9.5

Coronary

9.6

Blood

9.7

Blood

9.8

Lymph

heart

and

molecules

106

heart

disease

(CHD)

108

110

32 in

defence

112

and

for

tissue

uid

114

questions

116

10

Diseases

and

immunity

118

38

biological

molecules

questions

10.1

Disease

10.2

Defence

118

10.3

Aspects

10.4

Controlling

40 against

disease

120

Structure

5.2

Factors

and

action

of

enzymes

enzyme

Practice

Plant

and

pH

6.1

Photosynthesis

6.2

What

6.3

Products

of

Unit

11

Gas

spread

122

of

disease

questions

exchange

124

126

in

humans

128

11.1

The

gas

11.2

Gas

exchange

exchange

11.3

Breathing

11.4

Rate

system

128

needed

132

52

photosynthesis?

photosynthesis

photosynthesis

and

Practice

54

54

for

130

50

nutrition

of

46

the

48

questions

is

immunity

action:

temperature

Enzymes

Practice

46

affecting

of

44

Enzymes

Rate

104

42

5.1

6.4

exercise

vessels

38

DNA

Practice

6

100

36

molecules

tests

humans

28

Unit

Biological

in

34

questions

Biological

questions

9

Practice

Unit

92

22

questions

Practice

5.3

90

20

30

5

systems

uptake

18

Osmosis

Unit

90

8.2

3.2

4.3

88

8.1

28

4.2

questions

16

Diffusion

4.1

disease

14

3.1

4

82

12

organelles

Practice

Unit

stomach

10

Unit

3.4

and

18

2.3

3.3

76

8

Cells

Cell

3

74

deciency

6

questions

2.2

Unit

needs

nutrient

2

Unit

Practice

and

4

Practice

and

energy

2

organisms

1.4

Balancing

7.4 classication

organisms

1.1

1.3

and

7.3

Unit

12

of

breathing

134

136

Respiration

138

56 12.1

Aerobic

12.2

Anaerobic

respiration

138

58 respiration

140

60 Practice

production

depth

questions

questions

142

6.5

Glasshouse

62

6.6

Leaves

6.7

Mineral

requirements

66

13.1

Excretion

144

Practice

questions

68

13.2

Kidney

structure

146

13.3

Kidney

function

148

13.4

Kidney

Unit

Unit

7

7.1

Animal

A

13

Excretion

nutrition

balanced

diet

70 dialysis

Sources

of

nutrients

and

kidney

transplants

150

70 Practice

7.2

144

64

questions

152

72

iii

Contents

Unit

14

Coordination

and

control

14.1

Nervous

14.2

Neurones

14.3

Synapses

14.4

Sense

14.5

The

14.6

Hormones

14.7

Controlling

conditions

14.8

Controlling

body

14.9

Tropic

and

and

in

response

humans

reex

arcs

drugs

organs

eye

154

Unit

the

body

Unit

15

18.1

Variation

232

18.2

Mutations

234

158

18.3

Adaptive

236

160

18.4

Natural

162

18.5

Selective

15.2

Heroin

15.3

Alcohol

questions

and

Practice

Smoking

the

and

misuse

of

health

Asexual

16.2

Flower

16.3

Pollination

16.4

Fertilisation

16.5

The

male

16.6

The

female

16.7

Fertilisation

16.8

Pregnancy

and

sexual

reproduction

and

seed

formation

system

Pyramids

19.3

Shortening

19.4

Nutrient

174

19.5

The

176

19.6

Populations,

178

19.7

Human

Methods

reproductive

and

environment

244

ow

244

of

numbers

and

biomass

246

the

food

chain

248

Control

care

of

of

Sexually

system

implantation

nitrogen

250

cycle

252

communities

and

254

populations

Practice

256

questions

258

20

Biotechnology

and

genetic

engineering

260

184

20.1

Microorganisms

186

20.2

Enzymes

188

20.3

Fermenters

264

190

20.4

Genetic

engineering

266

Practice

questions

268

Human

inuences

and

and

biotechnology

biotechnology

260

262

194 21

on

ecosystems

270

196

and

birth

21.1

Food

21.2

Habitat

supply

270

21.3

Pollution

274

21.4

Water

276

21.5

The

21.6

Acid

21.7

Sustainable

21.8

Sewage

21.9

Endangered

destruction

272

200

202

cycle

birth

greenhouse

effect

278

206

fertility

transmitted

pollution

204

control

rain

280

208

infections

(STIs)

questions

resources

282

210

treatment

and

recycling

284

212

Inheritance

species

286

214 21.10

genes

and

Conservation

288

Practice

290

Chromosomes,

17.2

Protein

17.3

Mitosis

17.4

Meiosis

17.5

Inheritance

17.6

Monohybrid

17.7

Codominance

226

17.8

Sex

228

synthesis

and

genes

inheritance

linkage

questions

DNA

214

17.1

Practice

cycles

198

menstrual

Practice

iv

their

ecosystems

192

hormones

The

17

and

Energy

184

reproductive

Ante-natal

16.12

Unit

242

182

structure

16.11

16.14

Organisms

19.2

Unit

16.13

questions

19.1

180

Reproduction

Sex

19

drugs

questions

16.1

16.9

240

166

Unit

16.10

238

breeding

172

sport

Practice

16

features

selection

174

Drugs

Unit

232

170

Drugs

in

selection

168

responses

15.1

15.4

temperature

and

154

164

in

Variation

156

Unit

Practice

18

questions

216

Alternative

218

Glossary

298

220

Index

307

222

224

230

to

practical

paper

292

Introduction

This

book

is

designed

specically

for

Cambridge

®

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Biology

involved

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essential-biology-answers

1

1

Characteristics

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are

The

synthesis

simple

do

as

to

of

small

and

structure

have

all

a

other

eukaryotic.

classify

all

because

kingdoms,

cell

not

cells

example,

kingdom

ve

a

share

For

cytoplasm

respiration.

known

organisms

the

the

bacteria

are

kingdoms.

as

have

cells.

cells

in

protein

such

Bacteria

these

into

structure.

that

present

prokaryotic

features

known

have

1.3.1.

as

and

together

cell

also

in

Figure

nuclei

groups

same

types

known

have

classied

the

stored

involved

main

use

They

ribosomes

are

two

organisms

ve

DNA.

called

that

are

nucleus

and

them

into

bacteria

they

including

have

the

plant

wall

food

kingdom

and

the

animal

kingdom.

cell

reser ve

membrane

Plant

kingdom

plants

are

Plants

are

multicellular

organisms.

The

bodies

of

roots

spread

out

ribosomes

through

flagellum

not

the

compact

soil

to

like

gain

those

water

of

and

animals.

salts

and

Their

their

stems

grow

many

plasmid

leaves

DNA

of

Figure

1.3.1

A

typical

to

roots

absorb

and

light.

stems.

Growth

This

occurs

kingdom

in

special

includes

places

mosses

such

and

as

ferns,

the

tips

which

bacterium.

do

not

reproduce

conifers

out

and

the

using

photosynthesis,

chloroplasts

full

seeds,

owering

of

using

and

plants.

light

to

chlorophyll,

the

All

seed-bearing

plants

make

have

their

cellulose

cell

plants,

such

chlorophyll

own

walls

food.

and

a

as

and

Plant

large

carry

cells

have

sap-lled

vacuole.

Animal

animals

kingdom

have

throughout

their

not

food

have

nervous

Animals

much

the

by

more

body.

eating

cell

walls,

systems

are

also

compact

Animals

plants

do

which

bodies

not

and/or

chloroplasts

multicellular

or

coordinate

than

organisms.

plants.

photosynthesise

other

animals.

large

their

Growth

and

Animal

vacuoles.

All

responses

to

Most

occurs

obtain

cells

animals

stimuli

do

have

and

their

Prokaryote

you

Staphylococcus,

on

the

human

a

type

skin

of

bacterium

can

see

kingdom

in

Figure

are

rod-shaped.

are

a

Bacteria

1.3.1.

Many

exist

have

Some

in

a

simple

bacteria

short

chains

cell

are

of

structure

spherical

cells.

that

and

Most

some

bacteria

found

few

micrometres

in

length

and

can

only

be

seen

with

light

(×4000).

and

electron

microscopes.

(One

micrometre

is

one-thousandth

of

a

millimetre.)

Bacterial

species

There

is

Bacteria

called

from

cells

are

no

are

also

nucleus,

often

animal

mould,

Rhizopus

nigricans,

is

a

and

6

black

structures

contain

spores.

just

a

by

by

loop

additional

(see

page

plant

Some

cell

of

cells

as

of

The

they

have

The

cells

of

some

bacterial

capsules.

DNA

loops

267).

bacteria

walls.

slime

within

DNA

the

structure

do

not

cytoplasm.

inside

of

have

extensions

their

cytoplasm

bacteria

differs

chloroplasts

called

or

agella

fungus.

(singular: The

have

plasmids

mitochondria. Bread

surrounded

surrounded

agellum)

for

moving

through

water

or

other

uids.

tnemelppuS

movement.

tnemelppuS

Protoctists

This

are

in

classied

four

and

some

parasitic

and

are

this

kingdoms.

are

commonly

All

they

vary

in

kingdom

as

is

as

size

from

plenty

do

light

not

cells

they

any

are

of

many

include

‘forests’

to

in

the

are

which

other

unicellular

organisms

which

classied

organisms

can

in

organisms

Plasmodium,

Algae

unicellular

of

nuclei;

protoctists

underwater

so

group

belong

with

including

malaria.

tiny

form

of

diverse

Unicellular

causes

that

a

they

have

protozoans

that

seaweeds

there

contains

protoctists

multicellular .

known

organism

giant

where

kingdom

as

the

is

kelps

parts

of

the

protoctists

which

the

sea

photosynthesise. Paramecium,

a

single-celled

protoctist

(×206).

genetic

Fungi

kingdom

Fungi

are

visible

under

a

light

microscope.

Many

are material

also

visible

to

the

naked

eye.

Most

fungi

are

multicellular

although sur face

yeasts

are

single-celled.

Each

cell

has

a

nucleus

and

a

cell

wall

which coat

is

made

out

chlorophyll

The

main

its

chitin,

and

body

network

food

not

cannot

fungus

branching

of

of

source,

of

cellulose

carry

is

out

called

threads

releasing

in

plants.

Fungi

do

not

proteins

have

photosynthesis.

the

or

as

mycelium.

hyphae

enzymes

It

which

which

consists

grow

digest

of

over

the

a

the

food

surface

outside

Figure

the

fungus.

The

digested

food

is

then

absorbed

by

the

Viruses

Fungi

reproduce

Most

fungi

are

by

making

spores

saprotrophs,

that

which

can

be

means

carried

they

feed

by

the

on

wind.

dead

matter,

but

some

are

are

causes

in

or

of

decaying

1.3.2

Structure

of

a

human

virus.

hyphae.

inuenza

size.

a

extremely

(One

is

small.

about

nanometre

micrometre.)

120

is

Viruses

This

virus

that

nanometres

one-thousandth

are

visible

only

parasites under

an

electron

microscope.

Viruses

are

or

RNA)

of

a

not

cells.

surrounded

few

genes

that

They

by

a

are

particles

protein

code

for

the

made

coat.

The

proteins

up

of

genetic

that

genetic

material

material

form

the

is

coat

(DNA

composed

and

maybe KEY

other

cells

proteins

of

that

another

help

it

organism

reproduce.

(the

host)

Viruses

in

order

are

to

parasites

multiply .

that

Viruses

enter

take

over 1

the

host

cell

and

direct

it

to

make

new

viruses.

Viruses

are

not

POINTS

the

The

cells

have

in

any

in

the

of

the

kingdoms

described

here.

All

the

organisms

do

not

have

of

kingdoms

have

cells.

Viruses

cells

in

a

different

way.

Their

classication

is

based

and

so

material

and

protein

coat

that

they

on

the

type

There

are

Prokaryotes

under

The

plant

species

with

features

kingdom

that

are

animals.

tnemelppuS

Compare

a

Make

a

present

in

all

cells.

and

familiar

Y ou

the

to

should

animal

us.

kingdom

Make

include

a

table

similarities

contain

to

Why

the

table

6

How

are

Plant,

Protoctist

cells

be

without

seen

only

microscope.

organisms

with

as

well

eukaryoltic

structure

of

bacterial

cells

with

the

to

compare

the

features

of

the

as

cells

ve

viruses

not

classied

in

one

of

the

ve

plants

5

Fungi

called

differences.

of

a

nanometres

are

there

in

a

group

many

of

features

cells.

are

made

hyphae.

the

food

up

of

These

supply,

threads

grow

digest

it

plant. and

then

absorb

it.

kingdoms.

kingdoms?

Viruses

an

can

electron

are many

a

many

compare

6

5

can

light

externally

4

have

are

over

3

They

Protoctists

of

2

kingdoms:

QUESTIONS

4

the

ve

Prokaryote,

Fungi.

nuclei.

State

DNA.

have.

3

1

and

of

and

SUMMARY

organisms

cell

are

Animal, genetic

a

classied

2 classied

living

cytoplasm,

membrane

ve

all

classied

tnemelppuS

Viruses

not

be

seen

only

microscope.

cells

but

a

few

under

They

genes

metre? inside

a

protein

coat.

7

1.4

Vertebrates

Animals LEARNING

that

have

vertebrates.

•

Dene

•

Describe

the

term

vertebrate

bone

or

some

of

the

ve

vertebrates

external

main

using

visible,

characteristic

Describe

how

vertebrates

All

vertebral

vertebrates

column

cartilage.

They

invertebrates

all

that

have

an

or

backbone

belong

share

to

internal

are

the

common

skeleton

called

phylum

features

made

chordata

with

the

of

either

which

includes

vertebrates.

groups

There

are

ve

main

groups

of

vertebrates:

features sh,

•

a

OUTCOMES

amphibians,

reptiles,

birds

and

mammals.

these

are

adapted

to

Fish their

environment

Most

sh

as

the

of

time.

Typically,

This

dace

has

ns,

tail

and

a

their

–

adaptations

for

have

gills.

herring,

sh,

sound

and

eyes

They

Their

shark,

the

can

and

skin

and

a

is

there

out

of

have

lateral

line

and

of

for

for

with

some

for

species,

varying

swimming

detecting

oxygen

from

scales.

such

lengths

and

for

pressure

the

water

Examples

include

cod.

vertebrates

although

are

water

ns

dissolved

covered

classes

limbs,

but

survive

breathe

catsh

other

four

permanently,

that

streamlined

water.

Unlike

some

have

have

ears

evolved

for

into

detecting

legless

forms

streamlined

like shape

in

water

are

They

changes

tuna,

in

skipper,

sh

balance.

using

live

mud

snakes

and

some

lizards.

swimming.

Amphibians

These

vertebrates

amphibians

is

external

inside

a

hatch

into

On

are

have

on

the

body).

adult

water,

amphibians

they

sperm

swimming

in

smooth,

land,

because

female

land,

they

live

and

eggs

can

frogs,

is

which

amphibians

skin.

to

are

Development

tadpoles

they

include

moist

return

toads

external:

gills

using

through

and

to

released

have

breathe

breathe

Although

water

most

breed.

into

the

for

water

fertilised

(not

eggs

breathing.

lungs,

their

Fertilisation

the

but

skin.

when

Examples

of

salamanders.

Reptiles The

bright

thought

for

the

to

red

eyes

startle

frog

to

of

this

tree

predators,

frog

giving

are

time

Reptiles

have

dry,

scaly

skin

to

cut

down

water

loss.

They

can

live

in

escape.

dry

regions

Fertilisation

as

takes

development

shells

air .

they

which

is

not

place

them

lizards,

have

inside

external

stop

Crocodiles,

do

as

the

they

from

to

return

female’s

lay

eggs

drying

snakes,

to

out.

turtles

water

body.

with

breed.

However ,

leathery,

Reptiles

and

to

have

tortoises

waterproof

lungs

are

all

to

breathe

reptiles.

Birds

Birds

of

Birds

with

American

8

crocodile,

Crocodylus

acutus

have

them

feathers

are

have

able

no

different

and

to

teeth

types

y

but

of

their

but

front

some,

different

food.

limbs

like

are

modied

penguins

species

have

and

beaks

as

wings.

ostriches,

adapted

Most

cannot.

to

deal

Fertilisation

is

eggs

which

are

Birds

are

able

to

even

internal

protected

homeothermic

regulate

though

include

and

their

the

hawks,

development

by

eagles,

external

temperature.

temperature

sparrows,

as

the

females

lay

shells.

(warm-blooded).

body

outside

hard

is

This

They

can

changes.

parrots

and

means

keep

that

it

they

are

constant

Examples

of

birds

starlings.

Mammals

Mammals

internal

they

are

young

ones

Like

are

and

born

on

like

is

vertebrates

milk

that

development.

already

from

whales

birds,

internal

the

so

well

mammals

dolphins,

are

temperature.

also

or

All

lungs

bats,

Fertilisation

in

a

mammals

mammals,

for

is

womb

and

suckle

their

even

Grey

Heron,

long

beak

Ardea

for

are

all

maintaining

dolphins,

bears,

a

STUD Y

constant

lemurs

learn

ve

this

DID has

hands

and

feet

adapted

to

living

in

a

and

complete

the

sentences

using

these

ve

classes

wings

breed

scaly

y

sh

moist

fur

land

water

are

different

group

in

groups

called

and

have

skin

have

front

skin

limbs

have

and

or

feathers

of

vertebrate.

Sharks

2

a

the

learn

rare

spend

all

their

hair

that

are

most

and

and

lay

return

their

modied

are

give

and

able

birth

to

to

time

in

species

are

.

of

their

golden

were

an

lmed

Blood.

frogs

were

for

BBC

After

Sir

TV

the

moved

David

series

Life

lming

them

from

to

a

zoo

disease,

to

habitat

and

pollution.

Birds

They

Mammals

in

Panamanian

.

.

.

young

extinction.

.

to

on

form

to

to

water

eggs

with

belong

also

have

advanced KEY

state

you

KNOW?

amphibian

Cold

loss Amphibians

have

these

to pic.

protect

Reptiles

you

of

Mak ing

help

Attenborough’s

the

the

help

words: frogs

to

a

QUESTIONS

development

There

to

featur es

will

YOU

Some

Copy

table

the

threatened

1

with

trees.

Many

SUMMARY

bird

TIP

grou ps.

table

chimpanzee

a

and

mammals.

A

–

sh.

aquatic

Mak e wolves

cinerea

catching

breathing.

homeothermic,

Leopards,

fur.

develop

Female

glands.

use

hair

young

developed.

mammary

and

have

The

POINTS

.

State

the

features

that

are

exhibited

by

all

vertebrates.

1

Vertebrates

have b

Name

c

Give

the

ve

groups

of

a

are

animals

vertebral

column

that

or

vertebrates. backbone.

an

example

of

each

group.

2 3

T o

which

group

of

vertebrates

does

each

of

the

following

The

into

a

turtle

b

bat

f

hawk

g

shark

c

whale

d

salamander

e

vertebrates

are

divided

belong? ve

groups:

snake sh,

amphibians,

birds

and

reptiles,

mammals.

9

1.5

Invertebrates

Invertebrates LEARNING

are

animals

that

do

not

have

a

vertebral

column

or

OUTCOMES backbone.

•

Describe

the

external

features Arthropods

of

contains

•

Describe

of

is

the

largest

of

the

groups

in

the

animal

kingdom

as

it

arthropods

the

insects,

features

segmented

and

myriapods

used

body,

number

an

of

external

species.

skeleton

Each

arthropod

(exoskeleton)

species

and

has

jointed

a

legs.

hard

to

classify

them

exoskeleton

allows

arthropods

to

live

on

dry

land.

When

that they

are

largest

crustaceans, The

arachnids

the

grow

too

big

for

their

exoskeleton,

they

moult

and

grow

a

new

into one.

Some

moult

all

through

their

lives,

others

moult

only

during

the

groups early

•

Describe

these

their

how

groups

the

are

animals

adapted

stages

of

their

life.

in

Four

to

of

the

different

types

of

arthropod

are:

environment crustaceans,

myriapods,

insects

and

arachnids

Crustaceans

Crustaceans

and

abdomen.

hard

two

ve

and

crabs

of

Woodlouse

detecting

or

slater.

Notice

its

antennae

of

all

are

and

so

the

made

bodies

the

are.

and

crab,

Grapsus

feeding

grapsus.

and

exoskeleton

against

in

They

they

(also

do

crabs,

eyes.

breathe

water.

Some

use

shrimps,

as

They

water

have

a

very

have

between

gills

live

on

slaters)

for

craysh

provides

Crustaceans

using

crabs

known

not

that

predators.

(head-thorax)

land

and

breeding.

and

but

some

return

land

Examples

lobsters.

Notice

centipedes

up

of

many

not

divided

Centipedes

total

number

Centipedes

paralyse

have

slow-moving

two

and

into

have

of

are

millipedes.

separate

one

legs

pair

They

pairs

regions

of

depends

fast-moving

their

herbivores.

the

have

long

segments.

legs

upon

such

on

how

carnivores.

as

each

the

many

They

thorax

segment

segments

have

powerful

prey.

of

legs

You

can

on

each

often

body

nd

segment.

them

They

feeding

in

are

leaf

litter.

defence.

Millipede

moving

10

as

cephalothorax

compound

legs.

live

include

are

can

Millipedes

for

and

of

Woodlice

exceptions

are

that

jaws

claws

pairs

breed.

abdomen.

there

lightfoot

chalky

a

Myriapods

Their

large

a

into

for

stimuli.

bodies

its

have

crustaceans

to

divided

protection

antennae

crustaceans

These

Sally

body

Many

twenty

water

a

effective

pairs

and

Nearly

to

have

–

with

its

efciently.

many

legs

for

Centipede

–

a

fast-moving

carnivore.

Insects

Insects

and

On

have

bodies

that

are

divided

into

three

parts:

head,

thorax

abdomen.

the

two

thorax

pairs

of

compound

They

eyes

breathe

called

there

wings.

are

three

They

that

are

through

pairs

have

one

made

holes

in

of

of

legs

pair

of

many

the

and

tiny

sides

many

antennae

of

species

on

individual

the

thorax

the

have

head

and

components.

and

abdomen

spiracles

Monarch

Insects

have

colonised

most

habitats

in

the

world,

although

Notice

are

very

few

species

that

live

in

the

sea.

T wo

reasons

why

they

are

on

that

them

stops

This

is

the

beetles,

bees

is

that

losing

largest

ies,

and

land

group

locusts,

they

too

are

much

within

covered

water,

the

cockroaches,

by

and

a

waterproof

they

arthropods.

dragonies,

can

its

wings

Danaus

for

its

plexippus.

migration

over

so long

successful

buttery,

there

distances.

cuticle

y!

Examples

include

butteries,

moths,

wasps.

Arachnids

These

and

arthropods

have

bodies

divided

into

two

parts,

the

cephalothorax

abdomen.

Arachnids

antennae

They

have

but

paralyse

silken

webs

four

do

their

with

pairs

have

prey

their

of

legs

several

with

and

pairs

poison

spinnerets.

no

of

wings.

simple,

fangs.

They

not

Spiders

Scorpions,

have

no

compound,

are

ticks

able

and

eyes.

to

mites

weave

are

also T arantula

classied

as

arachnids.

paralyse

SUMMARY

QUESTIONS

1

four

a

Name

b

List

c

State

the

groups

key

of

features

ways

in

a

large

spider

with

venom

to

prey.

arthropod.

of

insects. DID

three

–

its

which

arachnids

look

different

YOU

KNOW?

from There

are

over

a

million

known

insects.

2

3

Distinguish

between

a

centipedes

b

crustaceans

Describe

the

successfully

4

Copy

and

and

the

and

basis

of

visible

features:

altogether ,

of

insects

that

adapt

them

for

of

the

knows.

crustaceans

insects

arachnids

KEY

POINTS

of Arthropods

are

segmented

legs

an

regions

number

of

one

table:

animals

body

no

living

1

pairs

but

arachnids

myriapods

number

the

land.

complete

feature

on

millipedes

features

on

following

pairs

2

of

with

jointed

legs

and

exoskeleton.

Arthropods

different

are

classied

groups

into

including:

antennae crustaceans,

type

of

myriapods,

eyes insects

and

arachnids

wings

11

1.6

Ferns

and

owering

plants

tnemelppuS

Like LEARNING

•

State

that

owering

making

•

State

and

plants

the

owering

•

ferns

non-

reproduce

by

the

between

plants,

ferns

green

in

These

chloroplasts

absorbs

made

spores

Describe

all

and

owering

plants

are

multicellular.

They

are

OUTCOMES

main

features

of

plants

Both

of

differences

dicotyledons

light

of

and

mineral

adapted

monocotyledons

for

tubes.

substances

and

because

many

contain

of

the

their

green

photosynthesis.

cells

contain

pigment

Each

cell

is

chloroplasts.

chlorophyll,

surrounded

by

which

a

cell

wall

cellulose.

ferns

tiny

and

colour

owering

These

salts,

such

to

live

are

and

as

on

plants

called

have

phloem

sugars.

transport

xylem

vessels,

tubes,

Both

ferns

which

and

systems

which

consisting

carry

transport

owering

water

dissolved

plants

are

well

land.

Ferns

Ferns

on

a

are

land.

waxy

them

to

left.

quite

supports

grow

If

fern

Dryopteris

lix-mas

you

will

Ferns

a

look

under

Features

Flowering

by

means

inside

the

Shoots apical

of

and

are

helps

the

at

leaves

that

carried

by

have

true

which

within

the

tree

stem

ferns

and

the

the

of

several

ferns

at

a

in

do

have

a

life

have

Most

of

photograph

some

thick

metres.

not

that

stem

Many

produce

times

of

microscopic

form

loss.

the

for

leaves

that

ferns

rhizome.

certain

to

Their

including

that

called

adapted

water

species

habitats

release

wind

well

leaves.

reduce

ferns

heights

of

make

of

plants,

and

to

different

owering

the

become

roots

those

many

leaves

have

underground

owers

ovary

in

owering

plants

of

of

and

are

which

largest

thick

structures

spores

that

stems,

resembling

live

crown

a

plants

strong

cuticle)

The

conifers

see

These

(the

dry.

of

have

leaves

from

Unlike

The

group

layer

have

the

are

a

Ferns

new

the

seeds.

year

you

spores.

plants.

plants

stems,

make

roots

and

seeds.

The

leaves.

seeds

They

are

reproduce

produced

ower.

roots

bud

The

up

shoot

of

a

is

stem

the

part

bearing

of

the

plant

leaves,

buds

above

and

ground.

owers.

The

The

shoot

apical

is

made

bud

is

leaf

stem

side

buds

side

main

root

Figure

1.6.1

root

root

cap

Structure

of

a

typical

dicotyledonous

plant. Magnolia

12

is

a

dicotyledon.

Maize,

Zea

mays,

is

a

monocotyledon.

part

where

the

stem

grows

new

leaves.

The

stem

supports

the clusters

structures

receive

The

which

stem

food

the

roots

are

anchor

blown

from

shoot,

are

the

by

soil

to

of

in

wind.

Topic

Dicotyledons

of

(see

out

to

of

owering

the

6.6)

also

the

the

not

It

soil

the

up

to

such

found

contain

they

of

flowers

can

owers

the

as

in

leaves

the

a

below

water

it

ground.

from

and

and

roots.

chlorophyll.

prevent

absorb

that

holds

plant,

and

so

place.

plants

do

ground

Roots

leaves

take

from

parts

they

the

Topic

water

since

rmly

(see

air

other

parts

the

spaces

pollination

white

plant

over

and

transport

leaves

usually

the

the

light

and

enables

allows

from

Roots

the

adequate

position

The

of

tnemelppuS

the

Roots

being

mineral

ions

8.2).

and

monocotyledons

leaf

Flowering

plants

dicotyledons

can

and

be

divided

into

two

main

groups:

monocotyledons Figure

1.6.2

Structure

of

a

typical

monocotyledon

Dicotyledons

look

like

Their

leaves

are

parts

of

ower,

often

the

plant

broad

at

with

the

a

bottom

network

of

of

the

opposite

branching

veins.

The

STUD Y

are

in

the

multiples

cotyledons

Grasses

are

of

example

four

(seed

and

for

or

leaves)

cereals,

like

ve

in

the

the

in

a

male

each

parts

ower.

known

as

Dicotyledons

have

two

Be

plant

at

the

bottom

of

page

and

12

of

have

most

long,

monocotyledons

narrow

leaves.

have

Other

parallel

veins.

Grasses

monocotyledons

have

a

variety

ower

inside

are

in

each

of

shapes,

multiples

such

of

as

three.

those

of

palm

trees.

Monocotyledons

The

have

parts

one

of

1

complete

and

the

parallel

sentences

two

using

these

words:

Flowering

plants

multicellular

narrow

network

are

with

plants

veins.

They

often

have

Dicotyledons

wall;

have

that

often

have

have

with

some

inside

a

the

names

of

ve

inside

dicotyledonous

that

grow

key

for

the

ten

plants

Make

a

table

of

differences

between

is

leaves

each

plants

where

you

in

ferns

and

and

have

their

one

seeds

and

seed.

you

have

contain

Monocotyledons

with

parallel

veins.

ve

live.

Dicotyledons

have

two

Construct

and

broad

leaves

identied.

with

3

in

stems

cotyledons dichotomous

cell

cellulose

the

3 plants

a

of

leaves

monocotyledonous

by

chloroplasts.

cotyledon

leaves

cotyledons

are

each

those

cotyledon They

–

one

2

a

2.1)

(from

owering

and

Monocotyledons

Find

in

POINTS

cell broad

2

(T opic

16).

surrounded

veins.

and

differ ences

cotyledon

1

seed.

plan ts

Note

repro duct ion

the

KEY

QUESTIONS

leaves

differ ences

seed.

SUMMARY

Copy

the

and

leaves

Unit with

the

struct ure

and cereals

of

owe ring

anim als.

learn

monocotyledons.

leaves

awar e

be tw een

cell The

TIP

stamens,

seed.

maize

plant.

page.

owering

plants.

a

network

of

branching

veins.

4

Ferns

to

life

xylem

are

on

plants

land.

and

means

of

well

They

adapted

have

reproduce

by

spores.

13

1.7

Dichotomous

Sorting LEARNING

Construct

and

use

identify

dichotomous

keys

to

•

Identify

in

a

name

book

of

a

until

plant

you

or

animal

found

the

you

right

a

lot

of

time

and

and

for

through

that

the

would

effort.

features

of start

useful

look

However,

animals

external

animals

could

one.

identify take

and

the

simple pictures

plants

out

OUTCOMES

To •

things

keys

plants

making

a

that

here

are

key

has

it

got

yes

no legs?

has

a

it

got

shell?

snail

has

it

no 6

has

it

earthworm

got

yes legs?

got

yes

no 2

pairs

of

wings?

Figure

1.7.1

Scientists

A

use

key

and

key

has

the

you

answer

to

Use

out

1

2

3

4

Figure

14

1.7.2

Five

invertebrates.

numbered

‘yes’

to

the

means

number

nd

another

above

at

a

a

of

key

‘no’

question

identify

numbered

or

steps

on

–

this

or

and

an

rst

to

to

2

Has

no

Go

to

4

Has

6

legs

Go

to

3

Has

8

legs

Spider

Has

1

pair

Has

2

pairs

Has

a

Has

no

shell

shell

wings

see

At

things.

or

it

Snail

Earthworm

step

at

the

the

in

Use

branching

the

the

key

branching

beginning

statement.

the

same

works

questions

Wasp

in

This

and

takes

branching

you

key

left.

but

Housey

them

each

Start

identify

the

Go

of

the

key,

legs

wings

can

question

to

living

two.

page.

Has

of

identify

identication.

answer

legs

to

you

rst

below

the

key.

statement.

the

to

into

animals

key

from

beginning

to

the

keys

dividing

question

or

differently

the

dichotomous

dichotomous

Dichotomous

A

branching

at

in

animals.

the

each

same

stage.

It

is

way.

set

Start

PRACTICAL

STUD Y Making

Now

try

a

leaf

making

a

key

of

your

Whe n

own.

‘size ’ 1

T ake

six

different

leaves

and

label

them

A

to

Put

the

six

leaves

3

Think

of

a

4

Write

down

5

Now

6

Write

7

Carry

question

think

the

up

these

on

out

in

front

that

will

of

you.

divide

into

two

Write

out

questions

you

your

to

divide

each

group

into

come

to

the

last

pair

of

as

a

branching

key

or

as

a

numbered

the

are

key.

making

a

livin g

muc h

featu re

thing s

in

size.

TIP

exam ination ,

usua lly

rather

key

of

these

pond

animals

below.

it

than

How ever ,

aske d

is

to

easies t

bran chin g damsel

fly

keys

num bered

if

key are

try

key ,

leaves.

keys .

Now

a

good

two.

STUD Y

key

animals

as

so

keys

Pond

a

question.

In

8

not

groups.

down.

until

use

vary

them

mak ing

is

F .

to

2

TIP

key

bran ched

you

mak e

to

a

mak e

key.

Y ou

key

a

may

lar va

also

be

freshwater

aske d

featur es

shrimp

for

that

mak ing

to

iden tify

are

suita ble

keys .

water

beetle

KEY

1

POINTS

Dichotomous

keys

are

used

water

to

scorpion

identify

plants

pond

snail

2

A

and

organisms,

such

as

animals.

dichotomous

key

includes

ramshorn

a

snail

series

or

of

paired

questions

identication. Figure

1.7.3

Pond

1

When

She

a

made

some

laboratory.

Give

b

Make

2

Write

an

Her

each

either

a

could

down

use

an

drawings

drawings

a

a

branching

the

features

a

pages

to

reptile,

8

and

identify

island

and

are

9

each

discovered

brought

on

an

dividing

into

two.

key

to

identify

or

as

to

of

a

would

bird

them

the

some

back

to

insects.

the

right.

name.

key

that

a

she

shown

suitable

dichotomous

as

on

visited

insect

amphibian,

photos

to

QUESTIONS

scientist

a

lead

Dichotomous

animals.

means

SUMMARY

statements

which

and

help

a

enable

Present

you

mammal.

you.)

these

them.

numbered

Now

to

classify

(Y ou

make

vertebrate

your

key

key.

a

a

sh,

can

use

key

that

the

you

groups.

15

PRACTICE

1

Which

QUESTIONS

process

organisms

is

that

carried

live

in

a

out

by

all

the

6

forest?

Which

is

not

associated

with

excretion

from

a

mammal?

A

moulting

A

exhaling

B

photosynthesis

B

release

C

pollination

C

removal

D

respiration

carbon

of

heat

of

dioxide

from

toxic

from

the

waste

the

lungs

skin

products

of

metabolism

D (Paper

1)

removal

of

water

that

the

body

does

not

[1] need

2

What

are

characteristics

of

all

organisms? (Paper

A

excretion

and

respiration

B

ingestion

and

growth

C

photosynthesis

D

respiration

7

The

2)

evolutionary

species

3

(Paper

1)

Which

group

and

and

[1]

are

relationships

shown

in

the

between

ve

diagram.

egestion

V

photosynthesis

[1]

of

animals

includes

those

with

W

a X

segmented

body,

an

exoskeleton

and

jointed

Y

limbs?

A

amphibians

B

arthropods

C

reptiles

D

vertebrates

Z

(Paper

1)

Which

group

time

[1]

An 4

of

vertebrate

includes

those

analysis

DNA dry

scaly

skin

and

A

amphibians

four

of

base

sequences

from

the

with

of

these

ve

species

was

carried

out.

legs?

Which

two

species

will

have

the

most

similar

sequences?

B

sh

C

mammals

D

reptiles

(Paper

5

Each

and

1)

cell

[1]

is

surrounded

contains

by

a

cell

membrane

table

Which

from

A

B

C

D

ve

shows

organisms

other

the

in

all

features

features

ve

of

shown

cells.

by

B

W

W

C

X

and

Z

D

Y

and

Z

and

(Paper

2)

Which

is

feature

X

[1]

an

example

used

in

of

a

classifying

morphological

vertebrates?

A

egg

laying

B

type

of

body

C

type

of

diet

D

pattern

kingdoms?

enzymes

nucleus

✗

✓

✓

✓

✗

✗

✓

✗

✓

✓

✓

✗

✓

✗

✓

✓

✓

✗

✓

✗

2)

and

cells

chloroplasts

(Paper

16

shows

row

V

cytoplasm.

8

The

A

DNA

ribosomes

[1]

(Paper

2)

of

covering

bones

in

the

front

limb

[1]

9

The

to

drawings

the

same

show

ve

arthropods

(not

drawn

11

(a)

scale).

Five

of

their

the

features

denitions

Match

each

denition

of

by

of

are

the

A

movement

B

respiration

D

a

things

and

below.

features

pairing

C

living

listed

with

letter

its

and

a

number.

sensitivity

nutrition

E

growth

Denitions

A

B

1

A

permanent

2

The

to

increase

chemical

break

release

reactions

down

of

in

size

that

nutrient

occur

in

molecules

cells

with

the

energy

C

3

An

action

change

4

The

by

of

an

ability

to

environment

5

The

taking

Make

a

table

to

compare

the

features

or

detect

and

in

environment (a)

organism

position

of

cause

changes

respond

materials

for

to

a

place

energy,

to

in

the

them

from

the

growth

and

of development

the

ve

arthropods

that

you

see

in

[3]

the

(b) drawings.

Explain

what

is

meant

by

the

term

species

[6]

[2] (b)

Use

in

the

your

features

table

arthropods.

to

that

you

make

(The

key

a

have

key

may

to

be

used

the

(Paper

ve

either

a 12

branching

key

or

a

numbered

3)

key.)

The

drawings

owering

(Paper

10

Copy

plant.

leaves

They

are

from

not

three

drawn

species

to

of

scale.

3)

and

crosses

show

show

[6]

to

the

complete

indicate

features

feature

sh

the

table

whether

or

using

the

ticks

four

and

groups

not.

amphibian

bird

mammal

backbone

ns

A

C

B

wings

(a)

(i)

Identify

the

group

of

owering

plants

fur to

which

each

species

belongs.

homeothermic (ii)

State

the

make (Paper

3)

features

your

that

you

used

to

identications.

[5]

[5]

(b)

List

ve

would

key

to

features

be

shown

useful

identify

in

by

the

devising

species

of

a

leaves

that

dichotomous

owering

plants.

[5]

(c)

(i)

State

ferns

three

have

structural

in

features

common

with

that

owering

plants.

(ii)

Explain

walls,

[3]

why

are

kingdom

(Paper

fungi,

not

with

which

classied

plants.

in

have

the

cell

same

[3]

4)

17

2

Cells

2.1

Structure

of

cells

Cells LEARNING

OUTCOMES

Cells •

Describe

the

structures

Very plant

and

under

•

a

animal

light

Describe

the

cells

are

the

small

building

blocks

that

as

microscope

differences

small

living

things

such

as

bacteria

An

insect

for

certain

such

as

how

a

y

many

may

contain

cells

there

millions

are

in

animal

plant

State

between

the

functions

of

organisms.

only

one

cell.

a

of

cells.

human

No

being

one

–

knows

estimates

10

×

12

10

and

50

×

10

seen

under

cells

Plant

cells

the

cell

membrane

the

cell

cell

living

of

cells

structures

light

all

and

Animal

•

up

made

in 12

between

are

seen

vary structure

make

of

microscope

and

in

the

in

the

animal

wall

plant

cell nucleus

cytoplasm

cell

membrane nucleolus

Figure

2.1.1

A

cheek

cell

(stained

nucleolus with

a

blue

dye).

nucleus

Figure

2.1.2

A

palisade

cell

Differences

Liver

cells

magnied

by

The

differences

this

table.

between

between

plant

plant

and

and

from

animal

animal

cells

are

mesophyll

a

leaf.

cells

summarised

in

×300.

feature

cellulose

cell

plant

wall

cell

animal

present

cell

absent

present; cell

STUD Y

membrane

present surrounded

TIP

permanent

Whe n

you

have

differ ence s

plan t

mak

e

state

wall

shape

determined

by

the

cell shapes

be tw een

shape

wall;

and

sure

of

anim al

you

cells ,

write

shapes

can

abou t

bo th

chloroplasts

nearly

spherical,

like

cylindrical

or

present

in

some

vary

as

there

be cell

wall

box-

cells

absent

cell. large

vacuole

permanent

vacuole

in

containing

present

nucleus

side

the

cytoplasm

18

cell

no

some thin g

type s

to

by

of

cell

present

cytoplasm

cell

(often

the

small

cell

wall)

sap

at

the

close

to

vacuoles

cytoplasm;

do

in

not

contain

cell

present

(found

anywhere

cell)

present

sap

within

the

is

Functions

of

cell

structures

STUD Y

cell

structure

•

forms

a

barrier

between

the

cell

and

Mak e

its

liver

surroundings

•

•

cell

TIP

functions

membrane

keeps

allows

cell,

•

simple

e.g.

controls

out

•

contents

of

often

of

cell

oxygen,

carbon

movement

the

cell,

e.g.

described

as

of

to

enter

dioxide

other

and

and

leave

the

the

water

substances

into

and

can

page

the

use

of

palis

cells .

struct ures

write

and

each

label

func tions .

your

ade

Labe l

Y ou

draw ings

permeable

to (see

and

unde rnea th

glucose

partially

cells

meso phyl l

inside

substances

draw ings

help

your

revisi on.

28)

•

controls

all

•

controls

how

activities

•

place

in

the

cell

nucleus

where

cells

many

develop

chemical

reactions

take

place,

cytoplasm e.g.

respiration

and

making

proteins

for

the

cell

chloroplast

(plant

•

photosynthesis

•

stores

•

stops

•

gives

•

allows

cells starch

only)

cell

wall

cells

cells

from

shape

to

bursting

when

they

ll

with

water

cells

(plant water

and

dissolved

substances

to

pass

only) through

freely

(often

described

as

freely

or

fully

permeable)

sap

vacuole

(plant

•

cells

full

of

water

only)

•

stores

salts

SUMMARY

QUESTIONS

1

complete

Copy

and

indicate

to

maintain

shape

and

‘rmness’

of

cell

if

the

this

structures

and

table

are

cell

cheek

structures

(animal)

by

using

present

cell

Cells

sugars

ticks

or

onion

and

crosses

of

onion

magnied

by

×250.

to

not.

cell

leaf

cell KEY

(plant)

POINTS

(plant)

nucleus

1

A

cell

and cell

epidermis

a

membrane,

nucleus

cytoplasm

are

found

in

wall

both

plant

and

animal

cells.

chloroplasts

2 large

All

plant

cells

have

a

vacuole

cellulose

cell

wall;

some

have

cytoplasm chloroplasts

containing

2

State

the

functions

a

chloroplast

e

cytoplasm

b

cell

of

the

following

membrane

c

parts:

cell

wall

d

cells

vacuoles

cell

not

a

vacuole

sap.

have

Animal

these

parts.

nucleus 3

f

do

and

Refer

for

to

the

the

table

functions

above

of

the

cell

structures.

19

Cell

LEARNING

OUTCOMES

As

you

know,

structures •

State

that

the

organelles

all

cells

contains

ribosomes

endoplasmic

on

Identify

rough

ER

in

•

State

that

occurs

in

Calculate

and

the

a

cell.

number

These

of

are

small

called

include

mitochondria,

vesicles

and

cell

ribosomes

on

reticulum

diagrams

of

and

The

cells

aerobic

endoplasmic

reticulum

and

endoplasmic

membranes.

respiration

which

reticulum

They

allow

contain

materials

to

(ER)

is

a

complex

uid-lled

be

spaces

transported

system

of

between

throughout

double

the

membranes

the

cell.

the

membranes

mitochondria

the

actual

specimens

as

contain

of

reticulum

Where

•

cells

cytoplasm

rough

mitochondria

photographs

and

endoplasmic

Rough •

animal

the

vesicles rough

and

and

in

cytoplasm organelles

of

plant

present

magnication

size

of

using

are

biological

of

micrometres

ribosomes

called

rough

rough

ER

is

are

present

on

endoplasmic

to

package

their

outer

reticulum

and

surface,

(ER).

transport

The

proteins

main

function

made

by

the

ribosomes.

units Cells

that

digestive

rough

Small

small

a

lot

in

of

the

protein,

for

alimentary

instance

canal,

those

have

large

making

amounts

of

ER.

pieces

of

vesicles.

rough

Ribosomes

produce

enzymes

ER

rough

In

and

this

ER

may

way

be

pinched

proteins

transported

around

can

the

be

off

at

the

made

cell

in

ends

and

the

to

stored

small

form

in

the

vesicles.

Ribosomes

Ribosomes

cells.

cells

Cisterna

They

but

are

are

smaller

cytoplasm,

The

Lamellae

small

not

function

organelles

about

in

20

prokaryotic

attached

of

that

are

nanometres

to

ribosomes

cells

rough

is

to

found

(nm)

where

in

in

huge

diameter

they

are

numbers

in

in

all

eukaryotic

found

free

in

the

ER.

synthesise

proteins,

such

as

those

of

enzymes

involved

in

respiration.

reticulum

made

of

up

double

Mitochondria membrane

Mitochondria Figure

2.2.1

Structure

of

are

relatively

large

organelles

found

in

all

eukaryotic

rough

cells. endoplasmic

reticulum

They

are

often

visible

under

the

electron

microscope

as

sausage-

(ER).

shaped

Each

structures

about

mitochondrion

controls

many

the

folds

entry

on

has

and

which

1 µm

a

exit

wide

double

of

some

and

the

long.

membrane,

materials.

of

5 µm

The

chemical

the

inner

outer

one

membrane

reactions

of

of

which

forms

aerobic

Folds

respiration

take

Mitochondria

they

Inner

Outer

membrane

Cells

are

the

with

vast 2.2.2

Structure

of

a

mitochondrion.

20

are

sites

high

often

of

described

aerobic

rates

of

as

the

‘power

plants’

of

the

cell

since

respiration.

respiration

have

many

mitochondria

to

provide

membrane

sufcient

Figure

place.

energy .

numbers

of

For

example,

insect

mitochondria.

ight

muscle

and

liver

cells

contain

tnemelppuS

2.2

Look

of

at

1000

cells

the

To

work

Now

larger

1000

out

magnied

we

specimens

photograph

times

magnied

and

can

than

of

in

actual

in

size

use

size

human

life.

of

millimetres.

this

a

This

cell,

Let’s

formula

image actual

some

real

cheek

means

cells.

that

The

they

cells

have

are

been

times.

the

cell

tnemelppuS

Size

to

measure

say

that

work

out

it

the

length

measures

actual

of

one

13 mm.

size:

size

= Human

cheek

cells

(×1000).

magnication

13 So

the

actual

size

of

our

cell

=

=

0.013 mm

1000

There

are

answer

We

as

can

in

1000

to

use

this

T o

a

similar

of

size

actual

using

calculate

the

1

2

Which

a

in

a

in

the

millimetre.

by

when

goldsh.

1000

the

This

of

you

an

image

size

actual

size

We

can

to

give

image

size

time

photograph.

formula

magnication

If

will

there

you

nd

image

we

it

convert

has

has

been

been

calculate

is

the

13 µm.

the

90 mm

reorganise

reduced,

a

sh’s

long.

the

formula:

=

The

image

(×0.33)

of

this

actual

goldsh

is

one

third

size.

QUESTIONS

organelles

manufacture

b

convert

c

control

d

carry

e

package

the

carry

out

the

following

functions?

proteins

light

out

and

( µm)

multiplying

same

a

Copy

of

size

the

magnication

SUMMARY

by

technique

photograph

reduction

actual

micrometres

micrometres

energy

into

substances

reactions

and

in

the

that

pass

aerobic

transport

complete

chemical

by

into

and

out

of

a

cell

respiration

proteins

table

energy

around

using

ticks

the

and

cell

crosses. Figure

2.2.3

An

of

feature

bacterial

cell

liver

cell

palisade

electron

a

micrograph

mitochondrion

cell (×80 000).

cell

wall

rough

ER

KEY

POINTS

chloroplast 1

mitochondrion

Ribosomes

the

on

cytoplasm

rough

make

ER

and

in

proteins.

vesicle 2

Rough

ER

packages

transports

3

a

Measure

the

length

of

the

mitochondrion

in

the

electron 3

micrograph.

It

has

been

magnied

80 000

times

and

proteins.

(x

Aerobic

respiration

occurs

in

80 000). mitochondria.

Calculate

the

micrometres

actual

length

of

the

mitochondrion

in

4

( µm).

Cells

with

high

respiration b

Calculate

the

actual

size

of

the

liver

cells

and

the

rates

have

of

many

onion mitochondria.

cells

on

pages

18

and

19.

21

2.3

Different

T o LEARNING

function

Identify

cell

different

from

types

diagrams

of

of

cells

In Relate

cells

the

to

features

their

the

of

to

body

organism

and

photographs

•

are

Calculate

and

organisms

have

cell

and

topic

certain

divided

we

between

from

change

look

a

to

at

functions.

different

fertilised

become

some

This

cells

egg,

groups

new

of

of

cells

specialised

examples

means

that

for

that

are

the

cells.

are

functions

an

produced.

certain

specialised

As

These

functions.

cells.

these

functions

cells

magnication

actual

size

of

biological Ciliated

specimens

using

cells

are

found

in

the

air

passages

in

the

lungs

(trachea

and

millimetres bronchi)

as

out

develops

grow

this

carry

Specialised •

many-celled

of

OUTCOMES specialised

•

efciently,

types

and

in

the

oviducts

in

the

female

reproductive

system.

These

units cells

have

current

cilia

in

the

on

their

uid

surfaces.

next

to

the

Cilia

cell

beat

back

and

forth

to

create

a

surfaces.

cilia move ciliated

these cells

cells

make mucus

In

the

up

to

the

area

root

2.3.1

Ciliated

cells

line

to

hair

to

move

and

throat.

the

the

mucus

In

the

that

traps

oviducts,

cilia

dust

and

move

pathogens

the

egg

from

uterus.

cells

absorb

hair

cilia

nose

ovary

Root

Figure

airways,

the

have

water

long

and

extensions

ions

from

that

the

give

them

a

large

surface

soil.

cells

xylem

vessels

the

airways.

STUD Y

Whe n

a

cell

TIP

explai ning

Figure

2.3.2

Root

and

is

adap ted

hair

to

thin

you

tions

give

featur es

each

one

carry

,

mak

the

say

helps

its

the

are

long

Figure

how

Xylem

vessels

columns

of

like

cellulose

water

and

tubes

the

help

from

are

pipes.

and

ions

Ner ve

cells

to

the

up

soil.

a

cylindrical

The

cell

and

walls

waterproof

to

move

support

cells

are

cytoplasm

form

Red

empty.

are

from

They

thickened

material

the

called

roots

of

nerve

blood

the

highly

like

and

specialised

wires.

impulses

cells

stem

are

carry

small

water

the

stem.

are

arranged

with

bands

lignin.

These

into

or

spirals

to

the

rest

of

the

cells

plant.

allow

They

They

are

around

leaves.

cells.

able

the

protein

that

carries

shaped

This

surface

their

Nerve

cells

carry

like

shape

the

oxygen.

They

thin

extensions

information

in

of

the

body.

blood

cells

attened

provides

volume

a

discs.

large

compared

which

are

with

makes

for Figure

impulses

body.

have

transmit

haemoglobin

area

efcient around

They

to

contain red

the

absorption

of

2.3.5

Red

blood

cells

have

a

substance

oxygen. called

haemoglobin

oxygen.

22

vessels

that

func tion.

Nerve

2.3.4

Xylem

cell

also

Figure

2.3.3

absorb

sure

struct ural

and

out

e

to

its water

func

cells

how

that

carries

Palisade

These

The

cell.

by

plant

cells

have

chloroplasts

have

cell

mesophyll

trap

cell

wall

In

the

cytoplasm

sap.

numerous

light

a

made

Starch

up

of

are

and

chloroplasts

energy

there

grains

photosynthesis

cells

tough

is

a

a

in

in

the

cytoplasm.

photosynthesis.

cellulose

large

found

are

for

which

vacuole

the

which

cytoplasm.

temporary

store

of

Palisade

strengthens

is

lled

These

cells

the

with

are

formed

energy.

Figure

Sperm

the

sperm

female

Egg

of

cells

have

carries

parent.

cells

are

energy .

a

tail

genetic

Genes

much

Genes

and

of

adapted

information

from

bigger

the

are

the

from

father

than

mother

are

sperm

are

for

the

male

present

cells.

found

swimming.

They

inside

in

parent

the

head

to

yolk

nucleus

Leaf

lots

palisade

of

cells

contain

chloroplasts

photosynthesis

for

(×500).

nucleus.

as

of

2.3.6

of

the

sperm

contain

the

The

a

the

store

egg. middle

head

Look

real

To

of

carefully

life.

work

the

This

out

cells

at

Figure

means

the

in

2.3.6.

that

actual

the

size

millimetres.

The

cells

of

cells

have

these

Let’s

are

say

been

cells,

it

500

times

larger

magnied

measure

measures

the

500

than

times.

length

20 mm.

Now

of

we

one

can

a

use

a

formula

to

work

out

the

image actual

size

actual

size

of

the

tail

piece

in

sperm

cell:

size

=

Figure

2.3.7

Sperm

cells

have

a

tail

for

magnication swimming

So

T o

the

actual

calculate

size

the

of

actual

cell

is

magnication

magnication

The

our

20

of

divided

an

image

size

actual

size

by

object

500

we

=

(×2000).

0.04 mm

reorganise

the

formula:

membrane

=

diameter

of

an

egg

cell

cytoplasm

is

0.1 mm.

To

calculate

its jelly

magnication

by

0.1 mm

to

in

Figure

give

SUMMARY

2.3.8

we

divided

the

diameter

of

the

×180.

nucleus

QUESTIONS

Figure

2.3.8

Egg

cells

store

1

Draw

its

a

table

correct

T ype

of

matching

shape

cell

and

the

type

of

cell

in

the

blood

Shape

cells

rst

hollow

like

with

the

air

from

passages

dust

water

and

wires ions

KEY

transmit root

hair

cells

at

energy

tube

transport cells

an

Function

free

ciliated

column

contain

(×180).

function:

keep red

coat

drawing

POINTS

electrical

discs

1

During

development,

cells

impulses change nerve

cells

long

and

thin

transport

often

absorb xylem

vessels

have

cilia

that

their

water

from

their

the

2

Specialised

structure

Here

the

out

are

some

functions

their

other

of

specialised

these

cells

and

cells.

how

Use

they

this

are

book

to

adapted

functions.

nd

to

out

carry

to

carry

muscle

d

pollen

cell

b

goblet

cell

c

white

blood

cells

that

out

a

function,

e.g.

have

to

cilia

along a

and

shape.

move soil

2

structure

oxygen

the

have

a

enables

them

particular

ciliated

move

cells

mucus

windpipe.

cell

cell

23

2.4

Levels

Tissues LEARNING

Dene

the

terms

tissue,

group

organ

Describe

of

same

examples

of

and

that

occur

in

is

work

called

a

tissue.

together

to

All

carry

the

out

a

cells

tissue

and

is

made

so

the

tissue:

blocks

similar

up

of

muscle

identical

tissue

muscle

cells.

in

working

the

groups

look

These

cells

work

system:

same

way

of

tissues

a

working

group

cells

contract

muscle

tissue

is

made

your

heart

is

made

of

cardiac

muscle

cells

that

contract

muscle

and

other

pumps

blood

tissues;

it

2.4.1

Levels

of

organisation

relax

in

the

together

human

An

circulatory

organ

together

The

STUD Y

heart

Lear n

these

book .

deni tions

orga n

and

Mak e

exam ples

plan t

as

work

system .

orga n

working

your

group

of

body

your

and

your

carries

blood

vessels

circulator y

blood

system

around

body

made

up

perform

an

of

a

specic

example

of

different

tissues

that

work

functions.

an

organ.

It

is

made

up

of

different

tissues

TIP such

tissu e,

is

organs

system.

is

to

around

up

which

relax and

heart

make

and of

of

together

together

your cardiac

of

a

list

of

and

orga ns

system s

together

muscle,

to

nervous

pump

blood

tissue,

around

brous

the

tissue

and

blood

that

body.

of The

anim al

tissu es,

cardiac

stomach,

lungs,

brain

and

kidneys

are

all

organs.

orga n

from

and

this

Different

systems

blood

are

to

other

and

a

work

digestive

liver

work

of

perform

vessels

some

The

organs

consist

together

•

body

of

as

part

organs

as

part

of

an

with

functions.

together

For

of

organ

related

example,

the

system.

functions,

the

circulatory

heart

Organ

working

and

system.

Here

systems:

system

is

made

up

of

the

gullet,

stomach,

pancreas,

intestines.

The

excretory

•

The

nervous

•

The

reproductive

and

vagina;

and

penis.

the

together

group

organ

•

All

24

tissue

contracts.

organ:

cells

together

Figure

a

function.

animals

building

muscle

in

shared

plants

cells:

the

cells

they

the together

above

similar

and

system Muscle

•

organs

organ the

and

organisation

OUTCOMES

A •

and

of

system

system

in

different

is

is

made

made

system

males

organ

it

is

in

up

up

of

of

the

the

females

the

systems

is

testes,

make

kidneys,

brain,

the

a

spinal

ovaries,

sperm

up

ureters

ducts,

living

and

cord

bladder .

and

oviducts,

prostate

organism

nerves.

uterus

gland

Plant

The

tissues

diagrams

and

show

photosynthesis

in

organs

the

tissues

leaves

is

in

called

a

leaf.

The

tissue

mesophyll.

The

that

cells

carries

out

making

up

DID

layer

of

the

mesophyll

are

called

palisade

cells.

These

cells

word

packed

and

full

of

chloroplasts

so

that

they

are

well

the

absorb

lots

of

light.

The

palisade

cells

make

up

the

tissue.

All

the

cells

making

up

this

tissue

is

are

used

close

like

the

wooden

stakes

palisade used

mesophyll

cells

adapted together

to

‘palisade’

are because

closely

KNOW?

the The

upper

YOU

look

alike

to

make

walls

known

as

and palisades.

do

A

the

leaf

Other

same

is

an

function

organ.

structures,

cells:

the

building

–

they

Other

such

absorb

plant

as

light

organs

owers

and

for

are

photosynthesis.

roots

fruits,

are

and

stems.

modied

leaves.

blocks

organ:

groups

working

tissue: leaf

similar

cells

of

tissues

together

working

palisade

together

in

the

same

way

the

leaf

food

for

palisade

mesophyll

makes

and

gas

allows

exchange

cells upper

epidermis photosynthesis

takes

place cells

in

the

mesophyll

tissue

organism:

milkweed

spongy

mesophyll

is

cells

made

the

plant

up

of

organs lower

Figure

2.4.2

Levels

of

organisation

SUMMARY

QUESTIONS

1

complete

in

a

owering

epidermis

cells

plant.

STUD Y

Mak Copy

and

the

sentences

using

these

e

words:

TIP

sure

explai n organ

system

cells

tissues

tissue

An

is

organ

made

is

An

formed

is

several

up

a

body

of

that

from

group

of

a

group

organs

carry

out

of

the

same

working

working

together

to

.

adap ted

together.

to

Copy

out

correct

the

organs

system

listin g

the

from

listed

those

on

the

listed

left.

on

Match

the

each

with

trachea

digestive

and

blood

vessels

nervous

brain

and

spinal

cord

gas

KEY

one

Cells

that

oviducts

and

uterus

stomach

and

intestines

the

bladder

following

with

the

are

to

grouped

form

tissues.

Different

tissues

make

up

circulatory

words

smallest

into

and

the

ending

correct

with

to

sequence,

the

system

tissue

do

a

which

work

particular

together

function.

largest: 3

organ

same

reproductive

organs

Arrange

the

excretory

2 and

have

exchange

together

organ

and

each

POINTS

function ovaries,

starting

how

helps.

the

1

3

by

featur es

right.

heart

kidneys

out

System

and

gullet,

is

functions.

Organs

lungs

cell

pho to synt hesis

perform

can

palis ade

carry

explai ning

2

a

function

meso phyl l

A

you

how

organism

cell

Different

together

organs

as

work

organ

systems.

25

PRACTICE

1

Which

QUESTIONS

structure

is

found

only

in

plant

6

cells?

The

diagram

liver A

cell

B

chloroplast

C

cytoplasm

D

nucleus

(Paper

shows

a

mitochondrion

1)

Which

[1]

structure

is

not

found

in

animal

cell

membrane

B

cell

wall

C

cytoplasm

D

nucleus

3

Which

the

is

[1]

the

correct

and

sequence,

ending

with

starting

the

7

tissue,

B

cell,

C

tissue,

D

cell,

organ

system,

organ,

organ

system,

×4000

B

×400

D

×40 000

The

(Paper

tissue,

organ,

organ

system

A

out,

A

CO

in,

specimen.

drawing

×40.

A

The

is

is

drawing

length

140

What

a

mm.

the

of

the

The

actual

5600 mm

of

CO

out,

and

out

of

CO

O

8

Cells

in,

nutrients

in

in,

nutrients

out

2

out,

(Paper

in

2

in,

CO

nutrients

O

out,

nutrients

out

2

2)

of

[1]

organisms

contain

classied

which

of

in

the

the

prokaryote

following?

biological

specimen

of

O

2

in

magnication

size

B

a

in

2

2

[1]

makes

O

2

2

1)

student

move

with

kingdom

4

that

are:

D system

[1]

substances

organ

organ

is:

2)

mitochondria

cell

organ,

diagram

C

largest?

cell,

the

×40

C tissue,

of

A

B A

magnication

(Paper

1)

smallest

µm

cells?

The A

(Paper

a

membrane

1.0

2

from

cell.

the

A

cell

membrane,

B

cell

wall,

enzymes,

nucleus,

vesicles

the

is

cell

membrane,

cytoplasm,

ribosomes

specimen?

C

56 mm

cytoplasm,

DNA,

endoplasmic

DNA,

enzymes,

reticulum,

ribosomes C

35 mm

D

3.5 mm

D

(Paper

1)

Which

is

cytoplasm,

(Paper

5

not

found

in

an

animal

2)

[1]

cell?

9 A

mitochondria

[1]

The

palisade

mesophyll

cell

is

a

type

of

plant

nucleus

B

permanent

C

ribosomes

D

rough

cell.

A

2)

cell

and

complete

is

a

type

of

animal

cell.

Copy

vacuole

endoplasmic

cells.

Copy

think

reticulum

you (Paper

liver

the

think

the

the

table

table

structure

it

is

is

to

and

compare

put

present

a

tick

and

a

these

(✓)

if

cross

two

you

(✗)

if

absent.

[1]

palisade cell

liver

structure mesophyll

cell

wall

cell

membrane

cell

cell

cytoplasm

nucleus

chloroplast

large

(Paper

26

vacuole

2)

[6]

10

The

diagram

shows

three

animal

(iii)

cells.

the

organ

system

for

transport

in

mammals;

(iv)

the

plant

[1]

tissue

that

transports

sugars.

(b)

Distinguish

[1]

between

the

following

pairs

of

terms.

B

A

(a)

Identify

the

(b)

State

the

(c)

State

where

(i)

Organs

(ii)

Cytoplasm

(iii)

Cell

(iv)

Organ

A,

functions

B

and

of

the

C.

[3]

three

cells.

the

body

these

cells

13

(a)

Five

cell

magnication

of

cell

A

is

system

and

and

cell

wall

[2]

organism

[2]

structures

and

their

functions

are

its

actual

size

in

below.

×1000. Cell

The

membrane

[3]

Calculate

11

[2]

3)

listed

(Paper

nucleus

are

found.

The

and

[2]

[3] (Paper

(d)

tissues

C

cells

in

and

millimetres.

structures

[2]

A

nucleus

B

cell

membrane

C

cell

wall

D

large

E

ribosome

F

rough

G

mitochondrion

3)

diagram

shows

three

plant

cells.

D

vacuole

endoplasmic

reticulum

E

Functions

1

controls

into

the

and

movement

out

2

stores

water

3

makes

4

withstands

of

the

and

of

substances

cell

ions

proteins

pressure

of

water

inside

F

the

(a)

Identify

(b)

State

(c)

For

the

each

organ

a

(d)

the

cell,

where

actual

Calculate

D,

functions

different

The

cells

D,

it

E

is

E

of

and

the

and

F,

found.

F.

three

state

In

cells.

a

each

the

5

carries

[3]

6

transports

7

stores

DNA

of

cell

give

organ.

length

[3]

plant

case

[3]

of

cell

D

is

magnication

Match

the

out

each

function

0.05 mm.

of

cell

by

of

(a)

proteins

and

the

within

controls

cell

writing

a

the

the

activities

structures

letter

and

cell

with

a

its

number.

[5]

[2]

(b)

A

student

looked

microscope.

12

respiration

the

drawing.

(Paper

aerobic

She

at

a

cell

made

a

under

a

drawing

light

of

3)

the

cell

the

nucleus

and

showed

the

diameter

of

Name:

(i)

an

animal

cell

which

does

not

have

nucleus;

a

[1]

She

(ii)

a

plant

cell

that

does

not

have

calculated

drawing

size

of

as

the

her

the

drawing

70 mm.

magnication

×10 000.

nucleus

as

in

What

is

the

of

her

actual

micrometres?

Show

a

your nucleus;

in

working.

[2]

[1]

(Paper

4)

27

3

Movement

3.1

in

out

of

cells

Diffusion

Molecules LEARNING

Dene

•

Describe

in

the

term

liquid

diffusion

and

do

move

the

importance

about

in

a

random

way.

They

bump

into

one

of

gases

Describe

the

water

a

and

as

in

a

out

well,

gas

to

ll

up

although

is

faster

as

all

it

the

takes

the

space

available.

longer

molecules

for

are

them

more

Molecules

to

ll

the

spread

in

a

space.

out.

The

of difference

diffusion

spread

this

Movement

in

speed

between

movement

in

gases

and

liquids

is

important

solutes for

as

gases

OUTCOMES another

•

•

and

importance

organisms.

This

movement

of

molecules

is

called

diffusion

of

solvent

water

molecules

substance

in

before

Figure

diffusion

after

3.1.1

Diffusion

in

a

gas.

a

coloured

gas

spread

the

TIP

you

write

molecules

of

them

not

as

that

place

to

they

ano th er ,

that

e

difference

in

A

entrat

one

you

has

a

large

so lu te

given

disso lved

high

is

the

ient.

that

are

easily ,

of

vo lu me

in

a

of

the

where

to

there

where

are

there

low

concentration).

The

difference

between

carry

on

in

two

places

diffusing

molecules

so

until

keep

is

a

they

moving,

diffusion

has

concentration

are

but

spread

there

is

out

no

evenly.

longer

stopped.

movement

to

a

of

molecules

region

of

lower

or

ions

from

a

concentration

region

down

a

the

substances

also

lose

they

some

of

need

their

by

diffusion

waste

from

substances

their

to

their

diffusion.

These

permeable

as

oxygen,

larger

substances

as

they

carbon

molecules.

allow

dioxide

The

have

the

and

to

water

movement

cross

cell

movement

of

to

membranes

of

pass

molecules

small

through

by

diffusion

cell

membranes

is

passive

movement

as

cells

do

not

need

to

use

a to

move

the

molecules.

the

energy

for

of

diffusion

molecules

comes

and

from

ions.

the

The

kinetic

more

energy

molecules

of

random

present,

the

has their

kinetic

energy

and

therefore

their

rate

of

movement.

so lu te

given

that

affect

diffusion

so lven t.

These

factors

•

distance

The

are

•

The

as

28

by

not

Factors of

of

They

such

but

across

in

so lu tion

mas s

from

of

The

disso lved

(a

molecules

the

net

partially

molecules

greater

smal l

out

concentration)

gradient.

some

movement

a

of

concentration

gain

energy

dilu te

spread

high

say

so lven t.

A

them

concentrations

concentration

so lu tion

mas s

vo lu me

they

(a

the

grad

conc entrat ed

diffuse

volume

alwa ys

down

ion

liquid.

abou t

surroundings

conc

of

happens

this

surroundings.

mov

a

are

from

sure

many

When

Cells

mak e

ions

given

Molecules

of

diffus ing

or

a

concentration

Diffusion

mo lec ules

in

gradient.

a

Whe n

in

container .

the

STUD Y

Diffusion

water

diffusion

out

are through

3.1.2

after

solute

Molecules

lots of

diffusion

of

through

diffusion

When

Figure

molecules

dispersed

tnemelppuS

before

soluble

water

very

inuence

the

molecules

efciency

have

to

of

travel

diffusion:

–

note

that

cell

membranes

thin.

concentration

quickly

as

gradient

possible,

so

–

they

cells

use

keep

a

the

low

substances

that

concentration

diffuse

inside

the

tnemelppuS

cytoplasm.

because

This

the

means

cell

is

that

molecules

maintaining

a

keep

steep

diffusing

into

concentration

the

cell

red

blood

cells

gradient. air

•

The

surface

give

•

The

a

area

large

some

surface

temperature

temperature

Gas

–

–

to

have

allow

many

molecules

move

increases.

versus

cells

Diffusion

is

cell

membranes

molecules

faster

faster

to

and

at

that

cross

collide

warmer

are

by

folded

diffusion.

more

often

as

the

temperatures.

liquid There

Animals

with

the

and

their

gas

plants

page

and

all

exchange

surroundings

exchange

(see

131).

at

surface

the

gas

is

gases

oxygen

exchange

formed

Blood

transports

in

body.

of

surfaces.

the

these

and

alveoli

two

carbon

In

in

gases

dioxide

red

a

short

cells

Magnication

mammals,

the

is

blood

distance

and

very

thin

opposite

cells

layer

of

the

cells

direction.

into

In

the

Breathing

the

alveoli,

blood.

Carbon

constantly

diffuses

dioxide

refreshes

the

blood

constantly

removes

oxygen

and

brings

air

in

in

the

concentration

gradients

are

always

steep.

carbon

There

the

TIP

Alway s

dioxide,

refer

are

many

give

a

very

large

surface

area

for

gas

dilu te

plants,

cells

gas

provide

exchange

a

large

spaces

between

this

(see

air

the

page

occurs

surface

cells

64).

in

This

300 000

times

faster

Water

as

solvent

a

inside

area

a

is

than

for

plant

the

the

to

and

efcient

through

‘stro ng’

exchange.

leaves.

The

exchange

each

cell

because

spongy

of

There

are

exchanges

gases

with

through

the

air

air

is

SUMMARY

QUESTIONS

1

complete

water.

Copy

and

sentences

A

solution

is

made

up

of

two

parts,

the

solute

and

the

solute

dissolves

in

the

solvent.

If

you

dissolve

sugar

using

in

water

a

sugar

solvent.

can

be

The

solution.

solute

solutes

dissolves

in

a

as

is

not

they

solvent

The

always

can

is

sugar

is

a

solid

dissolve

described

the

in

as

solute

like

sugar.

solvents

being

and

the

water

Liquids

too.

random

is

and

gases

Something

is

sometimes

called

the

universal

gas

is

which

of

soluble

solvent.

the

molecules

a

About

75%

is

water

and

it

is

the

main

component

of

of

from

an

blood,

and

xylem

sap

and

phloem

sap

in

transport

plants.

movement

a

or

an

area

area

of

of

of

as

a

result

of

uids

the like

high

net

concentration cytoplasm

diffusion

the

to Water

words:

you

low make

the

these

solvent. liquid

The

and

so lu tions .

mesophyll

gases.

diffusion

so lu tions ,

alveoli

‘ weak ’

In

to

so lu tions

so

neve r to

the

alveoli.

alveoli

and the

the

a

conc entrat ed and

in

lungs

across

diffuses

the

between

air

lungs

between

oxygen

the

×1500.

STUD Y the

space

to

movement

of

Everything

molecules. transported

of

the

water

KEY

1

is

plants

needed

and

reactions

for

animals

that

digestion

has

occur

and

to

in

dissolve

cells

excretion

in

happen

to

take

water

in

and

water.

most

Also,

2

place.

Diffusion

down

of

a

is

the

high

net

movement

concentration

concentration

Factors

that

surface

area,

affect

to

a

molecules

region

of

or

ions

low

from

diffusion

gradient.

are:

and

how

the

size

of

concentration

molecule,

steepness

of

distance,

the

into

a

distance

b

size

c

surface

d

concentration

e

temperature

of

factors

cells:

molecule

area

3

What

do

the

gradient

terms

concentration

the

following

diffusion

a

gradient.

temperature

concentration

of

State

affect

POINTS

region

2

in

chemical

4

Explain

why

important

and

solution

gradient

water

solvent

is

and

mean?

an

for

animals

plants.

29

3.2

Osmosis

Each LEARNING

of

•

Dene

the

•

Describe

the

term

on

and

osmosis

the

Explain

of

the

water

cells

surrounded

effect

animal

and

tissues

the

out

term

allows

cell

the

by

a

cell

small

outside.

membrane.

The

molecules

membrane

is

cell

It

separates

to

described

membrane

pass

as

through

being

has

the

but

tiny

contents

not

partially

holes

large

in

it

ones.

permeable

osmosis

movement

into

using

of

from

of

Osmosis

occurs

is

a

when

special

two

kind

of

solutions

diffusion

are

involving

separated

by

a

water

molecules.

partially

It

permeable

membrane

water Osmosis

is

the

diffusion

of

water

from

a

dilute

solution

into

a

more

potential concentrated

The

tiny

solution

holes

membrane

in

through

a

partially

permeable

membrane.

the

allow

Water

small

molecules

solute diffuse

water

molecules

to

pass

water

through,

solute

too

the

but

the

molecules

big

to

pass

partially

from

a

high

molecule

large

to

a

concentration

lower

water

concentration

are

through

permeable

fewer

membrane.

Water

is water many

diffusing

from

a

place molecules water

where

there

is

a

dilute molecules

STUD Y

TIP

solution

with

a

high

concentration

of

water dilute

If

aske d

to

dene

to

a

place

where

there

is

solution

concentrated

partially

osmos is

it,

mak

that

of

it

or

e

is

wate r

write

sure

the

abou t

you

say

diffus ion

mo lec ules.

concentrated

permeable

with membrane

a

low

concentration

of Figure

3.2.1

Osmosis.

water

Water

to

potential

move

by

available,

water

a

in

dilute

water

In

the

two

solution

of

water

A

dialysis

to

are

lot

is

a

free

a

of

on

a

of

ability

much

of

water

water

pressure

accurate

molecules)

is

exerted

to

say

has

(containing

potential

molecules

high

partially

water

a

on

that

high

fewer

left

since

hand

through

potential

gradient

diffuse

potential

permeable

through

However,

the

molecules

water

the

more

water

water

move

energy.

is

as

solution

water

region

to

It

the

how

water

potential

The

through

by

such

wall.

a

water

present

water

the

factors

cell

there

about

inuenced

concentrated

from

kinetic

of

down

Dialysis

A

potential

by

the

membrane.

molecules

model

by

above,

the

thinking

is

other

low

molecules

movement

right,

a

gradient,

directions

water

has

of

This

(containing

potential.

potential

way

by

cells

diagram

Water

a

also

plant

sides

lower

is

osmosis.

but

molecules)

30

solution

solution

a

the

the

to

a

this

the

water

region

of

membrane.

membrane

there

side,

between

down

are

there

in

many

will

membrane

both

more

be

from

a

net

left

to

gradient.

cell

tubing

tubing

represent

(Visking

to

the

tubing)

represent

cytoplasm.

the

is

partially

cell

permeable.

membrane

and

We

the

can

sugar

use

solution

tnemelppuS

tnemelppuS

•

is

cell

which

The

plant

cell

OUTCOMES

PRACTICAL

1

Cut

two

pieces

water diffuses

of

into ‘cell’

dialysis

12 cm

tubing,

long.

each

Tie

one

end

sugar

solution

of

each

with

cotton.

dialysis tubing

2

Fill

one

model

cell

with

a (partially

dilute

sugar

solution

permeable

(cell

membrane)

A).

Fill

the

other

model

water

STUD Y cell

with

water

(cell

‘cell

3

Tie

the

other

end

TIP

B).

of

A ’

Y ou

both

may

be

given

water diffuses

model

cells

and

resul ts

weigh out of ‘cell’

them

‘cell

on

A ’

water

a

a

balance.

into

and

beaker

a

Put

beaker

put

‘cell

B’

a

demon stratio n

and

into

the

be

resul ts.

solution

of

30

minutes

to solution

out

the

model

Mak e

the

sure

you

den ition

osmo sis

and

sugar permeable

take

osmo sis

explai n

dialysis tubing

of After

to

a

(partially

sugar .

of

expec ted

remem ber concentrated

the

pract ical

water

of

containing

of

the

resul ts

cells

apply

you

it

can

see.

membrane)

Alwa ys and

weigh

them

again.

‘cell

resul ts

‘Cell

A ’

increases

in

mass

explai n

because

are

molec ules capillar y

water

has

diffused

into

the

‘cell’

level

by

that

B’

due

to

the

water

movin g

by

of

osmo sis.

tube sugar

osmosis.

‘Cell

B’

decreases

in

mass solution

because

water

by

has

the

cell

An

osmometer

diffused

out

of

osmosis.

dialysis

tubing

containing

Y ou

can

you

set

Fill

the

see

up

the

this

partially

membrane

effects

of

osmosis

water

if

concentrated

apparatus.

sugar

solution

permeable

with

a

very

KEY

concentrated

solution

of

1

Tie

it

to

a

capillary

tube

and

stand

it

in

POINTS

sugar.

Osmosis

water

Very

quickly

measure

your

you

how

ideas

will

fast

about

it

see

is

the

liquid

moving

osmosis

to

moving

using

explain

a

up

ruler

why

is

the

diffusion

of

water.

the

and

the

a

tube.

Y ou

stopwatch.

liquid

rises

in

of

can

their

(dilute

Use

the

molecules

of

tube.

higher

their

lower

through

a

a

region

concentration

solution)

(concentrated

from

to

a

region

concentration

solution)

partially

permeable

membrane.

SUMMARY

QUESTIONS 2

A

partially

permeable

membrane 1

Dene

the

following

molecules

diffusion

2

Describe

osmosis

practical

osmosis

how

into

you

a

can

sugar

partially

nd

out

solution.

permeable

how

fast

water

Remember

to

membrane

diffuses

include

pass

tnemelppuS

Explain

all

details.

in

terms

water

potential,

how

water

passes

cells

placed

in

distilled

as

but

molecules.

3

Water

molecules

water

a

potential

water

not

to

large

region

of

diffuse

down

gradient

higher

water

into potential

plant

such

through

solute

a

of

small

by

from

3

allows

terms:

to

a

region

of

lower

water. water

potential.

31

3.3

Osmosis

animal

LEARNING

•

Describe

enter

OUTCOMES

how

and

water

leave

plant

and

cells

PRACTICAL

can

plant

in

Osmosis

cells

in

potato

cells

by 1

Cut

nine

cores

from

a

potato

so

that

they

are

exactly

the

same

osmosis length.

•

Describe

affect

how

animal

osmosis

Record

this

length.

can 2

Feel

3

Set

the

cores

to

see

how

rm

and

‘bendy’

they

are.

cells

up

the

following

test-tubes:

B

A

STUD Y

test-tube

A

test-tube

B

–

distilled

–

dilute

water

distilled

dilute

water

sugar

sugar

TIP solution solution

Whe n

cell

desc ribin g

mem bran e

say

that

it

is

test-tube

concentrated

the sugar

4

partia

no t

–

solution.

alwa ys Place

three

cores

of

potato

0

1

2

3

4

5

6

7

8

9 10

0

1

2

3

4

5

6

7

8

9 10

lly into

perm eable,

C

each

test-tube

and

tissue

swells

up

no

change

semileave

perm eable.

5

them

Remove

for

the

measure

60

cores

their

minutes.

C

and

concentrated

sugar

lengths.

solution

Calculate

of cell

the

the

cores

average

in

each

length

test-tube.

membrane

Compared

(partially

to

the

start,

cores

permeable)

will

0

be:

1

tissue water

A

cytoplasm

–

longer

and

2

3

4

5

6

shrunken

7

8

9 10

and

flaccid

rmer

passes

into

the

B

–

about

the

C

–

shorter

same

length

and

rmness

vacuole vacuole

by

and

softer

and

‘bendier’.

osmosis cell

wall

(freely

These

results

are

explained

in

the

text.

permeable)

the

cell

solution

is

less

outside

the

concentrated

Turgidity than

in

the

vacuole

The Figure

3.3.1

Osmosis

in

a

plant

cell

sap

inside

cells

are

there

STUD Y

tnemelppuS

Paper

expec ted

Y ou

4

to

you

use

osmo sis

may

the

As

be

wall

wall

in

and

refer

plan t

is

plant

a

cell

water,

solution

is

partially

the

of

water

gradient

salts

permeable

enters

so

and

the

that

sugars.

and

cells.

water

When

the

cell

This

is

plant

because

molecules

diffuse

enters

osmosis.

it

makes

water

stops

as

the

it

a

can

cell

the

cell

turgor

hold.

It’s

bursting.

swell

up.

pressure.

like

We

a

say

The

blown-up

that

water

Eventually

the

pushes

the

cell

balloon.

cell

is

against

contains

The

turgid.

strong

This

is

the

as

cell

what

or

to

happened

to

the

cells

in

the

potato

cores

in

tube

A.

The

cells

have

water ,

swollen

and

caused

the

core

to

get

slightly

longer .

‘ water T urgid

cells

plants

upright.

give

the

plant

support.

They

keep

the

stems

of

many

to This

is

because

the

cells

within

a

stem

are

supported

movem ent by

out

by

tissu es.

grad ients ’

water

and

tissu es.

the

potential

developing

absorbed

also

poten tial

into

in

water

cells

water

cell

term

has

cells

can

explai n

of

vacuole

placed

a

the

much

abou t

anim al

of

cells

turgor

pressure.

The

water

pressure

within

the

cell

acts

against

the

and inelastic

these

and

32

is

the

TIP into

In

membrane

cell.

cell

cells

leaves

walls,

lose

that

keeping

water,

have

they

lost

the

are

cells

no

water

turgid

longer

wilt

and

rm

rm.

and

However,

turgid.

when

Plant

stems

tnemelppuS

Plasmolysis the solution outside the

cell is more concentrated

When

plant

cells

are

placed

into

a

concentrated

sugar

or

salt

solution than in the vacuole

water

passes

vacuole

limp.

out

starts

We

say

of

to

the

cells

shrink.

that

they

by

These

are

osmosis.

cells

are

accid.

As

As

no

water

longer

more

passes

rm,

water

out,

and

leaves

the

sap

become

the

cells

water

out

the

by

cytoplasm

starts

plasmolysed.

cores

core

in

is

to

test-tube

shorter

move

This

is

C.

than

away

what

The

at

cells

the

from

has

the

cell

happened

have

wall.

to

the

decreased

in

These

cells

cells

in

the

volume

so

are

passes

of

the

cell

osmosis

now

potato

the

whole

as cytoplasm is pulled

start.

away from the cell

The

the

cores

in

water

water

test-tube

potential

potential

overall

about

of

diffusion

the

did

not

change

of

the

sugar

the

cell

sap

of

same

B

water

into

in

solution

in

the

or

out

length

was

potato

of

the

very

about

cells.

cells

much

the

There

so

because

same

has

they

as

been

have

wall, the cell becomes

plasmolysed

the

no

Figure

3.3.2

Water

cell

stayed

passes

by

out

of

a

plant

osmosis.

length.

a

Osmosis

Figure

in

3.3.3

placed

in

animal

shows

different

cell

membrane

The

red

blood

Their

The

cytoplasm

cells

cells

by

them

in

D

in

a

they

so

to

picture

have

cells

has

the

the

blood

blood

salt

been

water.

cells

when

solution.

they

E

same

of

they

are

Remember

passes

not

water

no

blood

shrink

into

proteins,

have

red

have

when

placed

Water

cells

When

(F),

in

red

a

solution

animal

burst.

solution

The

of

that

permeable.

distilled

they

salt

in

the

in

which

are

partially

However,

osmosis.

solution

how

happens

concentrated

were

swelling

by

is

in

a

osmosis.

concentrated

cells

is

what

concentrations

the

cells

cells

as

into

cells

potential

by

and

are

put

size

as

stop

into

out

as

the

blood

sugars.

b

to

passes

in

liquids.

the

wall

water

surrounded

salts

cell

changed

different

a

of

they

cells.

the

are

This

is

plasma.

D These

(a)

Figure

3.3.3

This

shows

water

as

(D)

they

what

and

a

appear

happens

when

concentrated

when

red

blood

solution

suspended

in

of

cells

salt

blood

are

(F).

E

put

into

shows

KEY

distilled

red

blood

epidermal

turgid

1

plasma.

Water

passes

osmosis.

of

what

is

turgid

water

meant

turgor

Some

potato

dilute

sugar

by

each

of

pressure

these

mass

and

accid

2

plasmolysis

If

plant

cores

were

solution.

dried

on

a

weighed

After

paper

2

and

hours,

towel

then

they

and

placed

were

weighed

into

taken

of

of

the

potato

What

does

sugar

solution?

Explain

tnemelppuS

Explain,

cells

are

passes

turgid.

cells

that

is

T urgid

cores

remained

this

tell

you

about

the

your

answer

to

part

a

in

using

the

term

water

These

cells

are

shrinks,

unchanged.

concentration

terms

potential,

when

they

are

placed

into

of

what

distilled

for

stems.

of

into

a

solution,

out

by

osmosis.

are

no

happens

to

for

60

accid.

longer

the

cell

away

As

the

rm,

vacuole

membrane

from

the

cell

wall

–

the

3

osmosis.

water

placed

sugar

again.

cell

Animal

cores

is

now

cells

into

plasmolysed.

burst

water

if

they

as

are

they

of have

potato

cell

support

young

water

placed

3

plant

the

the

b

are

a

out

moves a

onion

terms:

they

The

red

plant

is

concentrated

solution,

into

A

provide

leaves

2

a

QUESTIONS

cells

Explain

from

plasmolysed.

POINTS

full

1

cells

(b)

cells

by

SUMMARY

and

no

cell

wall

to

resist

the

minutes. increase

in

size.

33

3.4

Active

Active LEARNING

Dene

the

term

Look

tnemelppuS

the Explain

active

the

importance

transport

consuming

•

Describe

of

•

ions

the

by

villi

in

as

an

active

plant

glucose

up

molecules

at

the

and

ions

concentration

concentration

of

and

keep

them

in

high

concentrations.

of

magnesium

magnesium

ions

in

ions

the

in

soil

the

root

hair

cell

and

solution:

of

energy-

process

the

in

Describe

take

active

transport

•

transport

OUTCOMES

Cells •

transport

vacuole

of

root

hair

cell

transport

roots

active

uptake

epithelial

cells

of

in soil

and

kidney

tubes solution

soil

particle

Key:

=

magnesium

Figure

The

of

3.4.1

down

high

root

hair

‘conc

in

of

use

entrat

the

activ e

of

ion

deni

‘ Aga inst

of

cell

ions

to

diffusion

cells

magnesium

than

it

gradient.

inside

in

out

ions

the

of

The

the

by

active

is

far

water

the

transport.

greater

in

root

hair

magnesium

root

hair

the

cell

cell

ions

by

a

inside

soil.

We

into

are

the

vacuole

might

the

soil

expect

water

maintained

process

called

at

a

active

the

grad

term

ient’

a

cell

using

transport

through

energy

is

the

the

cell

released

movement

of

membrane

during

ions

against

or

a

molecules

in

or

concentration

out

of

gradient,

respiration.

tion

4000

a

conc entrat ion

from

to

cell

in

3000

water

outside

gm

conc entrat ion

md

means

3–

a

conc entrat ion.

/

high

is

diffuse

inside

low

ions

tran sport.

grad ient’

a

absorb

transport

TIP

the

a

hair

concentration

Active

No tic e

Root

concentration

the

magnesium

STUD Y

ions

noitartnecnoc

2000

1000

0 +

+

Na

Figure

The

of

a

bar

Ion

chart

against

have

a

the

plant

been

concentration

due

to

in

the

into

active

water

the

gradient

Ca

magnesium

concentrations

and

taken

2+

Mg

potassium

concentration

shows

freshwater

cannot

34

3.4.2

2+

K

sodium

plant

by

Cl

calcium

chloride

transport.

of

in

by

some

which

ions

it

lives.

diffusion.

active

inside

These

They

transport.

the

are

cells

ions

taken

in

tnemelppuS

Active

The

cell

the

with

to

membrane

cell

enter

leave

carrier

change

its

membrane.

and

the

a

and

cell

by

protein.

shape

The

carrier

needs

contains

membrane

or

a

transport

carrier

provide

active

to

carry

protein

proteins.

means

by

transport.

Energy

molecule

energy

from

the

or

reverts

to

First

the

respiration

ion

ion

is

or

to

original

carrier

ions

and

to

the

or

the

the

proteins

molecules

molecule

enables

molecule

released

its

These

which

ion

combines

carrier

inside

inside

of

of

the

span

can

protein

the

membrane

shape.

ions outside

cell

cell

outside

cell

membrane

+

membrane

energy

inside

3.4.3

Carrier

proteins

in

membranes

carry

out

active

transport.

STUD Y Epithelial

absorb

rates

cells

lining

glucose

of

by

the

villi

active

respiration

to

in

the

transport

provide

small

(see

energy

intestine

T opic

for

and

7.8).

this

the

These

active

kidney

cells

TIP

tubules

have

high

Roo t

hair

transport

against

a

upon

concentration

respiration

oxygen

relies

will

would

also

gradient.

affect

reduce

respiration

the

Any

rate

respiration

of

to

take

factor

active

rate

and

up

that

ions

or

affects

transport.

active

the

So

are

molecules

a

rate

lack

up

increase

to

The

a

in

point,

presence

active

temperature

so

of

transport

SUMMARY

tnemelppuS

1

Explain

2

a

3

would

have

such

stop

as

increase

the

the

same

cyanide

man y

transport.

rate

effect

can

their

stop

of

on

respiration,

active

to

transport.

respiration,

Make

a

Make

sure

be

is

meant

the

table

to

State

role

to

that

and

of

active

carrier

of

compare

you

have

‘active

from

think

what

transport,

rate

a

lack

proteins

and

respiration

an

c

the

respira tion

energ y.

in

active

transport

diffusion

with

taking

active

place.

KEY

of

three

columns

transport’.

the

cell’,

some

For

headed

features

‘concentration

other

features

to

transport.

can

gradient’.

in

your

transport

molecules

include

Y ou

Active

movement

‘features’,

you

use

POINTS

effect

in

each

each

case

of

the

give

following

reasons

for

would

your

have

answer:

of

is

ions

across

the

or

the

against

concentration

table.

on

of

membrane,

may

from

cell

a

gradient,

using

respiration.

active

2

Active

transport

cells

to

enables

take

up

root

ions,

and

oxygen

epithelial b

of

in

and

transport.

hair a

pro tei ns

mem bran es

provi de

energy 4

havi ng

altogether.

by

examples

energy

able

villi

activ e

so

1

‘needs

high

by

carrier

cell

of

for

transport.

two

‘diffusion’

and

QUESTIONS

Describe

Give

also

poisons

what

active

b

would

would

cells

adap ted

trans port

of

of

a An

cells

transport.

epith elial

Active

cell

tnemelppuS

Figure

cell

increase

in

of

the

villi

to

temperature take

presence

cells

of

a

poison,

such

as

up

glucose.

cyanide

35

PRACTICE

1

Which

A

is

cell

QUESTIONS

not

partially

membrane

B

cell

membrane

C

cell

wall

D

dialysis

permeable?

of

of

palisade

red

5

mesophyll

blood

cell

Which

A

the

cell

B

1)

A

is

the

best

partially

denition

of

solvent

permeable

concentration

net

of

the

net

molecules

D

through

membrane

down

random

the

of

net

from

molecules

down

of

molecules

against

diffusion

a

a

a

a

movement

of

molecules

in

a

molecules

down

solution

a

membrane

of

water

molecules

permeable

with

with

through

a

a

low

high

membrane

water

water

potential

potential

2)

[1]

Some

fresh

plant

tissue

salt

was

solution

put

for

into

60

a

minutes.

Which

explains

why

the

tissue

became

softer?

liquid

hair

cells

are

surrounded

by

soil

water ,

water

diffused

gradient

[1]

dilute

solution

nitrate

ions

higher

concentrations

hair

water

gas

1)

very

down

gradient

partially

solution

water

cells

and

absorb

of

mineral

magnesium

ions

of

ions.

these

from

soil

ions,

such

Plant

cells

ions.

How

active

B

diffusion

do

C

diffused

water

D

random

into

water

to

the

potential

their

cells

surroundings

so

that

they

out

of

the

cells

so

that

they

plasmolysed

water? the

cells

lost

turgor

pressure

and

became

accid

(Paper

osmosis

a

cells

turgid

diffused

became

root

transport

C

down

the

as

have

D

A

from

which

became is

molecules

a

B Root

a

gradient

A

3

through

a

best

(Paper

water

of

permeable

concentrated

a

molecules

gradient

potential

through

a

6

or

osmosis?

gradient

movement

concentration

D

of

membrane

of

diffusion

water

(Paper

net

water

potential

partially

diffusion?

gradient

movement

concentration

C

of

permeable

diffusion

water

to B

net

denition

[1]

movement

a

diffusion

the

a

Which

best

tubing

C

2

the

partially

a

(Paper

is

7

(a)

2)

Explain

[1]

the

importance

to

humans

of

the

movement following:

(Paper

4

A

1)

[1]

student

cut

up

a

potato

into

pieces

(i)

diffusion

of

oxygen

in

the

alveoli

(ii)

diffusion

of

carbon

dioxide

in

[2]

the

that

alveoli looked

pieces

three

like

as

chips.

‘fairly

different

results

that

the

The

rm’.

student

The

liquids.

pieces

Which

student

described

were

row

[2]

these

put

shows

(iii)

into

absorption

the

the

small

of

glucose

by

diffusion

in

intestine.

[2]

obtained? (b)

Explain

the

importance

to

plants

of

the

following: very very

dilute

salt salt

(i)

fairly

soft

Osmosis

osmosis rm

(Paper

swollen

36

soft

fairly

rm

soft

fairly

rm

and

D

of

magnesium

ions

by

cells.

root

[2]

is

a

type

of

diffusion.

Explain

how

and

rm very

1)

leaves

rm

fairly

soft

absorption

hair

(c)

(Paper

into

[2]

swollen soft

very

dioxide

and

rm very

C

carbon

solution

(ii)

B

of

solution

swollen A

diffusion

water

concentrated

rm

[1]

3)

differs

from

diffusion.

[3]

8

A

group

They

divided

of

of

students

began

10

the

by

peeled

onions

batch

was

and

surface

dried

calculated

The

for

table

small

onions

into

of

salt

two

and

the

50

into

weighed

placed

concentrations

immersion

investigated

peeling

a

hours

reweighed.

their

The

in

B

of

was

the

was

B

mass.

mean

mass

onions

/

set

Some

and

up

bubbled

a

oxygen

A

in

gas

gas

cut

three

solution

with

from

A;

a

solutions,

ions.

rich

a

in

A

each

oxygen

solution

very

solution

mixture.

ions

through

mixture

oxygen;

the

of

potassium

mixture

of

were

in

bubbled

through

gas

investigate

uptake

roots

placed

was

solutions.

to

the

containing

gases

concentration

results.

of

C,

of

received

no

conc.

roots.

and

was

inuencing

washed

mixture

After

students

change

plant

A,

different

batch

factors

plant,

chloride).

each

experiment

by

batches

of

An

the

They

Each

solution

percentage

shows

ve

them.

(sodium

9

osmosis.

onions.

C

The

low

received

roots

were

g

left

for

24

hours

and

then

the

rate

of

uptake

percentage of

of

salt

before

after

immersion

immersion

2

hours

change

potassium

ions

was

determined.

in

/

−3

mass

The

rate

of

uptake

of

potassium

ions

was

g dm

highest 0

147

173

25

153

165

+

in

solution

+

172

100

154

149

Explain

how

149

142

−4.5

200

183

175

−4.5 The

Journal

(a)

and

data

of

in

Biological

Calculate

used

to

vegetable

compile

Education

the

the

pickling,

(1993)

percentage

supply

uptake

table

Ray

27

W

(2),

change

was

of

of

solution

oxygen

to

C

roots

potassium

repeated

containing

temperatures.

gas

osmosis

the

their

experiment

solutions

150

Practical

in

ions.

[3]

−2.0 The

Information

lowest

8.0 inuences

176

and

18.0

(a)

50

A

mixture

results

They

that

are

roots

were

had

all

been

shown

in

with

kept

at

different

provided

given

the

to

with

the

solution

A.

table.

from

temperature

rate

of

/

ions

uptake

of

potassium

James.

pages

in

°C

/

arbitrary

units

90–91

5

3

10

5

20

10

30

20

40

15

mass

−3

for

the

onions

solution.

(b)

State

why

the

percentage

(c)

Plot

(d)

Use

a

which

(Paper

of

is

the

the

to

no

100 g dm

salt

working.

students

graph

there

in

your

change

graph

your

kept

Show

in

[2]

calculated

the

mass.

[1]

results.

nd

the

change

[5]

salt

in

solution

mass.

in

(b)

Draw

a

graph

(c)

Describe

of

the

results.

[6]

[1] the

results

shown

in

your

graph.

[4]

4)

(d)

Explain

uptake

(Paper

10

the

of

effect

Explain

the

(b)

Explain

why

Some

term

resources

and

concentrations

Describe

absorb

by

the

concentration

of

in

is

on

the

roots.

[3]

are

their

by

or

cells,

often

in

as

the

ions.

such

very

[2]

as

low

surroundings.

epithelial

molecules

gradient. [2]

described

molecules

required

ions,

how

contents.

(Paper

ions

diffusion

movement

molecules

(c)

temperature

4)

(a)

net

of

potassium

of

cells

glucose

of

the

from

villi

the

gut

[5]

4)

37

4

Biological

4.1

molecules

Biological

Biological LEARNING

List

in

the

elements

for

present

carbohydrates,

fats

Describe

large

the

synthesis

molecules

from

place

energy

of

cells.

Green

smaller

need

how

They

of

raw Describe

are

in

different

sequences

give

in

plants

from

the

Relate

proteins

chemicals

of

the

that

we

body.

protein

are

mean

These

synthesis,

needed

all

the

by

reactions

and

living

chemical

the

include

growth

organisms

reactions

the

and

release

repair

the

raw

for

complex

chemical

materials.

Carbon

photosynthesis.

compounds

dioxide

The

simple

wide

range

and

that

they

water

sugars

are

the

produced

in

need

are

used

minerals

to

to

make

make

a

some

of

these

of

other

complex

compounds.

compounds.

shapes

the

structure

shape

eat

of

plants

and/or

other

animals

that

feed

on

plants.

and

protein

molecules

that

animals

require

are

present

in

their

diet.

The

molecules different

their

carbohydrates,

different

Biological

to

like

amino

Animals

•

chemicals

metabolism

cells

make

simple

materials

Plants protein

useful

By

respiration,

photosynthesis acid

complex

of

molecules

•

fats.

metabolism.

taking

and

proteins

•

are

OUTCOMES and

•

molecules

molecules

biological

molecules

needed

for

a

balanced

diet

in

humans

function are

carbohydrates,

proteins,

fats,

vitamins,

minerals,

bre

and

water.

Carbohydrates

These

contain

the

Carbohydrates

a

simple

Glucose

sugar

molecules,

e.g.

in

is

a

b

complex

atoms

sugar

e.g.

and

sugar

and

which

transported

in

(C),

hydrogen

(H)

and

oxygen

(O).

starches.

is

made

the

in

blood.

photosynthesis,

It

consists

of

six

used

carbon

arranged

simple

made

to

is

a

double

sugars

by

bonds.

Plants

catalyse

It

is

stored

Starch

complex

carbohydrate

and

Cellulose

glucose Figure

4.1.1

Different

types

and

glycogen,

a

units.

unlike

The

of

by

two

They

together

starch)

is

animals

molecules

a

by

have

into

another

as

mo lecules

eaten

to

refer

is

also

to

by

the

used

which

an

are

made

animal.

bio logical

to

refer

of

carbohydrates

together

store.

glucose

animal

store

are

chemical

enzymes

long

chains.

complex

of

energy.

muscles.

sugars,

structural

glucose

up

Complex

molecules

energy

glucose

and

complex,

an

join

called

from

liver

sugar

as

that

made

bonds.

units

are

insoluble

carbohydrate

are

held

and

do

made

together

by

not

up

of

bonds

taste

sweet.

thousands

forming

bres,

chains.

which

give

These

plant

cellulose

cells

walls

molecules

their

are

strength

linked

and

of

long

together

rigidity .

TIP

Bio logical

ions,

simple

starch

made

the

molecule

chemical

reactions

unbranched

form

when

many

(sometimes

in

is

by

of

carbohydrate.

STUDY

ring.

sugar

store

the

carbohydrate

–

a

joined

joining

Glycogen,

starch

into

sucrose

Sucrose

38

simple

respiration

carbon

sugars

glucose

molecules,

c

elements

include

to

by

such

need

organisms.

term

mo lecules

ions,

organisms

T he

described

as

from

nutrient

nitrate

their

T hey

(or

in

only

T o pics

ions,

become

nutrient

4 .1

sodium

environment.

food

mo lecule)

and

ions

4 .2.

and

mo lecules

is

often

Beware

–

used

it

magnesium

to

Proteins

Proteins

are

complex

oxygen,

but

they

molecules

also

contain

made

up

nitrogen

of

(N)

carbon,

and

hydrogen

many

have

STUD Y

and

sulfur

Y ou (S).

Proteins

are

long-chain

molecules

made

up

of

smaller

TIP

may

compa re called

amino

acids.

After

formation

Topic

5.1)

they

are

either

folded

shapes

(see

or

become

arranged

into

long

of

bres.

to

compa re

peptide

head ings

bond

of

acid

part

molecules

of

a

protein

4.1.2

How

a

protein

is

made

from

amino

are

about

20

different

types

of

acids.

amino

this

acid.

and

will

Molecules

of

be

table

Whe n There

are

made

into

chains

as

you

can

see

in

the

diagram.

It

is

of

the

different

amino

acids

in

the

chain

usin g

as

‘Nam e

molec ules

‘Elem ents’.

which

able

in

to

add

T opic

nam ing

to

7 .2.

the

alwa ys

use

the

full sequence

table

amino

elem ents acids

such

a

molecule

Y ou

Figure

Mak e

them

biolog ical

grou p’ amino

to

three

biolog ical

molec ules.

different

aske d

these

into

grou ps different

be

molecules

nam es,

no t

determines

their

their

sym bo ls. the

type

the

chain

tnemelppuS

The

of

by

different

molecules.

to

protein

their

that

means

of

a

sequences

These

function.

is

formed.

chemical

of

amino

different

shapes

Enzymes

are

Each

bond

acids

of

individual

called

give

peptide

different

protein

proteins

a

amino

that

a

joins

bond.

shapes

molecules

provide

acid

can

to

be

surface

protein

related

fatty

acid

glycerol

molecule

for

molecule

reactions

are

to

take

proteins

enables

with

them

pathogens

place

to

and

a

called

structure

bind

with

make

the

the

‘active

that

has

chemicals

pathogens

site’

(see

binding

called

stick

page

sites

on

antigens

together

47).

its

on

(see

Antibodies

surface.

the

page

This

surface

of

120).

Figure

KEY

Fats

Fats

and

Each

to

fat

this

these

oils

made

molecule

are

can

energy

are

three

form

storage

is

up

made

fatty

the

up

acids.

different

and

of

fats

thermal

of

elements

one

There

with

carbon,

molecule

are

different

different

insulation

of

in

hydrogen

glycerol

types

properties.

the

of

and

and

fatty

Fats

oxygen.

acid

are

1

attached

for

body .

A

Carbohydrates

up

of

hydrogen

Proteins

of

the

List

the

Give

components

of

a

balanced

diet

for

a

a

fats

are

and

are

made

elements

plus

sulfur.

(e.g.

one

example

of

each

of

the

simple

sugar

ii

a

complex

are

simple

glucose),

and

human.

carbohydrates

such

following: as

i

same

and

Carbohydrates

complex b

fat.

QUESTIONS

sugars a

of

elements

oxygen.

up

2

1

and

the

carbon,

nitrogen

SUMMARY

molecule

POINTS

made

and

used

4.1.3

carbohydrate

found

in

starch,

glycogen

and

plants cellulose.

iii

a

complex

carbohydrate

found

in

animals 3

2

a

Which

in

elements

are

carbohydrates

present

and

in

proteins,

but

are

not

found

Small

fats?

Name

the

small

molecules

that

are

joined

together

to

Give

d

State

three

examples

of

proteins

that

are

made

in

the

the

Name

made

and

Amino

function

of

each

protein

that

you

named

in

the

molecules

that

are

reacted

together

to

into

acids

are

part

A

molecule

make

of

of

a

fat

is

made

c

combining

three

fatty

acid

a molecules

molecule

proteins.

body.

by

a

are

glycogen

chain

make

4

3

joined

long

molecules.

made c

are

make

Sugars

starch,

cellulose. protein

to

molecules.

into b

molecules

together

with

a

molecule

of

fat. glycerol.

b

Give

two

uses

of

fats

in

the

body.

39

4.2

Chemical

tests

biological

Simple LEARNING

how

the

following

and

are

carried

vitamin

can

be

used

to

identify

starch,

sugars,

proteins,

it

is

important

you iodine

test

•

Benedict’s

to

carry

out

these

tests

on

pure

forms

of

these

out: compounds.

•

C.

chemical First,

tests

tests

molecules

OUTCOMES fat

State

chemical

for

for

should

For

rst

example,

carry

out

if

you

the

are

testing

chemical

test

a

food

on

a

for

reducing

glucose

sugars,

solution.

starch Then

test

for

keep

the

results

to

compare

with

your

results

from

testing

other

reducing materials,

such

as

foods

or

animal

and

plant

tissues.

Y ou

should

also

sugars do

•

biuret

test

•

ethanol

for

a

emulsion

test

for

test

for

water

so

that

you

can

see

the

negative

from

the

material

result

as

well.

vitamin

will

need

to

make

an

extract

you

are

testing.

fat This

DCPIP

with

protein You

•

test

C

involves

water

The

with

eye

so

a

pestle

chemicals

Safety:

Safety:

grinding

will

Some

always

of

wear

and

be

the

eye

up

a

small

mortar

in

amount

or

solution

chemicals

of

putting

in

the

used

the

it

material

into

a

with

some

blender.

extract.

in

these

tests

are

corrosive,

protection.

protection

T esting

•

Half

ll

•

Add

two

Iodine

• Figure

4.2.1

Test

for

A

a

tests

If

drops

usually

result

the

contain

are

for

the

of

food

iodine

looks

starch

extract

if

wish

to

test

for

starch.

solution

yellow

is

you

the

or

light

iodine

brown.

extract

remains

a

yellow

or

solution

light

turns

brown

blue–

colour

it

does

starch.

•

as

they

‘food

can

any

anim al

be

sugars

Put

a

known

mad e

in

a

volume

of

the

extract

you

wish

to

test

for

reducing

test-tube.

carried

plan t

•

Place

a

beaker

•

Carefully

half

(or

the

on

a

heat-proof

mat.

and

or

up

ll

the

beaker

with

boiling

water

from

a

kettle

on

in

place

beaker

on

a

tripod

and

gauze

and

boil

the

water

the with

labo ra to ry.

•

Add

a

Bunsen

the

burner).

same

containing

Safety:

reducing

tests’,

mater ial

so lu tions

for

of ten

sugars

on

three

with

TIP

know n

but

or

positive

T esting

out

test-tube

starch.

not

T hese

starch

solution

black.

STUD Y

for

•

Benedict’s

•

A

positive

volume

the

food

solution

test

for

of

Benedict’s

extract

is

and

bright

simple

put

solution

it

into

the

to

the

hot

test-tube

water.

blue.

sugars

is

when

Benedict’s

solution

turns

eye red

or

orange

(if

you

look

carefully

you

can

see

it

turn

green

and

protection then

cool

•

d

t

you

can

present.

B

o

You

yellow

t

will

use

If

of

•

Test

for

reducing

colour

If

the

a

reducing

lot

colour

of

a

orange).

If

you

leave

the

test-tube

to

precipitate.

test

to

changes

sugars.

sugars.

reducing

remains

sugars.

reducing

40

see

Benedict’s

the

the

contains

4.2.2

also

turning

tell

to

how

much

green,

the

simple

extract

sugar

is

contains

only

a

o

little

Figure

before

blue

If

it

turns

a

deep

orange

colour

then

sugars.

then

the

extract

does

not

contain

any

it

T esting

for

protein Safety:

•

Half

ll

•

Add

ve

copper

a

test-tube

to

six

drops

sulfate

Safety:

T ake

•

solution

with

of

solution

care

as

the

extract

biuret

and

sodium

you

wish

solution

sodium

to

(this

solution

for

solution

hydroxide

hydroxide

test

protein.

contains

solution).

is

corrosive. S od

h

Biuret

•

A

positive

violet

•

If

the

or

usually

test

for

looks

protein

blue

is

if

in

the

colour.

biuret

solution

turns

C

um

yd ro x

s o

ut

e d

s

remains

Fats

will

for

not

solution

of

is

formed.

•

Chop

(Do

•

Put

up

not

the

blue,

then

the

extract

does

not

contain

protein.

Figure

4.2.3

Test

a

Put

•

Add

•

Shake

fat

in

water

ethanol

grind

add

in

a

small

water

extract

is

to

into

a

but

they

added

to

amount

make

clean

of

the

will

dissolve

water

a

material

extract

test-tube

cloudy

you

this

and

in

ethanol.

white

wish

to

If

a

1

emulsion

test

for

Describe

in

each

what

of

stopper

some

the

white

over

the

distilled

test-tube

water

contents

emulsion

positive

test

for

starch

b

a

positive

test

for

protein

c

a

positive

test

for

a

time.)

add

enough

ethanol

to

to

and

make

shake

the

up

the

test-tube

of

the

test-tube

once

d

a

negative

half

e

a

positive

test

for

that

looks

cloudy

does

not

for

Describe

of

is

vitamin

that

loses

C

its

happen,

juices,

can

Put

2

Fill

a

the

white

extract

or

a

milky

colour

is

does

not

contain

such

as

freshly-squeezed

made

from

when

it

volume

or

vitamin

comes

into

C

lemon

tablets.

contact

juice.

DCPIP

with

is

a

A

with

test

an

blue

vitamin

for

of

DCPIP

solution

in

a

dropping

pipette

with

a

a

juice,

the

e.g.

liquid

orange

one

drop

demonstrating

liquid

3

C.

You

the

are

each

the

colour

If

the

blue

of

DCPIP

solution

of

vitamin

C

a

glucose

given

are

a

to

carry

sugar

test

solution

four

a

of

test-tubes

different

glucose.

labelled

you

do

A,

not

B,

C

know

and

the

then

of

glucose

in

time.

the

the

test

test

is

is

positive

for

vitamin

tube.

C. have

been

told

to

nd

negative. which

most

is

the

solution

concentrated

least

is

the

and

which

concentrated.

POINTS Describe

the

procedures 1

Iodine

2

Benedict’s

solution

gives

a

blue–black

colour

when

added

to

solution

turns

orange

when

boiled

with

simple

to solution

gives

a

purple

or

violet

colour

when

you

would

and

the

observations

sugars. you

Biuret

practical

that

starch.

follow

3

how

reducing

containing

and

out

KEY

food

juice.

at

disappears

persists

a

sugar

or

You

colour

of

test-tube.

each

If

extract

reducing

concentration

Add

would

the

solution

D

3

of

procedures:

making

out

be

syringe

C

fat.

They a

vitamin

a

C

colour

known

for

you

each

concentration 1

starch.

fats.

vitamin

in

test

how

out

using C

for

more.

b

T esting

test

full.

to

Vitamin

sugar

contents.

a

this

see

a

following

positive

If

would

following:

a

carry

•

you

the

fats.

2

A

protein.

it.

•

•

for

QUESTIONS

reducing

cover

on

fats

dissolve

or

fate

ut

corrosive

SUMMARY

T esting

op p e

u

s o

on

purple,

lilac.

colour

eye

protection

added

would

give

expect.

safety

Remember

precautions.

to

protein. 4

Describe

the 4

A

white

emulsion

forms

when

fat

dissolved

in

ethanol

is

you

to

would

use

compare

C

content

of

the

different

water.

fruit

5

test

added

vitamin to

how

DCPIP

Vitamin

C

decolourises

DCPIP

juices.

solutions.

41

4.3

DNA

tnemelppuS

The LEARNING

Each •

Describe

structure

the

structure

of

two

to

form

strands

coiled

chromosome

double

State

that

DNA

chemicals

Describe

called

up

how

in

the

the

how

for

we

eye

the

bases

same

place

in

we

could

DNA

TIP

DNA

of

unravel

The

so

is

the

G,

of

DNA.

show

bases,

A,

each

are

Y ou

C,

remem ber

a

The

no t

need

what

colour

we

look

and

like.

height.

For

instance,

Some

genes

there

code

enzymes

that

control

all

the

chemical

reaction

thread

a

chromosome,

would

the

of

long

be

acid).

made

it

would

A

thread

gene

that

up

is

of

a

form

an

chemical

extremely

made

makes

up

up

a

of

a

called

long

short

DNA

length

chromosome

contains

genes.

belongs

to

acids.

a

complex

called

a

Each

DNA

group

of

molecule

biological

nucleotide.

A

single

is

made

up

molecules

nucleotide

of

known

is

thousands

made

up

of

of

as

units

three

phosphate

•

a

sugar

•

a

base

sugar

the

and

DNA

phosphate

strand.

The

molecules

bases

are

join

up

attached

and

to

form

the

the

sugar

backbone

molecules.

struct ure

nucl eo tid e

show n

you

look

at

Figure

4.3.1

you

will

see

that

DNA

is

made

up

of

two

in strands

Figu re

and

hair

to of

the

like

information

in

If

a

arranged

genetic

T

arrang ed

do

genes

the

molecules:

•

DNA.

of

block ’

diag rams

and

of

carry

a nucleic

how

that

always

hundreds

nucl eo tid e

T he

thousands

way

of

‘build ing

of

genes

cells.

(deoxyribonucleic

A

up

the

grow

colour,

production

take

thread.

STUD Y

is

bases

If pair

made

It

strands

that

•

is

necklace.

affects

genes

for

contain

a

helix are

•

in

together that

a

DNA

DNA beads

as

of

OUTCOMES

of

nucleotides.

It

is

rather

like

a

ladder.

The

whole

molecule

4 .3.2. is

twisted

bases

as

into

the

a

double

helix

–

a

bit

like

a

spiral

staircase

with

the

steps.

phosphate

base

P

sugar

The

DNA

looks

like

Figure

molecule

a

4.3.2

A

spiral

single

nucleotide.

phosphates

make

The

up

the

sugars

and

‘uprights’

of

staircase

the

ladder

and

the

bases

make

up

the

‘rungs’.

Base

A

T

So

C

G

If

how

you

Each

T

A

G

C

on

Figure

42

4.3.1

A

DNA

model.

of

bases

the

the

the

look

pair

at

of

The

DNA

don’t

bases

molecule

Figure

bases

bases

thymine

(You

pairs

is

different

•

form

pairing

in

4.3.3

held

you

together?

can

together

see

by

that

weak

•

have

to

adenine

(A)

remember

pair

up

in

•

each

the

of

same

the

•

cytosine

(A)

(C)

pairs

pairs

with

with

thymine

guanine

(T)

(G)

(C)

names,

way:

steps

adenine

bases

bonds.

cytosine

staircase

•

the

join

There

together.

are

four

DNA:

(T)

always

is

held

•

guanine

just

their

(G)

letters.)

are

the

weak,

double

bonds

there

helix

in

are

holding

many

of

the

two

them.

chains

So

of

nucleotides

altogether

they

tnemelppuS

Although

together

keep

the

DNA

shape.

cytosine

guanine

adenine

thymine

A

student

shows

(guanine)

thymine

examines

the

pairs

is

of

yellow

a

model

bases.

and

C

In

of

DNA

this

that

model

(cytosine)

is

G

red.

adenine

phosphate

guanine

cytosine

sugar

weak

Figure

4.3.3

How

SUMMARY

1

Figure

4.3.4

of

bases

pair

up

in

DNA.

QUESTIONS

molecule.

letters

the

bonds

shows

Copy

the

a

and

partially

completed

complete

missing

the

section

diagram

by

of

the

writing

DNA

in

the

bases.

James

the

They

G

Figure

2

The

table

DNA

below

from

four

C

A

T

Watson

structure

they

are

and

of

posing

made

in

Francis

DNA

with

by

Crick

worked

building

their

Cambridge

nal

in

the

out

models.

model

early

that

1950s.

4.3.4

shows

the

different

percentages

of

the

four

bases

in

KEY

POINTS

organisms.

1

percentage

of

each

base

The

two

DNA

molecule

strands

coiled

consists

of

together

organism

to A

C

G

T

human

31

19

19

31

locust

29

21

21

29

2

form

Each

a

double

strand

chemicals

and

yeast

32

18

18

32

bacterium

15

35

35

15

3

A

C

a

Explain

b

In

A.

c

an

the

pattern

organism

What

Explain

shown

26%

percentage

how

organisms

it

is

such

percentages

of

of

the

DNA

be

to

humans

bases.

the

table.

bases

would

possible

as

in

C?

have

and

in

4

DNA

Show

two

yeast

are

your

very

with

found

to

very

similar

called

always

bonds

bonds

chromosome

long

bases

bond

with

with

is

A,

C,

G

together.

T;

G.

made

super-coiled

up

strand

of

of

DNA.

working.

different

contains

which

always

A

a

be

T ,

helix.

5

A

gene

that

of

a

is

a

codes

length

for

particular

the

of

DNA

production

protein.

43

PRACTICE

1

What

QUESTIONS

are

the

chemical

A

carbon,

hydrogen

B

carbon,

hydrogen,

elements

and

in

Use

proteins?

the

nitrogen

and

molecules

molecules

oxygen

shows carbon,

hydrogen,

of

nitrogen,

oxygen

a

are

known

questions

6–8.

small

part

of

sub-unit

nucleotides.

of

a

DNA

The

diagram

molecule.

and

B

carbon,

(Paper

for

composed

as

sulfur

D

DNA

oxygen DNA

C

diagram

nitrogen,

oxygen

and

sulfur

1)

[1]

C A

2

The

small

proteins

molecules

that

are

built

up

into

are:

A

amino

B

fatty

acids

acids

(Paper

1)

Which

row

C

glucose

D

glycerol

[1]

D

3

four

gives

chemical

the

positive

results

for

the

tests?

Benedict’s

biuret

iodine

emulsion

test

test

test

test

green

violet

yellow

Adenine

no A

X

suspension

6

Which

of

the

labelled

parts

of

DNA,

A,

B,

C

or

D,

no B

blue

blue

indicates

yellow

a

base

pair?

suspension

(Paper

2)

Which

of

[1]

cloudy C

yellow

red

blue suspension

D

orange

7

indicates

blue-

cloudy

black

suspension

4

Water

1)

is

because

[1]

an

it

important

is

molecule

in

8

organisms

a:

A

solute

C

solvent

B

solution

D

suspension

What

9

5

1)

Enzymes

regions

that

form

[1]

and

of

bind

antibodies

these

to

parts

of

DNA,

A,

B,

C

or

proteins

other

specic

are

proteins.

have

molecules.

shapes

A

molecules

of

B

molecules

with

because

D,

different

[1]

the

structure

labelled

X?

A

adenine

(A)

C

guanine

(G)

B

cytosine

(C)

D

thymine

(T)

The

2)

[1]

diagram

molecule

below

increases

shows

in

how

specic

a

starch

length.

A

Special

Proteins

they

2)

is

(Paper

(Paper

labelled

nucleotide?

violet

(Paper

(Paper

the

a

shapes

can

have:

lengths

different

numbers

of

amino (a)

Name

molecule

(b)

Name

two

A.

[1]

acids

C

molecules

with

different

sequences

places

where

starch

is

stored

plants.

amino

[2]

acids (c)

D

molecules

with

other

molecules

or

Describe

to

plant

would

nd

out

whether

tissue

contained

details

of

the

starch.

test

in

Include

your

the

answer.

[4]

[1]

(Paper

44

you

them practical

2)

how

ions a

attached

(Paper

in

of

3)

10

The

diagram

shows

a

protein

5

molecule:

Repeat

steps

1

to

4

with

the

juices

to

be

tested.

The

(a)

Name

the

sub-unit

molecules

that

results

are

shown

in

the

table.

are

volume

assembled

into

the

protein.

added

to

DCPIP

[1] 3

test

(b)

Name

two

proteins

found

in

the

solution

substance

/

cm

human

body.

1

2

3

mean

1.8

1.9

2.1

1.9

2.4

2.6

2.3

2.4

3.2

3.1

2.9

3.1

9.6

9.1

9.4

9.4

[2]

−3

(c)

(d)

State

two

places

many

proteins

Some

seeds

the

are

are

chemical

in

the

body

in

that

10 g dm

where

made.

rich

test

human

proteins.

orange

Describe

would

use

juice

to grapefruit

determine

whether

different

types

of

rich

details

in

of

proteins.

the

test

Include

in

your

the

answer.

[4]

The

Explain

why

readings

3)

(b) 11

juice

practical

(a)

(Paper

juice

seed apple

are

diagram

shows

a

molecule

of

a

Use

the

the

for

results

(Paper

13

juices.

Name

the

(a)

components

of

the

DNA

of

vitamin

Show

molecules

X

and

Y.

the

your

C

in

the

three

working.

[3]

two

places

are

stored.

State

in

the

human

body

a

double

what

this

helix

means.

[2]

the

precise

site

of

DNA

in

an

cell.

[2]

where The

sequence

of

bases

in

a

small

sample

[2] of

three

have

Explain

[2] animal

State

calculate

[3]

molecule (b)

labelled

(c)

substance.

4)

structure.

fats

three

Y

X

List

to

test

took

fat.

fruit

(b)

student

each

concentration

(a)

C

solution

[2]

you

vitamin

roles

of

fats

in

the

DNA

is:

human ATAGATCCCGAA

body.

[3] (c)

(d)

Oils

have

the

same

molecular

structure

Write

out

opposite

fats.

Many

seeds

are

rich

in

oils.

chemical

test

to

nd

out

whether

different

owering

plant

The

oil

or

not.

Include

strand

DNA

of

of

the

test

in

your

A

student

the

used

vitamin

the

C

is

DCPIP

test

present

in

answer.

to

The

concentration

of

nd

out

different

the

the

DNA

molecule.

[1]

determines

of

a

a

small

protein.

above

to

explain

Use

how

determine

the

sequences

base

of

[4] acids

in

a

protein.

[1]

how In

2007,

scientists

compared

the

degree

fruit of

juices.

in

practical

(e)

much

this

structure

sequence

amino

12

in

sequence

the

sequences details

bases

species the

contain

of

seeds part

from

sequence

Describe (d)

a

the

as

DCPIP

similarity

between

some

of

the

DNA

solution taken

from

the

nuclei

of

white

blood

cells

−3

was

10 g dm

.

The

student

followed

these of

a

domesticated

cat

and

several

other

instructions. mammalian

species.

The

results

are

below.

3

1

Put

2

Use

2 cm

of

DCPIP

solution

into

a

test

tube. percentage

a

graduated

pipette

or

burette

to

similarity

between

add domesticated

cat

and:

−3

a

10 g dm

vitamin

C

solution

drop

by wild

drop

to

the

DCPIP

solution.

Shake

the

tube

human

dog

cow

rat

mouse

90

82

80

69

67

cat

gently

add

of

after

the

the

adding

vitamin

DCPIP

C

each

drop.

solution

solution

Continue

until

the

to

colour

99

disappears.

What 3

Record

that

4

the

was

Repeat

of

vitamin

C

a

(Paper

procedure

mean

two

more

do

you

conclude

from

these

results?

[3]

solution

added.

the

calculate

volume

times

4)

and

volume.

45

5

Enzymes

5.1

Structure

and

action

of

enzymes

A LEARNING

catalyst

end

•

Dene

the

substance

term

that

catalyst

speeds

chemical

reaction

changed

by

the

and

as

up

is

a

of

speed

Dene

enzymes

the

up

act

not

How

as

as

speed

biological

up

the

tnemelppuS

Explain

using

rate

how

the

an

‘lock

enzyme

and

key’

works

too

catalyses

many

of

in

Breaking

is

2

They

take

keep

are

different

of

3

of

storage

are

known

place

in

organisms

many

as

at

organisms,

biological

organisms.

alive

different

reaction.

shows

its

(see

we

will

Topics

of

3D

enzymes

Most

discuss

7.5

and

up

in

nutrition

the

large

cell

the

one

when

that

they

These

unless

types

they

of

enzymes

the

that

catalysts

reactions

are

enzyme

speeded

as

work

each

inside

cells,

here

work

outside

cells,

for

7.7).

gut

for

as

work

of

large

to

down

small

cells

and

types.

and

their

are

broken

then

food

used.

and

we

reason.

joined

inside

starch,

three

molecules

absorbed

break

from

into

ones

food

be

same

are

divided

ones

together

to

speed

structural

to

up

make

the

large

formation

molecules

such

as

plants.

small

chemical

as

be

small

the

glucose,

such

can

can

enzymes

enzymes

walls

into

molecules

such

molecules,

for

so

release

into

These

catalyse

molecules

ones

fungi

Converting

molecule

reactions

that

into

occur

another

inside

cells

involve

small

an

changes right)

that

molecules,

Many

image

that

gut

enzymes

cellulose

computer-generated

those

large

and

molecules.

to

molecules,

such

as

adding

or

removing

atoms

or

groups

shape.

of

atoms.

from

For

example,

compounds

Figure

5.1.1

breakdown

shows

of

a

there

during

the

are

enzymes

that

remove

hydrogen

respiration.

way

in

which

an

enzyme

catalyses

the

molecule.

TIP

writi ng

enzy mes

abou t

alwa ys

enzy mes

reactio ns.

say

enzyme

substrate

substrate

active

cata lyse

Figure

Figure

from

46

to

There

small

Building

Small

that

reactions

important

into

release

Whe n

a

the

reactions

Bacteria

STUD Y

unchanged

by

model

down

the

remains

produced

work

slowly

enzymes.

example

This

(on

and

reactions

1

enzyme

reaction

proteins,

of

The

This

reactions.

enzymes

chemical

by

but

•

chemical

are

catalysts

one chemical

chemical

proteins

up to

a

Enzymes

reaction

happen that

up

reaction.

a

Many •

speeds

OUTCOMES

in

enzyme

products

site

released

5.1.1

5.1.2

two

shows

smaller

how

an

enzyme

molecules.

is

involved

in

building

a

molecule

Enzymes

are

made

All

enzymes

have

1

They

are

all

2

Each

enzyme

3

They

can

4

They

are

inuenced

by

temperature.

5

They

are

inuenced

by

pH.

ve

of

protein

important

properties.

proteins.

be

catalyses

used

one

again

reaction.

and

again.

active

site

substrate

Enzymes

are

made

of

protein

molecules.

These

molecules

can

be enzyme

folded

a

into

shape

many

that

explains

different

makes

why

there

it

shapes.

suitable

are

many

for

Each

type

catalysing

different

of

enzyme

one

enzymes

type

–

one

molecule

of

has

reaction.

enzyme

for

This

each

substrate

in

reaction. active

Enzymes

catalyse

products.

Look

reactions

at

enzyme

matches

and

substrate

the

together.

Once

Figure

the

t

which

5.1.1.

shape

have

they

in

of

Notice

the

shapes

substrates

that

together

that

substrate

are

the

the

are

converted

shape

molecule.

of

part

The

complementary

reaction

can

take

site

into

of

the

enzyme

so

place.

they

t

product

Other

released

substrates

involved

have

in

the

the

wrong

reaction

shape

catalysed

to

t

by

into

this

the

enzyme

enzyme.

so

When

will

the

not

be

reaction

is

Figure

5.1.2

This

shows

enzyme

over

the

product

or

products

leave

the

enzyme

and

another

tnemelppuS

As

you

an

join

two

substrate molecules

molecule

how

can

together.

enters.

can

substrate(s)

This

way

of

key’

model.

lock

to

see

t

in

Figure

and

describing

The

form

an

5.1.2

where

the

how

enzyme

the

part

reaction

enzymes

and

of

work

substrate

enzyme-substrate

the

takes

is

enzyme

place

is

known

combine

like

where

the

as

a

the

active

the

key

site.

‘lock

substrate

A

substrate

B

and

entering

a

complex enzyme

Figure

5.1.3

Only

the

SUMMARY

Copy

and

complete

the

sentences

using

these

words:

1

Enzymes

catalysts

proteins

are

biological

that

up

the

rate

.

type

Enzymes

of

are

the

meant

3

Use

a

terms

by

the

why

the

‘lock

each

all

and

each

enzyme

why

an

rate

Enzymes

catalyse

in

substrate

reactions

acts

which

complementary

and

key’

enzyme

key’

model

will

and

active

model

act

to

of

site

to

enzyme

explain

what

is

only

on

molecules,

action.

explain:

3

one

converted

or

breaking

All

enzymes

molecules.

substrate

enzyme

can

be

used

to

catalyse

a

large

quantity

to

molecules

the

product

either

up

where b

the

.

‘lock

and

increase

reactions.

by

building

down.

are

Part

protein

of

the

reaction

enzyme

occurs

has

of

a

complementary

shape

to

substrate

the c

why

high

destroying

the

temperature

active

stops

site

the

by

heating

enzyme

from

the

enzyme

working

to

substrate

molecule(s).

a

4

The

of

active

the

site

enzyme

substrate

reaction

ts

is

the

part

where

and

tnemelppuS

tnemelppuS

Use

biological

that

chemical

are

2

are

of

2 chemical

one

t

site.

reactions

of

on

will

POINTS

catalysts speed

Enzymes

A

active

QUESTIONS KEY

1

substrate

enzyme’s

the

where

the

occurs.

47

5.2

Factors

affecting

action:

The LEARNING

activity

Carry

the

out

an

effects

enzyme

investigation

of

into

temperature

on

reaction

measuring

substrate

the

activity

Describe

enzyme

the

effects

temperature

on

that

how

is

e.g.

the

is

determined

enzyme

much

used

reaction

time, •

an

temperature

by

measuring

the

rate

of

OUTCOMES the

•

of

enzyme

product

over

a

measured

per

catalyses.

is

period

in

This

formed

of

time.

quantity

of

may

or

by

The

done

either

measuring

rate

product

be

or

is

like

how

the

substrate

by

much

speed

per

of

unit

of

minute.

of

enzyme

Effect

of

temperature

on

enzymes

activity

Explain

the

effects

activity

of

enzymes

is

inuenced

of 6.0

by temperature

on

temperature.

This

graph

shows

enzyme

effect

of

increasing

temperature

nim

the

1–

activity

on

the

rate

of

an

enzyme-catalysed

tcudorp

reaction.

the

can

reaction:

slow

are

use

this

some

from

the

answ er .

say

the

low

temperatures,

10 °C

desc ribin g •

like

at

at

increases

as

the

increases

to

40 °C

etar

alwa ys

your

of

observe

4.0

3.0

2.0

fo

you

grap h

take n

rate

and

noitcaer

is

e.g.

a

graph

TIP •

Whe n

the

/

that

STUD Y

at

gm

Look

5.0

temperature

one,

1.0

gu res

grap h

Here

•

reaches

a

maximum

•

decreases

at

0

40 °C

in

10

at

5.6

mg

min ute

at

high es

greater

t

prod uct

per

•

is

zero

the

than

be

describ e the

tempe rature

enzy mes,

4

aske d

40 °C

and

effec t

and

but

will

explai n,

enzyme.

fungal

•

human

•

some

which

Here

and

plant

are

the

some

maximum

37 °C

enzymes

rate

This

examples

enzymes:

enzymes:

of

the

temperature.

of

is

20 °C

temperature

produced

by

reaction

best

optimum

approximately

(body

of

the

–

bacteria

for

is

for

temperatures:

(see

see

occurs

temperature

page

T opics

use

in

250)

7.5

and

industry:

7.7)

90 °C.

be

saw

in

the

T opic

5.1,

an

enzyme

substrate

molecules.

by

between

molecule

The

shape

is

of

folded

an

into

a

enzyme’s

shape

active

that

site

bonds

different

parts

of

the

molecule.

is

Remember

that

the

shape

into

the

enzyme

of

the

active

site

determines

whether

the

substrate

will

t

on for

the

reaction

to

occur .

in

aske d

At

rst,

will

increasing

increase

have

the

greater

there

are

the

rate.

kinetic

more

temperature

This

is

energy.

chances

of

of

because

They

them

an

enzyme-controlled

enzyme

move

and

around

colliding,

the

substrate

more

reaction

molecules

quickly

substrate

tting

and

into

remem ber the

are

tempe ratures

of

we

of

pH

pH.

active

site

and

a

reaction

taking

place.

protei ns

denat ured

extrem es

by

and

At

higher

together

site,

We

so

say

temperatures

start

the

to

break

substrate

that

catalyse

48

at

optimum

maintained

only

you

enzy mes

are

the

to

inu ence enzy mes. Whe n

high

5.2.1

60 °C.

temperature

accepts

to exp lain ho w thes e fact ors

that

at

•

As

you

60

°C

TIP

may

Paper

50

/

40 °C .

called

Y ou

40

rate

The

STUD Y

30

temperature

Figure

is

20

temperatures

you

the

the

the

no

enzyme

reaction.

bonds

down.

This

longer

has

holding

the

changes

enzyme

the

shape

molecule

of

the

active

no

longer

ts.

been

denatured

and

it

can

tnemelppuS

tnemelppuS

The •

PRACTICAL

Investigating

Amylase

is

changes

iodine

iodine

an

the

enzyme

like

not

temperature

breaks

down

blue-black.

change

starch

When

colour.

on

enzyme

to

starch

Draw

a

action

maltose.

is

broken

table

for

Starch

down,

your

this.

temperature

and

will

of

that

solution

solution

results

effect

starch

at

which

was

kept

/

amylase

time

°C

taken

fully

for

broken

starch

down

/

to

be

min

Figure

5.2.2

T esting

starch

the

in

solution

for

iodine.

3

1

Put

A,

5cm

B,

C,

of

starch

and

solution

into

each

of

four

test

tubes

labelled

D.

2

Put

test

tube

A

into

the

refrigerator

3

Put

test

tube

B

into

a

test

4

Put

test

tube

C

into

a

water

tube

and

note

the

temperature.

and

note

the

temperature.

rack

bath

at

about

35°C

and

note

the

temperature.

5

Put

test

tube

D

into

a

water

bath

at

about

80°C

and

note

the

temperature.

3

6

Collect

7

Put

a

of

10cm

drop

spotting

of

amylase

iodine

solution

solution

into

in

a

clean

each

of

boiling

the

wells

tube.

on

a

tile.

3

8

Add

2cm

note

9

At

the

amylase

test

iodine

When

solution

to

each

of

the

four

tubes

and

KEY

time.

two-minute

the

10

of

intervals

solution

solution

the

from

on

each

the

amylase

use

a

clean

test

tube

spotting

solution

pipette

and

to

remove

add

it

to

a

some

drop

of

1

of

has

broken

down

all

the

Increasing

of

tile.

POINTS

an

iodine

solution

will

no

longer

turn

blue-black.

temperature

reaction

increases

reaction

up

to

a

the

rate

of

maximum,

starch which

the

the

enzyme-controlled

They

occurs

at

the

optimum

will temperature.

brown.

on

What

the

does

this

tell

you

about

the

effects

of

amylase?

This

is

because

energy

SUMMARY

QUESTIONS

is

number

enzyme

1

a

Sketch

a

graph

temperature

to

on

show

the

rate

the

of

effect

a

of

increasing

reaction

catalysed

enzyme,

such

as

salivary

Describe,

in

words,

what

is

Suggest

what

each

reaction

catalysed

of

by

the

shown

a

following

human

At

higher

by

your

a

temperature

below

b

a

temperature

of

c

a

temperature

of

temperatures

the

would

do

of

reaction

decreases

graph.

to

the

rate

of

it

stops

acting

as

a

catalyst.

enzyme: This

a

between

substrate

amylase.

until

2

collisions

and

kinetic

greater

a

rate

b

of

a

molecules.

by

2 human

greater

causing

tnemelppuS

light

temperature

tnemelppuS

stay

10 °C

is

shape

37 °C

due

of

to

the

means

the

longer

t.

a

change

active

site

substrate

The

in

can

enzyme

the

which

is

no

now

50 °C

tnemelppuS

denatured.

3

Use

the

‘lock

enzymes

are

and

key’

model

denatured

at

to

high

explain

what

happens

when

temperatures.

49

5.3

Enzymes

The LEARNING

Describe

enzyme

•

Carry

the

effects

of

pH

enzymes

on

i.e.

action

out

the

an

at

a

that

low

of

pH

tnemelppuS

Explain

active

in

the

is

can

be

present

affected

stomach

work

in

the

by

the

best

stomach,

pH

in

acidic

so

of

the

conditions,

pH.

bile

is

that

present

are

in

active

the

rst

here

part

work

of

best

the

in

small

alkaline

intestine,

so

conditions,

the

i.e.

at

a

activity

the

effects

of

pH

pH.

on

Most enzyme

enzymes

work

best

inside

cells

where

the

conditions

are

neutral.

action

The

optimum

Enzymes

Enzymes

Many

pH

of

and

are

these

is

therefore

about

pH

7.0.

pH

inuenced

enzymes

enzymes

work

by

best

the

in

pH

of

neutral

their

surroundings.

conditions,

but

some

work

best

substrate

enzyme

in

Enzyme

–

the

acidic

conditions

and

some

in

alkaline

conditions.

denatured

substrate

fits

Figure

are

acid

on

high

•

reaction

Hydrochloric

investigation

effects

enzymes

enzyme

enzyme-controlled

surroundings.

Alkaline

into

of

pH

OUTCOMES its

•

rate

and

no

active

longer

site

Look

and

at

the

graph

in

Figure

5.3.2

showing

the

action

of

enzymes

X

Y .

5.3.1

•

Enzyme

•

The

•

Up

X

works

optimum

best

pH

for

at

pH

2.0

enzyme

Y

–

is

that

pH

is

its

optimum

pH.

8.0.

6.0

to

pH

2.0

the

rate

of

reaction

increases

for

enzyme

X

and

then

5.0

between

pH

2.0

and

pH

5.5

it

decreases.

There

is

no

reaction

above

1–

fo

tcudorp

noitcaer

nim

pH

5.5.

4.0

•

3.0

Between

Y

and

pH

then

gm

etar

reaction

4.5

and

between

below

pH

pH

pH

4.5

8.0

the

8.0

and

rate

and

pH

above

of

reaction

10.0

pH

it

increases

decreases.

for

There

enzyme

is

no

10.0.

2.0

enzyme

X

enzyme

Y

As

we

vital

0

0

1

2

3

4

5

6

7

8

9

10

11

pH

if

have

it

is

structure

seen,

to

of

the

three-dimensional

function.

the

Many

enzyme

are

of

the

weak

shape

chemical

bonds.

If

of

an

bonds

these

enzyme

holding

bonds

is

the

that

acid

Figure

5.3.2

STUD Y

TIP

hold

the

enzyme

then

the

shape

reaction

is

that

substrate

At

is

say

kille d’.

no t

enzy me

Enzy mes

orga nism s.

are

pro te in

T he

co rrec t

dena tured.

50

‘the

are

T hey

mo lec ules.

wo rd

to

use

is

at

the

these

can

Never

molecule

of

values

affect

the

zero,

the

the

of

rate

extremes

denatures.

the

of

in

active

shape

of

molecules

pH

of

its

shape

site

the

will

enzymes

reaction

pH

are

can

be

active

no

are

an

by

altered.

site

longer

has

the

changed

Small

denaturing

enzyme

changes

When

in

pH,

rate

so

of

much

t.

denatured.

without

range

broken

changes

the

becomes

in

enzyme,

unstable

pH

but

and

tnemelppuS

/ 1.0

PRACTICAL

The

effect

Egg

white

egg

pH

on

contains

investigate

in

of

the

white.

a

lot

effect

You

the

of

will

action

of

protein.

protease

also

of

see

a

In

this

from

how

protease

the

pH

experiment

stomach

affects

the

you

on

will

the

way

protein

the

enzyme

works.

1

Set

up

a

water

bath

2

Using

syringe

put

3

Add

2 cm

4

Add

2 cm

at

40 °C

and

label

three

test

tubes

1–3.

3

a

of

5 cm

egg

white

into

each

test

tube.

3

of

sodium

of

water

carbonate

(an

alkali)

to

tube

1.

This

is

a

model

of

protease

that

breaks

3

to

tube

2.

down

proteins

intestine.

It

to

amino

works

best

acids

at

a

in

pH

the

of

small

about

8.5

3

5

Add

2 cm

6

Compare

each

of

the

tube

to

dilute

hydrochloric

pH

each

of

dip

into

test

the

acid

tube

by

solution

to

tube

using

and

a

then

3.

and

clean

touch

glass

the

rod

pH

at

37 °C.

for

test KEY

POINTS

paper.

7

Place

all

three

8

Add

9

Compare

test

tubes

in

the

water

bath

at

40 °C

for

ve

1

minutes.

Most

one

enzymes

value

of

work

best

at

pH.

3

of

protease

to

each

test

tube.

2 the

appearance

of

the

tubes

every

minute

until

At

either

side

optimum is

no

further

the

table

pH

value,

enzyme

At

some

shape white

appearance

+

changes 5

plus:

values

of

the

of

pH

active

the

site

after

pH

tube protease

decreases.

below. 3

egg

their

change. activity

Complete

of

there

tnemelppuS

1 cm

so

that

substrate

minutes

molecules

no

longer

t.

3

2 cm

of

sodium

1 carbonate

solution

3

2

2 cm

of

water

3

2 cm

of

3 hydrochloric

SUMMARY

1

Sketch

the

a

QUESTIONS

graph

optimum

2

Use

3

An

the

‘lock

to

pH

and

investigation

Eight

The

test

acid

tubes

show

is

7.0

key’

was

were

concentration

of

the

and

effect

there

model

carried

set

up

to

reducing

increasing

no

explain

out

at

of

is

a

into

activity

what

the

sugar

pH.

a

Plot

a

b

Explain

of

graph

the

reducing

to

show

effects

of

sugar

these

pH

produced

of

was

the

pH

pH

They

(product)

pH

concentration

on

happens

effects

different

pH

below

rate

4.0

when

on

were

then

of

and

an

enzymes

the

action

incubated

estimated.

4.0

5.0

6.0

1

12

26

enzyme-catalysed

none

are

of

in

above

The

enzyme

water

bath

results

are

reaction,

where

10.0.

denatured

the

a

pH

at

extremes

amylase

at

30 °C

shown

6.5

7.0

8.0

9.0

32

33

27

13

on

for

in

of

pH.

starch.

1

the

hour .

table.

10.0

5

results.

on

the

action

of

amylase

in

this

investigation.

51

PRACTICE

QUESTIONS

1

the

Which

is

correct

statement

about

enzymes?

5

In

an

enzyme-catalysed

binds A

Enzymes

are

biological

catalysts

to

B

inside

Enzymes

only

C

are

outside

catalysts

function

Enzymes

and

are

inside

are

used

they

catalyse.

up

of

protein

Enzymes

only

substances

catalyse

are

made

the

by

cells

reactions

reactions

broken

substrate

down

in

into

site

B

complementary

as

C

reaction

D

substrate

site

site

site

2)

[1]

which

smaller

6

Albumen

and

in

1)

is

the

at

a

protein

blood.

75 °C

A

and

found

solution

then

in

egg

of

added

white

protease

to

a

was

solution

of

[1] albumen.

The

the

molecule

the:

active

kept

2

enzyme

that

molecules.

(Paper

as

A

(Paper D

reaction,

the

that

cells.

during

of

cells.

made

continually

they

part

that

known function

the

equation

shows

a

reaction

catalysed

by

No

reaction

occurred.

an Which

is

the

most

likely

explanation?

enzyme.

A

75 °C

is

below

the

optimum

temperature

lipase of fat

+

water

→

fatty

acids

+

B

The

progress

of

the

reaction

the

protease

glycerol

can

be

albumen

cannot

be

broken

down

by

followed proteases

by

detecting

the

decrease

in

pH.

This

is C

the

protease

D

there

is

denatured

because:

A

fat

is

an

acidic

the

B

fatty

acids

they

lower

are

one

of

the

products

the

no

D

the

reaction

is

a

1)

Starch

and

kinetic

energy

for

2)

[1]

stops

when

the

pH

decreases

7

The

diagram

possible

shows

an

enzyme

and

four

substrates.

reactant A

(Paper

enough

pH

further

water

not

reaction

and

(Paper

C

was

substance

C

B

D

[1]

enzyme

3

together

human

at

salivary

different

temperature

will

amylase

were

temperatures.

give

the

fastest

mixed

Which

rate

of

starch

digestion?

A

20 °C

B

60 °C

C

37 °C

Which

of

substrate D

(Paper 1)

shown

is

the

enzyme?

pH

2)

of

enzyme-controlled

reactions

changed

affect

the

from

rate

of

pH

the

A

always

increases

B

always

decreases

C

has

effect

D

may

the

(Paper

no

change

on

the

7

to

pH

8.

How

does

The

optimum

reactions?

the

the

the

rate

rate

rate

rate

or

have

no

temperature

effect

reaction

is

the

for

an

enzyme-

temperature

at

which:

this

on

rate.

1)

[1]

may catalysed

52

substances

this

[1]

8 The

be

for

10 °C

(Paper

4

the

[1]

A

least

B

most

C

the

D

the

(Paper

substrate

product

rate

of

is

broken

is

down

formed

reaction

reaction

2)

is

is

at

completed

its

in

fastest

the

longest

time

[1]

9

(a)

Explain

the

following

statements.

A

(i)

Only

small

required

(ii)

Cells

quantities

inside

make

of

enzymes

cells.

many

B

are

[2]

different

types

of

1

3

enzymes,

The

the

table

shows

relative

solution

at

not

the

activity

pH

just

one.

effect

of

an

of

[2]

temperature

enzyme

kept

in

on

C

a

7.

2

relative temp

/

°C activity

5

4

15

8

(a)

State

(b)

Use

the

the

when

25

16

35

32

45

30

55

7

(c)

(d)

the

when

(b)

Explain

why

kept

the

at

all

the

same

reaction

mixtures

were

pH?

Draw

a

graph

(d)

Describe

of

the

results

in

the

table.

results

Hydrogen

shown

in

the

graph. [4]

(a)

model

to

is

what

a

happens

reaction.

known

explain

enzyme

what

molecule

temperatures

peroxide

is

produced

metabolism.

as

[4]

‘lock

or

happens

changes

extremes

of

shape

pH.

[4]

is

a

very

toxic

substance

The

by

cells

enzyme

peroxide

and

as

part

of

catalase

is

found

their

breaks

in

down

organisms

in

3) all

10

model

[3]

4)

hydrogen (Paper

describe

catalyses

C.

[6] which

the

and

[2] 12

(c)

the

B

[2]

the

high

(Paper

to

enzyme

why

A,

key’.

Use

in

of

diagram

an

Explain

and

names

Explain

the

following

kingdoms.

statements.

catalase (i)

Amylase

digests

starch,

but

proteases Hydrogen

do

not.

Human

enzymes

catalyse

reactions

student

but

not

at

73 °C.

table

shows

enzyme

kept

35 °C.

the

in

relative

solutions

activity

of

investigated

in

yeast

by

the

activity

measuring

of

the

the

enzyme

volume

of

a

different

collected

over

time.

The

graph

of

shows

the

results.

pH 3

human

water

[2] oxygen

The

+

at catalase

37 °C,

oxygen

[1]

A (ii)

peroxide

mc

at

7

/

relative

3

detcelloc

pH

activity

5

32

9

10

emulov

7

fo

14

negyxo

5

6

5

4

3

2

1

×

0

0

11

20

40

60

80

time

(a) (b)

Explain

why

all

the

reaction

mixtures

Use

at

35 °C?

Draw

a

graph

Describe

the

results

catalase

of

the

results

in

the

table.

140

on

shown

to

hydrogen

describe

the

[4]

Explain

results

shown

in

the

why

catalyse

catalase

the

is

the

breakdown

only

of

enzyme

hydrogen

graph. [4] peroxide.

(Paper

3)

(c)

Describe

catalyses 11

The

diagram

reaction.

effect

peroxide.

[6] to

(d)

120

s

[3]

(b) (c)

the

/

were of

kept

100

4

shows

an

[2]

what

a

happens

reaction.

when

an

enzyme

[4]

enzyme-catalysed

(Paper

4)

53

Plant

nutrition

6.1

Photosynthesis

The LEARNING

process

When

•

•

Dene

State

the

the

term

Describe

leaf tnemelppuS

•

for

State

photosynthesis

word

how

equation

for

look

round,

green

energy

to

into

to

test

a

green

starch

the

you

at

cells

Photosynthesis

raw

is

called

carbon

sugars.

This

the

materials

dioxide

process

process

using

Describe

the

by

can

role

of

chlorophyll

carbon

be

dioxide +

balanced

+

equation

This

is

full

of

not

that

TIP

tnemelppuS

this

is

there

of

the

balanced

write

it

out.

are

the

atoms

their

see

use

many

light

surroundings

photosynthesis

plants

make

carbohydrates

light.

in

of

and

this

word

equation:

chlorophyll

glucose

equation

6H

for

photosynthesis

and

a

case.

H

6

There

different

photosynthesis

are

oxygen

is:

C

that

+

chlorophyll

O

suggests

the

by

energy

transferred

sure

you

plants

many

is

one

reactions

in

O 12

+

6O

6

simple

2

reaction.

photosynthesis,

each

enzyme.

chloroplasts.

Light

Make

from

2

This

catalysed

STUDY

from

Green

water

2

are

called

summarised

chemical

6CO

cells

microscope

water

which

energy

light

plant

the

photosynthesis

The

These

and

is

light

•

under

chloroplasts.

chemical Photosynthesis

for

leaf

structures

convert

simple

from

balanced

equation

some

photosynthesis

photosynthesis

•

of

OUTCOMES

equation

when

you

Make

same

form

the

The

becomes

sure

are

the

carbon,

As

by

to

a

is

a

water

used

to

are

the

bond

Glucose

as

chemical

from

is

result,

starch

chlorophyll.

as

ions

chemical

produced.

converted

energy

hydrogen

carbohydrate.

number

absorbed

chlorophyll

carbohydrates

process

oxygen.

is

by

used

to

in

simple

store

of

energy

to

the

energy

in

carbon

simple

that

During

leaves

that

produced;

and

and

to

chlorophyll

sugars

is

ions

dioxide

by

is

reactions

hydrogen

absorbed

sugar

light

the

dioxide.

into

reduce

from

drive

carbon

water

energy

energy

one

and

split

light

The

energy

other

it

is

parts

of

plants.

hydrogen

and

both

of

sides

oxygen

the

on

Photosynthesis

arrow.

that

feed

show

that

oxygen

carbon

dioxide

on

where

in

it

provides

plants

oxygen

its

is

is

own

used

energy

directly

or

produced

respiration

by

other

for

plants

indirectly

as

or

it

a

and

(see

for

by-product.

may

all

page

diffuse

other

244).

The

out

plant

into

organisms

The

equations

may

the

use

atmosphere

organisms.

Sun

oxygen chlorophyll

Investigating

photosynthesis

light traps

light

energy

energy

Green

if

too

a

very

plants

much

make

sugar

simple

is

sugars

dissolved

in

from

the

carbon

cell

sap

of

dioxide

plant

and

cells

water .

it

However ,

would

make

sugar

cells

to

concentrated

by

osmosis

make

very

together

effect

starch

Figure

6.1.1

A

simple

overview

photosynthesis.

54

of

out

on

in

to

and

thick

form

leaves.

cause

cell

Y ou

As

you

This

the

walls.

larger

osmosis.

whether

solution.

will

cells

T o

starch

can

to

see

iodine

in

has

so

this,

water

much

glucose

which

solution

Topic

been

make

swell

prevent

molecules

use

photosynthesis

would

6.2

are

to

we

that

in

they

insoluble

for

use

or

from

the

this

not.

other

would

molecules

test

can

happening

move

are

and

need

linked

have

presence

test

to

no

of

nd

tnemelppuS

6

PRACTICAL

T esting

a

leaf

for

starch

Safety:

eye 1

Submerge

This

it

kills

easier

a

leaf

in

the

leaf

as

to

extract

boiling

it

water

destroys

the

for

one

wear

At

this

boil

3

Put

point,

the

the

turn

is

ethanol

ammable

minute.

membranes,

making

chlorophyll.

boiling

2

Safety:

protection

off

any

Bunsen

burners

used

water

ethanol

to

water.

leaf

into

chlorophyll

is

a

test-tube

extracted

by

of

ethanol.

dissolving

The

into

the

ethanol.

4

Stand

the

test-tube

in

a

beaker

of

hot

water

for turn

about

10

off

Bunsen

burner

minutes.

iodine

5

Wash

the

ethanol

makes

6

some

7

If

and

it

Spread

leaf

the

leaf

stays

to

leaf

drops

cold

water.

rehydrates

easy

the

in

of

out

there

is

SUMMARY

QUESTIONS

1

complete

and

oxygen

on

plants

chloroplasts

for

this

made

make

the

process

in

the

are

leaves

white

on

softens

surface

is

own

leaves

and

present.

and

put

If

it

Safety:

using

chlorophyll

food

traps

these

careful

2

To

nd

carry

of

this

out

out

a

if

process

is

the

by

the

are

.

Green

Sun’s

.

.

changed

gas

photosynthesis

to

burn

yourself

dioxide

in

Raw

Simple

to

.

the

materials

sugars

The

are

waste KEY

product

not

words:

carbon

and

some

be

photosynthesis

carbon

and

it

starch.

water

their

the

it.

sentences

starch

of

which

starch

no

the

energy

Green

a

solution

blue-black,

red/brown

Copy

leaf

removes

out.

at

iodine

goes

the

spread

This

has

POINTS

.

taken

place

in

a

leaf

we

can

1

test.

Chlorophyll

absorbs

energy

is

that

used

light

in

photosynthesis. Copy

out

correct

the

stages

reason

on

listed

the

on

the

left.

Match

each

one

with

the

right.

2

Photosynthesis

by Stage

in

test

which

the

leaf

in

cold

water

to

test

for

to

soften

to

remove

raw

the

leaf

add

drops

in

ethanol

iodine

solution

the

ethanol

the

glucose

leaf

rehydrate

using

from

light.

Carbon

the

dioxide

and

water

and

are to

materials

it

3 of

process

starch energy

boil

the

make

Reason

from wash

is

plants

the

raw

materials

for

leaf

photosynthesis. dip

the

leaf

in

boiling

water

to

extract

the

chlorophyll

4 3

Write

out

the

word

equation

for

photosynthesis

and

The

are the

raw

materials

and

Using

only

information

in

this

topic,

explain

why

plants

to

our

of

and

photosynthesis

oxygen.

A

leaf

that

has

been

exposed

are to

vital

glucose

products.

5 4

products

identify

light

will

give

a

positive

survival. test

for

starch.

55

6.2

What

is

needed

for

photosynthesis?

The LEARNING

requirements

Green

•

List

the

raw

needed

•

for

Describe

materials

that

plants

need

for

the

following

in

order

to

carry

out

photosynthesis:

•

light,

which

provides

•

chlorophyll,

energy

for

the

process

photosynthesis

the

that

dioxide

photosynthesis

are

experiments

chlorophyll,

and

light

are

a

green

pigment

that

absorbs

the

energy

from

light.

that Chlorophyll

prove

for

OUTCOMES

is

in

the

chloroplasts

of

the

leaf

carbon

•

carbon

•

water,

dioxide,

which

diffuses

into

the

leaves

from

the

air

needed

photosynthesis

Water

which

and

If

a

needed

plant

them

To

as

be

starch.

certain

leaves

the

dark

is

then

that

given

we

out

If

are

cannot

the

no

all

the

that

plant’s

raw

roots

from

materials

chlorophyll,

the

of

as

will

investigation

48

at

things

(It

the

hours.

is

that

plant

is

is

for

carbon

make

the

soil.

photosynthesis.

dioxide

it

is

to

water

do

so

a

you

sugars

will

not

must

and

this,

a

and

make

make

light

plant

that

plant

can

for

the

water

for

so

hardly

store

starch.

sure

is

left

de-starching.

except

show

by

it

we

called

needs

required

is

To

simple

then

valid,

start.

This

difcult

water

the

it

photosynthesise

starch

testing.

most

are

the

photosynthesis

least

photosynthesis,

things;

it

that

at

by

photosynthesis.

have

for

dioxide

demonstrate

for

carries

the

absorbed

carbon

Investigations

are

is

that

in

The

plant

substance

is

needed

many

‘take

it

for

other

away’.)

PRACTICAL

Showing

T ake

as

a

a

that

de-starched,

leaves

is

important

affect

to

understand

photosynthesis

in

the

order

to

factors

that

variegated

needed

plant

for

photosynthesis

such

are

means

white

chlorophyll

some

because

parts

there

of

is

the

no

there.)

increase

Place crop

is

geranium.

(‘Variegated’

It

chlorophyll

the

plant

in

sunlight

for

about

6

hours.

yields.

Draw

one

leaf

to

show

the

white

and

green

parts.

Now

STUD Y

TIP

the

test

this

starch

variegated

test

described

leaf

in

for

starch

T opic

using

6.1. Variegated

No te

and

that

carb on

wate r

mater ials;

sour ce

no t

a

of

are

the

ligh t

dioxid e

raw

is

energy ,

the

and

Y ou

should

The

green

that

parts

photosynthesis

only

contain

to

make

the

green

parts

chlorophyll

of

the

which

is

leaf

needed

blue-black.

for

starch.

white

parts

contain

no

chlorophyll,

so

no

photosynthesis

mater ial. occurs

here.

Therefore

the

starch

the

white

parts

of

the

leaf

give

a

negative

result

with

test.

Safety:

56

go

leaves.

is The

raw

nd

geranium

wear

eye

protection

STUD Y

Showing

for

You

that

carbon

dioxide

and

light

are

Y ou

needed

photosynthesis

could

own

prove

food

except

by

that

a

carbon

it

dioxide.

mus t

explai n

plant

providing

TIP

needs

with

Then

carbon

everything

test

to

see

if

dioxide

it

needs

it

has

to

for

make

in

we

to

need

these

experim ents .

photosynthesis

made

able

why

cont ro ls

its

be

starch.

PRACTICAL

Showing

1

T ake

a

that

de-starched

absorbs

2

Leave

carbon

carbon

the

plant

described

in

dioxide

plant.

dioxide.

in

the

Topic

needed

Enclose

(Soda

light

6.1.

is

for

The

a

leaf

it

in

lime

a

for

plastic

absorbs

few

hours.

should

photosynthesis

bag

Test

show

with

carbon

a

a

a

chemical

that

dioxide.)

leaf

negative

for

starch

result

for

as

the

plastic

starch

bag

test.

Deprived

make

of

carbon

dioxide

the

leaf

is

unable

to

photosynthesise

and

starch.

soda

lime

elastic

band

A

control

the

soda

carbon

can

This

dioxide

dioxide

Y ou

experiment

lime.

that

also

should

means

removed.

caused

show

the

that

a

be

the

Then

lack

we

of

plant

set

plant

up

in

can

starch,

needs

in

exactly

the

be

sure

and

light

the

control

it

not

to

same

was

the

keeping

carry

way

experiment

out

but

does

absence

the

plant

without

not

of

have

carbon

inside

the

plastic

bag.

photosynthesis.

PRACTICAL

Showing

that

light

is

needed

for

photosynthesis

aluminium

1

T ake

a

de-starched

plant.

Cover

part

of

the

leaf

with

some foil

aluminium

2

Leave

3

T est

the

the

foil

to

plant

leaf

for

of

the

test

leaf

of

the

leaf

that

prevent

in

the

starch

that

light

light

as

were

for

getting

a

few

described

left

in

through.

hours.

T opic

uncovered

6.1.

go

Only

the

blue-black.

parts

The

parts starch

carry

out

covered

photosynthesis

SUMMARY

1

were

did

and

so

not

receive

could

not

light

make

and

could

no

Describe

b

Explain

how

why

show

that

c

What

is

d

Describe

you

it

is

would

de-starch

necessary

plants

need

to

light

use

to

a

a

plant.

de-starched

carry

out

plant

to

photosynthesis.

KEY a

variegated

how

carbon

you

could

dioxide

POINTS

leaf?

carry

out

an

investigation

to

show 1

is

needed

for

Plants

need

in State

whether

the

following

light,

chlorophyll,

photosynthesis. carbon

2

starch

starch.

QUESTIONS

a

that

present

not

statements

are

true

or

dioxide

order

to

and

carry

water

out

false.

photosynthesis. a

Plants

get

all

b

Plants

need

their

food

from

the

soil.

2 chlorophyll

to

carry

out

We

can

light, c

Water

d

Leaves

for

photosynthesis

is

are

de-starched

absorbed

give

a

to

see

through

the

chlorophyll

blue-black

colour

with

are

needed

Explain

what

is

by

for

not

giving

iodine. plants

3

carbon

when photosynthesis

tested

that

and

leaves. dioxide

that

test

photosynthesis.

meant

by

a

control

experiment

each

testing

of

leaves

these

for

and

starch.

57

6.3

Products

of

photosynthesis

The LEARNING

products

and

•

State

the

products

in

outline

that

how

show

they

the

are

used

procedures

oxygen

of

the

is

such

as

glucose,

of

the

glucose

•

Some

of

the

glucose

in

•

Some

for

of

make

use

the

cell

Glucose

plant

needs

for

food

are

made

in

the

leaves.

is

used

for

respiration

in

the

leaf.

in

is

the

changed

future,

into

e.g.

at

starch

and

stored

in

the

night.

is

plant

•

Plants

get

•

Glucose

•

Plants

also

to

to

make

sucrose

phloem

be

(see

converted

nitrogen

and

Sugars

The these

the

need

energy

used

cellulose,

which

is

needed

to

by

nitrate

and

Topic

to

other

absorbing

are

used

transported

to

to

other

parts

of

8.4).

substances:

nitrate

form

ions

amino

from

the

acids,

soil.

which

are

built

proteins

enzymes

•

is

converted

in

can

into

glucose

walls.

Glucose

up

in

a

that

produced

food

which

Some

the

makes

sugars

•

•

proteins

and

are

in

for

growth

and

cell

repair

and

for

making

hormones.

converted

to

oils,

which

are

an

efcient

way

to

store

seeds.

importance

of

photosynthesis

wheat

plants.

Think

what

soya

STUD Y

sugars,

in

photosynthesis

Photosynthesis

simple

and

leaves Describe

are

are

photosynthesis

plants.

•

photosynthesis

oxygen.

Most

formed

of

OUTCOMES

TIP

If

about

you

beans

you

eat

the

eat

food

comes

and

meat

you

have

from

eaten

plants

like

in

the

rice,

last

24

maize,

hours.

wheat,

A

lot

of

potatoes,

nuts.

or

sh

then

that

comes

from

animals

that

have

eaten

plants.

Mak e

conc

how

a

diag ram

map

plan ts

simpl e

to

use

a

you

learn

mad e

T his

them

Oxygen

Some

is

58

is

is

is

a

a

by-product

product

used

upon

plants?

so

why

are

made

from

plants.

of

photosynthesis

by

the

of

photosynthesis.

plant’s

It

respiration,

is

but

not

the

usually

main

there

product.

is

most

it

is

diffuses

called

a

out

of

the

leaves

into

the

more

than

atmosphere.

by-product.

products

provide

more

about

also

timber

depends

is

needed,

Plants

food

margarine

all.

Plants

this

and

will

Plant

of

oil

in

That

much

cooking

the

is

How

like

show

Oxygen suga rs

pho to synt hesis.

help

or

Products

ept

and

us

with

this

on

provide

a

cotton.

including

digitalis,

extracted

from

the

our

food

page

range

Many

which

rosy

and

of

raw

food

materials

medicines

is

also

for

our

livestock.

There

248.

a

heart

periwinkle

have

drug,

from

for

been

and

industry,

such

discovered

two

in

anti-cancer

Madagascar.

as

plants

drugs

Plants

are

the

dominant

organisms

in

almost

all

environments.

As DID

such

they

provide

rainforests

support

make

more

habitats

up

than

only

half

for

6%

the

animals

of

the

and

microorganisms.

Earth’s

world’s

land

species

of

surface,

animals

but

and

YOU

Plants

they

plants.

provide

everything

works The

concentrations

of

gases

in

the

atmosphere

are

kept

constant

Without

green

plants,

the

concentration

of

of

in

the

air

would

increase

and

the

concentration

of

art.

Lignum

The

for

of

to

that

the

grows

in

is

the

hardest

wood

used

oxygen Fast-growing

trees

decrease. provide

is

PRACTICAL

Oxygen

1

timber

wood

vitae

commercially. would

with

construction

carbon Jamaica

dioxide

us

from

by tree

photosynthesis.

KNOW?

The

Set

the

collect

in

of

as

fossil

a

biofuel

form

fuels

of

(see

that

energy,

page

282).

photosynthesis

apparatus

bubbles

wood

renewable

unlike

produced

up

a

to

gas

gas

rich

in

oxygen

given

off

by

the

Canadian collecting

pondweed

(Elodea

canadensis).

light Canadian

A

lamp

provides

the

light

STUD Y

pondweed

energy

that

the

plant

Plasticine

Carbon

in

the

dioxide

water.

sodium

is

to

to

dioxide

Rem embe r

dissolved

Add

of

some

hydrogencarbonate

powder

This

is

the

water

make

in

the

sure

TIP

needs.

and

that

the

in

stir

to

there

dissolve.

is

always

by

the

respira tion.

carbon

that

water.

some

produc ed If

there

is

not

enough

carbon

dioxide

then

produc ed

the

down.

plan t

T his

is

fo r

its

means

oxyg en

is

no t

photosynthesis

into slows

some

pho to synt hesis

used

enough

that

oxyg en

relea sed

atmos phere

or

wate r .

2

Place

gas

3

Test

the

to

apparatus

the

gas

Standing

dioxide

for

the

the

oxygen

funnel

dissolved

photosynthesis

A

in

light

and

allow

a

few

hours

for

the

collect.

water

plant

downward

in

on

the

does

is

with

glowing

plasticine

water

not

used

a

slow

because

displacement

of

to

splint.

gives

reach

a

gap

the

to

allow

pondweed

carbon

so

down.

it

is

easy

to

collect

the

gas

by

water.

KEY

SUMMARY

1

QUESTIONS

POINTS

Products

include

1

What

a

are

the

glucose

following

b

starch

products

c

made

cellulose

in

d

plants

used

protein

e

to

for?

photosynthesis

glucose,

make

amino

oils

of

starch,

acids

which

is

used

cellulose,

(and

then

proteins). 2

a

Describe

as

a

how

you

by-product

practical

of

would

show

that

photosynthesis.

plants

produce

Remember

to

oxygen

include

all

2

Photosynthesis

it

details.

provides

medicines; b

How

would

you

show

that

light

is

necessary

for

us

it

is

important

with

helps

food

to

as

and

keep

oxygen

constant

concentrations

of

production?

carbon

3

Plants

are

important

because

they

provide

us

food

Give

three

b

fuels

examples

c

of

building

plants

materials

that

provide

d

us

and

oxygen

in

with: the

a

dioxide

atmosphere.

medicines

with

each

of

these.

59

6.4

Rate

When LEARNING

plants

Describe

how

effect

varying

of

temperature

dioxide

rate

of

to

investigate

light

and

the

much

by

carbon

concentration

the

products

intensity ,

on

photosynthesis

describe

carry

photosynthesis

out

photosynthesis

they

produce

oxygen.

We

can

OUTCOMES determine

•

of

the

as

by

results

that

starch

nding

use.

and

how

can

are

or

out

Instead,

we

or

slow

oxygen

the

an

is

dioxide

in

conditions

be

Starch

as

such

as

done

but

it

oxygen

by

the

light

is

is

described

measuring

concentration

occurs

by

an

be

in

T opic

rate

of

is

6.3.

method

much

This

oxygen

is

to

easier

done

produced.

temperature

of

the

how

measured

easy

produced

volume

the

can

not

intensity,

inuence

measuring

measuring

production

mass,

much

plant

by

can

dry

how

aquatic

or

This

made.

change

bubbles

Environmental

photosynthesis

produced.

measuring

use

counting

carbon

fast

and

photosynthesis.

PRACTICAL

Photosynthesis

Y ou

the

can

use

rate

1

Cut

2

Put

of

a

this

and

light

apparatus

intensity

to

measure

the

effects

of

light

intensity

Canadian

on

photosynthesis:

piece

of

pondweed

about

5 cm

in

length.

stream

a

paperclip

on

the

pondweed

to

stop

it

oating

to

the

surface.

of

bubbles

3

Put

a

lamp

close

to

the

plant

and

measure

the

distance

between

the metre

plant

4

and

Count

times

5

the

and

Repeat

The

less

number

this

the

of

of

bubbles

lamp

is

close

photosynthesis

energy

bubbles

the

for

the

released

over

5

minutes.

with

the

should

to

is

plant

the

high.

and

lamp

at

decrease

plant

As

the

the

the

rate

different

as

of

sis ehtnysotohp

of

In

the

light

lamp

distance

intensity

is

moved

graph

are

dark

very

fo

the

rate

as

the

the

This

away

some

plant.

lamp

gives

the

results

intensity

is

no

and

the

light

the

plant

plant

lots

intensity

etar

investigating

an

the

oxygen

intensity

increase

energy

on

of

of

increases.

energy

decreases;

experiment

rate

of

photosynthesis.

of

light

not

the

so

the

there

is

any

available

the

effect

At

further .

light

The

until

the

of

different

the

plant

for

intensities

rate

at

a

Increasing

to

measure

effect

photosynthesis.

low

produced.

increases

to

of

photosynthesis

certain

the

there

light

light

intensity

intensity

photosynthesis.

light

intensities

it

is

intensity

important

The

effect

light

of

increasing

intensity

on

the

to

T emperature

keep

can

the

be

other

kept

environmental

constant

by

conditions

putting

a

the

same.

thermometer

into

rate

the

beaker

of

water

and

adding

hot

or

cold

water

if

the

temperature

photosynthesis.

changes.

The

by

The

lamp

concentration

adding

dissolve.

60

high.

bubbles

the

from

decreases.

light

does

increases

of

is

there

few

increases

6.4.1

several

between

further

shows

increasing

the

When

Figure

distances

photosynthesis

The

light

Repeat

average.

procedure

of

rule

lamp.

calculate

number

When

rate

the

sodium

This

may

of

give

carbon

off

heat,

dioxide

so

in

hydrogencarbonate

ensures

that

the

plant

the

the

to

will

temperature

water

the

not

can

water

run

out

be

and

of

may

kept

increase.

constant

letting

carbon

it

dioxide.

PRACTICAL

Photosynthesis

and

To

of

nd

the

of

beakers

of

different

lamp

water

kept

at

one

The

to

similar

into

a

range

all

the

of

time

hydrogencarbonate

make

number

of

apparatus

test-tubes

temperatures.

across

distance

Sodium

test-tubes

constant.

placed

different

temperatures

constant.

the

at

are

sure

carbon

bubbles

of

The

10 °C

so

is

about

the

added

dioxide

be

are

used.

put

minimum

to

that

oxygen

can

which

ve

40 °C.

light

to

is

the

The

intensity

water

concentration

produced

inside

at

etar

in

temperature

fo

is

is

effect

pondweed

sis ehtnysotohp

Pieces

temperature

is

different temperature

temperatures

can

be

counted

in

the

same

Figure

Figure

6.4.2

shows

the

results

you

might

/

˚C

way.

expect.

The

6.4.2

The

effect

of

increasing

maximum temperature

rate

of

photosynthesis

occurs

at

the

optimum

temperature.

on

photosynthesis.

actual

temperature

depends

on

the

plant

that

is

used.

Plants

in

lower

temperate

than

those

latitudes

that

grow

have

in

optimum

the

temperatures

The

rate

of

rate

that decreases

grow

the

The

that

are

because

at

chloroplasts

tropics.

high

enzymes

are

temperatures

in

the

denatured.

PRACTICAL

The

same

Adding

water

of

carbon

apparatus

different

increases

dioxide

can

be

the

modied

quantities

the

on

of

for

sodium

concentration

of

rate

this

of

photosynthesis

investigation.

hydrogencarbonate

carbon

dioxide.

At

to

least

the

ve

deewdnop

The

effect

fo

sodium

test-tubes

You

can

intensity

see

that

and

the

the

light

intensity.

photosynthesis.

If

As

is

is

a

different

mass

of

added.

of

the

there

the

with

temperature

effect

photosynthesis

each

must

increasing

same

no

carbon

as

carbon

the

carbon

dioxide

be

effect

dioxide

kept

constant.

dioxide

of

on

the

etar

the

used

increasing

there

can

concentration

be

fo

light

of

be

hydrogencarbonate

The

rate

can

sisehtnysotohp

different

no

carbon

Figure

there

is

an

increase

in

the

rate

of

photosynthesis.

dioxide

concentration

increases

Above

a

6.4.3

The

on

concentration

SUMMARY

the

rate

remains

List

the

the

of

rate

carbon

of

dioxide

photosynthesis.

constant.

QUESTIONS KEY

1

effect

certain

main

environmental

factors

that

inuence

the

rate

POINTS

of 1

The

release

of

oxygen

photosynthesis. from

2

A

student

used

the

distances

25,

30 cm

the

and

and

apparatus

the

24,

shown

numbers

40 cm

and

of

18,

opposite.

bubbles

60 cm

per

and

He

wrote

minute:

10,

20 cm

100 cm

to

down

and

Explain

how

the

student

kept

other

conditions

Make

a

c

Explain

table

of

the

results

and

plot

them

as

a

constant.

line

Light

and

intensity,

the

your

graph

does

not

look

like

Figure

is

used

of

temperature

concentration

dioxide

are

of

three

graph. environmental

why

rate

6.

carbon

b

plants

the

photosynthesis.

and

2

a

aquatic

measure

6.4.1.

that

inuence

factors

the

rate

of

photosynthesis. 3

Describe

carbon

the

effect

dioxide

on

the

rate

concentration,

of

photosynthesis

and

b

increasing

of

the

a

increasing

temperature.

61

6.5

Glasshouse

tnemelppuS

We

LEARNING

•

Dene

•

Identify

the

OUTCOMES

the

term

and

limiting

environmental

in

of

the

enrichment,

use

light

of

•

Temperature

•

Carbon

carbon

and

in

inuences

dioxide

These

to

three

intensity,

the

rate

determines

concentration

enzymes

light

inuence

intensity

is

a

use

to

raw

temperature

of

activity

there

is

and

photosynthesis

energy

material

make

are

the

the

increases

factors

available

of

for

carbon

in

to

enzymes

photosynthesis.

in

the

photosynthesis,

more

of

it

dioxide

plants.

available

chloroplasts.

so

if

for

the

chloroplast

carbohydrates.

limiting

factors

optimum

Limiting temperature

that

Light

conditions

dioxide

seen

•

different

Explain

optimum

factor

explain

photosynthesis

•

limiting

factors

have

concentration

production

factors

glasshouse

systems

A

limiting

short

Light

dioxide sisehtnysotohp

CO

2

is

of

In

of

fo

CO

etar

2

something

it

restricts

does

water

and

energy

this

case

increases

increases

also

see

because

that

the

warm

rate

environment

of

if

in

photosynthesis.

the

is

the

6.5.1

of

plant

temperature

intensity

light

rate

rate

matter

Figure

the

the

photosynthesis

light

In

in

such

processes.

the

not

a

for

present

life

influences

it

photosynthesis.

intensity

0.04%

Y

l o w,

and

shortage

high.

is

that

intensity

intensity

0.4%

factor

supply

and

can

photosynthesis

intensity

becomes

is

the

rate

that

constant

for

as

however

is

very

rate

light

The

Yo u

much

a

be

the

the

f a c t o r.

light

carbon

there

increases.

limiting

the

of

cannot

factor

see

If

lots

because

the

limiting

you

has

rate

can

the

light

X

light

Figure

6.5.1

The

is

f a c t o r,

must

it

dioxide

intensity

effect

intensity

of

be

on

the

photosynthesis

concentrations

of

at

carbon

on

page

certain

reactions

move

61

grap h

and

you

a

the

ruler

from

lines

the

rate

a

grap h

alon g

left

The

substrates

and

more

can

the

rate

see

rate

by

as

enzymes

from

of

when

longer

the

temperature

the

increase

graph

in

photosynthesis

the

increases

enzymes

often

at

(see

to

higher

are

or

limiting

carbon

with

Figure

6.4.2

in

rate

reaches

because

the

To p i c

the

The

of

and

a

and

energy

increase

rate

until

maximum

kinetic

chloroplast

5.2).

increases

a

of

then

the

they

photosynthesis

Here

on

you

because

To p i c

the

enzymes

in

5.3).

Look

at

the

graph

in

Figure

6.5.1.

rate

of

photosynthesis

at

point

X.

rate

of

photosynthesis

at

point

Y .

Light

intensity

Another

is

factor

limiting

is

the

limiting

This

could

be

carbon

the

dioxide

right or

temperature.

or

H o w e v e r,

can

grap h

cond ition s

to

(see

the

trend s

the

temperatures

denatured

to

alwa ys

concentration

the

starts

cons tant .

62

use

ques tion,

follo w

nd

such

no

TIP

patte rns.

rule

that

decreases.

chloroplasts

a

catalysed

Yo u

temperature

decreases

Whe n

else

now

two

collide

answ er

something

is

rate

dioxide.

STUD Y

intensity

increasing

intensity

temperature. of

Light

concentration.

Chemical light

increased.

to

carbon

there

is

you

can

dioxide

more

see

that

the

concentration

of

this

raw

rate

is

of

photosynthesis

increased

material

from

available.

This

remai n

factor

at

Y

is

carbon

dioxide

to

means

when limiting

increases

0.04%

concentration.

0.4%

that

if

as

the

Growers

best

try

to

possible

Conditions

earlier

•

grow

in

•

improve

inside

grow

The

production

the

conditions

•

in

a

yield

for

of

their

crops

photosynthesis

glasshouse

the

places

following

tnemelppuS

Glasshouse

allow

to

plants

by

giving

take

them

the

place.

to:

year

where

they

conditions

would

inside

not

normally

glasshouses

are

grow

well.

controlled.

T emperature

Sunlight

The

heats

glass

up

stops

a

the

lot

inside

of

this

of

the

heat

glasshouse.

from

escaping. Glasshouses

Electric

heaters

Ventilator

•

glass

when

and

lets

light

in

opened

in

sunlight.

intensity

shading

cold

to

weather.

cool

dioxide

Growers

can

gas

pump

dioxide

which

the

too

the

as

glasshouse

of

lighting

low.

Blinds

temperature

carbon

dioxide

concentration.

provides

temperature

Articial

gets

lowers

Carbon

carbon

•

are

used

on

hot

can

temperature,

control

light

limiting

intensity

factors,

and

such

humidity.

days.

Light

The

•

aps

are

carbon

They

in

cold

used

out

also

grow

plants

strong

light

countries.

burn

also

to

very

glasshouses

can

and

be

keep

tropical

into

dioxide

glasshouses

in

can

heat

to

increase

butane

to

raise

or

natural

the

weather.

Water

Many

and

All

glasshouses

humidiers

these

factors

concentration,

process

data

which

are

automatic

ensure

monitored

humidity,

from

SUMMARY

have

the

light

watering

plants

and

sensors

and

always

controlled

intensity

systems

and

control

get

by

using

enough

all

heating,

Water

so

detect

few

staff

changes

ventilation,

QUESTIONS

are

in

lighting

needed.

these

and

Explain

process

2

State

what

of

is

meant

by

the

photosynthesis

which

factors

term

to

would

help

be

limiting

explain

limiting

factor.

your

of

shading

Give

your

reasons

in

each

glasshouse

Use

A

for

factors.

in

crop.

the

carbon

dioxide

Computers

glasshouse.

POINTS

limiting

factor

is

a

factor

the

in

the

in

such

environment

that

is

answer.

photosynthesis

in

short

supply

that

it

the restricts

following.

a

Sensors

limiting

KEY

1 1

misting

water.

computers

temperature

sprinklers

a

life

process,

such

as

case. photosynthesis.

a

Plants

growing

on

a

high

mountainside

early

in

the

2

Light

intensity,

temperature

morning.

and b

Plants

c

A

d

The

e

A

growing

in

a

dense

tropical

forest

at

carbon

dioxide

midday. concentration

eld

of

same

maize

eld

early

late

on

in

a

the

very

bright

morning.

factors

plant

in

a

photosynthesis.

shaded

position

in

a

warm

room.

Carbon

light

dioxide

intensity,

temperature 3

Explain

how

each

of

the

following

can

be

controlled

to

give

optimum

conditions

for

carbon

b

light

dioxide

and

controlled

glasshouse

in

systems

give

optimum

conditions.

concentration This

intensity

humidity

are

growth:

to a

concentration,

in

modern glasshouses

limiting

afternoon. 3

house

of

are

c

ensures

that

the

rate

of

temperature photosynthesis

is

plants

maximum

produce

kept

high

so

yield.

63

6.6

Leaves

The LEARNING

of

•

Identify

a tnemelppuS

•

and

label

the

parts

of

a

and

Leaves

Explain

how

leaf

of

absorbing

into

leaf

of

shape

a

leaf

makes

it

ideally

adapted

to

carry

out

its

functions

OUTCOMES

is

the

out

light

of

for

the

photosynthesis

leaf

and

allowing

gases

to

diffuse

tissues.

have:

structure

adapted

•

a

large

•

a

thin

•

many

surface

area

–

to

absorb

light

rays

for shape

–

so

gases

can

diffuse

in

and

out

easily

photosynthesis

place

•

veins

the

leaf

–

to

nd

–

to

absorb

light

for

the

reactions

that

take

photosynthesis

to

leaf

Inside

To

chloroplasts

in

support

cells,

all

a

and

other

the

to

leaf

take

parts

of

surface

sucrose

the

and

and

to

carry

amino

water

acids

and

away

ions

from

to

the

plant.

leaf

out

how

a

leaf

works

we

can

look

at

the

structure

of

a

typical

leaf. A

leaf

has

an

ideal

shape

for

photosynthesis.

upper

layer

epidermis:

of

cells

with

chloroplasts.

cuticle:

down

waterproof

the

water

layer

lost

by

that

also

straight

cuts

lots

of

Most

mesophyll:

air

spaces

more

rounded

between

cells

vein:

with

and

lower

epidermis:

no

thick

cuticle.

Has

here

contains

that

ions

tiny

holes

called

stomata

(singular:

allow

gases

to

diffuse

in

and

the

water

leaf

tubes

that

and

take

stoma) away

These

to

xylem

bring

lots phloem

of

the

contain

chloroplasts.

vessels

them

mesophyll:

cells

photosynthesis

occurs

of

goes

evaporation

palisade

lots

Light

through

palisade

spongy

single

no

sucrose

and

amino

out acids stoma guard

6.6.1

Leaf

cell

structure.

Some

of

the

internal

features

are

adaptations

for

photosynthesis.

PRACTICAL •

Palisade

upper Looking

at

a

leaf

surface

Observe

a

transverse

a

leaf

on

a

the

are

leaf

to

packed

tightly

maximise

together

absorption

near

of

light

the

slide

is

where

its

highest.

section •

of

of

cells

section

intensity

1

mesophyll

under

There

are

many

chloroplasts

in

the

palisade

mesophyll

cells

to

the absorb

as

much

light

as

possible.

microscope.

•

Look

for

the

tissues

in

Stomata

dioxide

6.6.1

under

low

(usually

in

the

lower

epidermis)

open

to

allow

carbon

Figure to

diffuse

into

the

leaf.

Carbon

dioxide

is

a

raw

material

for

power . photosynthesis.

Now

look

tissue

64

at

under

each

high

type

of

power.

•

Leaves

the

are

thin

so

atmosphere

that

to

the

carbon

cells

of

dioxide

the

does

palisade

not

and

have

to

spongy

diffuse

far

mesophyll.

from

tnemelppuS

Figure

There

are

large

intercellular

air

spaces

within

the

spongy

tnemelppuS

•

mesophyll palisade

layer.

This

makes

mesophyll

from

cell

cells.

to

it

easy

for

Diffusion

carbon

through

dioxide

air

is

to

diffuse

much

faster

to

all

than

cells

the

diffusion

cell.

spongy

•

Xylem

in

veins

bring

water

and

ions

to

the

mesophyll

cells.

Water

is cells CO

a

raw

by

material

the

cells

to

for

photosynthesis

make

and

magnesium

ions

are

2

needed

chlorophyll. CO 2

•

The

sugar

produced

in

photosynthesis

is

converted

to

sucrose

lower

and

epidermis

transported

away

from

the

leaf

in

the

phloem

in

CO

veins.

guard

cell

2

Figure

6.6.2

Carbon

into

Stomata

the

dioxide

leaf

diffuses

for

photosynthesis.

Stomata

to

are

diffuse

small

into

epidermis,

pores

and

but

out

some

(holes)

of

the

plants

in

the

leaf.

like

epidermis

Stomata

water

lilies

are

that

allow

usually

have

them

in

in

gases

the

the

lower

upper closed

stoma

epidermis.

guard pore

In

cells

partly

closed

sunlight:

•

carbon

dioxide

•

oxygen

made

•

water

diffuses

in

vapour

in

for

photosynthesis

photosynthesis

diffuses

diffuses

out

out.

chloroplast

Opening

and

closing pore

Stomata

are

Stomata

usually

cells

by

opened

open

osmosis.

Carbon

dioxide

diffuses

out.

and

during

This

into

vapour

by

the

makes

diffuses

Water

closed

guard

day.

them

the

also

Water

bend

leaf

for

so

passes

the

into

stoma

the

guard

opens.

photosynthesis

diffuses

and

oxygen

out. Figure

At

night

osmosis

the

and

stomata

prevent

stomata

they

pores.

the

SUMMARY

Water

straighten

The

plant

close.

stomata

passes

and

move

also

close

out

closer

in

of

the

guard

together

hot,

dry

so

cells

closing

weather

to

6.6.3

Closed

by

Match

function

on

the

STUD Y

the

leaf

See

parts

on

the

left

with

their

open

help

wilting.

of

and

the

QUESTIONS

each

stoma

stoma.

TIP

T opic

your self

1

open

cells

which

correct

into

right:

is

3.2

to

abou t

how

and

remin d

osmo sis,

water

out

of

moves

guar d

cells. stomata

palisade

spongy

carry

mesophyll

water

allow

mesophyll

up

gases

to

from

pass

the

into

stem

and

out

of

leaf

contain

chloroplasts

for

photosynthesis

cuticle

contain

chloroplasts

for

photosynthesis

veins

prevent

too

much

water

being

lost KEY

2

a

Which

gas

would

pass

b

Which

gas

passes

out

into

a

leaf

during

1 of

a

leaf

during

POINTS

daylight?

The

diagram

structure

3

Leaves

Lay

a

have

leaf

area

by

Find

out

same

a

large

onto

graph

counting

if

leaf

leaves

area.

surface

the

area

paper,

to

draw

absorb

around

light.

it

different

and

work

out

have

its

carry

squares.

from

Record

the

top

your

and

results

bottom

and

of

the

internal

daylight?

of

a

explain

plant

them.

have

the

2

a

leaf

important

shows

which

each

functions

to

out.

Stomata

of

of

tissues

gases

control

into

the

and

diffusion

out

of

a

leaf.

65

6.7

Mineral

Plants LEARNING

need

Describe

the

nitrate

ions

ions

plant

in

importance

and

Explain

the

They

Nutrients

of

magnesium

active

are

light,

need

absorbed

transport

effects

of

carbon

in

the

mineral

dioxide

from

roots

salts

and

the

soil

(see

(also

water

in

Topic

called

for

small

plant

healthy

quantities

nutrients).

as

ions

by

3.4).

nutrients

nitrate

Nutrients and

also

nutrition

Plant •

than

OUTCOMES growth.

•

more

requirements

magnesium

deciency

are

needed

for

healthy

growth

of

plants.

They

are

used

for

on

a

variety

of

purposes

in

plants.

If

these

nutrients

are

lacking

in

the

soil

plants

then Use

do

not

grow

well

and

show

certain

symptoms

known

as

hydrogencarbonate

solution

to

exchange

kept

in

investigate

of

the

an

light

aquatic

and

deciency

symptoms.

which

are

used

plants

decient

Plants

need

nitrate

ions

to

make

amino

acids

gas

in

to

make

proteins.

As

proteins

are

required

for

growth,

plant

the

in

nitrate

show

poor

growth.

dark

Magnesium

Leaves

as

for

the

may

ions

plants

chlorosis.

and

If

of

are

absorbed

decient

Plants

need

in

by

plants

chlorophyll

phosphate

for

and

look

used

to

yellow,

making

a

make

chlorophyll.

condition

compounds

known

such

as

DNA

respiration.

soil

does

add

more

not

as

contain

enough

fertiliser

to

nutrients,

replace

the

farmers

missing

and

growers

nutrients.

tnemelppuS

•

plants

PRACTICAL

The

effects

Some

of

plants

grown

in

culture

nutrients

on

growth

are

water

to

show

that cotton

seedling

plants

need

different

wool

nutrients.

1

Set

up

some

normal

test-

culture

tubes

as

shown solution

here.

This

plant

has

magnesium

deciency.

Cover

the

tubes 1

with

black

black

paper

to

to

prevent

growing YOU

in

3

4

no

distilled

magnesium

nitrates

water

keep

algae out

DID

2

no

paper

light

the

KNOW?

water.

Legume

plants,

such

as

peas

and

Each beans,

have

bacteria

in

their

has that

are

able

nitrogen

plants

(see

can

page

clover

back

are

into

nitrogen

66

into

to

a

use

‘x’

252).

that

make

Plants

grown

the

soil

content

all

of

lacks

a

certain

nutrient

except

test-tube

1

which

them.

atmospheric

form

to

solution

roots

and

to

for

the

3

Leave

4

After

5

Y ou

the

apparatus

in

good

light

for

6

weeks.

proteins

such

ploughed

increase

crops.

6

weeks

you

could

examine

the

colour

and

size

of

leaves.

as

the

could

growth.

measure

length

of

stems

and

roots

to

compare

All

exchange

living

in

organisms,

plants

including

plants,

carry

out

respiration

all

the

time. tin

Plants

they

are

need

waste.

At

During

In

no

a

supply

night,

the

bright

different

day,

light,

of

from

plants

when

other

oxygen

plants

tnemelppuS

Gas

and

exchange

carry

there

out

is

organisms.

a

they

T o

produce

these

gases

carry

carbon

with

photosynthesis,

high

rate

of

out

dioxide

their

as

foil

respiration

as

pond

weed

a

surroundings.

well

as

respiration.

photosynthesis,

some

of hydrogen

the

oxygen

aerobic

of

is

the

produced

respiration.

plant.

used

by

The

in

The

their

rest

carbon

chloroplasts

chloroplasts

of

the

dioxide

for

is

oxygen

used

is

produced

photosynthesis.

not

by

by

mitochondria

required

so

mitochondria

However ,

this

is

for

diffuses

in

carbonate

indicator

out

respiration

not

enough Test

so

carbon

dioxide

diffuses

in

from

the

tube

Figure

Gas

exchange

in

aquatic

plants

is

1

Test

carbon

solution.

dioxide

This

and

solution

investigated

two

pH

contains

with

it

dissolves

in

water

indicators.

it

forms

Carbon

dioxide

is

an

to

Hydrogencarbonate

carbonic

atmospheric

air

through

indicator

it.

This

acid,

solution

gives

which

is

acid

a

the

is

prepared

indicator

a

by

red

Explain

why

in

Set

up

three

test

tubes

as

shown

colour .

2

3

plants

in

Figure

Describe

a

the

plant

Add

3

Cut

in

hydrogencarbonate

two

each

pieces

of

test

of

indicator

pondweed

tubes

1

and

to

in

to

each

length

test

and

tube.

place

plant

at

growth

and

Put

test

5

Leave

If

carbon

tube

1

in

darkness

test

tubes

near

a

ii

is

added

hydrogencarbonate

to

by

covering

it

in

carbon

dioxide

is

light

the

indicator

taken

up

carbonate

for

water

solution

from

indicator

2–3

In

test

tube

dioxide

1,

was

the

the

by

the

will

plant,

turn

water

solution

indicator

released

by

the

Plant

from

for

the

by

the

red

to

plant,

roots

will

turned

turn

yellow

pondweed

In

test

tube

2,

the

indicator

turned

was

taken

up

by

the

from

red

because

during

purple

pondweed

nutrients

ions

needed

growth.

Nitrate

ions

are

to

amino

needed

acids;

to

magnesium

purple. are

make

carbon

used

by

the

plants

to

chlorophyll.

respiration.

because

for

nitrate

healthy

yellow.

If

mineral

ions

are

lacking,

carbon a

dioxide

absorb

the

3

•

i

sunshine.

hours.

ions

•

surroundings

bright

POINTS

make hydrogen

its

in

foil.

2 If

gas

between

2.

including

dioxide

the

occurs

one

1 the

without

explain

that

and

night,

KEY

4

appearance

6.7.1.

solution

10 cm

likely

ions.

Describe

a

2

need

ions.

exchange

1

plants

bubbling

nitrate

respiration

QUESTIONS

gas.

of

and

3

weak

PRACTICAL

Photosynthesis

tube

provide

mineral acid.

Test

hydrogencarbonate

hydrogencarbonate

1 When

2

6.7.1

SUMMARY indicator

tube

surroundings.

plant

develops

deciency

photosynthesis. symptoms.

•

The

purpose

of

test

tube

3

was

to

act

as

a

control. 4

The

indicator

The

colour

the

plant

oxygen

to

solution

changes

in

the

light

dissolves

monitor

the

in

only

are

or

to

absorbed

water

changes

responds

nothing

it

in

does

by

not

oxygen

to

do

changes

with

the

the

plant

change

in

carbon

oxygen

in

the

dark.

and

by

pH.

If

you

concentration

you

would

have

an

oxygen

probe

and

a

data

pond

weed

solution

remains

same.

at

is

low

red

as

kept

light

the

in

a

test

intensity,

rates

of

carbon

photosynthesis

by

oxygen.

only

At

night

carbon

respiration.

Hydrogencarbonate

indicator

logger . solution

If

up

to 5

use

in

use

produce

dioxide

wanted

plants

release

plants

When

the

light

dioxide

dioxide.

released

In

tube

the

of

hydrogencarbonate

colour

of

photosynthesis

the

and

solution

indicator

usually

respiration

are

the

changes

is

in

used

carbon

concentrations

of

gas

to

as

exchange

detect

dioxide

a

by

result

aquatic

plants.

67

PRACTICE

1

Photosynthesis

cells.

out

Which

occurs

in

structure

palisade

inside

mesophyll

these

cells

light

carbon

intensity

concentration

A

chloroplast

B

cytoplasm

C

nucleus

D

vacuole

The

1)

raw

materials

A

carbon

B

light

energy

/

A

high

low

30

B

low

high

20

C

low

low

30

D

high

high

35

for

photosynthesis

dioxide

C

light

energy,

D

water

and

nitrate

(Paper

2)

(Paper

and

ions

Which

feature

good

and

carbon

carbon

supply

a

dioxide

and

ions

cellulose

B

chlorophyll

large

B

many

C

thin

are

used

by

plants

for

D

xylem

internal

air

a

cells

spaces

chloroplasts

cuticle

on

in

the

and

and

palisade

lower

phloem

mesophyll

cells

epidermis

in

veins

2)

[1]

Hydrogencarbonate

atmospheric

indicator

air

is

solution

bubbled

is

red

through

it.

A

oils placed

a

piece

1)

[1]

tube

Y

that

contained

T ube

Y

was

covered

was

Which

represents

the

movement

of

of

pondweed

inside

test

through

the

open

stomata

of

a

repeated

leaf

uncovered.

indicator

completely

test

tube

Z,

in

but

solution.

foil.

the

This

tube

Both

tubes

were

left

in

was

bright

during sunshine.

the

for

this

gases left

After

60

minutes

the

colour

of

the

day? indicator

gas

into

leaf

gas

out

of

was

leaf

A A

oxygen

carbon

in

B

water

vapour

carbon

tube

purple.

pondweed

carbon

D

oxygen

dioxide

Which

does

water

vapour

pondweed

dioxide

had

the

in

and

in

tube

reason

absorbed

for

Z

this?

pondweed

in

carbon

Z

had

dioxide

Y

had

the

produced

pondweed

in

carbon

Z

had

oxygen

[1]

not

occur

during

pondweed

dioxide,

photosynthesis?

A

absorption

of

light

by

B

conversion

of

glucose

to

carbon

dioxide

to

of

molecules

using

light

9

energy

The

see 2)

Which

row

would

provide

in

Y

pondweed

in

carbon

Z

had

dioxide

had

in

Z

produced

had

oxygen,

absorbed

but

oxygen

2)

[1]

diagram

transverse

(Paper

carbon

pondweed

(Paper

water

produced

pondweed

a

carbohydrate

splitting

had

sucrose

the of

Y

the

chlorophyll

D

reduction

in

but

absorbed

it

in

a

on

the

section

next

page

through

a

shows

leaf

as

a

you

would

microscope.

[1]

of

the

table

the

(top

of

conditions

next

for

(a)

Name

photosynthesis

of

a

the

tropical

the

(b)

Describe

tissues

labelled

E,

F,

G

and

H. [4]

column)

the

functions

of

the

parts

of

the

highest

leaf of

and

correct

oxygen

C

rate

Y

yellow

the

carbon

produced

1)

was

is

dioxide

B

(Paper

in

and

produced

C

Y

What

dioxide

dioxide

labelled

I

and

J.

[3]

plant?

(c)

Explain

and

68

ensure

the

proteins

(Paper

6

to

to

making:

student

D

dioxide

leaf?

A

when

C

adaptation

dioxide

8

5

an

carbon

water

(Paper

4

is

of

[1]

A

fats

[1]

water

1)

Magnesium

D

°C

are:

inside

C

temperature

[1]

7

3

dioxide

carries

photosynthesis?

(Paper

2

QUESTIONS

G

how

are

cells

in

adapted

the

for

tissues

labelled

photosynthesis.

F

[3]

I

(a)

State

how

the

student

would:

E

(i)

vary

the

light

(ii)

determine

intensity;

the

rate

of

[2]

photosynthesis;

[2]

F

(iii)

maintain

constant

a

constant

carbon

throughout

the

temperature

dioxide

and

concentration

investigation.

[4]

G

(b)

J

for

3)

plants,

several

K

and

days.

L,

were

They

placed

were

then

in

the

placed

dark

into

carbon

L

was

the

student’s

results.

the light

apparatus

if

shows

etar

T wo

below

fo

10

graph

sisehtnysotohp

H

(Paper

The

shown

dioxide

provided

below

is

in

the

required

with

for

carbon

K

light

to

nd

photosynthesis.

Using

dioxide.

the

L

(Paper

12

the

limiting

shown

in

the

factors,

explain

graph.

[4]

4)

groups

that

were

M

group

term

results

T wo

Group

bag

intensity

out

N

of

seedlings

decient

was

was

in

grown

grown

were

two

grown

ions

without

without

that

in

solutions

plants

nitrate

need.

ions;

magnesium

ions.

bag

Group

O

received

all

the

ions

that

plants

require.

soda

lime

The

band

results

are

shown

in

the

table.

band

group

of

colour

of growth

seedlings

(a)

Explain

why

the

plants

were

put

in

leaves

reduced

the

growth

yellow

dark

for

several

days.

but

[2] (especially

M

Explain

why

the

plants

were

well

watered

lower

kept

in

bright

light.

Describe

how

you

did

not

carry

would

out

any

show

that

leaves

–

plant

photosynthesis

inside

the

bag,

but

plant

L

did.

Explain

why

plant

L

was

included.

A

student

investigated

intensity

the

effect

of

varying

normal

growth

Explain

the

on

the

apparatus

rate

of

shown

the

effects

of

the

deciencies

of

the ions

and

magnesium

ions

as

shown

photosynthesis in

using

green

green

nitrate light

reduced

growth

3)

(a) 11

–

[2]

O

(Paper

leaves

[4]

pale (d)

severely

N upper

while

N

[2]

yellow K

in

leaves)

lower (c)

much

seedlings

group and

as

the as

(b)

not

the

table.

[4]

below.

(b)

Why

was

seedlings

(c)

Many

it

in

crops

grown

in

(Paper

group

to

achieve

the

yields.

world

Explain

controlled

high

the

[2]

throughout

are

include

O?

glasshouses.

conditions

to

necessary

in

are

how

glasshouses

[6]

4)

69

7

Animal

nutrition

7.1

A

A LEARNING

balanced

balanced

Dene

what

balanced

•

Describe

and

provides

an

adequate

intake

of

the

biological

OUTCOMES molecules

•

diet

diet

is

meant

by

a

health

and

and

energy

needed

to

sustain

the

body

and

ensure

good

growth.

diet

how

activity

age,

affect

gender

dietary

needs

•

Describe

the

pregnancy

on

•

the

diet

Describe

effects

and

of

the

of

breast-feeding

the

mother

effects

malnutrition

on

of

heart

disease

Figure

STUD Y

A

TIP

7.1.1

balanced

Which

diet

carbohydrates,

Rem embe r

bala nced

energy

that

die t

as

Each

of

well

as

•

T o

these

carries

provide

and

T o

fats.

diet

proteins

energy

one

released

will

keep

from

the

brain

T o

(see

The

if

you

to

energy

in

8-year-old

a

the

in

are

this

or

is

used

and

more

mainly

for

of

three

the

energy

role

only

development,

repair

source

and

bre

basic

functions.

of

of

body

amino

if

of

repair

cells

acids

for

carbohydrates

they

are

and

and

in

excess

replacement.

tissues.

cells

of

to

Proteins

make

their

in

own

4.1).

body’s

very

small

aged

14

a

used

day

/

kJ

8 500

8 500

12 500

9 700

11 000

9 800

little

Diet

worker

have manual

worker

woman

breast-feeding

mother

15 000

in

The

about

you

your

still

metabolism

quantities

have

for

a

and

in

–

vitamins

the

diet

and

repair,

these

varies

per

body

from

day.

energy.

on

age,

greater

your

chemical

this

basal

completely

beating,

The

7000 kJ

need

higher

bed

heart

BMR

depends

a

in

growth

required

(BMR).

requires

lying

constant.

involved

Children

70

one

growth,

Topic

keep

energy

rate

pregnant

water

to

and

help

minerals

regulate

our

metabolism.

active

those

adult

minerals,

hour.

temperature

office

–

are

growth

needed

energy

adult

for

provide

regulate

are

one

Even

teenager,

vitamins,

KNOW? •

for

components:

fats,

out

energy

Proteins

allow

the

peanut

meal?

provid es

•

The

better-balanced

these

proteins,

requirements

YOU

has

the

a

nutr ients .

DID

is

So

sex

energy

metabolic

inactive

lungs

reactions

are

functions

even

and

if

to

your

is

the

lie

are

and

still

but

down

body

such

require

basal

using

your

body,

and

person,

you

as

energy.

metabolic

an

and

adult

do

very

activity

requirement

rate

working

in

occurring

person

you

than

adults

because

they

(BMR).

12 500

10 000

11 500

A

young

BMR

per

child

may

kilogram

weigh

per

day

less

than

because

an

adult

they

are

but

still

may

have

growing.

a

higher

Y oung

they

children

are

people

lower

stay

constantly

generally

BMR.

men.

tissue

have

has

a

Figure

The

Fat

a

they

daily

and

a

energy

to

of

and

eat

relatively

fat

tissue,

rate

per

need

to

to

occupations

body

new

mass

cells.

needs

fat

and

diet

if

under

so

because

Elderly

have

they

content

example

muscle,

than

the

make

higher

for

of

balanced

a

are

to

in

their

bodies

the

skin.

Fat

women

generally

men.

requirements

explain

unit

protein

a

than

requirement

try

needs

and

need

have

in

protein

energy

metabolic

energy

the

lower

stored

lower

7.1.2

energy

is

more

developing

have

Women

lower

Compare

need

However ,

healthy.

than

also

of

the

people

shown

in

differences.

that

involve

physical

activity

pregnant

are

10 000

greater

who

than

take

and

high

less

part

they

months

9 MJ

pregnancy

can

fat

provides

proteins.

that

The

extra

need

us

be

with

However ,

may

for

a

protein

extra

about

at

a

required

during

a

desk.

require

0.8 MJ

more

teenage

day

fat:

saturated

fat

that

in

the

that

comes

energy

is

a

of

the

from

sh

be

per

the

woman.

gram

aware

comes

and

concentration

from

plants.

chemical

made

cholesterol

genes

that

that

determine

tend

to

high

concentration

High

in

increase

the

we

the

than

that

carbohydrates

there

animals

Saturated

risk

concentrations

cholesterol

liver

and

produce

our

in

of

of

found

depends

metabolism

of

the

are

two

or

main

and

male

types

manual

girl,

producing

in

fats

in

our

the

upon

in

the

which

more

blood.

blood.

our

we

8 500

developing

types

of

of

the

high

blood

cholesterol

(see

in

page

pressure

fat.

diet

diet

The

cholesterol

per

cholesterol.

concentrations

the

blood

108),

and

an

heart

Monounsaturated

Polyunsaturated

which

will

7.1.2

Typical

energy

a

b

What

High

and

as

fat

the

diets

having

a

are

linked

increased

to

risk

a

disease.There

fats

have

little

of

are

thick,

inner

of

sur face

two

effect

Figure

7.1.3

A

healthy

and

on

help

to

fats

may

reduce

help

heart

an

artery

artery

to

reduce

State

meant

how

following

who

the

will

does

not

by

term

protein

differ

take

and

from

much

balanced

energy

those

of

diet?

16-year-old

of

A

balanced

an

iii

a

elderly

person

pregnant

mother

and

minerals,

the

correct

female

the

fat

wall.

diet

provides

proteins,

fats,

water

and

vitamins,

bre

in

the

quantities.

exercise: 2

i

(left)

with

POINTS

carbohydrates,

requirements

a

layer

deposit

cholesterol

1

the

in

rough

fatty

disease.

QUESTIONS

is

needs.

quantity

well

energy

1

day

may

KEY

SUMMARY

per

day

Cholesterol

as

inherit.

kJ

deposited

blood

years

blood.

arteries

unsaturated

8

kJ

unsaturated

smooth

narrowing

years

day

three

than

Figure

increase

14

per

and

last

15 000

fat

kJ

energy

worker

of

boy,

12 500

muscle

pregnancy

woman

per

People

high

for

woman

us?

energy

should

is

example,

non-pregnant

more

also

nutrients

For

for

sitting

sports

require

bad

we

involve

physical

breast-feeding.

recommended

Why

Fat

of

diets.

Women

are

jobs

vigorous

protein

development.

when

active

in

kJ

ii

a

2-year-old

iv

a

male

child

Requirements

depend

gender

athlete

on

a

and

of

the

diet

person’s

how

age,

active

they

are. 2

a

What

are

b

Explain

the

health

risks

associated

with

a

diet

high

in

fat?

3 how

a

person

may

reduce

the

fat

content

of

Saturated

fats

cholesterol diet.

(You

may

nd

it

useful

to

look

at

pages

73

and

answering

this

blood

which

is

linked

to

74

narrowing before

increase

their

of

the

arteries

and

question.)

heart

disease.

71

7.2

Sources

Eating LEARNING

•

State

of

nutrients

healthily

OUTCOMES

some

good

components

of

and

the

describe

sources

a

of

balanced

Diets

in

different

from

each

parts

of

the

world

vary.

However,

we

should

all

eat

the of

the

food

groups

shown

in

the

food

guide

pyramid.

diet

importance

of

Carbohydrates them

Carbohydrates •

Describe

the

source symptoms

due

to

lack

mineral

C

sugars

and

starches,

which

provide

us

with

a

ready

of

energy

and

salts

D,

iron

and

and

that

is

easily

respired.

Simple

sugars

are

absorbed

almost

of

immediately vitamins

include

deciency

by

the

stomach

into

the

blood

to

give

an

immediate

result

of

respiration.

source

the

of

energy .

of

carbohydrates

This

energy

is

released

as

a

Good

sources

calcium

are

rice,

potatoes,

bread,

yams,

sugar

and

honey .

Proteins

fats,

oils,

sweets

In

it

order

needs

protein

meat,

poultr y,

yogurt,

beans,

cheese

your

protein

into

body

to

to

grow

make

amino

new

acids

and

and

cells.

then

develop,

You

use

digest

these

to

fish,

make

milk,

for

eggs,

your

own

proteins.

There

are

20

different

nuts

types

of

fruit

of

these

Cell

amino

to

acid

make

membranes

and

its

your

own

and

body

protein

cytoplasm

must

(see

have

Topic

contain

a

all

4.1).

great

vegetables

deal

bread,

or

cereal,

pasta,

rice

of

protein.

damaged

your

food

growth

daily

Figure

7.2.1

exercise

The

food

and

guide

weight

energy.

control

for

and

Y our

cells

so

this

as

repair

Good

it

body

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well.

may

sources

may

need

If

protein

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are

need

to

enough

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respired

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sh,

replace

protein

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to

old

in

used

for

provide

milk

and

nuts.

pyramid.

Fats

Fats

are

under

the

releases

one

STUD Y

can

now

infor mation

you

each

(e.g.

in

starte d

featu re

energy

kJ)

write

mak e

0

add

to

in

(e.g.

provi de

gram

the

Fats

are

Fats

also

a

4 .1.

long-term

around

than

twice

the

as

carbohydrate

energy

heart

much

or

store.

and

kidneys.

energy

protein.

The

than

When

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can

we

fat

be

are

is

stored

gram

of

fat

released

short

of

from

thick

you

uses

also

energy

fat.

good

give

layer

the

thermal

buoyancy

of

blubber.

to

insulators,

marine

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since

animals,

sources

are

they

for

cut

down

example

butter,

heat

whales

cheese,

fat

in

loss.

have

meats

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nuts.

inclu de

sure

and

if

Water you

for

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when

the

you

up

drink

two-thirds

or

of

your

body

mass.

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take

in

water

eat.

answ er

vitam ins,

water

makes

each

do

energy ).

not

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few

to

a

take

go

without

food

days

without

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place

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the

that

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in

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urine,

faeces,

72

of

and

a

conten t

bre ,

any

table

body

and

even

min erals

more

T opic

someth ing

nutri ent

is

skin

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as

TIP our

Y ou

important

solution.

intake

sweat

water

of

and

in

water

are

our

number

is

blood

day

of

weeks,

needed

for

transports

passed

sweat

each

breath.

a

Water

The

chemicals

and

for

out

of

cools

equals

bodies

down.

your

you

substances

our

us

but

chemical

loss

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of

in

is

would

die

reactions

dissolved

solution

important

water

in

urine,

Vitamins

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be

of

need

and

small,

healthy.

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minerals

regular

these

deciency

amounts

are

lacking

of

in

vitamins

the

diet

and

we

minerals

can

develop

if

we

are

to

symptoms

diseases:

deciency

rich

symptoms

food use

name

in

body (deciency

source

disease)

oranges,

tissue

lemons,

resistance

repair, bleeding

vitamin

C

other

gums

to (scurvy)

citrus

sh

fruits

oil,

butter vitamin

disease

milk,

D made

strengthens

soft

by

bones

bow

the

and

outwards T angerines

are

a

good

source

of

vitamin

C.

(rickets)

Sun)

used

in

formation

liver,

legs

skin teeth

in

bones,

(also

meat,

of

haemoglobin

in

tiredness,

lack

of DID

YOU

KNOW?

iron cocoa,

eggs

red

blood

cells

energy

(anaemia)

In for

transport

1747,

James

Lind,

a

Scottish

of

ship’s

surgeon,

was

able

to

oxygen

show weak, milk,

sh,

strengthens

green

bones

teeth

The

Fibre

bre

cabbage,

the

The

or

bulk

gut

muscles

helps

the

plant

part

to

of

the

the

and

our

from

comes

cell

of

sweetcorn

adds

entire

roughage

from

important

Fibre

disease

preventing

the

citrus

walls.

diet.

food.

gut

Although

High-bre

Since

to

wall

of

plants.

it

It

is

made

cannot

foods

be

up

digested,

include

bran

Fibre

from

diet

it

anus

need

food

constipation

bacteria

lowers

reduces

the

the

in

is

not

and

digested,

does

something

the

not

to

alimentary

it

passes

provide

fruits

provided

C

the

push

canal

down

any

energy.

against.

by

Fibre

KEY

(see

Topic

7.3).

Fibre

POINTS

peristalsis

absorbs

Carbohydrates

in

our

gut.

Many

doctors

believe

concentration

risk

of

heart

of

disease

cholesterol

and

bowel

in

that

the

List

the

a

each

of

an

balanced

diet

and

give

a

2

good

source

one.

2

Explain

why

3

Explain

the

quick

of

energy,

energy

while

fats

store.

blood.

cancer.

Protein

is

needed

repair

Lack

can

a

a

high-

QUESTIONS

components

are

poisonous

3

SUMMARY

of

on

vitamin

it

and

1

sailors

years;

cereals,

are bre

for

mainly

source wastes

affected

voyages

celery.

mouth

movement

from

1 so

as

successfully

remedy.

cellulose

an

lemons,

cramps

in

is

and

(rickets),

long

of

such

weakness

teeth and

Dietary

fruits,

and muscle

vegetables

citrus

bones oranges

and calcium

brittle

that

of

of

calcium

cause

lack

of

and

lack

and

rickets

iron

of

for

growth

tissues.

vitamin

(soft

causes

D

bones);

anaemia

vitamin

C

causes

scurvy.

the

diet

must

contain

each

component.

4

Roughage

of

term

deciency

food

helps

through

the

the

passage

gut.

disease

73

7.3

Balancing

Getting LEARNING

the

reasons

why

put

• Describe

on

food

as

a

result

If

health

in

a

day

should

provide

you

with

enough

energy

to

day.

risks

happens

if

we

eat

too

much?

of

malnutrition

the

eat

that

and

What

you

eat

more

food

than

you

need,

your

body

stores

the

extra

as

fat.

associated Your

with

you

through

weight

obesity

constipation

• List

right

some get

people

balance

needs

OUTCOMES

The • State

the

energy

energy

intake

is

the

energy

you

get

in

your

food

in

a

day

in

obesity proteins,

• Explain

the

role

of

Your

(bre)

in

the

carbohydrates

and

fats.

roughage energy

output

is

the

energy

your

body

uses

in

a

day.

If

diet energy

body

intake

and

body

overweight

page.

that

or

People

become

greater

mass

even

with

diet

foods

low

or

a

energy

increases.

We

Obesity

basal

obese

contains

with

than

obese.

a

overweight

their

rened

is

of

may

is

run

than

the

rate

those

foods,

added

then

dened

metabolic

fattening

lot

output,

risk

in

stored

box

high

in

the

becoming

are

higher

as

is

of

the

(BMR)

with

such

fat

on

the

more

BMRs.

fat

next

likely

It

is

foods

to

likely

and

sugar.

Obesity

In

rich,

suffer

if Many

children

do

not

eat

this

sort

of

meal

a

industrialised

from

person

countries,

overeating

takes

in

than

more

like

from

energy

Britain

eating

in

and

too

food

the

little.

than

they

USA,

As

more

we

use,

have

then

people

seen,

the

at

excess

is

stored

as

fat.

T aken

to

extremes,

people

can

put

on

so

much

lunchtime!

weight

Major

•

high

that

of

obesity

intake

of

fatty

•

too

•

social

People

Exercise

helps

ght

heart

disease

and

74

growing

and

rened

foods

containing

a

lot

emotional

are

people

9.5),

sugar

stress,

overweight

to

have

high

(see

Topic

and

health

blood

leading

obese

and

‘comfort

are

problems

pressure,

10.3)

to

eat

•

take

of

much

such

as

diabetes

arthritis

eating’.

more

heart

caused

(worn

likely

than

disease

by

high

joints).

could

someone

lose

weight?

could:

•

A

a

foods

obesity.

They

is

and

Topic

How

Obesity

include:

exercise

who

thinner

obese.

sugar

little

blood

become

causes

added

(see

they

less

high-energy

more

sensible

exercise

approach

•

a

balanced

•

a

gradual

•

having

diet

foods

(increase

to

with

increase

(lower

slimming

a

in

their

lower

their

energy

energy

should

intake

of

intake)

output).

combine:

energy

exercise

problem.

an

ideal,

but

achievable,

target

for

weight

reduction.

DID

YOU

KNOW?

Obesity

STUD Y

There

are

two

ways

in

which

people

can

identify

being

Y ou • being

20%

above

the

recommended

weight

for

his

or

TIP

obese:

her

do

no t

remem ber • having

a

body

mass

index

(BMI)

greater

than

body

mass

index

mass

/

inde x,

kg

be

2

/

the

but

metres

awar e

person

with

a

BMI

of

less

than

20

is

underweight;

between

is

severely

body

overweight;

obese.

mass

These

same

is

If

in

your

the

calculations

way

for

more

BMI

than

is

in

acceptable

are

for

children

30

the

the

obese;

range

of

more

20

to

than

24,

40

then

or

indigestible

but

is

grea ter

is

The

BMI

is

calculated

interpretation

important

is

bulk

to

our

in

the

for

a

healthy,

balanced

diet.

It

TIP

is

food.

This

is

important

for

moving

down

the

alimentary

canal.

The

muscles

of

the

gut

die ts

that

to

squeeze

the

food

along.

Soft

foods

do

not

stimulate

to

contract

as

effectively

as

the

harder,

indigestible

too

little

foods

muc h that

form

roughage.

If

the

movement

of

food

is

slow

it

will

result

making

it

difcult

to

defecate.

or

A

diet

containing

fruit

and

vegetables

contains

lots

of

certai n

far

are

the

best

foods

to

relieve

complete

Copy

and

the

exercise

sentences

energy

you

take

.

long

by

in

more

than

Eating

periods

eating

of

foods

time

can

less

lead

foods

using

muc h

is

to

the

List

four

health

problems

that

are

A

is

stored

added

Calculate

person

can

more

as

KEY

lose

weight

1

the

the

body

BMI

mass

category

index

in

for

each

linked

the

.

to

people

their

a

man

1.70 m

b

a

woman

in

1.75 m

height

in

is

following

people

a

man

a

State

1.85 m

in

height

a

body

with

a

mass

body

of

mass

110 kg

of

Obesity

and

a

50 kg

with

a

body

mass

of

two

good

sources

of

Explain

the

effects

of

a

roughage

lack

output

can

lot

intake

rened

of

in

the

than

(in

their

(in

their

exercise).

be

of

roughage

in

of

caused

fatty

by

a

foods

added

of

too

foods

containing

sugar

little

plus

the

exercise.

A

diet

lacking

in

roughage

diet.

(bre) b

greater

weight

75 kg

3 4

on

intake

and

effects c

put

energy

case:

with

height

roug hage .

obesity.

high

a

of

die t

POINTS

Some

if

2 name

fo rm

the

over

energy

3

as

words:

excess

with

.

taking

in

a

fatty

use,

foods

lack ing

food) 2

of

obesity

fat

you

and

and

these

sugar

high-energy

If

shor tage

constipation.

is

1

too

compo nent s.

malnu trition

QUESTIONS

or

compo nent s

Cons tipat ion

SUMMARY

a

roughage;

those these

too

there

energy

energy ,

in

of constipation

no t

beca use

the

is muscles

are

wall

bala nced contract

refers

keeping

to food

their

30.

different.

Malnu trition adds

is

your

STUD Y

bre

if

than

is

Constipation

Roughage

someo ne

obese

range.

adults.

but

is

as

mas s

shou ld

25

BMI 30

body

you

that

classi ed

and

to

to

=

height

A

how

30.

calcul ate

body

have

height

the

can

lead

to

diet. constipation.

75

7.4

Starvation

and

nutrient

deciency

People

can

water.

•

Describe

the

effects

upon

of

are

starvation

This

its

no

tnemelppuS

Describe

•

Discuss

the

effects

of

of

many

weeks

causes

vitamin

without

and

in

the

The

During

body

muscles

wasting

energy

by

to

a

lack

the

to

are

of

the

dietary

food

fat

food,

provided

starvation,

and

protein

starvation

uses

stored

use

as

a

the

fat

source

the

they

for

basal

and

body

have

energy,

draws

but

metabolic

then

breaks

there

rate

down

of

energy.

This

leads

to

In

(swelling

abdomen

legs);

hair;

appearance.

that

and

(PEM).

energy

or

with

shown

lack

on

the

In

which

of

so

its

worst

terms

are

food.

in

suggests,

are

These

two

In

given

have

The

protein

form

to

is

it

caused

can

describe

lead

the

ways

conditions,

However,

adapted

food.

is

this

different

both

marasmus.

marasmus

when

undernutrition

term

protein.

more

with

better

of

the

PEM.

to

though

children

are

and

marasmus,

responds

respond

form

As

it

better

is

to

symptoms

in

children

of

lack

of

these

left.

of

kwashiorkor:

and

emaciated

common

children

body

conditions

the

of

underweight,

thought

oedema

an

most

kwashiorkor

which

Symptoms

and

malnutrition

appearance

sparse,

aky

both

cases,

frequent

causes

children

servings

cells

enzymes

of

are

of

the

are

small

in

pancreas

secreted

danger

quantities

and

and

the

and

of

feeding

food.

intestine

surface

to

area

should

This

die,

for

is

so

involve

because

fewer

absorption

PEM

digestive

of

digested

skin;

food

is

reduced.

During

starvation,

there

are

deciencies

of

the

accumulation

protective in

water.

reduced.

Worldwide,

fat

carbohydrate,

of

iron

deciencies

dry

of

periods

and

D

of

of

during

scurvy

muscle

effects

for

because

stores

is

protein

the

is

stores

(BMR) •

survive

OUTCOMES

vitamins;

people

are

at

risk

of

developing

infectious

communities

in

developing

diseases.

liver.

Dietary

shown

of

surveys

that

cells,

with

has

these

Children

such

as

of

with

to

poor

be

which

used

conditions

who

these

other

and

are

protein

as

are

develop

cassava

content,

Symptoms

of

protein,

an

the

in

foods.

be

energy

suffering

potato;

protein,

Staple

used

for

source.

from

symptoms

sweet

low

should

a

may

while

so

This

lack

be

fed

need

such

on

a

have

and

that

energy

in

be

wheat

repair

children

the

tropical

high

to

as

nations

growth

shows

of

having

they

foods

the

diet.

crops

energy

supplemented

and

rice

will

marasmus:

satisfy

very

low

mass;

energy

legs;

muscle

we

also

76

is

found

seen,

symptoms

protein

of

two

energy

This

can

Vitamin

protein

malnutrition.

C

have

calcium

of

needs

a

in

oranges,

deciency

of

lemons

and

vitamin

C

other

leads

citrus

to

the

fruits.

disease

called

face.

gums.

forms

protein.

old-

scurvy.

Typical

enough

fat;

As

7.4.1

provide

arms

Vitamin wizened,

Figure

also

little

or

looking

and

body

thin

Nutrient and

intake

by

C

helps

bones

used

helps

cause

in

to

and

make

the

bleeding

bond

teeth.

skin,

healing

of

in

cells

parts

of

together

Vitamin

tendons,

wounds

C

is

the

body,

and

helps

used

ligaments

and

the

to

particularly

in

form

and

the

an

blood

formation

of

use

the

of

important

vessels.

scar

It

tissue.

tnemelppuS

LEARNING

It

is

also

D

needed

needed

Deciency

rickets

is

in

children.

children

body.

Rickets

the

of

can

Iron

bones

is

found

iron.

It

Foods

needed

in

red

is

to

rich

in

a

of

iron

iron

grow

the

the

of

by

In

bend

carry

oxygen

day.

liver,

At

is

puberty,

rich

soft,

weight

in

leads

protein

the

of

vitamin

gives

to

a

so

the

D

like

rise

to

softening

which

combined

is

with

body.

If

occur.

girls

become

the

cells.

causing

haemoglobin

a

cocoa.

can

bone

fractures.

around

meat,

in

bones

deciency

which

protein

anaemia

in

and

foods

of

calcium.

calcium

with

adults,

chance

blood

of

absorb

calcium

eating

milk.

to

properly

bones

Haemoglobin

called

each

to

fail

increased

include

disease

lack

and

cells.

to

deposition

osteomalacia,

make

blood

needed

diet,

16 mg

an

as

intestine

the

prevented

eggs

known

and

the

walking

be

small

include

Bones

start

butter,

condition

the

the

oil,

the

regulate

symptoms

when

sh-liver

to

for

there

An

need

to

is

a

adult

make

lack

of

needs

sure

iron

in

about

they

have An

enough

iron

in

their

diet

as

they

start

to

menstruate

(have

X-ray

bowed

The

lack

The

main

of

iron

shortness

of

breath,

SUMMARY

1

a

leads

symptoms

to

of

a

reduction

anaemia

heart

are

in

the

number

tiredness

palpitations

and

a

and

pale

of

red

lack

of

blood

the

main

inadequate

are

causes

the

of

symptoms

kwashiorkor

Explain

why

frequent

starvation

in

terms

of

servings

of

of

very

below

is

mouth

are

these

small

two

conditions

/

amounts

of

as

a

box

containing

breakfast

Fat

/

/

g

per

a

result

much

energy

would

How

c

The

to

3

Make

the

in

a

this

table

fat

of

How

get

diet.

the

much

protein

much

mass

to

2

Scurvy

be

in

a

150 g

serving

of

the

is

to

body,

in

good

with

a

cereal

in

a

75 g

adult

serving

female

would

a

of

the

needs

female

cereal?

per

have

day

to

3

iron,

table

dietary

The

fallen

C

in

in

a

very

of

the

eat

vitamin

C

and

and

the

vitamin

about

D

their

deciency

in

roles

diseases

4

cause

bones

a

parts

iron

in

of

of

D

by

can

the

anaemia

Vitamin

plus

a

low

fat

and

lack

of

a

vitamin

and

in

ability

of

infections.

of

diet

transport

information

sources

nutrient.

Lack

cause

is

protein?

your

each

be

young

more

of

have

vitamin

lack

caused

bleeding

the

with

wasting,

deciency

there

there

compare

Include

associated

would

enough

results

mass

particularly

mass

60 g.

not

resistance

cereal?

b

scurvy.

POINTS

muscle

3

How

of

Starvation

in

a

has

teeth

100 g

83

g

the

cereal.

6

Carbohydrate

who

and

food.

1800

g

person

diet.

body

Protein

a

involves

1

kJ

of

inamed

marasmus?

from

Amount

/

and

of:

ii

treatment

information

Energy

bones

rickets.

an

KEY The

weakened

with

diet.

the

2

the

child

complexion.

out

c

a

cells.

gums

i

of

energy,

The

What

legs

QUESTIONS

Explain

b

showing

periods).

C

cause

of

the

body,

gums.

the

diet

which

the

tnemelppuS

tnemelppuS

Vitamin

can

affects

blood

to

oxygen.

deciency

softening

causing

of

can

the

rickets

and

osteomalacia.

77

7.5

Digestion

During LEARNING

the

different

•

Dene

mechanical

Dene

ingestion,

Ingestion

the

and

be

along

the

alimentary

canal,

a

number

of

identied.

the

taking

and

of

lipase,

amylase,

Digestion

into

of

substances

(food

and

drink)

into

the

mouth.

is

the

and

soluble

breaking

the

molecules

down

so

that

of

large

they

can

insoluble

pass

molecules

through

the

into

gut

wall

blood.

listing •

substrates

the

egestion

function

protease

the

is

through

small

State

food

absorption, •

assimilation

•

of

can

digestion body

•

processes

and •

chemical

passage

OUTCOMES

the

Absorption

is

the

movement

of

small

food

molecules

and

ions

endthrough

the

wall

of

the

intestine

into

the

blood.

products •

Assimilation

cells

•

of

the

Egestion

is

absorbed,

The

large

gut,

food

which

system

the

the

as

mechanically

is

body

out

are

of

with

2.4).

food

the

This

the

digestive

used,

that

has

proteins

happens

liver

and

the

food

When

food

molecules

becoming

part

not

of

been

into

the

the

cells.

digested

or

anus.

starch,

chemically.

Topic

of

are

through

molecules

and

they

passing

faeces

together

(see

movement

where

in

and

the

pancreas

has

fats.

form

been

Digestion

alimentary

your

occurs

canal,

or

digestive

digested,

it

is

absorbed

mouth

through

the

molecules

wall

can

of

go

the

small

through

intestine

the

gut

into

wall

the

they

blood.

must

be

Before

the

dissolved.

food

Large

food

food

molecules

through

the

molecules

wall

of

another

digestive

are

the

are

wall

insoluble;

of

the

soluble.

small

body

They

intestine

uid

that

they

small

will

not

intestine.

will

and

dissolve

enter

absorbs

the

and

dissolve,

On

so

the

therefore

other

they

blood

can

and

transports

fat

hand,

get

the

cannot

small

through

lymph,

(see

page

get

food

the

which

is

114).

enzymes

gut

Mechanical

digested

digestion

food

Mechanical

smaller

digestion

pieces

of

food

is

the

breakdown

without

changing

of

the

large

food

pieces

of

food

molecules.

into

This

anus

starts

in

pieces

7.5.1

Digestion

in

the

alimentary

canal.

STUD Y

that

continue

faeces

Figure

broken

about

n

‘diges

deni

tions

tion’

dige stion’

prepar

,

‘mec

the

hani

‘chem

to

e

the

betw een

body

Muscular

small

globules

digestion

can

into

use

by

in

food

small

digestion

into

contractions

intestine,

large

emulsication

the

next

few

by

into

of

the

globules

bile.

smaller

stomach

of

There

fat

is

are

more

topics.

that

has

been

eaten,

the

food

must

be

molecules.

is

smaller

the

breakdown

soluble

of

molecules

the

by

large

the

insoluble

action

of

food

enzymes.

be occurs

in

the

mouth,

stomach

and

small

intestine.

Mechanical

distin guis h

differ

them .

ence

gives

a

larger

surface

area

for

the

enzymes

to

work

on.

s)

The

three

types

carbohydrases

specic

to

remind

of

enzymes

and

enzyme

lipases.

because

yourself

breakdown

78

the

food

ical

digestion

(giv

In

down

digestion

down

molecules

and

swallowed.

breaks

cal

This

ed

chewing

of

Chemical

and

be

where

process.

smaller

Chemical

TIP

stion’

can

this

into

broken

dige

mouth

mechanical

Before

Lear

the

about

proteins,

in

the

Each

they

the

alimentary

type

have

of

food

different

reason

carbohydrates

for

and

canal

are:

molecule

shapes.

having

fats.

proteases,

needs

See

different

Topic

a

5.1

enzymes

to

a

protein

many

molecule

different

is

amino

made

up

amino

of

protease

down

a

starch

molecule

acids

acids

is

made

up

enzymes

protein

break

molecules

of glucose

many

glucose

molecules

amylase

starch

a

fat

fatty

molecule

acid

and

is

made

glycerol

up

to

maltose

break

(a

down

sugar)

of

fatty

molecules

lipase

fatty

enzymes

acid

down

enzymes

fat

acids

break

molecules

glycerol

glycerol

Figure

The

7.5.2

The

chemical

carbohydrase

breakdown

enzyme

that

of

protein,

breaks

starch

down

and

starch

fat.

is

called

amylase

KEY

SUMMARY

POINTS

QUESTIONS

1

Mechanical

the 1

Name

the

enzymes

and

end-products

involved

in

the

particles

starch

b

protein

c

surface

a

Explain

why

b

Explain

the

digestion

is

necessary.

of

large,

is

difference

between

mechanical

digestion

chemical

what

happens

to

food

after

it

has

been

graph

into

food

smaller,

molecules

by

water-

the

shows

the

activity

of

the

enzymes

of

enzymes.

digested.

2 The

Chemical

breakdown

digestion.

action Outline

the

and

soluble

3

increase

insoluble

molecules

c

to

area.

fat digestion

2

of

of:

their a

is

breakdown

chemical

food digestion

digestion

physical

amylase

Amylase

breaks

down

and starch

molecules

to

glucose

pepsin. molecules.

a

i

At

what

ii

How

pH

does

pepsin

work

best?

Protease does

hydrochloric

acid

in

the

stomach

breaks

molecules pepsin

to

What

are

formed

when

pepsin

breaks

down

i

At

what

ii

What

is

amino

protein

acids.

pH

does

formed

amylase

when

the

work

breaks

down

fats

to

proteins?

fatty b

to

work?

Lipase iii

down

help

acids

and

glycerol.

best?

amylase

breaks

down

starch?

iii

Why

is

it

useful

that

saliva

contains

an

alkali?

emyzne

pepsin

fo ytivitca

amylase

2

3

4

5

acid

6

7

pH

8

9

10

11

12

alkaline

79

7.6

T eeth

The LEARNING

teeth

breaks

The •

Describe

the

structure

in

teeth

and

mechanical

surface

their

State

the

decay

care

mechanical

area

into

of

smaller

digestion

food

is

pieces

increased

so

when

chewing

so

making

making

it

food.

it

easier

This

easier

to

swallow.

for

enzymes

catalyse

the

reactions

needed

for

chemical

digestion.

digestion

causes

and

of

out

food

function

Adult

•

down

of

to human

carry

OUTCOMES

of

describe

tooth

the

They

humans

have

have

different

32

teeth,

shapes

but

for

not

all

of

performing

the

teeth

different

are

the

same.

functions:

proper •

incisors

are

chisel-shaped

•

canines

are

pointed

•

premolars

•

molars

for

biting

and

cutting

teeth

are

Counting

there

8

teeth

During

teeth,

small.

to

be

the

uneven

‘cusps’

premolars

number

4

in

of

and

each

and

for

are

type

tearing

grinding

for

of

and

chewing

tooth,

chewing

up

you

food.

should

nd

that

our

are

canines,

lives

back

we

small

Between

will

8

premolars,

and

12

molars,

which

makes

all.

replaced

teeth

our

like

piercing

are:

incisors,

32

have

for

the

by

come

have

teeth

two

and

ages

our

of

or

6

of

and

when

wisdom

teeth.

are

only

12

permanent

through

molars

sets

there

we

8

these

teeth.

are

at

The

rst

molars

teeth

The

least

set,

as

or

our

gradually

last

18,

of

if

our

at

milk

jaws

fall

are

out,

permanent

all!

These

are

teeth

enamel

pulp

A

child

usually

has

20

milk

cavity

crown

teeth.

dentine

canine molar

gum

premolar

root

STUD Y

Mak e

TIP

sure

iden tify

type s

from

of

you

ner ves

can

the

differ ent

hum an

tee th

pho to grap hs

their

and

Figure

7.6.1

Adult

Figure

teeth.

7.6.2

Vertical

section

through

molar.

and

Enamel

the

tions

part

forms

above

the

hard,

the

gum.

outer

layer

Inside

this

of

is

the

crown

softer

of

the

dentine,

tooth,

which

is

which

more

is

like

in bone

in

bony

socket

structure.

A

layer

of

cement

xes

the

root

of

the

tooth

into

a

dige stion.

The

pulp

blood

Tooth

to

in

the

cavity

jaw.

is

a

The

root

space

in

is

the

the

part

tooth

that

is

below

containing

the

gum.

nerves

and

vessels.

Healthy

80

vessels

socket

incisor

a

can

func

mecha nica l

and

bony blood

diag ram s

state

that

teeth

decay

form

is

and

caused

plaque,

by

which

gums

bacteria

is

a

layer

in

your

that

mouth.

sticks

to

They

your

mix

teeth

with

and

saliva

gums.

decay

enamel

dentine

DID

pulp

YOU

KNOW?

Periodontal

abscess

No

pain

Slight

toothache

Severe

toothache

the

7.6.3

Stages

in

tooth

if

space

between

get

tooth

to

the

forming

base

an

of

abscess

can

make

The

bacteria

holding

decay.

and

After

a

meal,

Bacteria

in

respiring

of

a

this

be

be

this

will

your

should

plaque

and

acid

will

make

the

of

very

The

starts

attack

red

food

the

acid

off

the

painful

gums

sugary

changes

anaerobically.

tooth

away,

particles

tooth

and

cause

may

sugar

can

dentine.

and

the

between

acid

the

the

7.6.4

on

the

degrees,

your

brush

teeth

with

up-and-down

at

the

45

Clean

gentle,

of

your

short

the

gently

movements.

sure

inside

teeth

back

not

surface

moving

to

and

your

the

The

shows

of

Brush

brush

forwards.

forget

the

also

the

is

worn

pulp

acid

how

both

Be

with

the

teeth.

short,

and

the

make

gums

They

can

rot

teeth

them

unhealthy.

the

in

fall

bres

position

out.

STUD Y

TIP

cavity

can

our

biting

upper

the

are

No te

also

surfaces

lower

scrubbing

that

uo rid e

streng then s

teeth

of

outside

the

can

into

surface

brushed.

clean

get

teeth.

they

the

enamel

reaches

toothache.

Figure

your

because

enamel

When

cavity

severe

swollen.

left

into

attack

decay.

If

be

a

Holding

bacteria

Agony!

bacteria

Figure

disease

occur

the

tee th ,

hard

the

exterio r

KEY

POINTS

KEY

POINTS

enam el

giving

them

surf ace.

of

teeth

strokes.

1

back

Incisors

are

cutting,

for

biting

canines

for

and

piercing

teeth.

Figure

7.6.4

Make

SUMMARY

sure

you

clean

all

surfaces

of

your

Copy

tearing,

and

molars

and

complete

the

and

chewing.

sentences

using

these

Tooth

decay

bacteria

words:

in

changes dentine

crown

mechanical

bite

enamel

chew

are

of

is

used

to

digestion.

gum

and

the

a

hard,

which

is

and

Each

which

outer

similar

layer

of

to

tooth

is

tted

the

your

consists

into

tooth;

a

of

food.

a

is

above

bony

inside

This

this

.

is

the

a

a

Name

b

For

c

What

the

The

softer

3

Tooth

by

each

is

type

the

permanent

d

Describe

e

State

in

part

types

a,

difference

of

caused

to

by

which

acid

that

the

of

enamel

the

and

tooth.

decay

good

can

be

brushing

toothbrush,

foods

and

avoided

with

a

avoiding

visiting

the

regularly.

teeth.

describe

between

its

the

shape

milk

and

teeth

its

function.

and

the

teeth?

the

three

main

sugar

regular

sugary

.

four

is

plaque,

type

the

dentist

2

grinding

bone dentine

teeth

premolars

for

socket attacks

root

The

and

are

QUESTIONS

2

1

and

teeth.

stages

ways

in

of

tooth

which

decay.

tooth

decay

can

be

prevented.

81

7.7

Mouth,

and

stomach

Chewing LEARNING

Describe

the

events

that

during

the

and

of

chewing

food,

of

Describe

Describe

in

the

the

digestion

of

TIP

rst

our

enzy me

food

amyl ase.

what

starch ,

they

mou th

smal l

the

are

is

Mak e

and

pieces.

digestion

the

moistened

into

a

ball

molar

It

easier.

food

or

salivary

through

and

the

canine

mouth.

teeth

bite

When

it

into

is

teeth

grind

important

to

these

chew

chunks

your

of

food

food

well

The

tongue

mixes

the

food

with

as

saliva

is

chewed

by

the

teeth.

The

food

is

then

bolus

mucus,

to

act

a

glands

slimy

down

amylase,

the

pro te in

pass

to

the

saliva,

that

which

contains:

lubricates

the

passage

of

the

food

throat

enzyme

that

catalyses

the

breakdown

of

starch

to

maltose.

no te s

nasal

to

and

from

end

intest ine.

wher e

make

substance

the

ball

prod uced

they

body

teeth

saliv ary

happ ens

enzy mes

them ,

premolar

smaller

makes

bolus

•

as

The

much

rolled

food

•

on

the

stomach

STUD Y

on

into

incisor

peristalsis

The

T he

the

saliva

and

•

ingested

mouth,

including

this

•

are

the

and

into action

drink

enters

chunks. swallowing

the

swallowing

take food

place

and

OUTCOMES

Food •

oesophagus

the

passage

food

fat

the

of

The

food

soft

palate

pushes

your

the

List

that

of

act

This

stops

going

on

up

upwards.

the

food

your

hard

nose!

palate

enzy mes Before

and

you

swallow,

what your

tongue

food

into

rolls

the

do. epiglottis

opening

So

food

the

The

covers

to

food

your

your

doesn’t

wrong

the

trachea.

go

and

down

a

soft

pushes

back

of

it

your

ball

to

the

mouth

way!

squeezes

epiglottis

oesophagus.

into

past

trachea

your

Gulp!

oesophagus

Figure

7.7.1

Events

during

swallowing.

muscle direction

The

oesophagus

Food

passes

contracting food

is

moving

stomach.

ball

longitudinal

of

down

The

the

oesophagus

oesophagus

muscles

in

its

(also

from

known

as

the

the

mouth

gullet)

to

the

has

circular

and

wall.

food

The

movement

muscular

of

food

contraction

down

called

the

oesophagus

peristalsis.

The

occurs

circular

by

a

wave

muscles

of

contract

muscles

and

relaxing

it

the

along.

longitudinal

In

front

longitudinal Figure

7.7.2

Peristalsis

in

contraction

the

82

the

muscles

relax

bolus,

contract

the

to

behind

circular

widen

the

food

muscles

the

bolus

relax

oesophagus

to

and

to

push

the

allow

the

the

bolus oesophagus

of

muscles

is

to

stomach.

a

wave

pass

of

food

to

move

along.

Movement

of

food

in

the

small

and

of

food

to

large

intestines

also

occurs

by

peristalsis,

though

to

a

lesser

extent.

The

oesophagus

stomach liver

stomach

The

stomach

food

but

can

stomach

The

a

walls

juice.

tnemelppuS

Gastric

a

muscular

stretch

number

of

This

proteins

is

the

smaller

juices

also

the

that

usually

accommodate

things

stomach

contains

to

to

of

bag

happen

make

a

molecules

contain

more.

to

pepsin

called

about

When

1

food

litre

of

reaches

the

it.

digestive

protease

holds

juice

which

known

starts

as

the

gastric

digestion

of

polypeptides.

hydrochloric

acid

which

carries

out

gall

two

bladder

important

functions

due

to

its

low

pH. pyloric

•

It

kills

any

bacteria

in

the

food.

The

low

pH

denatures

the

sphincter

enzymes

pancreas

in

any

harmful

microorganisms

in

the

food.

bile

duct pancreatic

•

The

the

acid

pH

action

of

of

about

the

1.5

to

protease

2.0

gives

enzyme

the

optimum

conditions

for

small

pepsin.

duct

intestine

Figure

7.7.3

Upper

part

of

the

digestive

system.

The

mixture

chyme.

making

is

a

of

The

sure

type

of

contents

of

food,

gastric

muscular

that

it

is

walls

mixed

mechanical

the

juice

of

and

the

well

with

digestion.

stomach

are

like

a

hydrochloric

stomach

the

After

juices.

2–3

runny

churn

acid

up

This

hours

of

is

the

called

food

muscular

KEY

POINTS

action

churning,

1

the

Food

by A

ring

of

muscle

called

the

pyloric

sphincter,

is

teeth.

liquid.

opens

to

let

the

the

a

little

at

a

time

into

the

duodenum

which

is

the

rst

is

up

then

actions

by

the

swallowed

of

the

tongue,

food saliva,

pass

chewed

It

part

soft

pallette

and

of epiglottis.

the

small

intestine.

2

Peristalsis

of

that

3

In

the

the

carrying

oesophagus

mouth

a

wave

contractions

squeeze

bolus,

salivary

involves

muscular

it

to

food

down

the

stomach,

the

stomach.

food

is

churned

gland

up

and

and

mixed

with

hydrochloric

gastric

acid.

juice

This

oesophagus

starts

liver

SUMMARY

the

digestion

of

proteins.

QUESTIONS

stomach

1

With

reference

events

that

to

take

the

place

following,

when

describe

food

is

the

chewed

pancreas

and

swallowed:

a

saliva

c

the

tongue

b

mucus

d

the

epiglottis

a

Describe

small

2

one

function

of

the

muscle

layers

in

intestine

the

b

i

stomach

Name

wall.

the

type

of

protease

produced

large

by

the

walls

of

the

stomach.

intestine

ii

Describe

the

function

of

this

type

of

enzyme.

c

Explain

briey

why

a

different

enzyme

is

rectum appendix

required

anus

food Figure

7.7.4

The

digestive

for

the

digestion

of

each

type

of

substance.

system.

83

7.8

Small

intestine

and

absorption

The

The •

Describe

small

the

digestion

small

in

the

small

the

emulsifying

its

role

of

bile

Dene

the

The

fats

term

Describe

how

intestine

is

efcient

after

the

the

absorption

for

of

food

•

amylase

•

trypsin

lipase

Bile

a

globules

emulsied

globules

to

of

of

are

to

increase

Bile

is

fo r

TIP

lipas e

no t

a

incr eases

of

of

as

chan ged

it

is

the

about

large

6

metres

intestine.

long;

The

rst

duodenum

that

leads

into

the

ileum

to

the

down

duodenum

the

duct

to

by

meet

the

pancreatic

food

arriving

duct.

juice

from

contains:

to

protease

starch

that

to

breaks

maltose

down

proteins

and

polypeptides

do

the

enters

the

not

also

stomach.

to

the

made

fatty

well

in

in

an

and

acidic

glycerol.

environment,

hydrogencarbonate.

along

the

a

liver

neutralises

This

acids

duodenum

duodenum

uid

and

to

sodium

enters

the

fats

work

alkali,

which

alkaline

in

down

gives

from

tube

and

the

the

stored

the

in

for

bile

the

which

pH

so

pancreatic

neutralises

the

stomach.

called

acid

best

the

This

duct.

gall

was

is

bladder

added

enzymes

Bile

in

to

the

the

small

work.

emulsies

Cells

globules.

over

fat

fats

which

into

fatty

lining

the

by

breaking

These

the

minute

enzyme

acids

ileum

and

down

large

droplets

lipase

can

globules

have

act

to

a

much

break

of

fats

larger

down

into

surface

molecules

glycerol.

make

enzymes

that

complete

the

digestion

of

food.

fat

•

Proteases

•

Sucrase

•

Maltose

which

break

down

peptides

to

amino

acids.

act which

breaks

down

sucrose

to

glucose

and

fructose.

is

chem ical

the

a

down

fats

Emul sica tion

dige stion

no t

area

enzy mes

type

ows

breaks

food

intestine

of

upon .

as

of

area.

area

surf ace

the

connected

breaks

enzymes

smaller

Emul sica tion

–

–

also

food

smaller

fat

surface

fat

–

yellow-green

Bile

the

is

Pancreatic

contains

acidic

STUD Y

small

that

peptides

juice

their

is

juice

stomach.

These

Large

so

than

small

adapted

•

7.8.1

really

less

stomach,

pancreas

to

Figure

is

absorption

the •

not

in

Pancreatic •

is

diameter

intestine, part,

including

intestine

of however

food

intestine

OUTCOMES

of

the

is

broken

epithelium

down

lining

by

maltase

the

small

to

glucose

on

the

membranes

intestine.

is

chem ically .

Absorption

Absorption

the

microvilli

wall

of

the

the

movement

intestine

into

of

the

digested

blood

or

food

the

molecules

lymph.

through

Digested

food

forming

includes brush

is

simple

sugars,

amino

acids,

fatty

acids

and

glycerol.

These

border

molecules

goblet

diffusion

cell

The

small

pass

or

by

through

active

intestine

is

the

wall

of

the

small

intestine

either

by

transport.

adapted

for

efcient

absorption

of

food

as

it

has:

nucleus

•

a

very

large

•

a

thin

lining

surface

area

of

about

9

square

metres

basement

membrane

the

Figure

7.8.2

Detailed

structure

epithelial

small

84

cells

of

lining

intestine.

the

the

wall

into

(only

the

one

cell

blood

thick),

and

so

lymph.

digested

food

can

easily

cross

tnemelppuS

LEARNING

It

is

possible

because

has

villi

a

the

such

lining

villus).

called

a

large

intestine

inner

(singular:

cell

t

small

folded

projections

the

to

is

of

the

area

long

millions

epithelial

microvilli.

membrane

very

with

The

surface

cells

These

epithelial

(at

of

least

tiny,

tnemelppuS

wall

cell

is

small

metres

in

space

an

adult).

projections

the

villi

have

the

absorptive

(see

Figure

acids

It

called

microscopic

area

of

7.8.2).

and

sugar

molecules

only

are one

6

a

increase

amino villus

such

nger-like

lining

vastly

cells

into

absorbed

through

the

thin

villus

thick

wall

into

the

blood

capillar y Villi

increase

the

surface

area

of

the

small

intestine.

blood

capillar y

fatty

acids

absorbed

and

into

glycerol

the

are

lacteal

lacteal

(lymph

blood

pick

coming

up

lymph

food

to

capillar y)

villus

blood

to

coming

to

takes

away

molecules

to

lymph

villus

fluid

glycerol

Figure

The

7.8.3

digested

capillaries)

to

the

in

liver

lymph

walled

result,

the

lymph.

slowly

veins,

the

food

portal

through

enter

to

the

and

molecules

body

carries

away

to

vein.

of

Fatty

the

lymphatic

enter

lacteals

molecules

Movement

eventually

not

capillaries

Absorbed

hepatic

the

does

reaches

villi.

moves

like

fat

the

in

of

fatty

rest

of

acids

and

body

villus.

food

by

transported

the

A

food

rest

into

acids

gut

blood

too

(lymph

transported

and

glycerol

empties

vessels,

the

bloodstream

are

the

which

near

quickly

(see

are

lacteal

are

the

quickly

and

thin-

heart.

page

As

a

115).

KEY

1

SUMMARY

POINTS

Bile

fat

1

Match

with

each

its

part

correct

of

the

emulsies

duodenum.

QUESTIONS

digestive

function

in

oesophagus

makes

bile

stomach

moves

food

the

system

second

in

the

rst

lipase

column:

2

from

the

stomach

to

globules

surface

column

the

area

can

Enzymes

intestine liver

makes

pancreatic

in

the

smaller

have

a

upon

larger

which

act.

produced

pancreas

ileum

fats

The

and

the

by

the

small

complete

chemical

juice

digestion. gall

bladder

carries

pancreas

mixes

duodenum

food

food

stores

to

the

with

stomach

gastric

by

peristalsis

3

juice

bile

Absorption

is

of

food

digested

through

2

a

State:

i

the

components

of

bile,

ii

the

organ

where

bile

iii

the

organ

where

bile

is

wall

movement

molecules

of

the

is intestine

produced,

the

the

into

the

blood

and

stored. lymph.

b

Describe

two

ways

in

which

bile

aids

the

digestion

of

fats. 4

3

a

How

are

conditions

conditions

in

the

in

the

small

stomach

different

from

the

The

for

small

absorption

long,

intestine?

lining b

State

the

composition

of:

i

gastric

juice,

ii

pancreatic

intestine

having

with

a

by

is

adapted

being

folded

millions

of

very

inner

tiny

villi.

juice.

85

7.9

Large

intestine

intestinal

The LEARNING

Describe

the

large

its

Describe

diarrhoea

symptom

intestine

the

is

about

appendix,

1.5

the

metres

colon

long

and

and

the

can

be

divided

into

rectum.

Explain

as

of

cholera

how

cholera

the

time

food

gets

to

the

colon

there

is

not

much

useful

food

left.

a

It

is

now

it

has

mainly

been

bre,

absorbed

dead

in

cells,

the

bacteria

small

and

some

water,

as

most

of

intestine.

bacteria

3

cause

diarrhoea

The

and

small

food

dehydration

intestine

passes

absorbs

along

the

about

colon,

5 – 10 dm

more

water

of

is

water

every

absorbed

into

day.

the

As

blood

–

3

about

The

0.3 – 0.5 dm

solid

faeces

waste,

are

per

or

egested

day.

faeces,

through

are

stored

the

anus.

in

the

The

rectum.

passing

Eventually

out

of

the

digestible

stomach

food

liver

through

the

anus,

in

the

form

of

faeces,

is

called

egestion

Cholera

Cholera

is

cholerae.

a

water-borne

The

dehydration.

main

Diarrhoea

Some

people

suffer

from

infected

the

disease

symptom

is

the

with

disease

of

loss

the

and

caused

cholera

of

the

called

bacterium

diarrhoea

watery

cholera

are

by

is

faeces

bacterium

as

a

from

may

symptomless

Vibrio

result

the

not

of

body.

actually

carriers

colon

Transmission caecum

small

Cholera

tends

sanitation,

anus

The

large

that

of

the

is

people

is

transmitted

Almost

acidic

seen

in

an

on

all

the

cholera

and

mucous

as

in

reach

lining

by

by

occur

food

conditions

survive

cholerae

can

handling

Effects

where

supply

there

or

is

a

lack

of

contaminated

proper

food.

Water

when

their

infected

people

pass

out

large

faeces.

the

by

or

drinking

water

or,

containing

contaminated

utensils

more

the

water ,

without

rarely,

food

bacteria.

by

washing

infected

their

hands.

body

the

the

the

of

material

cooking

bacteria

in

ingestion

faecal

ingested

stomach.

small

wall

of

by

However,

intestine.

the

humans

Here

intestine

some

they

and

are

killed

pathogens

burrow

start

by

to

the

may

through

produce

a

the

toxin.

electron

Molecules

of

this

toxin

enter

the

epithelial

cells

of

the

intestinal

wall.

(×13 000).

Here

they

epithelial

the

from

and

disrupt

cells.

intestine

lumen

cells

water

functioning

a

ions

intestinal

water

and

from

of

the

Chloride

(the

creates

the

symptoms

86

areas

contaminated

bacteria

contaminated

T ransmission

microscope

in

water

intestine.

Cholera

Vibrio

occur

unclean

become

numbers 7.9.1

an

rectum

supplies

Figure

to

intestine

appendix

tnemelppuS

tnemelppuS

•

large

caecum,

function

By •

intestine

intestine the

and

disease

OUTCOMES

The •

large

and

the

blood

cholera

–

of

This

cell

surface

the

cells

the

into

Water

the

lumen

dehydration

and

membrane

into

the

accumulation

gradient.

blood

into

the

out

lumen).

potential

from

the

pass

of

ows

lumen.

of

the

of

space

ions

by

diarrhoea.

the

inside

in

the

osmosis

Movement

intestine

of

of

cause

ions

the

tnemelppuS

Oral

To

rehydration

treat

diarrhoeal

infected

not

people

effective

drinking

being

and

An

lost.

because

or

to

water

to

•

sodium

•

glucose

bottled

is

like

is

not

water,

treated

This

cholera

possible.

is

by

is

important

giving

absorbed

does

not

giving

oral

it

Just

by

them

the

contain

people

a

rehydration

to

rehydrate

water

is

intestine,

the

ions

solution

therapy

and

that

of

are

salts

(ORT).

contains:

rehydrate

ions

as

water

drink.

solution

•

soon

Cholera

glucose

ORT

diseases

as

water,

therapy

to

the

blood

replace

the

and

ions

other

lost

tissues

from

blood

and

tissue

uid

Cholera

to

provide

energy

for

the

active

uptake

of

sodium

there

from

the

other

is

a

most

lack

easily

of

transmitted

clean

water

and

where

sanitation

is

intestine poor

•

is

ions

ions

such

as

potassium

and

chloride

to

replace

ions

lost

or

non-existent.

in

diarrhoea.

and

made

a

a

cholera

glucose

into

person

until

are

a

to

solution

water

ions

cells

that

with

boiling

and

is

with

The

a

water.

given

powder

contents

This

regularly

of

containing

each

takes

and

sachet

little

in

salts

are

training

large

for

volumes

recover.

these

epithelial

sachets

available.

administer

people

When

outbreak,

made

are

reabsorbed,

decreases

was

lost

in

and

the

water

water

is

potential

absorbed

to

of

make

the

up

for

the

diarrhoea. A

child

during

SUMMARY

1

a

What

QUESTIONS

sort

of

receives

the

KEY

organism

causes

1

cholera?

How

does

c

What

are

the

the

organism

symptoms

enter

of

the

Diarrhoea

a

What

b

How

sort

of

conditions

2

cholera?

encourage

the

spread

of

effective

treatment

of

drinking

water

help

control

sewage

the

is

the

Why

are

these

developing

measures

not

put

and

the

spread

of

is

tnemelppuS

Explain

in

how

th e

into

place

in

a

Diarrhoea

be

disease

caused

treated

The

diarrh o ea

and

loss

bact eriu m

of

br in g s

s a lts

f rom

caused

by

by

by

cholera

using

oral

the

a

bacterium

toxin

that

causes

a bout

blo od

ions

to

pass

into

the

in intestine.

the

watery

therapy.

cholera

chloride dehydration,

of

some

4

cholera

loss

intestine.

cholera?

countries?

detail

2010.

chlorination

produces 3

in

bacterium.

rehydration c

the

from

Cholera

can of

therapy

Haiti

cholera?

3 can

in

body?

a 2

rehydration

epidemic

POINTS

faeces b

oral

cholera

tnemelppuS

During

This

causes

water

to

intestine. pass

out

resulting

the

in

by

osmosis,

diarrhoea

dehydration

the

cells

loss

of

and

ions

from

blood.

87

PRACTICE

1

The

QUESTIONS

breakdown

of

large,

insoluble

food vitamin

molecules

into

small,

water-soluble

molecules

C

vitamin

D

calcium

gums

bowing

of

bleed

leg

iron

is:

muscle A

absorption

B

digestion

C

egestion

D

ingestion

weakness

A

(Paper

and

1)

[1]

tiredness

bones cramps

bowing

muscle gums

B 2

Which

is

a

correct

description

of

the

action

of

leg

tiredness

of

weakness

bleed bones

a

and

cramps

protease?

A

breaks

down

fat

into

fatty

B

breaks

down

protein

C

breaks

down

starch

D

converts

acids

and

C

scurvy

rickets

D

tiredness

rickets

anaemia

soft

gums

glycerol

muscle into

amino

acids

bones

bleed

weakness

amino

into

acids

glucose

into

proteins (Paper

(Paper

1)

The

an

[1]

[1] 6

3

2)

drawing

incisor

shows

a

vertical

section

The

drawing

shows

part

of

the

digestive

system.

1

through

tooth.

1

2 2

3 3

4

What

part

is

1,

the

function

stored

in

A

to

digest

B

to

increase

C

to

acidify

D

to

digest

of

part

proteins

the

the

2

liquid

and

to

produced

released

amino

surface

into

by

part

3?

acids

area

of

fat

droplets

4

Which

parts

row

is

shown

the

in

correct

the

identication

drawing

of

(Paper

above?

2

3

fats

contents

to

fatty

of

part

acids

4

and

glycerol

the

7 1

the

The

2)

[1]

following

events

occur

during

the

passage

4

of

A

cement

pulp

enamel

dentine

B

dentine

enamel

pulp

cement

1

starch

through

Amylase

is

the

alimentary

secreted

in

saliva

canal.

from

salivary

glands.

C

enamel

dentine

pulp

cement

D

pulp

cement

dentine

enamel

2

4

1)

A

C

is

a

anaemia

rickets

symptom

B

D

Which

to

4

Glucose

enters

5

Glucose

is

into

epithelial

the

surface

of

intestine.

breakdown

of

glucose.

the

blood

plasma.

absorbed

by

active

transport

cholera

the

cell.

scurvy

1)

Amylase

catalyses

the

breakdown

of

starch

[1]

row

the

the

small

of

of

the

table

(top

of

next

deciency

symptoms

for

maltose.

column) Which

gives

onto

the

catalyses

to

5

in

maltose

6

(Paper

secreted

cells

Maltase

[1]

Diarrhoea

is

epithelial

3

(Paper

Maltase

vitamin

is

the

correct

sequence

for

these

C, events?

vitamin

D,

calcium

and

iron? A

1,6,2,3,5,4

B

6,1,3,2,4,5

C

2,3,1,6,5,4

D

3,2,6,1,4,5

(Paper

88

2)

[1]

8

Which

area

of

a

villus

increases

12

surface

The

diagram

alimentary

capillaries

B

goblet

C

lacteal

D

microvilli

Copy

its

absorption?

A

(Paper

9

feature

for

shows

a

villus

from

the

canal.

cells

2)

[1]

the

diagram

from

question

6. A

(a)

On

the

diagram

oesophagus,

label

the

stomach,

following:

pancreas

and (a)

duodenum.

Copy

and

(b)

Draw

arrows

on

the

diagram

to

show

taken

by

food

as

it

passes

the

parts

of

the

alimentary

canal

on

(c)

State

the

diagram

use

label

lines

and

lacteal.

the

part

villi

F

an

letters

site

of

Name

three

to

the

secretion

of

hydrochloric

H

the

With

that

secretes

molecules

of

place

13

with

organ

A

State

diet

what

provided

It

is

is

an

that

alkaline

stores

essential

reference

A

meal

in

a

an

balanced

State

three

increased

that

they

that

a

increased

components

[4]

(a)

starch,

Describe

good

should

health.

The

be

diet.

[4]

when

woman’s

quantity

she

is

components

and

explain

should

be

diet

of

the

in

bread

diagram,

the

from

A

[3]

explain

alimentary

and

cheese.

cheese

starch

canal.

In

that

diagram

is

the

canal.

[6]

Bread

contains

digested

your

and

molecule

where

molecule

you

shows

molecule

in

answer

protein.

the

state

where

the

to

describe

a

small

places

1

break

place.

[5]

protein

along

proteases

help

take

the

and

it

2

act

on

down.

should

1

certain

2

1

breast-feeding.

that

why

it

should

is

be

important

increased.

(b)

[6]

How

many

after

the

two

fragments

molecule

will

has

be

been

produced

digested

by

proteases?

[1]

3)

(c) The

to

villi

and

how

changes

the

11

of

contains

contains

pH

bile

for

components

important

include

(Paper

pass

villus.

4)

the (b)

that

the

3)

balanced

(a)

into

a

the

10

canal

[1]

substances

diagram

alimentary (Paper

alimentary

acid

protease

a

the

located.

show:

(Paper organ

G

[2]

of

are

signicance the

capillaries

the

(d) following

E

the

[2]

on On

label

the

diagram.

(c)

and

through where

the

diagram

the (b)

direction

the

[4]

liver

performs

important

functions

in

Suggest

protein digestion

and

assimilation

of

food.

One

why

protease

2

cannot

act

on

the

the in

the

same

places

as

protease

1.

of [4]

these

is

the

production

of

an

alkaline

digestive (d)

juice

that

breaks

down

large

globules

of

State

the

where (a)

(i)

Name

the

digestive

juice

secreted

liver.

proteases

Explain

how

The

this

digestive

alimentary

canal

protein.

[2]

fragments

produced

by

digestion

by

the

food

in

the

1

and

2

are

not

absorbed

into

juice the

reaches

the

[1] proteases

(ii)

in

digest

by (e)

the

organs

fat.

small

blood.

Explain

why

this

is

so.

[2]

intestine. (f)

Describe

what

happens

to

these

fragments

[3] so (iii)

Explain

why

this

digestive

juice

that

alkaline.

down

(b)

Explain

(Paper

how

large

what

is

completely

broken

[2]

[2]

(Paper Outline

protein

is down.

(iv)

the

is

this

digestive

globules

meant

by

of

juice

4)

breaks

fat.

assimilation.

[4]

[2]

4)

89

8

Plant

transport

8.1

Transport

Most LEARNING

living

organisms

State

and

•

the

and

functions

of

xylem

the

positions

phloem

sections

of

transport

rely

phloem

Identify

in

of

xylem

stems

on

and

such

diffusion

Vertebrates

so

transport

system.

tube.

This

blood

systems:

and

have

for

throughout

water

root

Only

very

from

of

transport

regnans

is

the

tallest

in

the

so

remove

as

food

systems

same

and

and

move

up

to

90

two

of

a

dioxide.

have

water,

uids

through

within

pump

separate

are

plant

body

in

in

from

upwards

xylem,

to

Topic

in

and

the

the

unlike

These

stems

mineral

soil.

stem

in

composed

2.3).

roots,

water

ions

stem

tissues

(see

each

(the

heart)

transport

the

the

in

The

enter

phloem,

is

that

are

are

found

in

roots

the

leaves,

absorb

xylem

owers

one

in

the

the

and

fruits.

direction

only

–

leaves.

Phloem

xylem

sucrose

cells

leaves.

ions.

These

to

of

tissues

and

tissue

transports

phloem

sucrose,

owering

acids

and

bud

metres.

hormones

sunlight

YOU

have

can

ow

leaf

DID

not

they

carbon

amino growing

do

that

direction

consisting

have

worms,

at,

organisms

such

mass

system

or

phloem

plant

the

via

large

in

plants

some

and

transport

called

circulatory

Flowering

and

are

moves

is

and

small,

substances,

These

uid

transports

water

of

a

so

oxygen

plants

transport

mineral

roots

uptake

the

are

obtain

carry

transport

travel

Transport

plant,

small

phloem

the

tissue

and

and

of

phloem

specialised

Xylem

to

vessels.

and

to

bodies.

of

xylem

Xylem

Xylem

all

type

Vertebrates

and

their

protoctists

bodies

owering

systems

that

bacteria,

Their

alone

and

throughout

tubes

as

systems.

transport

transverse

roots,

leaves

Eucalyptus

a

OUTCOMES organisms,

•

need

systems

the

throughout

plant.

Sucrose

is

KNOW? energy

a

carbon

The

world’s

redwood

It

is

in

114 m

tallest

tree

is

a

giant

dioxide

California.

tall.

simple

made

simple

made

sugars

sugars

from

and

the

minerals

soil

sugar

which

made

especially

for

transporting

energy.

It

leaves

is

made

with

the

from

moves

growing

root

growing

bud

down

or

up

and

to

to

in

sugars

photosynthesis

from

storage

as

water

is

by

into

sucrose

complex

photosynthesis

sucrose

water

soluble,

starch

organs,

swollen

roots

in

such

and

and

stems. minerals

taken

by

up

roots

Figure

8.1.1

Substances

from

leaves

buds;

90

also

Transport

are

to

in

the

transported

roots

from

and

storage

xylem

in

the

upwards

organs

to

and

phloem.

phloem

from

new

in

two

leaves

stems

to

directions:

owers,

and

leaves.

downwards

fruits

and

Hormones

They

also

Inside

control

control

the

cell

the

nd

the

to

give

transverse

root

and

growth

root

To

and

transport

hairs

for

of

growth

owers

of

and

the

stem,

fruits

roots

(see

and

page

leaves.

170).

stem

tissues

of

roots

and

stems,

we

cut

across

them

sections.

absorb

mineral

division

water

ions

cortex

stores

some

food

This

as

starch phloem

amino

transports

acids

from

sucrose

the

are

used

to

make

at

root

as

it

Figure

the

root

cap

the

through

8.1.2

transports

ions

up

The

root

the

root

tip

tip

cells

the

grows

internal

structure

of

a

make

new

red

dye

the

for

xylem

with

dye.

water

root

as

the

cells

divide

vascular

phloem,

bundle

is

cambium

made

and

up

xylem

new

The

and

a

are

root.

of

xylem

in

strands

soil

a

cambium

lled

standing

red

tip

protects

grows

vessels

left

The

new and

cells

was

hours.

leaves xylem

which

celery

several

and

tissue

in

the

centre

of

this

root

is

phloem cortex

as

the

plant

xylem,

grows

which

between

the

is

stained

xylem

are

red.

The

phloem

green

areas

tissue.

pith

epidermis

is

a

single

layer phloem

of

cells

on

the

outside

amino the

stem

which

the

stem

and

acids

See

up

xylem

loss

8.1.3

Topic

sucrose

to

the

and

roots

to

the

flowers

and

fruits

reduces

transports

mineral

Figure

down

protects and

water

transports

of

The

6.6

for

internal

the

structure

positions

of

of

a

ions

up

water

to

the

and

leaves

stem.

xylem

and

phloem

in

the

leaves.

A

transverse

Note

SUMMARY

QUESTIONS

1

complete

the

KEY

Copy

and

the

sentences

using

these

sucrose

water

amino

ions

fruits

blood

heart

have

a

Flowering

transport

plants

system

have

two

Xylem

vessels

mineral

made

up

transport

of

a

the

transports

and

up

the

,

owers

and

.

and

acids

Phloem

the

stem

from

the

Phloem

tissue

from

leaves

to

all

parts

Using

the

roots

leaves.

vessels

made

transport

in

the

leaves

photosynthesis

and

in

transports

of

the

organs,

to

other

parts

plant, the

plant.

organs.

3 2

to

roots

of as

water

the

Xylem

storage

such

from

and

systems.

during to

transport

ions

stem

sucrose, tissue

stem.

storage

2 .

young

vessels

up

Vertebrates

a

POINTS

and mineral

through

bundles.

words:

1 leaves

section

vascular

the

diagrams

above,

state

the

functions

of

each

of

Xylem

and

phloem

are

these distributed

in

a

central

core

issues: inside

a

phloem

e

root

b

xylem

c

cambium

d

f

root

cortex

root.

Inside

a

stem

epidermis they

cap

a

are

vascular

organised

into

bundles.

91

8.2

LEARNING

Water

uptake

Water

by

The •

Identify

root

hairs

as

the

main

microscope

take

their

structure

to

hairs.

Soil

water

such State

the

pathway

taken

through

root,

of

and

roots

are

mineral

to

anchor

ions.

Just

the

plant

behind

the

in

the

root

soil

tip

and

are

small

Water

passes

into

the

root

hairs

by

osmosis

as

is

a

dilute

nitrate

and

solution

of

potassium.

various

Root

solutes

hairs

including

have

thin,

mineral

permeable

ions,

cell

by

walls water

water

water

uptake

•

functions

up

and root

relate

roots

seen to

under

uptake

OUTCOMES

stem

and

provide

a

large

surface

area

to

absorb

water .

The

cell

sap

and

in

the

root

hair

cells

is

a

more

concentrated

solution

than

soil

water .

leaf

This

is

because

solutes

water

particle

soil

as

diffuses

hair

sugars.

from

cells

The

the

water

also

cell

soil

cell

then

Most

walls

From

the

hair cells

of

here

stem

enters

cortex water

passes

up

in

the

by

by

the

other

permeable

so

osmosis.

cortex

of

the

the

in

water

the

moves

spaces

through

between

the

the

a

from

xylem

water

and

to

cell

in

the

cell

to

the

moves

the

Water

centre

up

leaves

cells.

walls,

cell.

cells.

the

of

the

xylem

where

Much

eventually

of

evaporates

it

through

enters

the

to

root.

the

water

form

water

and

then

diffuses

through

stomata

to

xylem

the water

across

mesophyll

vapour stem

of

cells

have

the

airspace

Absorption

of

and

the

spongy

8.2.1

hair

passes

moves

reaches

Figure

root

partially

and

B

Some

root

the

is

ions

vessel

root.

A

mineral

membrane

into

Water xylem

absorb

atmosphere.

root.

We

describe

and

into

Water

a

hair

movement

xylem

passes

potential

root

the

in

vessel

down

the

cell.

potential

lower

water

in

in

in

the

potential

in

cells

soil

the

to

a

root

hair,

potential

gradient,

lower

from

cortex

xylem

a

water

passes

of

the

of

into

potential

the

turn,

in

water

terms

water

solution

Water

water

a

of

the

and

(see

from

water

root

across

a

the

Topic

high

potential

hair

cell

eventually

to

to

an

cortex

3.2).

water

in

a

tnemelppuS

soil

such

root

the

lower

even

vessel.

PRACTICAL

Look

then

with

at

Root

hairs

on

as

can

a

a

92

hairs

of

a

germinating

bean

seed.

a

at

a

root

are

also

section

have

of

a

hairs.

long

look

germinating

or

a

osmosis

hairs

microscope.

the

bean

They

by

root

closely

Look

You

Root

at

a

and

at

thin.

root

hairs

seedling

such

radish.

large

and

surface

mineral

area

ions

through

are

which

absorbed

by

water

active

is

absorbed

transport.

tnemelppuS

Looking

Xylem

that

vessels

lls

instead

are

them.

it

is

like

pipes

Water

pulled

is

by

as

not

the

they

are

pushed

empty

from

evaporation

of

the

except

roots

for

up

the

to

water

the

leaves,

water.

tnemelppuS

STUD Y

Transpiration

pull Mak e

T ranspiration

cells

in

the

vapour

is

leaves

can

the

evaporation

and

diffuse

TIP

the

out

loss

of

the

of

of

water

water

leaf

from

vapour

when

the

the

to

surfaces

the

stomata

of

mesophyll

atmosphere.

are

sure

the

correc t

We

say,

leaves

The

is

by

This

•

is

As

from

up

the

xylem

transpiration

water

wilting.

up

‘pulled’

used

water

the

mass

for

is

xylem

ow

cohesion

–

of

the

stem

from

the

roots

to

the

and

the

photosynthesis

up

vessels,

lost

rather

up

water

or

the

and

from

like

xylem

molecules

to

stop

the

water

relies

tend

being

on

to

the

leaves,

plant

more

‘ water

vapo ur

each

of

‘ water

the

leaf’

goes

out

of

leaf’.

sucked

up

properties

attract

not

out

from

is

sucked

two

use

Water

pull

used

water

the

in

you

term inolog y.

open.

diffus es

Water

that

a

straw.

of

other,

water:

sticking

together

adhesion

the

So

xylem

there

is

a

–

the

water

molecules

also

tend

to

stick

to

the

inside

of

vessel.

continuous

ow

of

water

from

the

roots

to

the

leaves.

This STUDY

movement

of

water

up

the

xylem

is

called

the

transpiration

When

SUMMARY

QUESTIONS

1

complete

TIP

stream

you

and

the

sentences

using

these

in

stomata

osmosis

large

transpiration

are

for

2

into

taken

taking

leaves

of

passes

also

up

a

.

root

A

water

by

the

Look

up.

cell

root

and

This

is

hair

hair

cell

mineral

ions.

controlled

ions

the

.

a

water

xylem,

Mineral

leaf

water

of

that

from

with

water

pulls

the

in

the

roo ts.

surface

Water

by

the

start

evaporation

area

by

has

how

words:

always

Water

are

explaining

moves

Copy

tnemelppuS

•

the

is

lost

from

opening

and

the

closing

.

at

the

diagram

of

the

root

hair

in

the

soil:

A B

KEY

1

POINTS

Water

enters

osmosis.

the

cells

osmosis

It

a

root

then

of

the

hair

passes

root

before

cell

by

across

cortex

passing

by

into

the

C

xylem

D

F

the

and

then

up

the

stem

to

leaves.

E

2 a

Name

the

parts

labelled

A

to

Root

the

b

Explain

c

Give

how

water

gets

into

tnemelppuS

3

Explain,

root

using

hair

vessels

other

cells,

and

up

the

functions

term

across

to

the

water

the

cells

leaves,

of

a

root

root

hair

hair

potential,

of

are

well

cell

from

the

absorption

the

where

cells.

how

cortex,

it

is

lost

to

have

have

water

into

passes

the

the

of

adapted

water

for

since

soil. they

two

hairs

F .

into

xylem

atmosphere.

3

Loss

a

of

‘pulls’

stem

thin

large

water

more

from

cell

walls

surface

from

water

the

transpiration

the

up

roots

and

area.

leaves

the

in

the

stream.

93

8.3

Transpiration

Plants

absorb

water

•

Dene

•

Describe

the

term

transpiration

passes

where

it

is

diagram how

water

is

related

to

cell

lost

of

are

spaces

Describe

and

how

temperature,

light

from

humidity

can

There

and

affect

rate

tnemelppuS

how

a

the

leaf

atmosphere

you

will

see

through

the

soil.

as

that

stems

Much

water

there

and

of

vapour.

are

many

If

enters

this

you

air

leaves

look

spaces

at

a

by

mesophyll

cells

which

have

damp

cell

inside.

walls.

from

this

huge

internal

surface

so

the

air

spaces

Water

become

wilting

with

water

vapour.

in

is

usually

the

outside

the

air.

more Describe

water

up

stomata

variations

intensity

transpiration

•

of

moves

surfaces,

saturated

•

quantities

roots,

to

lined

evaporates air

into

vapour These

loss

large

OUTCOMES

The

air,

more

so

water

water

from

water

water

lost

the

vapour

vapour

from

the

in

the

diffuses

spongy

air

spaces

through

than

the

mesophyll

there

stomata

cells

is

is

in

into

replaced

by

xylem.

occurs

Transpiration

evaporation

the

of

diffusion

is

the

loss

water

of

at

water

of

water

the

vapour

surfaces

vapour

of

through

from

the

the

plant

mesophyll

leaves

cells,

by

the

followed

by

stomata.

Wilting

More

the

T wo

open

transpiration

stomata

are

open

the

Carbon

during

place

during

the

dioxide

the

day

is

a

during

so

raw

day

that

the

and

day

closed

carbon

material

than

at

at

night.

dioxide

for

night

can

because

The

diffuse

photosynthesis

into

and

stomata.

diffuses

The

STUD Y

into

stomata

chloroplasts

close

as

Whe n

form s

refer

water

evapor ates

water vapo ur .

to

at

night

in

mesophyll

to

reduce

cells.

the

volume

of

water

lost

by

TIP transpiration.

xylem

open

stomata

leaf.

takes

it

as

just

Do

air

lost

in

may

also

close

transpiration

is

in

not

hot,

being

dry

conditions

replaced

by

during

water

the

from

day

the

soil.

it

not

‘ water

vessel

water

They

’.

space

The

stomata

enough

so

much

are

rm

plant

close

water

it

water

and

that

give

becomes

up

will

reduce

they

the

soft.

to

start

to

are

plant

The

transpiration.

wilt

no

(see

longer

support.

stem

is

above

no

If

If

the

plant

on

the

right).

turgid

the

or

cells

longer

full

of

become

upright

and

still

Its

does

cells

water .

T urgid

accid

the

not

then

leaves

get

have

lost

cells

the

droop.

water

evaporates

off

cell

wall

stoma

vapour

Wilting

is

not

a

bad

thing.

The

leaves

move

downwards

so

are

diffuses

out

of

the

direct

rays

of

the

Sun

so

do

not

get

as

hot.

When

the

out

temperature Figure

8.3.1

Loss

a

94

of

leaf.

water

vapour

decreases

and

they

can

absorb

from

by

transpiration

the

leaves

will

recover.

more

water

than

is

lost

tnemelppuS

LEARNING

Factors

As

factors

see

the

light

intensity

of

In

very

humidity

is

a

dry

the

is

of

the

measure

is

of

rate

high.

of

the

are

air

rate

and

the

of

the

transpiration

Figure

the

other

Y ou

8.3.2.

increases

conditions,

temperature.

the

air

in

transpiration

by

quantity

when

As

environmental.

factors

determined

conditions

transpiration

humid,

that

these

of

water

humidity

becomes

is

etar

the

Humidity

air .

increases,

maximum

as

of

etar

such

a

transpiration

two

fo

to

of

fo

up

affecting

effects

noitaripsnart

can

transpiration

noitaripsnart

Other

affecting

vapour

low,

more

the

and

in

the

25

rate

more

50

75

humidity

decreases.

Figure

8.3.2

10

100

/

15

T wo

20

temperature

%

factors

affecting

the

rate

/

25

°C

of

transpiration.

The

rate

of

transpiration

increases

as

the

air

temperature

increases.

KEY

Transpiration

evaporation Light

causes

stomata

to

open.

As

the

light

intensity

increases,

wider .

As

light

intensity

decreases

when

it

is

cloudy

or

stomata

close

so

that

less

water

is

lost

by

transpiration.

conditions,

there

may

be

nearly

as

much

water

vapour

followed

in

water

as

concentration

low.

In

dry

vapour

cell

out

rate

the

surfaces

water

air

conditions

the

inside

the

gradient

diffuses

inuences

cells

in

of

leaf.

have

of

inside

for

the

water

vapour

the

concentration

the

leaves

of

temperature

more

kinetic

This

so

the

the

water

rate

and

is

that

of

from

very

enter

the

is

steep

so

such

molecules

air

2

is

inside

as

the

not

easy

velocity

the

leaf

the

If

water

water

rate

of

transpiration

but

you

can

use

to

water

lost

slightly

roots.

This

and

in

is

is

measure

less

because

keeping

cells

the

rate

than

some

the

of

of

water

volume

the

water

uptake.

of

is

water

used

The

taken

up

in

volume

in

by

potometer

shown,

is

making

allowed

bubble

is

is

to

a

sure

form

in

loss

of

by

the

in

increasing

the

greater

plants

lack

of

of

rate.

than

wilt

and

turgor

in

leaves.

of

photosynthesis

the

of

submerging

stem

in

the

capillary

the

rate

of

it

in

water.

stopper

tube.

The

water

is

It

is

set

air-tight.

distance

up

An

air

moved

cut

by

bubble

1

How

you

rate

shoot

of

State

a

capillar y

rate

set

measure

how

explain

a

the

by

it

a

cut

works.

how

conditions

of

up

uptake

Explain

and

an

to

water

these

the

reser voir

would

potometer

the

uptake.

air

QUESTIONS

as

of

A

rate

the

2

8.3.3

the

while

is

stems

shoot?

Figure

Increasing

wind

turgid.

lled

measure

and

decreases

SUMMARY

The

increases

rate.

uptake,

opens

a cells

potometer

diffusion

intensity

and

transpiration,

as

transpiration

measure

the

through

increases

humidity

to

the

atmosphere.

light

stomata

because is

the

temperature

the

on

to

transpiration

3

It

by

vapour

Increased

the

water

vapour .

Measuring

at

mesophyll

no

T emperature

surfaces,

water

there

transpiration

stomata.

increases,

energy

means

gradient

through

evaporation

As

leaves.

water

the stomata

atmosphere

of

the

In of

humid

of

towards cells

evening,

the

stomata surfaces

open

is

tnemelppuS

tnemelppuS

1

Explanations

POINTS

each

affects

transpiration:

increase

in

light

intensity

tube

bubble

b

a

decrease

c

an

in

increase

temperature

in

humidity

potometer.

95

8.4

Translocation

tnemelppuS

Food LEARNING

is

made

in

include

•

Dene

•

State

that

the

term

acids

move

parts

translocation

sucrose,

of

the

•

to

Explain

plant

a

sink

the

sucrose

a

in

at

phloem

from

a

The

act

as

a

parts

a

of

Compare

transport

source

times

to

growth

a

and

during

the

take

converted

plant

photosynthesis.

in

solution

which

and

in

means

fatty

the

acids.

The

soluble

These

phloem.

‘from

place

to

This

are

products

carried

transport

is

to

all

called

place’.

food

regions

place.

in

where

of

the

takes

of

The

leaves

growth

place

storage

simple

into

or

from

or

to

regions

sugars

sucrose.

storage

regions

to

is

production

where

produced

This

occur

of

by

respiration

or

photosynthesis

transported

provide

(the

to

energy.

parts

are

of

Sucrose

the

is:

plant •

•

by

acids

amino

leaves)

some

different

of

and

sink

that

may

life

leaves

amino

plant

translocation

source

the

OUTCOMES

transpiration

with

broken

down

by

an

enzyme

to

give

simple

sugars

that

are

used

in

respiration

translocation •

changed

•

used

and

•

to

Leaves

in

use

make

are

also

DID

tissues.

make

where

If

the

the

the

and

can

stylet

sap

so

be

of

stylet

collected

above

for

96

are

crop

on

phloem

their

piercing

pests.

sap

They

by

using

mouthparts.

the

at

the

and

photosynthesis

cells

are

are

cuticle

for

isotope

of

and

in

seeds

growing

root

tip

all

over

made

stored

on

the

and

the

in

in

attract

nitrate

plant

shoot

many

upper

animals.

to

and

seeds

surface

ions

make

root

as

of

tips.

oils

the

and

leaves.

to

some

the

and

sap

insert

of

maple

tubes

trees.

through

which

buckets.

feed

the

the

study

on

the

called

stem

into

the

sap

stylets

a

phloem

aphid

aphid

single

tube

with

cut,

the

phloem

which

can

phloem

causes

it

be

tube.

to

of

plants.

inserted

The

pass

along

food.

transport

is

in

the

of

sugars

sugary

sap

in

the

will

phloem.

pass

out

time.

sucrose

aphid

and

in

that

inside

phloem

tree

transport

the

feeding

below

from

the

collects

provide

used

a

from

and

cortex

sweet

needed

mouthparts

surface

Isotopically-labelled

feed

into

insects

piercing

of

root

walls

them

that

waxy

prepared

holes

small

the

stylet

the

of

Aphids

new

phloem

pressure

cell

from

are

acids

and

Aphids

8.4.1

These

Aphids

the

Figure

sugars

fatty

for

is

drill

have

the

KNOW?

syrup

are

in

new

make

and

through

living

acids.

to

ows

They

are

for

sap

Aphids

tubes

simple

needed

Farmers

Phloem

fruits

especially

Maple

the

the

YOU

storage

cellulose

some

also

for

tip

amino

proteins,

Leaves

starch

make

shoot

stored

to

to

stylets,

leaf.

the

can

be

that

The

injected

have

been

contents

passage

of

the

of

into

a

leaf

inserted

the

sucrose

sap

and

into

can

traced.

be

samples

the

stem

analysed

In

plant

transport,

journey

Water

empty

relies

a

is

called

and

owers

and

ions

and

upon

tension

The

the

in

part

of

absorbed

(the

the

The

sinks).

by

plant

part

roots

Xylem

where

where

(the

are

of

water

in

evaporation

of

water

vapour

xylem.

stream.

This

pulls

up

T ranspiration

xylem

water

is

it

a

substance

ends

source)

vessels

movement

the

transpiration

translocation

source.

are

fruits

cells.

the

a

tnemelppuS

Transpiration

its

and

from

from

greatest

travel

columns

vessels

the

the

on

is

(or

to

leaves

dry

is

to

a

its

sink

leaves,

pipes)

passive,

roots

hot,

begins

journey

of

dead,

since

it

producing

give

and

the

windy

days.

Black

Translocation

is

an

active

process

which

occurs

in

phloem.

The

food

are

the

source

of

food

substances

and

the

sinks

are

the

bean

and

tissues,

regions

of

growth

(root

and

shoot

tips)

cells

active

tubes

the

such

that

as

the

contain

transport

to

build

sinks.

root

some

of

up

cortex

sucrose

a

and

cytoplasm.

head

Translocation

at

of

is

the

the

source.

pressure

most

seeds.

Movement

Water

that

active

Phloem

in

on

the

regions

tubes

forces

sunny,

the

are

phloem

enters

the

days

very

spraying

are

producing

increased

levels

of

rapidly.

sap

Movem ent

in

sugar.

is

the

way

–

roots.

in

the

b

What

the

term

translocation

substances

are

translocated

in

the

T he

What

are

the

materials

transported

in

the

phloem

both

used

and

for?

leave s

2

3

Draw

a

table

Substances

the

xylem

to

are

and

compare

transpiration

transported

in

plants

with

from

translocation.

sources

to

sinks

to

grow th

in

sink

of

for

substances substances

substances

in

in

in

the

from

stem

In

it

is

leave s

tips,

and

to

from

wher e

and

this

of

phloe m

season

fruits

ques tion

only

from

trans port

occu rs,

owe rs,

is

upwa rds

answ ering source

them

and

direct ions.

Rem embe r

phloem.

water

xylem

upwa rds

down ward s

phloem?

of

grow ing

roots c

control

to

when

QUESTIONS

Dene

Farmers

TIP

subs tanc es

a

of

aphids

insecticide.

STUD Y

the

1

plenty

living

one

SUMMARY

is

requires

ions plants

there

favourable,

of

phloem

phloem

warm

are

respiring

and

by

storage

When

conditions

reproduce

plant

aphids.

leaves

to

seeds.

when

Sum mary

3b.

transported

transport

in

the

plant

the

plant

the

KEY

POINTS

xylem

1

transport

Translocation

movement

the

is

the

in

of

sucrose

and

phloem

amino

acids

from

the

leaves

(translocation)

to

regions

growth a

Copy

are

in

and

complete

transported

each

in

the

each

table

tissue

by

giving

and

one

two

substances

source

and

one

Explain

2

Regions

called

case.

how

a

root

tuber

can

be

a

source

and

a

sink

times

of

the

Aphids

feed

on

storage,

How

are

b

Suggest

are

are

regions

respiration

called

and

sinks.

Transpiration

is

a

passive

plants.

they

used

to

investigate

movement

in

involving

why

farmers

and

growers

control

dead

tissue.

phloem? Translocation

spraying

and

year.

process a

production

at

3 4

of

sources

growth different

respiration,

storage.

that

sink

of b

of

and

aphids

by

process

is

an

involving

active

living

tissue.

insecticides.

97

PRACTICE

1

In

QUESTIONS

which

water

conditions

by

would

a

plant

lose

of

most

environmental

caused

transpiration?

A

cool

and

dry

C

hot

and

dry

B

cool

and

humid

D

hot

and

humid

it

to

conditions

is

likely

to

have

wilt?

air light

2

(Paper

1)

Which

row

transported

in

describes

the

the

phloem

amino

B

amino

D

glucose

(Paper

3

acids

sucrose

Which

is

and

molecule

A

root

leaf

B

and

and

and

and

of

ions

sucrose

sucrose

ions

water

and

and

amino

sucrose

correct

water

ions

it

taken

moves

xylem

cell,

mesophyll

pathway

as

mesophyll,

hair

D

low

B

low

low

high

C

high

low

high

D

low

high

low

water

acids

and

(Paper

water

and

7

Which

water

ions

air

cortex,

root

moves

in

by

Which

through

root,

root

cortex,

air

spaces

spaces

hair

root

in

leaf,

xylem

a

phloem

C

xylem

down

in

xylem,

cortex,

leaf

D

xylem

from

water

potential

a

down

a

a

water

water

low

in

2)

mesophyll,

8

Which

statement

xylem,

mesophyll

the

from

root

water

from

B

mesophyll

D

xylem

of

spaces

best

the

to

high

which

the

water

pathway

is

lost

water

vapour

from

stomata

intercellular

into

the

from

of

water

and

mesophyll

diffusion

cells

of

through

soil? into

the

atmosphere.

hairs Evaporation

and

vessel

of

diffusion

into

water

of

the

from

water

mesophyll

vapour

cells

through

the

atmosphere.

[1]

potato

plant

grows

in

a

eld

Evaporation

sunlight.

Which

row

shows

the

of

carbohydrate

in

the

source

destination carbohydrate

A

glucose

leaves

tubers

B

glucose

tubers

leaves

C

sucrose

leaves

tubers

D

sucrose

tubers

leaves

9

The

A

diffusion

of

water

stomata

into

2)

water

for

6

days.

vapour

the

from

air

spaces

atmosphere.

[1]

diagrams

root,

B

show

stem

and

transverse

C

after

being

Which

leaf.

B

[1]

wilted

cells

2)

A

has

mesophyll

of

carbohydrate

plant

from

phloem?

(Paper

of

water

correct through

movement

of

in and

left

combination

C

98

gradient

potential

describes

by

through

Evaporation

D

without

gradient

leaves?

air

cell,

1)

potted

potential

potential

water

mechanism

cuticle

A

gradient

[1]

Diffusion

C

6

potential

atmosphere.

root

(Paper

water

[1]

absorbs

type

down

(Paper

atmosphere

C

bright

of

leaf

1)

sweet

movement

cells?

stem,

A

cuticle

A

the

leaf

from:

B

stomata

5

into

plant?

cell

A

(Paper

explains

stem

a

water

4

the

mesophyll

B (Paper

statement

atmosphere

cells,

stoma,

stoma,

[1]

A

and

xylem,

2)

from

Water

water

stoma

C

high

[1]

cortex,

root

xylem?

1)

the

high

xylem

acids

C

A

substances

phloem

A

humidity temperature

[1]

best

intensity

sections

of

(a)

Copy

that

the

diagrams

represent

phloem

in

A,

the

B

and

shade

positions

and

the

of

11

areas

xylem

and

C.

[3]

A

leafy

into

Copy

and

complete

functions

term

sap

of

the

refers

xylem

table

to

the

and

to

was

a

balance.

uptake

two

from

and

Topic

The

the

a

plant

8.3)

table

rate

and

which

shows

of

placed

was

the

rate

transpiration

the

leafy

shoot

during

a

hot,

dry

day.

The

transported

in rate

these

cut

(see

compare

phloem.

liquid

on

water

by the

shoot

potometer

placed

of (b)

a

tissues.

time

/

of

water

rate

of

water

h –1

loss

feature

phloem

composition

direction

of

of

the

ow

/

g

–1

h

absorption

/

g

h

xylem

midnight

4

7

0300

6

9

0600

12

12

0900

18

14

1200

24

17

1500

22

19

1800

18

20

2100

8

14

midnight

6

10

sap

in

the

stem

destinations

[6]

(c)

Describe

how

pathway

through

above

(Paper

10

A

you

taken

the

would

by

parts

water

of

the

discover

as

it

the

travels

plant

that

are

ground.

[3]

3)

potometer

measure

(see

water

Topic

uptake

8.3)

by

a

was

used

leafy

to

(a)

Plot

(b)

Calculate

rate

shoot.

a

of

1200

time

the

Describe

move

A

cool,

humid

air

in

B

cool,

dry

/

min

(d)

Explain

daylight

C

warm,

dry

D

warm,

humid

air,

in

daylight

E

warm,

humid

air,

at

night

in

air,

the

daylight

in

of

percentage

loss

your

the

change

between

Show

in

0600

table.

in

[5]

the

hours

working.

and

[2]

the

changes

over

the

in

water

24-hour

loss

and

water

period.

[4]

the

how

stem

water

to

the

moves

from

atmosphere.

the

cut

end

[4]

4)

6

daylight

rate

data

2

(Paper air

the

100

of

Calculate

hours.

absorption

mm

(a)

the

water

show

water

conditions to

to

taken

(c) for

graph

1

3

60

water

movement

in

−1

mm min

E,

(b)

and

Draw

the

for

each

present

a

ve

bar

of

your

chart

to

conditions

the

conditions,

answers

show

on

the

in

the

a

table.

effect

rate

of

A

From

the

of

movement

(d)

State

two

shoot

with

(Paper

a

[5]

results,

conditions

that

state

affect

through

ways

would

[3]

water

movement.

(c)

to

be

in

three

the

the

of

water

plant.

which

affected

transparent

environmental

rate

the

if

plastic

it

air

[3]

around

was

bag.

the

covered

[2]

3)

99

9

Transport

9.1

Describe

The

circulatory

Most

animals

the

one-way

ow

around

the

Describe

the

of

pump

the

ow

heart

of

as

a

of

valves

blood

to

and

circulatory

system

vessels.

that

consists

Circulatory

systems

of

in

blood,

some

animals

useful

permit

substances

surface

and

such

nutrients

as

oxygen

from

the

absorbed

part

of

the

from

gut

a

gas

that

is

the for

absorption.

Circulatory

systems

also

transport

waste,

only such

one-way

a

blood

pump

adapted

role

and

body

exchange

for

have

of

transport

•

system

OUTCOMES

sort blood

humans

Circulation

LEARNING

•

in

as

carbon

dioxide,

from

all

over

the

body

to

the

gas

exchange

ow surface.

•

Describe

of

•

a

the

single

circulation

sh

Describe

Blood

the

circulation

double

of

a

The

mammal

heart

its

the

blood

very

ows

body.

close

their

The

flow

let

the

Valves

towards

blood

close

to

stop

heart

from

The

wastes

from

blood

delicate

so

helps

to

the

they

blood

the

through

blood

vessels.

heart

to

the

different

organs

the

and

a

blood

so

heart

to

in

veins

a

veins.

are

good

can

have

The

smallest

capillaries.

supply

their

of

Cells

oxygen

carbon

are

and

dioxide

and

efciently.

allows

to

the

receive

one-way

giving

maintain

capillaries,

capillaries

reduce

to

arteries

removed

pumps

this

back

capillaries

system

heart

getting

arterioles

ows

these

circulatory

small

pressure

a

but

it

ow

pressure

one-way

high

the

blood

so

that

ow.

pressure

muscular

before

of

it

This

vessels

blood

enters

ows

is

blood

blood

around

inside

good

will

the

for

damage

known

as

capillaries

(you

flowing

nd

out

more

about

arterioles

on

page

107).

When

blood

leaves

backwards

capillaries Figure

circulates

away

connect

capillaries

and

can the

that

arteries

the

blood

which

arteries

Blood

to

other

body.

to

pump

in

vessels

nutrients

open

a

advantages

of

Valves

is

and

Blood explain

circulation

9.1.1

How

semi-lunar

permit

one-way

the

blood

pressure

is

even

lower.

valves

ow

of

There

are

semi-lunar

valves

in

veins

to

make

sure

blood

does

blood.

not

ow

backwards

happens,

valve

of

gills

has

the

back

veins

swell

three

blood

to

ll

away

of

and

these

pushes

the

from

the

the

blood

pockets.

against

heart

is

The

them,

(see

not

circulated

valves

but

Figure

open

they

9.1.1).

when

close

If

properly.

when

the

this

Each

pressure

blood

ows

pockets.

arteries

heart

A

semi-lunar

the

between

heart

the

single

Fish

body

9.1.2

Fish

have

a

circulation

ows

once

the

100

are

valves

chambers

chambers

of

in

to

the

heart

enter

the

at

the

arteries.

heart

(see

places

There

page

are

where

also

blood

valves

102).

circulation

veins

organs

Figure

leaves

single

in

in

a

body.

the

circuit

a

single

during

from

the

oxygen

which

through

have

once

it

a

organs

and

circulation

complete

is

ows

called

because

circuit

into

the

of

the

heart

blood

body

from

deoxygenated

ows

(see

veins.

blood.

through

Figure

This

The

the

9.1.2).

blood

heart

heart

Blood

has

little

pumps

blood

blood

into

blood

ows

an

artery

that

takes

it

to

the

gills

to

be

oxygenated.

heart

around

on

from

the

gills

in

arteries

to

the

body

organs.

The

tnemelppuS

detanegyxo

detanegyxoed

doolb

doolb chambered

There

tnemelppuS

A

double

circulation

lungs

Mammals

twice

have

during

a

one

this

by

The

mammalian

is

a

circulation.

complete

following

septum

double

the

heart

thick

circuit

pathway

wall

Blood

around

that

blood

ows

the

through

body.

takes

is

divided

into

two

of

muscle

that

separates

You

around

halves:

right

the

the

can

heart

conrm

Figure

and

two

9.1.3.

left.

halves

The

of

the right

heart

that

stops

blood

in

the

right

side

mixing

with

blood

in

the

side

left

side

left of

heart

of

heart

side.

Blood

circulation

•

right

The

and

side

back

to

has

of

the

two

the

functions:

heart

heart

pumps

again.

The

deoxygenated

pressure

blood

required

to

to

the

force

lungs

blood the

to

the

the

lungs

lungs

occurs

as

as

absorbs

returns

is

not

they

blood

the

are

a

ows

oxygen

to

very

and

high

spongy

in

a

is

little

lled

capillaries

carbon

vein.

there

tissue

through

loses

heart

since

with

in

dioxide.

This

blood

resistance

the

The

is

air.

Gas

lungs.

to

red

heart

in

exchange

Blood

oxygenated

bright

ow

in

blood

colour

rest

and

of

body

is

•

shown

The

of

left

the

red

side

body

leaving

is

in

the

much

of

on

the

and

left

more

diagrams

heart

back

side

to

is

the

pumps

the

much

resistance

of

to

circulation.

oxygenated

heart

again.

greater

ow

than

than

blood

The

on

there

to

pressure

the

is

right

through

the

of

rest

Figure

9.1.3

Mammals

side

the

as

exchange

such

and

as

occurs

muscles,

carbon

capillaries

the

dioxide

and

as

blood

gut,

liver

enters.

ows

ows

and

The

through

through

kidneys.

capillaries

Oxygen

deoxygenated

veins

is

dark

blood

red

in

in

leaves

that

colour,

shown

as

ows

through

twice

in

but

may

and

be

complete

KEY

2

the

sentences

using

these

words

body

veins

The

heart

right

.

The

is

Here

of

it

gas

blood

it

side

of

tissues

left

lungs

deoxygenated

the

pumped

to

to

mammalian

absorbs

is

returns

and

carbon

right

dioxide

3

oxygen

heart

and

removed

from

the

the

side

the

is

of

where

pumps

now

blood

the

it

to

in

complete

circuit

valves

up

lungs.

and

from

its

of

ensure

a

a

around

system.

single

passes

once

the

blood

circulation,

through

during

one

the

circuit

body.

Blood

ows

heart

the

twice

during

body

in

a

th ro u gh

one

circuit

m a mmal.

the

blood.

the

have

blood

the

called

heart

gives

blood

ow

circulatory

Fish

of The

a

body.

POINTS

heart

(some

twice):

oxygenated

the

blue.

QUESTIONS

used

blood

heart

is

so

Copy

the

blood

leaves

the

1

double

organs

the

one-way

SUMMARY

a

which

lungs.

1 always

in

there

of

Gas

have

circulation

blood

4

The

heart

pumps

low

pressure

to

blood

the

at

lungs

The

and

at

rest

of

high

pressure

to

the

here

and

the

body

in

a

double

is

circulation. now

the

2

3

called

heart

blood.

in

what

double

circulation

Explain

the

Blood

b

Blood

c

Veins

passes

back

to

the

side

of

.

Explain

a

It

is

5

meant

following

the

terms

statements

on

the

right

on

the

left

contain

by

side

side

of

of

semi-lunar

the

the

single

about

heart

heart

is

circulation

the

is

at

low

high

ows

in

from

the

veins

towards

arteries

heart.

Blood

away

ows

in

and

mammalian

at

Blood

the

heart.

heart.

pressure.

pressure.

valves.

101

9.2

The

Heart LEARNING

Describe

the

four

human

the

heart

and

locate

of

blood

vessels

and

•

State

that

the

with

the

place

The

page

one

heart

consists

of

that

away

from

blood

the

two

pumps

and

the

lying

left

side

side

of

by

the

side.

The

heart

is

almost

entirely

of

cardiac

muscle

tissue

one

to

is

aorta

pumped

heart

body

body

vena

cava

(main

into

vein) pulmonary

arteries

heart

•

and

in

Explain

of

the

returns

to

to

right

lung

importance

septum

to

left

oxygenated

deoxygenated

lung

in pulmonary

separating

artery

the

veins

the

right

another

events

during

from

State

of

pump

24).

heartbeat

•

consists

is

heart

sequence

take

heart

valves (see

associated

the

the pump.

major

heart

chambers side

of

structure

OUTCOMES

The •

heart

veins

and

blood

from

•

Locate

the

and

name

the

valves

heart right

atrium left

•

Explain

why

ventricles

those

of

the

are

the

walls

thicker

atria

of

left

than

ventricle

than

and

the

is

why

thicker

valve

right

cava

TIP

left

Whe

n

tendons

valve*

vena

STUD Y

atrium

the

atrioventricular

the

lungs

in

you

look

at

ventricle

a right

diag ram

the

it

hear t

from

or

draw ing

you

of

ventricle

from

are

*Supplement septum

the

fron t

of

the Figure

body

the

–

so

hear t

side

of

the

is

the

lef t

on

the

side

YOU

9.2.1

The

septum

right

draw ing.

KNOW?

Al-Nas

physician

was

the

the

the

side

On

each

are

called

have

was

He

an

of

13th

the

suggested

puried

in

the

show

how

the

blood

moves

through

the

heart.

(wall

mixing

of

tissue)

side

of

atria

When

much

prevents

the

oxygenated

heart

(singular:

the

atria

more

they

with

deoxygenated

there

contract

the

are

atrium).

muscular

pump

blood

blood

out

the

into

left

empties

pump

than

the

chambers.

Blood

they

walls

two

on

blood

on

the

blood

atria.

arteries

side.

The

into

into

chambers

from

ventricles,

When

at

upper

them

the

higher

which

ventricles

pressure.

Arab

person

functions

lungs.

102

of

rst

was

arrows

righ t

contract Ibn

The

of

veins.

DID

body

view ing

century.

to

He

connect

heart

that

lungs.

and

blood

Between

prevent

right

walls

each

the

and

blood

left

than

further

atrium

owing

ventricles

the

than

and

atria

the

ventricle

back

–

into

contract.

because

atria

to

a

right

to

or

left

have

pump

lungs

valve.

and

ventricles

have

the

one-way

the

The

they

either

is

to

The

valves

atrium

more

when

the

muscular

the

blood

the

tissues

much

of

the

body.

The

left

ventricle

because

more

it

tnemelppuS

contract,

The

at

more

pump

to

pumps

the

muscular

blood

around

wall

the

than

body

the

right

and

has

ventricle

to

from

from

heart

relaxation

overcome

ow.

two

sides

same

blood

chamber

chamber

the

a

action

heart

each

to

resistance

Heart

The

has

has

when

gets

contracts

of

the

time.

it

heart

The

its

smaller

relaxes

work

the

relaxation

phase,

During

the

contraction

and

so

it

contract.

squeezes

lls

together.

ventricles

During

muscles

contract

blood

up

the

with

The

and

ows

When

relax

into

the

blood

blood

atria

the

out.

the

atria

phase

filling

After

again.

contract

at

muscles

and

same

from

relax

right

left

atrium

atrium

time.

the

veins.

left

phase:

ventricle

•

The

atria

between

against

contract

and

force

the

and

ventricles

atria

blood

into

open

the

due

ventricles.

to

the

The

valves

pressure

of

blood

right

them.

ventricle

heart

•

Then

The

The

the

valves

right

artery.

aorta

The

ventricles

close

left

(main

phase

They

they

prevent

pumps

ventricle

to

force

blood

blood

owing

to

pumps

blood

the

blood

out

into

the

arteries.

back

into

the

atria.

lungs

to

the

in

the

rest

of

of

full

blood

to

to

lungs

body

pulmonary

the

body

in

the

artery).

semi-lunar

arteries.

to

ventricle

The

contract

valves

act

shut,

like

occur

the

at

the

ones

preventing

in

base

of

Figure

back

ow

the

aorta

9.1.1.

of

and

During

blood

into

pulmonary

the

the

relaxation

ventricles. heart

During

the

the

lungs

contraction

and

the

phase

they

open

allowing

blood

to

leave

to

contraction

body.

Figure

Deoxygenated

blood

returns

to

the

right

atrium

in

the

vena

9.2.2

The

cardiac

changes

cava

heart

(main

vein).

pulmonary

phase

pumping

Oxygenated

blood

returns

to

the

left

atrium

in

cycle

that

during

–

the

occur

one

in

the

heartbeat.

the

veins. KEY

1

POINTS

The

heart

muscular

consists

pumps

of

two

divided

by

a

septum. SUMMARY

QUESTIONS

2

1

a

What

are

the

two

upper

b

What

are

the

two

lower

chambers

chambers

of

of

the

the

heart

heart

called?

Ventricles

blood

make

called?

one c

What

is

the

function

of

the

Explain

each

The

atria

The

left

blood

ows

in

The

atria

have

less

muscular

statement.

have

less

muscular

walls

than

the

ventricle

has

a

much

more

than

the

ventricles,

as

ventricles. they

b

that

force

valves

direction.

walls a

sure

to

arteries;

septum?

3 2

contract

into

muscular

wall

than

only

force

blood

into

the

the ventricles.

right

ventricle.

4 3

In

each

of

the

following

cases,

which

blood

vessel

The

right

blood

a

blood

to

the

rest

of

the

blood

from

the

lungs

c

blood

from

the

body

to

to

to

the

forces

lungs,

then

the

body left

b

ventricle

carries:

the

the

left

atrium

right

atrium

as

a

ventricle

it

has

to

pressure

greater

is

more

pump

that

muscular,

blood

at

overcomes

resistances.

103

9.3

Heart

There LEARNING

•

State

can

be

to

the

activity

in

monitored

pulse

rate

sounds

of

the

by

heart

monitored.

These

listening

the

Investigate

listening

valves

of

The

the

state

physical

pulse

Explain

control

activity

variety

the

activity

of

the

sounds

of

the

heart

valves

(ECGs),

heart

pulse

may

rate

be

and

closing.

(ECG)

of

of

the

heart

heartbeat

disorders

depends

can

upon

produce

electrical

activity.

irregularities

in

this

activity.

on electrocardiogram,

or

ECG,

is

a

useful

diagnostic

tool

that

can

rate

the

effect

of

on

the

these

defects.

Electrodes

are

taped

at

various

positions

on

the

physical body

activity

to

electrocardiogram

detect

•

which

and

The the

by

electrocardiograms

closing

A effect

methods

include

ECG,

and

The •

different

exercise

OUTCOMES

that

taking

are

and

heart

and

the

electrical

activity

of

the

heart

is

then

displayed

on

a

rate monitor.

ECGs

The

its

Figure

for

a

9.3.1

heart

resultant

trace

characteristic

contracting,

the

P ,

the

ventricles,

shows

a

normal

ECG,

while

Figure

9.3.2

shows

disorder.

can

be

QRS

QRS

and

compared

and

T

‘spike’

the

T

waves.

with

The

immediately

wave

represents

the

P

normal

wave

ECG

shows

precedes

the

ventricles

with

the

atria

contraction

of

relaxing.

R

egnahc lacirtcele

A

boy

an

using

ECG

to

an

exercise

monitor

his

bicycle

heart

while

T

P P

having

Q

function.

S

0

0.1

0.2

0.3

0.4

0.5

0.6

time

Figure

Heart

ECG A

normal

(ECG)

the

of

the

this

example

one

heart

0.9

1.0

s

beats

takes

0.8

seconds.

sounds

The

heart

The

noise

of

During

fibrillation

contractions

In

0.8

trace

sound

ventricular

9.3.1

/

0.7

ventricles

are

extremely

valves

of

the

your

the

respond

blood

contraction

to

force

blood

pressure

of

blood

pressure

when

heartbeat

contract

to

–

the

changes

valves

open

during

and

a

close

cardiac

make

cycle.

the

‘lub-dub’.

phase,

out

of

the

muscular

the

pulmonary

walls

of

the

artery

and

ventricles

aorta.

The

irregular

shut,

rst

complete

heart

the

ventricles

atria

and

part

During

block

are

preventing

beating

independently

high

of

the

9.3.2

A

normal

ECG

trace

ECG

traces

disorders.

for

in

the

the

going

sound

from

back

–

phase,

arteries

blood

atrioventricular

into

the

valves

atria.

causes

This

them

produces

to

the

‘lub’.

the

ventricles

causes

going

the

relax.

The

semi-lunar

backwards

into

blood

valves

the

to

under

shut,

ventricles.

produces

the

second

part

of

the

heart

sound

–

‘dub’.

Doctors

are

heart

able

any

104

heart

the

and

This two

blood

relaxation

pressure

preventing Figure

the

against

to

listen

to

irregularity

these

in

the

heart

sounds

heartbeat.

with

a

stethoscope

and

identify

tnemelppuS

The

heart

During

order

exercise,

to

muscles

These

and

your

contract.

dilate

changes

exercise

muscles

So

the

increase

the

an

increase

in

supply

•

an

increase

in

removal

can

time

you

can

wrist.

the

detect

the

left

same

the

You

as

the

The

resting

The

tter

The

same

energy

faster

are,

of

of

and

carbon

blood

a

and

from

respiration

arteries

in

supplying

muscles

and

result

in:

glucose

through

arteries

passes

pulse

per

to

dioxide.

wave

your

pulses

heart

ow

oxygen

nd

of

pulse

you

blood

beats,

can

number

of

ow

ventricle

feel.

The

more

beats

(widen).

•

You

need

heart

by

minute

along

feeling

is

your

as

a

the

an

‘pulse’.

arteries

artery

pulse

at

rate

Each

which

your

and

this

is

rate.

rate

the

A

gives

lower

a

good

your

indication

resting

pulse

of

a

rate

person’s

(see

person

minute

but

with

of

blood

fewer

is

being

passed

out

of

the

heart

and

shows

levels

of

the

taken.

POINTS

per

heartbeats. ECG

traces,

sounds

table

pulse

tness.

1

The

their

table).

KEY volume

having

general

relationship

between

resting

pulse

rate

used

of

to

pulse

valves

monitor

rate

and

closing

heart

the

can

be

activity.

tness.

2

pulse

less

rate

than

level

50

of

tness

Pulse

rate

and

then

resting

pulse

with

decreases

to

rate.

outstanding

3 50–59

Physical

activity

increases

the

excellent

heart 60–69

good

70–79

fair

ow

80

increases

activity

and

over

rate,

to

more

muscles,

oxygen

removing

poor

increasing

blood

supplying

and

carbon

glucose

and

dioxide.

PRACTICAL

Investigating

the

Sit

a

still

and

get

effect

partner

of

to

exercise

measure

on

your

pulse

pulse

SUMMARY

rate

rate

at

rest. 1

Try

doing

step-ups

for

1

minute

(light

QUESTIONS

a

State

pulse

exercise).

what

rate

happens

when

a

to

person

exercises. As

soon

as

you

have

nished,

sit

down

and

count

your

pulse

rate.

b

Wait

until

your

pulse

returns

to

the

resting

rate.

Explain

pulse

how

rate

and

why

changes

with

exercise. Now

do

(heavy

step-ups

exercise).

Remember

have

the

exercise

until

that

same

each

your

as

quickly

Then

to

make

person

time,

pulse

as

count

this

doing

rest

returns

for

to

you

your

a

valid

the

5

its

can

pulse

for

3

minutes

rate.

2

investigation

exercise,

minutes

resting

do

the

between

you

should

same

each

type

can

your

also

results

repeat

more

the

tests

and

Draw

b

Explain

to

of

exercise

T

or

calculate

an

average

to

make

Pulse

can

explain

how

reliable.

the

results

in

terms

the

normal

what

heart

ECG

is

at

trace.

happening

P ,

QRS

and

waves.

of

supplying

substances

rate

certain

be You

a

rate. 3

You

a

is

risk

some

the

affected

factors.

of

result

these

of

a

by

Explain

can

person’s

to lifestyle.

your

muscles

and

removing

their

wastes.

105

9.4

Blood

Blood LEARNING

ows

them

arteries Name

to

the

and

and

arteries

to

all

main

from

blood

the

in

and

veins.

This

table

organs

shows

of

you

the

body

some

of

and

the

heart,

organs

vessel

Describe

the

function

of

structure

arteries,

lungs

liver

kidneys

and

veins

and

vena

cava

right

atrium;

to

hepatic

artery;

bringing

blood

renal pulmonary

hepatic

(see pulmonary

the

functions

vein

artery

vein

arterioles,

venules

page

(see 146)

of

and

artery

portal

to

organ State

away

important

veins.

lungs

kidney

capillaries

•

ows

most

vessels

heart

•

the

OUTCOMES from

•

in

vessels

to

left

atrium

page

144)

shunt taking

pulmonary

blood

artery

away

right

from

aorta

organ

ventricle

vessels tnemelppuS

from

hepatic

vein

renal

vein

pulmonary •

Explain

how

the

structure

of

ventricle;

(see

page

(see

page

vein arteries,

are

veins

adapted

and

for

capillaries

their

functions

from

left

144)

head,

and

vena

thick

146)

neck

arms

cava

outer

layer

lungs pulmonar y pulmonar y

vein arter y

aorta

vena

which

blood

thick

and

right

left

atrium

atrium

cava

flows

layer

elastic

of

right

left

ventricle

ventricle

hepatic

muscle

vein

fibres

liver

hepatic

arter y Figure

9.4.2

An

artery. hepatic

portal

vein

renal

gut

vein

renal

kidneys

body

arter y

and

legs

two

are

outer

layers

thinner

outer

layer Figure

than

9.4.1

Main

blood

vessels

of

the

body.

arteries

Structure

large

space

When which

and

function

of

blood

vessels

through

blood

your

heart

muscles

contract

they

force

blood

into

at

muscle

and

a

high

the

pressure.

blood

to

Arteries

ow

have

along.

quite

They

a

have

narrow

thick

space

walls

and 9.4.3

in

made

fibres

106

arteries

the

centre

elastic

for

Figure

the

flows

A

vein.

elastic

bres

to

withstand

the

pressure

of

blood.

of

muscle

Veins

have

thinner,

veins

is

walls.

that

The

a

less

There

squeeze

are

in

branch

so

tnemelppuS

blood

and

than

one

it

is

less

valves

times

very

wall

easy

elastic

at

–

the

a

do

to

substances

adapted

to

such

veins

to

(see

cell

can

from

to

a

and

their

inside

thick

ensure

page

branches

blood

are

pressure

heart

pass

and

need

along

the

made

to

The

not

smallest

red

is

arteries

walls.

intervals

capillary

are

than

they

back

until

a

ow

so

narrow;

of

for

vessels

to

arteries

direction

are

The

blood

have

in

many

Capillaries

cells

for

semi-lunar

through.

thin

How

lower

ows

arteries

capillaries.

space

muscular

much

blood

very

wider

100).

form

only

single

from

just

layer

the

of

blood.

functions

red

The

like

elastic

a

bres

piece

original

of

where

it

the

elastic

length.

maintaining

in

The

its

walls

when

recoil

enters

an

you

of

pressure.

As

organ

is

of

the

stretch

elastic

a

arteries

a

and

bres

result

only

it

the

little

stretch

then

helps

less

let

to

pressure

than

and

then

recoil

it

return

to

push

blood

along

at

the

when

end

it

left

of

is

estimated

that

there

are

over

80

000

km

of

capillaries

so

heart.

in

9.4.4

A

capillary

body.

These

tiny

vessels

provide

a

huge

surface

area

magnied

capillary

between

blood

and

cells.

Blood

ows

through

slowly

(about

substances

cells

the

with

diffusion

This

makes

and

to

it

the

by

pressure

mm

As

to

of

from

second)

walls

blood

the

oxygen

dioxide

in

and

the

blood

is

for

from

and

exchange

one

cells

nutrients,

other

of

time

made

and

veins

contraction

giving

are

between

supply

carbon

pressure

per

the

distance

easy

remove

As

1

cells.

is

layer

very

such

as

of

surround

the

are

other

wastes.

very

body

low,

it

is

muscles

squeezed

and

other

along

KEY

POINTS

organs Arteries

in

the

circulatory

system.

elastic

blood

have

much

small

subdivisions

of

arteries

that

carry

blood

blood

networks.

from

ow

blood

pressure.

hormones

in

Like

They

the

arteries,

transport,

order

through

muscular

receive

to

they

have

arterioles

nerve

regulate

are

muscle

important

impulses

their

in

and

diameter.

their

in

withstand

less

tissue

Blood

Veins

muscle

and

have

pressure

and

thin

in

veins

low.

walls.

regulating

respond

This

to

pressure.

to is

Apart

thick

walls

high

walls.

capillary

have

veins.

vessels

the

removed

cells).

short.

elastic

are

blood

glucose,

Arterioles

Arterioles

section

red

of

and

There

view

thin

1 that

actually

capillaries to

very

is

for cylindrical,

exchange

×2500

the

(the

human

cells

capillar y

artery

Figure

It

a

its

an

the

blood

inside

to

2

are

various

regulates

Capillaries

one

have

cell

substances

blood

and

capillaries.

out

of

walls

thick

can

the

so

that

that

pass

easily

blood

in

in

body

tissues.

Venules

Venules

are

from

the

veins

which

small

blood

capillary

beds.

transport

vessels

These

whose

function

thin-walled

deoxygenated

is

vessels

blood

back

to

collect

then

to

blood

unite

the

to

SUMMARY

QUESTIONS

form

1

heart.

Make

a

table

differences

Shunt

and

vessels

veins.

columns:

A

shunt

vein,

allowing

Shunt

In

vessel

vessels

is

the

can

endotherms

response

and

to

a

blood

vessel

to

control

thereby

heat

that

bypass

blood

(warm-blooded

cold,

reducing

blood

links

the

ow

off

artery

capillaries

by

directly

in

certain

constriction

animals),

cutting

an

the

shunt

blood

and

vessels

ow

to

areas.

dilation.

the

show

Include

feature,

the

main

arteries

three

artery,

vein.

a

constrict

to

to

between

in

extremities

2

In

what

well

ways

adapted

materials

and

body

are

for

the

capillaries

exchange

between

the

of

blood

tissues?

loss.

107

9.5

Coronary

heart

disease

(CHD)

You LEARNING

need

muscle

•

Describe

the

coronary

State

nature

heart

the

of

disease

possible

preventative

coronary

•

Describe

CHD

(CHD)

causes

measures

heart

the

may

get

then

blocked

to

be

in

could

the

and

heart

heart

cause

in

the

blood

heart

to

around

keep

coronary

could

it

7.2

arteries.

die

Slowing

Healthy

which

the

arteries

However,

people

from

each

cause

countries.

death

The

become

is

for

one

starved

have

a

smooth

cholesterol,

This

can

condition

narrow

is

which

the

called

lining,

is

letting

made

artery

and

in

the

slow

blood

liver,

down

death

It

rate

in

is

with

can

from

has

the

CHD

There

are

these

differences

of

atherosclerosis

Fatty

deposits

break

Fatty

deposit

of

a

–

blood

9.5.1

The

artery

clot

and

the

healthy

Blood

walls

block

108

blocked

formed

with

of

is

if

can

the

the

become

vessel.

artery

gets

or

angina.

rough,

The

coronary

activity

called

flow

arter y

along

stops.

Atherosclerosis.

coronary

heart

blockage

artery

partly

emotion

It

is

which

is

causes

caused

by

cause

called

a

serious

blocked

makes

can

it

the

not

can

blood

to

thrombosis

problems.

cause

heart

the

work

enough

chest

pains,

harder.

oxygen

getting

to

by

to

fatty

deposits.

further

the

narrow

healthy

artery

muscle.

Angina

should

a

attack.

heart

total

act

blockage

and

the

unless

as

or

a

warning

thrombosis

supply

the

beating

follow

Compare

arter y.

artery.

stop

has

the

flow

chest

artery

blocks

them.

happens,

it.

their

blood.

many

A

above

to

of

is

the

artery.

stick

ow

lowest

This

the

easily.

the

especially

clot

and

the

If

blood

oxygen

many

Narrowing

coronary

are

arteries

in

Figure

A

of

ow

the

the

A

these

ow

3

Cross-section

If

coronary

year.

country

Japan

rate.

reasons

diet

of

death

Ukraine;

Heart

These

attack

2

highest

body.

and

treated

million

disease

leading

your

contracting.

KNOW?

world

heart

the

muscle

a

1

Around

pump

oxygen

of

disease

ways

This

This

YOU

heart

glucose

to

walls.

DID

healthy

needs

transported

die. •

a

OUTCOMES

of

affected

oxygen

part

altogether

the

heart

–

of

this

starts

to

the

can

is

cause

cut

the

is

sufferer

off.

heart

called

beating

a

It

is

because

heart

attack.

causes

a

again

The

arrest.

within

may

lead

When

severe

damaged.

cardiac

it

this

pain

heart

Death

minutes.

to

in

the

may

will

Risk

These

•

factors

are

factors

eating

can

less

a

diet

increase

page

71).

fresh

being

•

smoking

People

•

These

age

•

sex

fruit

–

too

increase

much

concentration

diet

–

down

and

of

eating

on

fried

–

but

other

inherited

the

from

control

chances

men

risk

are

parents

the

of

more

likely

to

getting

the

reduce

little

or

fat,

which

blood

sh,

less

CHD:

red

the

no

(see

which

meat

are

and

risk.

exercise

stress

risk

cannot

–

CHD

metabolism

getting

to

taking

these

factors

in

and

eating

helps

of

(animal)

poultry

foods;

•

about

chance

cholesterol

more

vegetables

something

the

saturated

•

genes

–

the

good

do

life,

genes

•

with

to

overweight

can

of

CHD

thought

cutting

•

way

A

fatty;

more

for

CHD

get

factors

be

avoided

tends

of

fat

to

than

changing

such

run

and

increase

CHD

by

in

their

as:

families.

cholesterol

with

age

women.

tnemelppuS

Figure

Treatment

of

9.5.2

Three

you

A

coronary

of

CHD.

the

arm

below

A

artery

blood

or

the

leg,

bypass

vessel

and

is

narrowed

is

can

taken

attached

or

relieve

from

to

blocked

patients

another

the

coronary

area.

with

part

of

the

the

artery

Depending

on

above

the

CHD,

a

number

of

separate

grafts

may

be

there

is

just

one

incidence

of

narrowing,

or

severity

STUD Y

angioplasty

widen

open.

it.

and

A

This

tube

Antiplatelet

the

arteries.

people

with

angina,

involves

small

metal

is

may

be

inating

tube

called

a

medicines,

T aking

CHD,

attack,

SUMMARY

is

then

carried

out.

This

is

a

less

ao rta

a

small

then

balloon

inserted

to

inside

help

like

the

keep

artery

the

aspirin

stroke

coronary

or

prevent

daily

other

stent

and

is

blood

part

forms

of

of

bypass

clots

the

forming

treatment

heart

Dene

d

a

T hey

a

If

the

disease,

tissu es

in

vent

for

of

ricles

blood

the

to

atria

the

and

.

e.g.

surgery.

heart

disease

b

thrombosis

c

angina

1

arrest

heart

POINTS

Coronary

caused

is

full

of

blood,

then

why

does

it

need

its

heart

by

disease

blockage

arteries

of

that

is

the

supply

own the

blood

the

tran sport

coronary 2

of

QUESTIONS

coronary

cardiac

base

abov e

valv es.

to

artery

oxyg enat ed

aspirin,

the

just

complex

KEY

1

put

a

stent

low-dose

known

heart

can

disease.

arterie s

from

semi-l unar operation

that

heart

TIP

co rona ry

the coronary

of

of

needed.

blockage,

risk

usually

and

bran ch If

at

symptoms

body,

T he the

activities

CHD

heart

with

glucose

and

supply? oxygen.

b

How

c

Why

is

the

heart

muscle

supplied

with

oxygenated

blood?

2 does

the

heart

muscle

need

this

oxygenated

Risk

factors

control

3

There

are

getting

risk

heart

factors

that

can

increase

the

of

a

person

sex.

disease.

List

some

of

the

factors

that

cannot

b

List

some

of

the

factors

that

can

c

What

advice

would

attack?

are

you

give

to

a

be

be

controlled.

person

recovering

diet,

exercise

controlled.

3

from

a

genes,

Avoidable

include

a

heart

chances

which

we

cannot

blood?

CHD

and

may

aspirin

be

and

angioplasty

risk

age

and

factors

stress,

lack

of

smoking.

treated

surgery

and

by

(stents,

bypass).

109

9.6

Blood

Blood LEARNING

•

List

as

the

red

components

blood

cells,

of

Y ou

have

and

cell

•

platelets

white

Identify

cells

as

red

and

and

seen

microscope,

5

litres

fragments

of

blood

suspended

in

in

your

a

body.

yellow

Blood

liquid

is

called

made

of

plasma.

cells

The

red

blood of

blood

is

due

to

the

pigment

haemoglobin

in

red

blood

cells.

plasma

white

under

in

about

blood

colour cells,

composition

OUTCOMES

blood

the

light

plasma

photographs

–

liquid

part

of

blood

(55%

of

blood

volume).

3

Plasma

10 cm

and

•

in

consists

of

water

with

chemicals

dissolved

in

it:

diagrams

Describe

cells

and

that

they

the

the

role

of

red

•

nutrients,

•

wastes,

•

blood

•

hormones,

and

blood

such

mineral

as

ions,

such

as

glucose,

e.g.

urea

amino

sodium

and

acids,

and

carbon

lipids,

chloride

vitamins

ions

dioxide

haemoglobin

contain

in

proteins,

such

as

albumen

and

antibodies

oxygen such

as

insulin,

glucagon,

and

adrenaline.

transport 3

5 cm

•

State

the

roles

of

white

blood and

cells,

platelets

and

red

Figure

9.6.1

When

it

Blood

There

Red

are

they

shows

cells

red

with

smear

blood

their

seen

cells

nuclei

with

and

a

light

two

stained

are

white

in

in

three

no

of

a

centrifuge

(or

left

to

stand

for

24

hours),

is

full

layers.

have

cell

nuclei

molecules

a

colourless

shown

the

blood

in

bacteria

process

group

as

nuclei.

they

do

the

and

of

centrifuge

in

blood.

have

cytoplasm

haemoglobin

They

(see

not

look

Figure

have

for

white

that

transporting

when

9.6.1).

separated

Under

haemoglobin

of

oxygen.

or

a

by

microscope

see

them,

stain

has

to

be

added

as

in

the

any

blood

other

of

photograph.

and

is

takes

known

white

blood

One

them

as

group

into

white

vacuoles

phagocytosis

cells

of

makes

where

(see

protein

blood

cells

smear

they

Figure

are

9.7.1).

molecules

searches

digested.

Another

called

antibodies

cells

to

protect

that

us

invade

Platelets

example

transport

dioxide

against

the

are

as

of

and

different

types

of

disease-causing

organisms

body.

tiny

when

substances

fragments

you

cut

listed

ions,

in

of

yourself.

Figure

nutrients,

cells

which

The

9.6.1.

such

as

cause

plasma

Among

glucose

blood

contains

its

to

functions

and

clot,

many

amino

are

for

soluble

the

acids,

carbon

hormones.

platelets

Red

Red

and

white

and

platelets.

blood

blood

cells

transport

oxygen

cells

Red

a

blood

large

to

110

types

have

of

cells

blood

To

This

9.6.2

spun

blood

phagocyte

Figure

main

cells

pigment.

out

lymphocyte

is

into

microscope

blue.

red

three

blood

spinning

blood

cells

blood

separates

thousands

White

blood

cells

blood

many

This

platelets

plasma

cells

surface

absorb

are

disc-shaped

area

oxygen.

compared

with

with

the

their

middle

pushed

volume

and

in.

this

They

helps

have

them

Haemoglobin

have

red

this

enough

blood

is

in

(see

more

Haemoglobin

special

iron

cells

makes

a

type

of

protein

diet

to

make

your

anaemia

space

for

combines

on

page

that

contains

enough

77).

As

iron.

You

haemoglobin

the

cells

have

for

no

must

your

nuclei

haemoglobin.

easily

with

oxygen

in

the

lungs

to

form

oxyhaemoglobin:

haemoglobin

Look

at

the

+

→

oxygen

diagram

oxyhaemoglobin

below:

There

are

5

million

red

blood

cells

like

these

3

in

molecules

an

of

in

the

Oxygen

the

to

diffuses

blood.

the

The

from

oxygen

haemoglobin

in

the

alveoli

attaches

the

red

millimetre

(mm

)

of

blood.

in

lung

the

1

cubic

alveolus

capillaries oxygen

every

lungs

into

temporarily

cells

making

red

blood

cell

oxyhaemoglobin.

4

The

cells

for

red

blood

return

more

to

the

lungs

oxygen. haemoglobin

cell

membrane 2

The

carr y

the

red

the

cells

blood

cells

oxygen

which

to

Figure

need

9.6.3

Red

blood

cells

magnied

it. ×2500.

red

blood

cells 3

The

oxygen

leaves

oxyhaemoglobin

out

The

of

the

blood

and

to

just

diffuses

the

oxyhaemoglobin

now

the

cells.

is

haemoglobin

again.

SUMMARY

capillaries

body

cells

in

body

tissues

1

a

List

9.6.4

Transport

of

oxygen

from

the

lungs

to

body

Notice

that

capillaries

•

oxyhaemoglobin

in

the

alveoli

Oxyhaemoglobin

capillaries

in

gives

body

in

forms

the

out

while

blood

ows

found

as

blood

ows

c

through

a

a

the

is

cell

white

white

How

ways

blood

Name

of

tissues.

three

red

from

lungs.

oxygen

plasma.

Give

a

through

2

KEY

chemicals

tissues.

b

•

four

tisses

in

Figure

QUESTIONS

in

which

blood

two

main

blood

the

in

differs

cell.

types

cell.

red

blood

POINTS cell

adapted

for

oxygen

transport? 1

The

main

components

of

blood

are

plasma,

red

blood

cells,

b white

visible

blood

under

cells

and

the

light

platelets.

Red

and

white

blood

cells

i

What

microscope.

ii

Where

with 2

Red

blood

cells

contain

haemoglobin

which

combines

is

haemoglobin?

are

does

oxygen

to

form

combine

and

what

with molecule

oxygen

it

is

formed?

oxyhaemoglobin.

111

9.7

Blood

tnemelppuS

White LEARNING

how

white

such

as

blood

lymphocytes

them

protect

cells

than

the

red

defend

blood

us

against

cells.

The

disease.

two

There

groups

of

are

far

white

fewer

blood

cells

and described

phagocytes

from

cells

blood of

cells

blood

defence

OUTCOMES

White • Describe

in

in

T opic

9.6

are

phagocytes

and

lymphocytes

body

disease

Phagocytes •

State

in

•

the

role

producing

Describe

of

lymphocytes

These

antibodies

the

process

of

are

white

blood

cells

that

ingest

pathogens,

such

as

bacteria.

blood They

surround

the

pathogens,

ingest

them

and

take

them

into

food

clotting vacuoles.

The

Then

process

is

they

called

entrapment

food

digest

them

by

using

enzymes

and

this

kills

them.

phagocytosis

of

formation

particle

food

of

vacuole

within

cell

nucleus

tiny

vacuoles

filld

with

food

enzymes

vacuole

cell

membrane

cytoplasm

bacteria This

image

was

microscope

computer

blood

The

It

image

a

and

then

program.

cells

shows

taken

and

can

white

was

phagocyte

an

with

see

in

ingesting

red

cells.

the

a

ingested

a

two

blood

taken

being

electron

coloured

Y ou

three

below

with

same

yeast

way.

cell.

digestion

of enzymes

added

to

bacteria the

Figure

When

They

Find

9.7.1

A

white

pathogens

can

out

squeeze

about

blood

invade

the

through

tissue

cell

destroys

body,

on

vacuole

bacteria.

phagocytes

capillary

rejection

some

food

move

towards

them.

walls.

page

151.

Lymphocytes

Lymphocytes

enters

not

Like

112

be

the

are

body

there.

a

type

the

white

Lymphocytes

enzymes,

antibodies

Enzymes

have

active

Similarly,

each

type

one

of

type

of

blood

lymphocytes

sites

of

then

are

make

with

combine

has

When

that

proteins

proteins

that

antibody

pathogen.

cell.

recognise

a

it

a

is

called

many

with

bacterium

‘foreign’

binding

site

virus

should

antibodies

different

their

or

and

shapes.

substrates.

that

combines

with

attack

•

they

make

•

they

dissolve

•

they

neutralise

some

There

After

a

you

produce

the

have

their

Blood

again.

in

together

cell

the

a

number

of

ways:

(agglutinate)

membranes

toxins

(poisons)

that

some

pathogens,

such

as

produce.

had

of

pathogens

stick

different

more

body

When

them

bacteria,

is

the

tnemelppuS

Antibodies

type

a

antibody

disease,

the

This

of

such

appropriate

makes

you

as

for

each

measles,

antibodies

immune

to

type

of

pathogen.

lymphocytes

should

that

the

are

ready

pathogen

particular

to

enter

disease.

clotting

you

cut

yourself

you

Like

the

two

white

white

Before

long,

platelets

help

the

thicken

and

the

bleeding

thickened

clot.

blood

Without

has

clotting,

formed

blood

lost

and

pathogens

cell

in

this

of

smear

is

a

is

another

way

would

that

The

skin

the

in

blood

of

is

a

cells.

are

They

small

the

the

is

cut

are

body.

and

blood

blood

However

starts

called

come

there

like

fragments

made

the

in

blood

the

The

fibrinogen.

in

contact

with

a

blood

vessel

is

The

of

the

fibrinogen

threads

make

into

a

threads

net

over

of

Whe n

they

the

white

fibrin

writi ng

blood

to

plasma

into

sure

you

use

‘phag ocyt es’

are

bres.

which

Red

forms

blood

a

these

The

threads

cells

clot

to

the

get

hardens

to

time

keeps

the

the

skin

cut

heals

a

clean.

and

no t

blood

their

call

cells ’.

Red

blood

cells

get

caught

in

the

net

clot.

scab

and

make

cut.

The

the

New

With

a

blood

clot

skin

dries

clot

to

which

make

a

seals

the

grows

under

the

scab.

POINTS

scab.

scab 1 Figure

falls

when

of

KEY which

e

trapped

the

make

mak

nam es

and

do

‘ white

protein

meshwork

make

–

the

2

in

,

desc ribin g

the

in

them

brin,

abou t

cells

platelets

change

insoluble

cell

When

brinogen

the

white

cut.

func tions protein

smaller

bone

cells.

damaged,

substances

soluble

larger

blood

When

air

you release

a

TIP

protein

‘lym phoc ytes ’ a

of

leaking

is

scab

marrow

photograph

phagocyte.

disease. turn

Platelets

these

The

enter .

platelets

against

110,

stained.

lymphocyte.

STUD Y

defends

page

a

out

This

on

been

would

1

be

have

stops. fibrin

The

smear

cells

blood threads

to

blood

bleed.

9.7.2

Blood

Phagocytes

ingest

pathogens

clotting.

off. and

digest

them

using

enzymes.

2 SUMMARY

Lymphocytes

that

protect

pathogens 1

a

b

State

where

Explain

how

white

blood

cells

lymphocytes

act

are

to

defend

the

body

from

3

After

a

how

a

disease,

person

can

become

immune

to

an

the

to

like

a

b

Explain,

What

has

had

a

lymphocytes

for

that

more

pathogen

measles.

in

detail,

would

exposed

c

body.

infectious

if

3

the

produce

antibodies

disease

in

person

remain

Explain

antibodies

against

made.

pathogens.

2

make

QUESTIONS

Describe

to

role

happen

the

the

the

air

at

process

if

a

of

a

of

platelets

person’s

in

the

blood

cut?

phagocytosis.

clotting

did

not

of

clot

disease

again.

blood.

when

the

4

This

Platelets

encountered

called

help

brinogen

blood

is

is

to

to

immunity

convert

brin

during

clotting.

113

9.8

Lymph

tnemelppuS

Tissue LEARNING

Describe

the

exchange

between

tissue

blood

Describe

tissue

the

lymphatic

functions

of

gaps.

the

vessels

lymphatic

and

lymph

uid

the

may

protect

uid.

from

our

disease

immune

Experiments

have

all

able

to

cells

stable

the

cells.

squeeze

stay

in

the

environment

substances

glucose

and

Most

Fluid

but

know

cut

of

is

and

waste

to

White

out

of

blood.

for

diffuse

the

oxygen

found

is

blood

the

cells,

which

capillaries

Tissue

uid

through

‘bathes’

the

and

tissue

of

it

uid

like

then

owing

drains

from

out

of

urea

pass

passes

from

into

tissue

cells.

our

the

uid

Useful

out

back

of

into

plasma

lymphatic

into

cells.

cells

the

and

into

the

blood

back

into

system.

system

produced

white

not

cells

a

the

so

stress,

than

is

circulatory

our

heart

system

beating

–

we

and

videos.

Not

glucose,

all

taken

amino

vitamins,

Our

other

But

feel

circulatory

system

the

beneath

glands

–

the

fluid

and

tonsils

lymphatic

–

these

vessels.

In

are

the

Unit

7,

lymph

page

lower

nodes

85,

leaves

at

the

This

is

a

thin-walled

vessel

that

absorbs

part

of

the

lymphatic

when

veins

system

jaw,

think

you

that

saw

are

a

fat

from

the

lacteal

gut

system.

of

in

the

tissue

one-tenth

of

capillaries.

(e.g.

acids,

ions)

oxygen,

fatty

acids,

uid

it

returns

enters

Once

a

to

plasma

separate

inside

these,

waste

(e.g.

the

products

carbon

metabolites,

in

blood

system

of

tissue

given

dioxide,

excess

capillaries.

capillaries

uid

is

called

called

lymph

out

unwanted

ions)

the

venule

arteriole

capillary

network

back

arteriole

the

rest

enters

lymph

The

blood

our

lymphatic

your

some

9.8.1

see

see

those

nutrients

the

by

another

lymph

of

skin.

obvious.

adenoids

villus.

About

end

feel

and

non-humorous

capillaries

blood

can

signicantly

and

tissue

our

we

humorous

blood

reduced

about

that

in

114

the

form

them.

into

pass

chemicals

constantly

some

ourselves,

connected

Figure

of

to

and

about watching

watching

walls

systems. –

had

a

lymphatic

through

more

constituents

capillary

our we

videos

the

the

KNOW?

We

people

surrounds

are

blood

helps

like

plasma,

The

boost

Red

dioxide

capillaries.

bodies

of

in

nodes

tissue

Laughter

some

gaps

system

Carbon

YOU

that

shape,

providing

substances

DID

tissues,

small

system

Tissue

as

body

through

the

cells

Outline

out

uid

change

these

•

reaches

move

uid can

•

uid

capillaries the

and

uid

of plasma

materials

tissue

OUTCOMES

When •

and

formation

of

tissue

uid

and

vessel

lymph.

of

the

the

tissue

lymph

fluid

capillaries

tissue

into

fluid

the

passes

capillaries

but

capillaries

will

lymph

not

the

vessels.

thin-walled

ows

let

in

and

one

have

tiny

lymph

These

valves

pass

have

contain

a

that

out

allow

again.

structure

semi-lunar

the

They

similar

valves

to

tissue

join

to

uid

up

to

veins;

make

sure

to

tnemelppuS

Lymph

enter

form

they

are

lymph

direction.

The

lymphatic

The

contraction

system

of

has

no

pump

surrounding

so

the

muscles

ow

helps

of

to

lymph

make

it

is

slow.

ow.

STUD Y right

into

lymphatic

the

right

duct

empties

subclavian

left

vein

TIP

subclavian

vein

Plas ma,

lym ph

that

tissu e

are

are

very

compo sitio n,

in

the

the

thoracic

duct

out

differ ent

body .

text

uid

three

uids

simila r

but

Read

e

they

in

occu r

places

in

throug h

carefu lly

wher

and

to

are

nd

and

remem ber! lymphatic

from

of

lymph

Figure

Lymph

join

9.8.2

to

subclavian

the

blood

lymphatic

from

form

the

two

veins,

before

lacteals

small

in

villi

intestine

nodes

The

ows

up

vessels

system.

tissues

large

under

joining

to

lymph

the

the

the

heart.

vessels

collar

vena

The

which

bones.

cava

smaller

empty

Here

just

the

before

lymph

into

lymph

it

vessels

the

mixes

enters

the

with

heart. KEY

At

intervals

along

the

length

of

the

lymph

vessels

are

lymph

1 There

are

many

lymphocytes

in

the

nodes

and

during

an

POINTS

nodes. When

tissue

lymph they

multiply

by

cell

division

and

make

antibodies.

Some

uid

enters

the

infection capillaries

it

is

termed

leave lymph

lymph

nodes

patrolling

an

and

for

important

circulate

fresh

part

around

invasions

of

the

of

body’s

the

body

pathogens.

immune

in

the

The

blood,

constantly

lymphatic

system

is

2

system.

Lymph

and

has

SUMMARY

QUESTIONS

a

What

is

tissue

uid

no

large

3 1

and

what

are

its

The

consists

white

red

What

is

lymph

and

what

are

its

Explain,

in

as

much

detail

as

you

slow

and

how

the

circulation

can,

is

What

main

are

lymph

function?

nodes,

where

are

proteins.

lymphatic

why

the

ow

of

lymph

system

circulation

has

a

which

lymph

to

the

blood.

is Lymphocytes

are

in

lymph

maintained. nodes

3

but

or

functions?

4

so

cells

functions?

returns

2

plasma

cells,

blood

plasma

separate

b

of

blood

they

found

and

what

is

their

during

where

an

produce

they

multiply

infection

and

antibodies.

115

PRACTICE

1

Which

the

QUESTIONS

chamber

of

the

heart

pumps

blood

into

4

Which

row

shows

components

aorta?

A

left

atrium

B

left

ventricle

of

the

the

correct

functions

of

the

blood?

red plasma

blood

platelets cells

C

right

atrium

D

right

ventricle

antibody

oxygen

formation

transport

A

(Paper

1)

clotting

[1] B

2

The

plan

system.

diagram

Which

is

shows

the

the

human

pulmonary

antibody

oxygen

formation

transport

clotting

circulatory

transport

artery?

of

oxygen

C

clotting ions

transport

A head

and

oxygen

antibody

fore-limbs

D

clotting transport

(Paper

formation

1)

[1]

D

5

In

a

single

through

circulation

the

circulation

C

leaves

the

heart

of

the

of

once

body.

a

sh,

the

during

What

a

blood

ows

complete

type

of

blood

heart?

B

lower

and

A

deoxygenated

blood

at

high

B

deoxygenated

blood

at

low

C

oxygenated

blood

at

high

D

oxygenated

blood

at

low

pressure

pressure

pressure

pressure

body

hind

limbs

(Paper

2)

[1]

Key

oxygenated

deoxygenated

3

(Paper

1)

Which

is

owing

A

B

6

blood

blood

blood

the

correct

body

→

the

vena

pathway

human

cava

taken

ventricle

→

lungs

left

ventricle

→

aorta

cava

lungs

→

→

atrium

right

body

(Paper

1)

arteries

to

veins

B

arteries

to

capillaries

that

transport

C

capillaries

to

veins

left

D

capillaries

to

venules

system?

atrium

→

(Paper

right

→

body

2)

pulmonary

→

left

ventricle

→

right

artery

ventricle

→

[1]

→ Blood

capillaries

are

exchange

vessels.

They

atrium

aorta

→

→

→

the

exchange

of

substances

between:

left A

cells

and

lymph

B

plasma

and

lymph

C

plasma

and

tissue

D

lymph

aorta

lungs

→

uid

atrium

and

tissue

uid

[1]

(Paper

116

vessels

A

permit

D

blood

blood

circulatory

→

left

by

7

C

are

from:

[1]

through

vena

Arterioles

2)

[1]

8

Prevention

of

coronary

heart

disease

may

11

The

diagram

shows

the

heart.

involve:

A

A

angioplasty

B

eating

C

putting

D

taking

B

(Paper

9

This

saturated

stents

more

into

fats

coronary

arteries

exercise

C

2)

is

seen

more

a

[1]

drawing

with

a

light

made

of

a

blood

smear

as

microscope. E

F

H

D

(a)

(i)

Name

(ii)

Give

A

to

the

E.

[5]

letters

from

the

diagram

that

G

indicate

(a)

(i)

Name

(ii)

State

the

the

cells

F,

G

functions

and

of

H.

the

oxygenated

[3]

cells

F

to

(b)

H

The

magnication

×1100.

(c)

Calculate

Show

your

Some

blood

separate

of

the

the

drawing

diameter

(c)

is

of

cell

was

the

in

a

components.

centrifuge

The

to

(Paper

the

why

lower

rest

of

vessels

contain

blood.

happens

capillaries

blood

[1]

to

in

blood

the

owing

pressure

the

that

than

as

it

ows

lungs.

to

the

blood

[4]

lungs

owing

body.

is

to

[3]

3)

(a)

Copy

and

complete

the

table

to

compare

results.

arteries, (i)

what

the

blood

diagram

12 shows

a

the

[2]

spun

Explain

at

H.

working.

Describe

through

[3]

(b)

the

Identify

the

veins

and

capillaries.

cells J

that

would

found

in

feature

be

regions

arteries

veins

capillaries

K relative

and

L.

Give

reasons thickness

for

your

answer.

[3]

of

(ii)

Name

the

uid

at

thin

very

thin

some

none

K

wall

J muscle

and

describe

its

role tissue

in

the

body.

L

[5]

elastic some (Paper

10

3)

tissue

T aking

the

health

of

pulse

is

one

way

to

monitor

direction

the

heart the

of

heart.

to

arteries

to

blood organs

veins

ow (a)

What

is

(b)

Describe

during

the

pulse?

what

and

[2]

happens

after

to

the

pulse

exercise.

rate

[5]

[4] (b)

(c)

State

of

two

the

other

heart

can

ways

be

in

which

monitored

the

health

helps

3)

it

how

to

the

carry

structure

out

its

of

an

artery

function.

[3]

[2] (c)

(Paper

Explain

Describe

muscle

(Paper

how

cells

substances

by

are

capillaries.

provided

to

[4]

4)

117

10

Diseases

10.1

and

immunity

Disease

Pathogens LEARNING

that

•

Dene

and

the

terms

Describe

cause

disease

how

pathogens

are

spread

from

person

that

The

Outline

the

against

disease

body’s

humans

cause

fungi,

protoctists

transmissible

or

are

disease.

transmitted,

bacteria

and

diseases

from

one

and

Most

of

worms.

because

person

viruses.

the

organisms

The

the

to

Other

diseases

that

pathogens

another.

They

they

are

are

also

infectious

diseases.

to

person

•

are

in

can called

be

organisms

disease

pathogens

pathogen

transmissible

cause

passed, •

are

OUTCOMES

table

shows

different

ways

in

which

diseases

are

transmitted.

defences method

examples

of

of

description diseases

transmission

pathogens

are

in

tiny

droplets inuenza,

of through

the

liquid

from

the

airways

and

air

tuberculosis, lungs

of

infected

people

(see common

photo

people

not

preparing

wash

contaminated

are

food

human

not

their

food

hands;

cooked

do

foods

properly; cholera,

and

drink

water

direct

contact

faeces

supplies;

insect

uninfected

people

people,

infected

people

the

e.g.

droplets

her

of

nose

she

is

water

and

using

a

are

bodies

touch

or

items,

have

of

an

that

athlete’s

foot

used

feed

infected

malaria,

dengue

vectors and

then

feed

on

an

fever

person

handkerchief,

containing

mouth

transfer

mosquitoes,

blood

uninfected though

their

infected

person

Even

ies

on

insects,

typhoid

contaminate

pathogens

on

cold

opposite)

pathogens

entering

the

blood

from

air

and

from

person

an

enters

infected

the

blood

of HIV/AIDS,

may

be

inhaled

by

others.

body

uids

an

uninfected

person,

an

unsterilised

e.g.

in hepatitis

between

drug

pathogens

sexual

activity

person

blood,

Defences

We

have

prevents

three

These

houseies

may

have

picked

up

third

their

and

bodies

human

them

118

to

while

wastes

uncooked

feeding

and

are

meat.

on

bacteria

now

rubbish

transferring

that

line

pathogens. on

different

pathogens

pathogens

The

against

to

break

pass

semen

shared

addicts

from

sexual

or

infected

HIV/AIDS,

partner

in

specic

vaginal

uid

(NSU),

non-

urethritis

chlamydia

disease

lines

entering

of

defence

the

through

produces

needle

body;

the

antibodies

rst

that

against

the

line

disease.

second

and

defend

line

enters

us

The

rst

destroys

the

against

line

any

blood.

specic

Barriers

to

infection

STUD Y The

defences

chemical

we

have

against

entry

of

pathogens

are

mechanical

barriers.

Y ou

Mechanical

The

•

The

dead

barriers:

outer

layers

of

the

skin

form

a

barrier

to

entry

(see

T opic

in

the

nose

trap

larger

particles

that

you

breathe

are

The

•

Topic

Cells

that

small

from

The

If

dust

is

a

Blood

White

enter

and

The

are

is

and

and

know

diseas es

show n

in

How ever ,

you

in

the

acid

that

kills

pathogens

in

up

(trachea

and

bronchi)

microorganisms.

to

swallowed

the

and

throat

any

by

The

cilia

make

mucus

(see

pathogens

are

mucus

is

Topic

moved

easier

me th ods

food

that

it

you

fo r

traps

of

may

learn

the

tran smis sion

learn

each

to

an

exam ple

one.

away

11.3).

destroyed

by

acid.

get

second

through

line

of

these

barriers

to

enter

the

blood,

then

defence.

defences

blood

the

cells

body’s

viruses

into

process

white

during

airways

particles

pathogens

there

hydrochloric

if

the

lungs

mucus

any

makes

7.7).

line

the

stomach

to

barriers:

stomach

(see

the

tran smitt ed

ways

nd

•

have

of

in.

table. Chemical

no t

14.8)

the hairs

do

exam ples

that •

TIP

and

of

a

line

or

vacuoles

of

the

cells

infection

which

by

defence

blood.

where

phagocytosis

blood

an

form

tissues

they

is

against

are

digested

described

produce

pathogens

any

Phagocytes

in

and

T opic

antibodies.

they

produce

pathogens

engulf

that

bacteria

destroyed.

9.7.

Lymphocytes

When

activated

antibodies

which

are All

proteins

that

have

a

variety

of

effects,

such

as

stopping

outdoor

activities

involve

some

risk

of

pathogens infection.

moving

engulf

through

them.

antibodies

the

body

Vaccination

and

give

and

is

a

making

way

long-term

to

it

easier

make

protection

for

phagocytes

lymphocytes

against

to

produce

certain

KEY

POINTS

diseases.

1

A

pathogen

causing SUMMARY

Copy

and

complete

the

Pathogens

from

following:

one

through Pathogens

are

that

cause

disease.

Human

diseases

by

bacteria,

and

.

The

airways

have

that

make

to

trap

kills

.

any

pathogens

form

in

The

pathogens

stomach

that

the

a

.

barrier

lining

enter

the

Dead

to

cells

makes

on

the

Explain

why

you

always

b

never

c

always

d

use

e

never

wash

share

and

your

hands

towel

your

surface

of

the

3

The

are

pathogens.

before

with

hands

handling

skin

and

of

Explain

how

dog

the

and

vectors

in

the

barriers

nose

to

pathogens.

Mucus

in

acid

the

in

lick

climber

in

airways

stomach

and

are

someone

after

when

your

the

going

to

the

barriers.

toilet

Phagocytes

are

white

blood

sneezing

face

that

digest

engulf

them;

antibodies 3

hairs

mechanical

cells

a

food

animal

food

5 handkerchief

let

by

mosquitoes).

chemical

a

droplets,

in

should:

a

wash

in

contact,

which

4 a

air

transmitted

another

body

entry 2

be

to

cells

(e.g. people

can

host

the

direct

water

when

disease-

are by

caused

a

QUESTIONS

2

1

is

organism.

the

photograph

is

at

risk

of

to

pathogens

lymphocytes

attack

and

make

pathogens

infection.

that

enter

the

blood.

119

10.2

Defence

tnemelppuS

If LEARNING

pathogens

Explain

has

that

each

antigens,

own

specic

pathogen

each

with

Explain

that

specic

is

their

provided

antibodies

shapes

that

to

have

by

the

our

help

the

blood

mechanical

and

chemical

may

and

destroy

in

order

antibodies

to

engulf

defences,

nd

and

produced

by

engulf

them.

Many

are

the

shapes

of

these

have

are

chemicals

made

lymphocytes

respond

the

on

Describe

how

antigens

are

help

lymphocytes.

the

of

by

on

their

protein.

making

surface

of

surface

When

you

antibodies,

the

called

antigens.

catch

which

a

disease

can

‘lock

your

on’

to

pathogens.

They

active

cause

for

Some

This

STUD Y

•

TIP

no t

becom e

be tw een

is

a

all

begin

Unit.

helps

Bacteria

prod uce

secre ted

help

are

‘anti-’

antibody

molecules

attack

•

such

as

group

stick

together

to

nd

agella

can

them

in

a

and

to

to

group.

engulf

that

This

much

them.

that

the

to

and

blood.

combine

them

move

and

stop

Each

have

pro te ins

that

destro y

If

Antito xins

that

type

shapes.

a

mak e

a

is

walls.

kill

bacteria

This

causing

the

you

of

The

3

shape

have

that

an

and

and

healthy

antigens

diphtheria

with

cells

the

by

cell

the

‘punching’

to

burst.

its

own

walls

so

on

bind

receptors

on

ts

a

If

again,

to

toxins

through

enters

by

you

Lymphocytes

week

strain

will

are

or

which

against

antigen.

have

each

The

specic

type

of

antibody

antigen

has

a

shape

as

the

common

symptoms.

two

you

of

the

virus

not

get

the

responsible

for

will

that

same

this

You

be

cold,

will

back

causes

you

then

to

the

are

be

your

to

You

will

activated

ill

for

feel

normal,

common

symptoms.

and

will

begin

cold

not

be

during

an

response

virus

are

large 4

lymphocytes

born

with

number

of

a

very

different

lymphocytes

are

activated

and

types 5

divide

active

secrete

of

lymphocytes.

lymphocytes

antibodies

These

to

6

to

antibodies

virus

are

different

the

specic

antigens

surfaces

of

of

bacteria,

particles

throughout

particles

bind

cells

the

body

viruses

and

other

throughout

pathogens.

body

pathogen

When

invades,

lymphocytes

antibodies

person

10.2.1

so

to

virus

the

are

antigen.

such

of

antigens

made

the

the

variety

a

the

are

around

infection,

have

within

self.

has

that

specific

inhaled

spread

the

moving.

release

holes

water

You particles

virus

them

harmless.

directly

weakens

pathogen

antibodies

complementary

while

better

harm less.

2

through

Antitoxins

immune

Figure

it

that

ill.

measles

makes

bacteria.

tetanus

into

making

use

agella

these

cause

antibodies

and

they

the

destroy

substances)

of

them

which

attach

those

antibodies

cells

osmosis

lym phoc ytes

antib odies

Some

their

lym phoc ytes

to

have

(poisonous

special

invades

particles

pathogens.

in

antig en

are

by

path ogen s.

toxins

which

wo rd s

antib odies .

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conf used

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stim ulates

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120

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antibodies

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1

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pathogens.

antigens

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•

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shapes

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th e

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disease

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10.2.2

circulating

respond

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whenever

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antigen

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therefore

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right

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greater . KEY

1

POINTS

Antibodies

‘lock

onto’

Vaccination antigens

It

is

This

possible

is

done

to

by

promote

injecting

active

a

immunity

vaccine

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to

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ill.

pathogens,

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antigens

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the

surface

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pathogen

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to

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that

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what

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antigen

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b

antibody

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immunity

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how

e

memory

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transmissible

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pathogen

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and

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body .

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lymph

in

after

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provide

much

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cells

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3

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immunity

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specic

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blood a

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have

antibodies.

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immunity.

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SUMMARY

which

protection of

against

the

measles, shapes

rubella

to

pathogens.

Each antigens

vaccine

of

dead 2

pathogens

leading

destruction

response

to

an

antigen

differs

from

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after

immunity

an

is

infection

pathogen

or

by

gained

by

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vaccination.

121

tnemelppuS

Many

10.3

Aspects

tnemelppuS

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far

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passive

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to

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pathogen

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body

antigens

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involving

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production

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antibodies

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of

others

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cells.

immunity

protection

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paralysis.

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from

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spiders

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immunity

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to

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baby

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STUD Y

Immunity

and

only treatment

protection.

malfunction

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type

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of

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or

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or

babies

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injection.

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immunity,

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an

person

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fed

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at

course

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bitten

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quickly.

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venomous

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animals

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antibodies

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122

advantages

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to

of

important

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is

baby

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made

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body

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it

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horses

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to

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from

sheep.

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collected

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where

animals.

instantaneous.

antigens

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or

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short-term,

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breast-feeding

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antigens

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of

collectively

these

and

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1

1

immune

known

diseases:

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the

as

system

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examples

are

a

variety

diseases.

rheumatoid

arthritis,

of

diseases

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many

of

sclerosis

diabetes.

diabetes

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type

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diabetes

the

rapidly

is

cells

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often

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pancreas

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age

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insulin.

attacks

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usually

20.

Milking

Insulin

helps

to

control

the

concentration

of

glucose

in

the

The

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made

in

response

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increase

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the

glucose

the

concentration

venom

blood

usually

while

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meal

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liver

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needed

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•

cells

loss

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due

lowers

tiredness

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to

of

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to

store

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release

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cells

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diabetes

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glycogen

for

times

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when

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it

to

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its

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water

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of

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snake.

antigen

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fat

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of

glucose

as

sources

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concentration

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glucose

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the

blood

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meals.

the

presence

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glucose

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the

urine.

with

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regular

injections

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manufactured

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techniques

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genetic

Topic

diabetics

20.4)

can

SUMMARY

What

is

and

many

control

their

different

blood

types

glucose

are

with

programmable

insulin.

diabetes

pumps

into

to

body

use

deliver

fat

insulin

through

a

tube

engineering known

2

an

14.7).

continuously

1

dangerous

be

Many

(see

a

as

potential

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energy

indicator

People

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from

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by

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catheter.

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efciently.

QUESTIONS

meant

a

passive

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b

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by

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following

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explain

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example

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form

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immunity.

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a

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the

cause

and

describe

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symptoms

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diabetes.

Figure

b

Suggest

why

insulin

has

to

be

injected

or

delivered

10.3.1

Human

cells

catheter

KEY

1

not

taken

orally

(by

made

mouth).

genetically

by

make

this

modied

human

to

protein.

POINTS

Passive

immunity

against

another

2

and

insulin

by

No

is

pathogens

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short-term

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defence

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3

from

milk.

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in

passive

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cells

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to

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baby

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against

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by

in

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the

blood

against.

immune

that

breast

diseases

vaccinated

pancreas

control

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system

make

and

glucose.

123

10.4

Controlling

of

•

Explain

good

food

spread

of

tnemelppuS

Explain

in

in

Personal

hygiene

infectious

diseases.

hygiene,

and

proper

•

sewage

preventing

the

role

controlling

important

in

preventing

the

spread

of

some

•

of

all

urinate

Hair

ages

or

should

should

defecate

be

wash

and

washed

also

with

their

hands

before

after

handling

shampoos

to

going

or

to

the

eating

prevent

toilet

food.

dandruff

and

headlice.

of

the

People

to

disease

the

is

of

preparation,

disposal

treatment

•

importance

personal

waste

infection

OUTCOMES

the

hygienic

spread

disease

Preventing LEARNING

the

vaccination

spread

•

Everyone

•

Dental

should

wash

themselves

frequently,

especially

in

hot

weather .

of hygiene

is

most

important

in

ghting

dental

caries

disease (see

•

Topic

Cuts

and

applied

bruises

to

Hygienic

•

Food

•

Kitchen

•

Food

as

•

should

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is

important

the

hands

spread

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with

of

everyone

soap

and

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water

to

to

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•

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•

be

keep

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cleaned

plasters

away.

with

thoroughly

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to

disinfectants

make

sure

to

any

kill

bacteria.

bacteria,

such

be

to

be

eaten

cold

should

be

kept

separate

meat.

and/or

water

drinking

purication

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tablets

if

be

it

boiled

comes

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contaminated.

attract

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often

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bacteria,

to

be

such

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safe

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it

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buried

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may

houses

health

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into

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covered

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properly

tips

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at

contain

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where

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landll

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chemicals

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efuent

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pollution.

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(see

that

a

down

Topic

cause

hazard

sewage

by

if

it

is

not

treatment

disposed

properly

works.

microorganisms

in

sewage

21.8).

typhoid

and

cholera

are

transmitted

as

faeces

and

transmitted

is

contaminated thoroughly.

from

not

be

weekly.

rubbish

rats

tips

through is

is

or

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The

it

onto

treatment

is

should

e.g.

collected

through

•

waste

so

Sewage

124

and

disposal

correctly

rubbish

cooked

is

might

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will

It

antiseptic

killed.

cooking

intervals,

garbage

Salmonella.

to

especially

waste

incinerated

meat

an

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regular

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cooked

adding

that

with

wash

prevent

•

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should

that

for

by

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preparation

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be

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be

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raw

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be

surfaces

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food

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Salmonella,

from

•

7.6).

with

raw

sewage.

to

people

who

drink

food

or

water

•

Thorough

and

sewage

cholera

so

treatment

these

breaks

diseases

are

the

transmission

unknown

in

of

typhoid

countries

with

proper

sanitation.

tnemelppuS

The

role

of

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protection

children

and

Many

e.g.

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of

the

was

programmes

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the

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in

polio

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used

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of

citizens.

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the

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parts

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health

1991,

of

the

and

in

world,

1994

successfully

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world Household

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introduced

into

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Americas

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travellers.

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in

there

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countries

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follow

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93

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people

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of

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neighbouring

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Kenya.

polio

to

bins

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substance

health

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be

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to

SUMMARY

a

health

hazard.

and

can

neighbourhood

HIV ,

For

some

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disease

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dengue

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diseases

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fever .

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100

million

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destroy

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teach

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Quetta,

Pakistan

right

1

important

children

POINTS

The

spread

to

wash

to:

waste

into

is

personal

their

food

hands

covered

of

transmissible

prevented

hygiene,

preparation,

waste food

in

it.

QUESTIONS

why

polio

2014.

diseases

Suggest

put

becoming

protected

the

workers

spread

ways.

KEY

b

kept

before

the

in

a

be

You

Vaccination

1

should

collected

KNOW?

may

specicity

and

everyone.

be

with

immunity

their

two

can

contact

by

and

people.

are

in

eradicate

but

have

surveillance

diseases

examples

to

more

Somalia

covered

‘polioeradication’.

of

them

with

Africa,

to

people

contact

(as

Pakistan

West

respond

disease.

have

the

attempt

vaccinating

YOU

There

not

most

the

by

do

in

of

programmes

chances

who

stopped

come

as

of

searching

schemes

the

polio

parts

progress

by

people

of

Syria,

eradication

vaccination

Some

in

the

world

During

cases

and

garbage

2013,

disposal

by

good

hygienic

proper

and

sewage

bins

c

connect

d

cook

toilets

to

the

main

drainage

system

2 chicken

Vaccination

tnemelppuS

used

2

The

Americas

children

were

declared

throughout

the

free

of

Americas

polio

in

receive

1994.

polio

Why

do

Why

is

offered

it

important

by

their

that

everyone

country’s

health

receives

service?

the

to

prevent

transmissible

the

are

spread

of

diseases.

vaccinations?

3

3

programmes

thoroughly

vaccinations

Many

diseases

effectively

by

vaccination

are

controlled

mass

of

children.

125

tnemelppuS

treatment.

PRACTICE

1

A

QUESTIONS

pathogen

A

feeds

is

on

an

organism

dead

B

lives

in

an

C

lives

inside

and

decaying

organism

6

that:

and

A

organisms

causes

During

host

organism

harm

make

all

lymphocytes

spreads

disease

organisms

specic

phagocytes

divide

antibodies

disease

divide

to

produce

cells

that

without

C D

response:

and

to

make causing

immune

lymphocytes

B a

an

from

infected

antibodies

phagocytes

engulf

and

completely

digest

to

bacteria uninfected

people

D (Paper

1)

specic

that

2

Which

is

a

transmissible

cholera

B

coronary

B

rickets

D

scurvy

7 heart

make

Which

Passive

[1]

immunity

A

being

bitten

B

being

treated

barrier

to

cholera

of

B

skin

C

stomach

infection

is

most

effective

D

phagocytosis

is

gained

by:

a

venomous

snake

antibodies

to

the

injecting

snake

The

in

a

quantity

of

antivenom

snake

with

venom

antibodies

horse

2)

[1]

second

the

rst

A

[1]

immune

measles

invasion

the

response

people

long-term

transmissible

is

virus

many

much

concentration

measles

gives

small

to

an

invasion

acid

1)

hand

venom

spider

D

by

A

snake

with

a

produced

8

against

a

by

injecting

bacteria?

mucus

Which

to

C

(Paper

4

cells

[1]

A

(Paper

produce

disease

1)

against

to

2)

venom

3

divide

antibodies

disease? (Paper

A

(Paper

lymphocytes

[1]

remains

months

faster

of

antibodies

high

after

the

because:

from

the

specic

rst

to

response

protection B

lymphocytes

respond

C

lymphocytes

specic

faster

with

age

diseases?

to

other

viruses

washing

B

garbage

C

sewage

D

vaccination

respond

as

well

memory

cells

collection D

are

present

in

the

blood

and

treatment lymph

(Paper

(Paper

1)

9

5

An

antigen

2)

[1]

[1]

is:

Some

that

A

a

disease-causing

B

a

molecule

and

organism

produced

by

a

(a)

lymphocyte

microorganisms,

cause

cause

State

cholera,

such

enter

as

the

the

body

bacteria

in

our

food

disease.

the

term

given

to

a

disease-causing

organism. C

any

substance

that

stimulates

an

[1]

immune

(b)

response

State

two

ways

contaminated D

a

which

food

can

become

microorganisms.

[2]

pathogen

(c) (Paper

2)

Explain

how

the

stomach

provides

a

[1] defence

(d)

(e)

against

microorganisms.

Microorganisms

may

Explain

body

in

the

Some

and

how

(Paper

diseases

water.

3)

the

enter

the

prevents

[2]

blood.

their

spread

blood.

infectious

126

in

with

[4]

are

State

transmitted

four

diseases

other

can

be

in

ways

food

in

which

transmitted.

[4]

10

(a)

Explain

the

importance

maintaining

(i)

good

personal

of

the

following

in

12

The

diagram

and

health:

an

shows

antibody

four

different

antigens

molecule.

hygiene

Y

W

(ii)

sewage

(iii)

proper

treatment Z

(b)

Rubella

by

a

is

virus.

against

11

A

disposal

transmissible

Many

rubella.

provides

(Paper

a

waste

disease

children

Explain

protection

[6]

are

how

against

X

caused

vaccinated

vaccination

disease.

[3]

3)

child

received

measles

at

booster

at

four

a

eight

antibodies

to

rst

vaccination

months

of

months.

measles

is

age

The

against

and

then

(a)

a

concentration

shown

in

the

The

the

of

graph.

(i)

Which

(ii)

Explain

doolb

There

has

antibody

forms

a

complex

with

one

of

antigens.

is

no

been

one?

[1]

your

vaccine

for

vaccinated

eht

including

measles,

answer.

[1]

chicken

against

tetanus

pox.

several

and

A

child

diseases

rubella.

ni noitartnecnoc

The

child

catches

symptoms

(b)

Use

of

the

ydobitna

explain

many

(c)

3

4

5

6

7

8

9

10

the

it

is

diseases,

Explain

such

how

eradicate

a

pox

and

has

the

disease.

information

why

disease,

0

chicken

in

the

possible

but

as

still

be

chicken

be

ill

to

immune

with

to

another

pox.

vaccinations

disease

diagram

to

from

[4]

can

a

be

used

to

country.

[3]

months

(d)

Suggest

must (a)

Explain

why

no

antibodies

were

present

blood

for

the

rst

vaccination

to

be

against

carried

out

diseases

even

if

in there

the

why

continue

week.

are

no

cases

of

the

disease

for

many

[3] years.

(b)

The

response

vaccine

is

to

the

different.

the

graph

the

booster

to

two

Use

describe

infections

the

how

of

information

the

response

(Paper

in

eight

months

differs

4)

to 13

at

(a)

The

lymphatic

response

to

the

rst

injection

at

and

Describe

why

the

response

to

the

the

is

different

to

the

and

response

to

The

injection.

Suggest

why

further

boosters

of

how

may

be

given.

(i)

lymphatic

(ii)

lymph

nodes

[4]

system

consists

lymphocytes

of

and

the

immune

antibodies.

system

this us

against

infection

by

bacterial

[2] pathogens.

(Paper

of

[4]

defends

vaccine

functions

immune

Explain

(d)

lymphatic

the phagocytes,

rst

of

second (b)

injection

consists

nodes.

[4] vessels,

Explain

lymph

four

months.

(c)

system

from vessels

the

[3]

the

[5]

4) (Paper

4)

127

11

Gas

exchange

11.1

The

in

humans

gas

exchange

system

Structure LEARNING

•

Identify

name

on

the

bronchi,

lungs,

•

diagrams

larynx,

associated

capillaries

the

need

We

breathe

to

breathe

air

of

The

lungs

form

The

lungs

are

surrounded

and

functions

in

We

The

the

thorax

the

volume

part

into

our

of

spongy

and

from

of

our

lungs

the

gas

organs

protected

is

a

the

the

intercostal

enters

larynx

lungs

to

in

get

order

rid

of

exchange

found

by

sheet

of

the

inside

ribs

brous

abdomen.

lungs

to

which

the

the

enter

Its

move

to

get

carbon

oxygen.

dioxide.

system

and

the

chest

the

sternum

tissue

and

movement

air

exchange

The

lungs

which

appear

tubes

It

throat

or

to

which

through

deep

nose

then

the

lung.

takes

between

during

mouth

each

bronchioles,

gas

muscles

especially

(voice-box).

connects

healthy

air

of

(thorax)

muscle

up

and

and

are

(breastbone).

that

down

separates

when

you

breathe

out

changes

and

in.

trachea

Air

of

system

the

breathing,

X -ray

out

diaphragm

The

An

exchange

alveoli,

ribs,

muscles

cartilage

gas

trachea,

diaphragm,

the

the

and

bronchioles,

intercostal

State

of

OUTCOMES

and

the

lungs.

It

in

move

air

through

trachea

branches

continue

tiny

ribs

passes

enters

These

end

the

the

ribs

during

the

throat

breathing.

to

sacs

(windpipe),

to

divide

called

form

to

two

form

alveoli.

It

to

the

which

bronchi

many

is

small

here

that

place.

which

air

moves

are

often

called

airways.

black.

nasal

lar ynx

(voice

box)

C -shaped

cartilage

trachea

(windpipe) intercostal

muscle

right

left

bronchus

left

lung

lung

epiglottis (cut

open)

lar ynx

bronchioles

trachea rib

oesophagus

Figure

11.1.1

Entry

and

of

air

into

the

nose

rib

trachea.

heart

diaphragm

Figure

128

11.1.2

The

gas

exchange

system.

tnemelppuS

The

larynx

make

This

to

sounds.

is

down

You

because

cover

The

contains

the

your

the

cannot

when

you

opening

trachea

trachea

is

vocal

kept

to

(see

cords.

breathe

by

a

larynx.

page

open

and

swallow,

your

When

air

passes

swallow

ap

at

called

This

stops

over

the

the

any

these

same

time.

epiglottis

food

trachea

you

from

bronchiole

moves

going

82).

C -shaped

rings

of

cartilage.

The

‘arms’

of

left

the

C

are

joined

by

prevents

the

pressure

decreases.

Deeper

There

is

surface

trachea

into

a

very

area

diffusion).

capillaries

muscle

the

back

collapsing

of

as

the

you

trachea.

breathe

The

in

lung

cartilage

when

the

air

lungs

number

diffusion

Each

for

the

large

for

from

at

alveolus

efcient

of

(see

is

gas

alveoli

page

in

28

surrounded

exchange

the

to

remind

by

into

lungs

a

to

yourself

network

and

give

out

of

of

a

huge

about

blood

the

blood. bronchiole

The

alveoli

short

have

distance

thin

for

walls

made

diffusion.

of

They

a

are

single

moist

layer

so

of

cells,

oxygen

so

there

dissolves

in

is

a

alveoli

(air

capillar y

watery

uid

before

diffusing

through

the

walls

into

the

network

blood.

Figure

SUMMARY

sacs)

this

11.1.3

Describe

the

route

taken

by

inspired

air

(air

we

breathe

the

nasal

cavity

to

the

alveoli

in

the

The

lung.

diagram

shows

the

human

TIP

a

simpl e

lungs.

of

2

a

in)

Draw from

of

QUESTIONS

STUD Y

1

Structure

breathing

system:

the

gas

syst em

some

diag ram

exchan ge

and

no te s

label

to

the

A

explai ning

B

of

E

C

the

By F

are

the

this

Add

func tions

differ ent

doin g

it.

labels

parts.

you

anno tatin g

your

diag ram .

D

G

KEY

a

Name

structures

A

to

1

G.

POINTS

The

the b

Match

parts

A

to

G

with

these

inspired

larynx,

sheet

ii

one

of

muscle

forming

the

oor

of

the

these

enters

each

contains

iv

exible

v

where

the

vocal

Cartilage

kept

open

by

rings

of

slippery

vii

an

of

gases

takes

made

of

the

trachea

passes

spongy

Gas

exchange

air

blood

tissue

it.

occurs

between

place

membranes

organ

air

cartilage

the

vi

alveoli.

cords

3

exchange

the

keeps

when

through

tube

to

lung open

iii

down

bronchi,

thorax

2 of

passes

descriptions: bronchioles

i

air

trachea,

and

found

in

the

chest

in

in

the

the

alveoli

and

the

surrounding

capillaries.

129

11.2

Gas

exchange

Breathing LEARNING

Carbon • Compare

the

composition

and

expired

the

dioxide

features

exchange

of

if

dioxide

it

is

builds

a

up

waste

in

gas

made

in

respiration.

can

become

breathe

out

in

order

to

get

rid

of

the

carbon

dioxide.

gas

surfaces composition

• Describe

It

cells.

air

We • List

carbon

of toxic

inspired

out

OUTCOMES

gas

exchange

at

the

gas

inspired

air

/

%

expired

air

alveolus (breathing

oxygen

carbon

dioxide

page

28

to

16

0.04

4

78

78

abou t

conc

vapour

variable

saturated

remin d The

your self

and

out)

TIP

water

See

(breathing

21

nitrogen

STUD Y

in)

table

shows

that

we

breathe

out

more

carbon

dioxide

than

we

diffus ion

entrat

breathe

in.

We

and

air

that

breathe

in

more

oxygen

than

the

air

we

breathe

out,

ion the

we

breathe

out

has

a

lot

more

water

vapour.

grad ients .

The

following

more

carbon

practical

demonstration

conrms

that

we

breathe

out

dioxide.

PRACTICAL

Carbon

mouthpiece

limewater

1

Set

2

Then

up

the

apparatus

breathe

gently

as

in

you

breathe

in

•

When

you

breathe

out

•

The

limewater

more

limewater

The

carbon

turns

limewater

in

A

and

the

will

Figure

of

the

comes

air

expired

go

in

air

air

11.2.1.

mouthpiece

in

goes

rst

also

expired

in

out

air

the

in

and

shown

cloudy

dioxide

through

through

B,

cloudy

in

if

times.

A.

B.

showing

than

several

that

inspired

you

there

is

air.

breathe

through

11.2.1

apparatus

long

concentration

Gas STUD Y

Gas

alveo li

have

We

and

walls

cells ,

but

have

anim al

can

say

that

capilla ries

mad e

no t

remem ber

cells

of

exchange

enough,

carbon

showing

dioxide

in

there

is

a

lower

atmospheric

(inspired)

air.

surfaces

TIP

Bewa re!

cell

only

cell

of

exchange

a

human,

exchange

oxygen

and

as

in

the

gills

common

carbon

of

a

that

sh

and

adapt

alveoli

them

for

(air

sacs)

efcient

dioxide:

•

a

very

•

moist

•

a

large

surface

area

for

the

diffusion

of

gases

surfaces

so

that

gases

can

dissolve

before

diffusion

plan t

walls

do

such

features

walls

thin

surface

(only

one

cell

thick

in

each

alveolus)

so

the

gases

do

, not

cells

of

surfaces,

have

of

have

to

diffuse

very

far

no t. •

a

good

and

blood

lots

of

supply

carbon

concentration

130

inspired

When

the

–

in

•

• Figure

dioxide

so

that

dioxide

is

gradients

lots

of

oxygen

supplied

for

these

is

quickly.

gases

removed

This

quickly

maintains

the

•

ventilation

is

of

changed;

between

Gas

the

this

air

in

lungs

helps

the

exchange

When

inspired

contains

a

alveolus.

through

lot

It

the

diffusing

at

of

oxygen.

capillary

and

the

diffuses

through

the

that

the

gas

in

air

in

the

air

passages

concentration

the

gradients

blood.

alveolus

in)

air

reaches

Oxygen

into

cells,

the

the

the

the

dissolves

through

wall

two

that

maintain

alveoli

(breathed

then

ensures

wall

blood.

distance

alveoli

in

the

of

the

(air

water

very

it

lining

alveolus

Although

is

sacs)

this

each

SUMMARY

1

involves

List

four

alveoli

small.

them Each

alveolus

has

a

network

of

capillaries

around

it.

combine

oxygen

from

with

to

the

alveolus

diffuse

haemoglobin.

the

body

The

into

blood

the

cells

is

wall

ver y

of

can

then

cells

the

film

inside

of

of

moisture

the

carbon

O

O

O

adapt

exchange

transport

this

2

Look

on

at

the

apparatus

used

in

experiment:

the

cells

gauze

making

dioxide

O O

O O

the

that

alveolus

respiring

using

oxygen

O

efcient

cricket

cells

of

lungs

gases.

this

alveolus

for

the

and

thin

respiring

O

blood

tissues.

thin

the

red

features

of

Oxygen of

molecules

QUESTIONS

and

O

O

O

O

O O

O

O

O O

lime

O

blood

carries

oxygen

blood

carries

carbon

water

dioxide A

from

the

Figure

the

lungs

to

from

the

cells

to

the

B

lungs

cells

11.2.2

Gas

exchange

at

an

alveolus.

After

an

hour

the

tubes

were

examined.

There

is

a

lot

of

carbon

dioxide

in

the

capillary.

in

the

blood

It

has

been

carried a

there

from

the

respiring

tissues

plasma.

It

diffuses

in

What

result

would

you

the expect?

opposite

into

the

Alveoli

direction,

space

are

through

inside

the

surrounded

by

the

capillary

alveolus.

elastic

From

tissue.

wall

here

This

across

it

is

the

alveolar

breathed

stretches

when

wall b

Explain

your

c

Explain

why

answer.

out.

you

tube

B

is

breathe included.

in

and

recoils

when

you

breathe

out

to

help

remove

air

from

the

lungs.

3

The

air

we

breathe

out

is

saturated

with

water

vapour

that

Give

of

evaporated

from

the

moist

walls

of

the

an

the

When

to

There

is

a

you

cold

droplets

POINTS

b 1

more

carbon

dioxide,

less

oxygen

and

more

water

Expired

expired

air

than

in

inspired

Gas

area

exchange

and

a

surfaces

good

blood

are

Alveoli

are

well

adapted

moist,

thin,

have

a

large

surface

supply.

for

and

are

gas

surrounded

on

form.

air

turns

cloudy

c

Alveoli

thin,

exchange

as

they

have

inspired

by

many

(air

have

quicker

and

air.

sacs)

a

are

large

have

very

surface

walls

with

these

elastic features

out

water

air .

area 3

each

vapour

than

2

breathe

surface,

limewater in

for

following.

alveoli. a

KEY

explanation

has

bres.

capillaries.

131

11.3

Breathing

tnemelppuS

When LEARNING

ribs

•

you

Describe

how

pressure

changes

ventilation

of

volume

your

and

lead

the

outwards.

Explain

cells,

the

dust

role

mucus

protecting

system

it

lungs

to

so

inside

lungs

of

and

the

from

This

diaphragm

they

the

moves •

breathe

feels

as

if

the

lungs

are

expanding

to

push

your

OUTCOMES

in

is

and

to

through

so.

When

ribcage

occupy

lungs

not

a

move

larger

below

your

the

volume.

the

nose

you

chest

This

pressure

and/or

breathe

of

in,

cavity

movements

and

decreases

pull

the

atmospheric

on

air

air

of

the

pressure

so

that

air

mouth.

goblet

cilia

gas

in

When

exchange

pathogens

relax

and

you

and

pressure

particles

is

forced

alone

This

when

in

out,

causes

the

out.

(try

is

breathe

this

lungs

You

ne

you

for

quiet

exercise

diaphragm

chest

cavity

increases

can

breathing

the

the

do

this

without

to

the

by

moving

but

intercostal

intercostal

decrease

above

just

breathing,

and

to

in

atmospheric

movement

your

The

pressure

your

air

so

air

diaphragm

ribs).

during

muscles

of

muscles

volume.

deep

breathing

contract

to

and

move

the

ribs.

PRACTICAL (Intercostal

the A

model

of

the

external

Obtain

a

model

like

the

one

diagram.

The

rubber

the

that

are

ribs.)

closer

There

to

the

are

two

layers

skin,

and

the

of

these:

that

are

deeper

into

the

chest

wall

(see

Figure

internal

11.3.3).

diaphragm

is

made

of

tough

brous

tissue

in

the

centre

and

sheet strong

represents

muscles

the

in The

the

between

chest

muscles

1

means

muscles

that

connect

to

the

backbone,

the

lower

ribs

and

the

diaphragm. sternum

glass

(breastbone).

tube

passage

bell

of

air

jar

muscles

contract

balloon ribs

lungs

move

up

and

out

the

volume

the

chest

of

ribcage

rubber

sheet

cavity

increases

diaphragm diaphragm

contracts

and

2

Pull

and

the

rubber

then

sheet

push

it

front

up.

Figure

3

Do

this

watch

a

few

what

times

moves

down

down

view

of

chest

side

view

of

chest

11.3.1

and

happens

to

the

balloons.

Inspiration

This

model

shows

• movement

of

the

in

the

the

the

volume

thorax

bell

jar .

As

the

and

the

inate

lungs

increase

in

pressure

the

132

in

The

external

in

as

the

intercostal

muscles

contract

and

the

internal

a

result

space

relax,

raising

the

ribs

upwards

and

outwards.

•

At

the

•

Both

same

time,

the

diaphragm

contracts

and

attens.

by

the

downwards,

and

muscles

pressure

diaphragm

moves

volume

balloons.

and

represented

contracts

in)

diaphragm intercostals

changes

(breathing

how

of

an

decrease

around

•

of

these

pressure

Since

they

actions

inside

atmospheric

inate.

increase

the

thorax

pressure

is

the

to

volume

inside

the

thorax,

causing

decrease

greater,

air

moves

into

the

lungs

and

(breathing

passage

of

tnemelppuS

Expiration

out)

clavicle

air

trachea

external

intercostal

muscles

relax

breastbone

internal ribs

move

down

intercostal

ribs

lungs muscles and

in

ribcage the

volume

the

chest

of

cavity external

diaphragm

decreases

intercostal

muscles

relaxes

and

diaphragm

bulges

upwards

front

view

Figure

•

The

This

•

The

chest

side

view

of

chest

11.3.2

internal

muscles

•

of

intercostal

muscles

contract

and

the

external

intercostal

relax

lowers

the

muscle

pressure

ribs

downwards

in

the

diaphragm

from

the

organs

and

inwards.

relaxes

below,

for

and

it

bulges

example

the

up

due

to

liver

and

stomach, internal

and

•

contraction

Both

of

these

of

the

actions

abdominal

decrease

the

volume

external

intercostal

muscles.

inside

the

muscles

intercostal

muscles

thorax, cilia move dust

ciliated

causing

the

pressure

inside

the

thorax

to

particles

cells

•

Elastic

recoil

Cleaning

of

the

As

you

by

evaporation

the

air,

The

the

breathe

trachea,

helps

to

force

air

out

of

the

in

through

water

particles

bronchi

your

from

and

nose,

the

and

air

lining.

some

is

warmed

Hairs

and

inside

moistened

the

nose

lter

goblet cells

pathogens.

bronchioles

are

lined

with

ciliated

epithelial

Figure

11.3.4

Goblet

cells

epithelial

cells

and

goblet

cells

which

secrete

mucus.

Dust

particles

become

trapped

in

the

slimy

mucus.

The

cilia

and

cells

ciliated

keep

the

and lungs

pathogens

make mucus

lungs.

air

of

removing

alveoli

these cells

increase

beat

free

of

dust

and

to pathogens.

carry

a

stream

particles

and

of

mucus

pathogens

up

to

your

which

you

nose

then

and

throat,

removing

the

swallow. KEY

SUMMARY

1

QUESTIONS

POINTS

Inspiration

occur

1

When

a

person

breathes

in,

describe

what

happens

due

volume

in:

and

to

and

expiration

changes

pressure

of

in

the

thorax. a

the

intercostal

volume

inside

muscles

the

b

thorax

the

e

ribs

the

c

the

diaphragm

pressure

inside

the

d

the

thorax

2

The

internal

muscles, 2

Look

at

the

model

of

the

chest

in

the

Practical,

Which

part

of

the

model

the

lungs

ii

the

and

the

diaphragm

represents: control

i

intercostal

opposite.

muscles a

intercostal

external

diaphragm

iii

the

these

changes

during

ribs? ventilation.

b

Make

some

criticisms

of

the

model

as

a

way

of 3

representing

the

changes

that

occur

during

Goblet

which

3

Explain

free

the

from

role

dust

of

mucus

particles

and

and

cilia

in

keeping

pathogens.

cells

produce

mucus

breathing.

the

air

passages

traps

pathogens

beat

the

to

dust

in

the

remove

particles

air

and

mucus

and

cilia

from

airways.

133

11.4

Rate

and

depth

of

breathing

Breathing LEARNING

At •

Investigate

and

describe

exercise

rest

effects

of

on

rate

physical

and

you

probably

take

between

12

and

16

breaths

per

minute.

the When

the

and

OUTCOMES

you

exercise

this

breathing

rate

changes.

exercise

depth

of

breathing tnemelppuS

PRACTICAL •

Describe

of

how

exercise

dioxide

the

effects

increase

carbon

concentration

The

You the

blood

and

how

effects

the

rate

and

exercise

on

breathing

rate

can

measure

your

breathing

rate

by

counting

the

number

of

this times

affects

of

in

depth

that

you

breathe

out

in

a

minute.

of

breathing

You

could

record

your

results

in

a

table

like

this:

–1

breathing

at

rate

/

breaths

per

min

light

heavy

exercise

exercise

rest

1

2

3

average

•

Try

•

As

=

doing

soon

as

you

breathing

rate.

•

Wait

until

your

•

Now

try

(heavy

•

Then

•

You

for

have

1

minute

nished,

breathing

doing

step-ups

sit

rate

as

(light

exercise).

down

returns

quickly

as

and

to

its

you

count

your

resting

can

for

value.

3

minutes

exercise).

count

will

change

Performing

step-ups

your

notice

after

breathing

that

doing

your

rate

when

breathing

you

rate

have

and

nished.

depth

of

breathing

exercise.

step-ups.

•

Repeat

this

twice

and

calculate

averages.

plastic

container

breathe

out

The

here

are

rate

and

working

They

also

depth

hard,

of

breathing

your

produce

muscles

more

carbon

increase

need

with

more

dioxide

in

exercise.

oxygen

for

When

they

respiration.

respiration.

rubber

tubing

Increasing

blood

and

continue

a

trough

Figure

11.4.1

This

apparatus

used

to

capacity

can

measure

(see

top

of

vital

heart

134

to

rid

respire

Your

of

and

of

quite

oxygen

pulse

beating

depth

more

fast

rate

to

of

breathing

carbon

fast

after

and

they

remains

deliver

dioxide

exercise

still

high

plenty

gets

the

nishes.

have

carbon

after

of

more

from

They

to

this

extra

oxygen

and

have

their

carbon

dioxide

the

need

to

because

your

into

Muscles

still

dioxide

exercise

blood

oxygen

blood.

be

your

muscles

next

gain page).

is

rate

gets

supply

removed.

be

your

good

the

removed.

so

they

oxygen

delivered

muscles

rate

of

respiration

rate

in

and

depth

more

to

STUD Y

quickly

TIP

of

exercise muscles

breathing

increases

See

increases

carbon

page

your self removed

muscles

11.4.2

The

effect

of

exercising

on

to

diffus ion.

quickly

Com pare

resu lts

with

you

go t

inve stigat ing

(pag

is

adult

their

out

can

vital

after

105)

take

in

about

capacity

breathing

in

–

5

the

as

litres

of

air

maximum

much

air

as

in

their

volume

possible.

deepest

of

air

At

breath.

that

rest,

is

This

on

breathed

about

half

a

effect s

the

the

air

is

breathed

in

and

out.

During

exercise

approximately

four

litres

of

extra

air

can

be

taken

in

during

a

deep

and

body

add

tnemelppuS

You

don’t

happens.

exercise?

you

So

exercise

dioxide

about

what

the

more

your

makes

brain

which

become

Y ou

some

(see

has

lowers

you

a

tissues

respire

pH

They

–

breathe

special

the

acidic).

breathing

part

more

in

the

may

most

faster

for

the

and

time

deeper

controlling

quickly

tissues

also

of

and

and

make

page

brain

gluc ose

when

of

the

more

blood

blood

acid

(i.e.

which

When

STUDY

they

does

TIP

the

this

rise

in

carbon

dioxide

and

the

lowering

of

are

reaching

it.

The

brain

sends

nerve

impulses

to

and

to

the

increase

dioxide

turn

and

in

this

through

more

the

has

intercostal

the

rate

rapidly,

blood

the

them.

muscles!

muscles

so

they

contract

and

depth

of

breathing.

By

and

same

This

is

you

this

effect

an

lower

raises

on

the

the

example

the

concentration

blood

tissues

of

pH

back

because

homeostasis

the

hard

faster

require

work.

the

extra

and

and

glucose

and

breathing

of

carbon

to

normal.

the

–

organs

the

need deeper

the

the

the

oxygen to

14 .

carbon

T hey

further

and

Unit

140).

detects

diaphragm

in

you

doing pH

able

abou t

just

breathing.

make

the

lactic

it

T hey Your

and

be

more

tempe ratu re

Remember same

hear t

will

breathing

think

The

ise

includ ing

breath.

blood

of

mar

exerci se

a

body

Control

of

rate

litre

to half

Sum

mus cles,

lung s. of

.

breathing the

An

e

when

puls e

tnemelppuS

of

the

breathing.

resu lts

Depth

remin d

abou t

from

more

your

Figure

28

dioxide

blood

see

page

to

taken

In

have

away.

answer

ows

the

166.

in

on

wastes

Start

this

changes

the

their

that

muscles

any

topic

with

occur

during

exercise.

1

When

a

2

QUESTIONS

you

the

exercise,

rate

Describe

of

what

describe

breathing

happens

what

b

to

the

happens

the

to:

depth

of

concentration

breathing

of

carbon

KEY

dioxide 1

in

the

blood

when

you

POINTS

Exercise

rate tnemelppuS

3

a

Explain

how

the

brain

monitors

and

controls

the

rate

when

you

and

depth

Explain

what

happens

An

increase

to

the

following

when

you

the

intercostal

iii

the

heart

the

breathing.

in

the

muscles

ii

the

of

carbon

exercise: dioxide

i

both

exercise. concentration

b

of

of 2

breathing

increases

exercise.

diaphragm

the

in

brain

changes

the

blood

triggers

in

reaching

these

breathing.

rate

135

tnemelppuS

SUMMARY

PRACTICE

1

Which

QUESTIONS

is

a

pathway

that

air

takes

from

the tube

atmosphere

to

the

gas

exchange

surface

in

A

tube

B

the A

cloudy

cloudy

B

cloudy

no

C

no

change

cloudy

D

no

change

no

lungs?

A

mouth

larynx

bronchiole

B

alveolus

mouth

nose

alveoli

C

nose

trachea

bronchus

larynx

trachea

(Paper

bronchus

trachea

bronchiole

bronchus

What

A

1)

many

lled

a

conical

ask

with

lime

put

student

water

cross

the

a

drawing

then

to

test

of

a

breathed

nd

out

became

after

features

of

a

gas

exchange

how

The

three

beneath

the

long

invisible.

doing

cross

into

it

ask

took

thick-walled,

C

area,

small

surface

area,

capillaries

thin-walled,

many

the

repeated

of

surface

The

lime

before

student

minutes

it.

of

large

capillaries

water

few and

the

thick-walled,

[1]

student

are

alveolus

B 2

[1]

surface?

A

(Paper

1)

alveolus 4

nose

change

bronchiole

bronchiole

D

change

bronchus

D

large

few

area,

capillaries

thin-walled,

strenuous

surface

small

surface

area,

capillaries

exercise.

Which

describes

the

time

taken

for

the

5 to

become

invisible

in

the

test

after

(Paper

1)

Which

is

The

cross

became

invisible

in

a

the

function

of

the

cartilage

in

exercise? the

A

[1]

cross

trachea?

shorter A

cleans

the

B

contracts

C

increases

air

as

it

moves

to

the

lungs

time.

B

The

cross

become

took

three

times

as

long

to

move

air

into

the

lungs

to

resistance

to

air

owing

to

the

invisible.

lungs C

The

cross

took

twice

as

long

to

become

D

prevents

the

trachea

collapsing

invisible.

D

The

(Paper

time

was

the

same.

(Paper

1)

[1]

6

The

act 3

The

diagram

shows

apparatus

to

2)

[1]

diaphragm

together

production

of

carbon

dioxide

the

intercostal

expiration

at

muscles

the

end

of

investigate strenuous

the

and

during

exercise.

Which

of

the

following

during occurs?

respiration

to

see

in

of

insects.

tubes

A

and

What

would

B

minutes

ve

you

expect

after intercostal

setting

up

the

apparatus?

muscles

diaphragm

internal

external

relax

contract

relax

contract

contract

relax

contract

relax

moves A

contracts down

B

contracts

C

relaxes

moves

up

moves

down

limewater

D

relaxes

moves

up

limewater

(Paper

potassium

living

hydroxide

animals

solution

carbon

136

(absorbs

dioxide)

air

flow

2)

[1]

7

The

gas

photograph

exchange

shows

some

cells

from

the

(b)

(i)

Calculate

system.

the

(ii)

(c)

changed

minute.

per

of

of

in

same

class.

so

What

A

is

cell

X?

alveolar

B

ciliated

C

goblet

D

muscle

cell

10

The

the

cell

(a)

cell

(b)

cell

2)

50

step-

of

exercise

on

the

to

on

that

between

the

two

they

they

investigate

boys

features

would

could

the

the

and

have

make

boys

of

to

the

keep

valid

and

girls.

3)

[2]

diagram

thorax

Name

(i)

shows

from

A

to

the

the

ribs

and

muscles

of

side.

C.

Describe

the (Paper

to

the

[2]

State

that

comparisons

(Paper

rest

in

when

[2]

effect

exercise

investigation

the

from

decided

this

the

the

change

breath

breathing.

students

effect

girls

each

ups

Describe

The

percentage

of

student

rate

X

the

volume

[3]

how

structures

[1] shown

8

The

it

percentage

passes

composition

through

the

lungs

of

air

changes

bring

as

about

breathing

because:

A

movements A

carbon

dioxide

and

water

vapour

are C

during absorbed

from

the

air

inspiration B

carbon

dioxide

is

absorbed

and

and

oxygen expiration.

[6]

excreted

(ii) C

oxygen

is

absorbed

and

carbon

Explain

how

dioxide

B

the

movements

excreted you

D

oxygen

(Paper

is

absorbed

and

nitrogen

excreted

2)

air

move

into

Some

students

investigated

the

effect

Here

on

are

the

the

rate

results

and

for

volume

activity

each

depth

one

of

of

of

the

and

lungs.

[5]

3)

breathing.

the

students.

number

breaths

breath

of

of

(Paper exercise

to

[1]

out

9

describe

cause

11

Look

(a)

of

at

the

table

Describe

the

student’s

taken

of

results

effect

of

in

question

exercise

on

9.

the

breathing.

[5]

3

/

cm

rest

20

minute

500

18

750

25

1200

34

(b)

50

Explain

why

changed

(Paper

step-ups

per

the

during

student’s

exercise.

breathing

[6]

4)

minute

step-ups

per

(a)

per

minute

(i)

Calculate

of

each

the

change

breath

changed

from

when

20

to

in

the

the

50

volume

student

step-ups

minute.

(ii)

[1]

Describe

volume

per

the

of

effect

each

of

exercise

breath.

on

the

[2]

137

12

Respiration

12.1

Aerobic

Aerobic LEARNING

Dene

aerobic

respiration

we

the

word

State

that

is

respiration

catalysing

cell

in

State

the

uses

human

Investigate

oxygen

energy

by

of

energy

reactions

in

body

is

living

in

the

released

the

uptake

respiring

of

tnemelppuS

State

the

that

living

petrol,

gives

off

oxygen

a

lot

of

is

used

light

up

and

and

carbon

heat.

organism

cells

is

needs

called

energy.

glucose,

A

but

fuel

unlike

used

to

burning

very

gradually

in

a

series

of

small,

petrol,

enzyme-

cells

In

aerobic

balanced

for

break

to

Respiration

down

release

involves

nutrient

a

number

molecules,

such

of

as

chemical

glucose,

energy.

respiration

oxygen

is

used

in

the

breakdown

of

glucose:

organisms +

→

oxygen

carbon

dioxide

+

water

+

energy

released

chemical Cells

equation

reactions.

in

glucose

•

as

cells

the

•

every

energy

controlled

•

such

ame

reactions the

in

fuel

The

involves provide

enzymes

a

made.

equation

Every •

burn

and dioxide

state

respiration

OUTCOMES

When •

respiration

also

respire

fats

and

proteins

to

provide

energy,

but

you

only

have

aerobic to

know

about

the

respiration

of

glucose,

which

is

a

carbohydrate.

respiration

Using

Your

the

energy

body

needs

following

•

muscle

•

cell

•

absorption

•

sending

•

protein

energy

for

many

different

things.

Energy

is

used

in

processes:

contraction

division

of

nutrients

impulses

synthesis

in

along

for

the

gut

by

active

transport

nerves

making

enzymes,

some

hormones

and

antibodies

• computer

generated

mitochondrion.

made

in

these

Most

cell

image

of

the

of

ATP

structures.

in

Each

cells

is

during

is

new

STUD Y

keeping

the

no t

a

with

C

H 6

in

proces s

for

O 12

Most

in

of

lo ts

structures

like

the

nucleus

temperature

constant.

Some

of

the

energy

place

of

in

+

heat.

all

by

Wha t

living

no t

energy

cells

→

to

all

stay

of

the

alive.

time

The

because

balanced

cells

chemical

is:

6CO

2

+

6H

2

O

+

energy

released

2

of

the

energy

you

breath e

released

Cells

in

that

aerobic

require

a

respiration

lot

of

is

energy

released

have

For

instance,

insect

ight

muscle

has

many

numerous

each

its

located

between

the

muscle

bre.

The

mitochondria

own the

energy

for

the

muscles

to

contract

during

ight.

Liver

cells

do have

you

of

respiration

6O

6

mitochondria.

provide

enzy me.

supply

aerobic

mitochondria

is

form

of

reactio ns,

cata lysed

when

the

takes

mitochondria.

chem ical

138

cell

Respi ratio n

chem ical

cons istin g

out

body

constant

equation

conf use

breath ing.

a

is

Respiration

respira tion

one

and

TIP

need

is

membranes

long.

released

Do

cell

growth

about

• 0.002 mm

making

a

in

and

respira tion!

cells

a

of

active

high

the

metabolism

small

transport,

and

intestine

so

have

have

absorb

large

many

mitochondria.

glucose

numbers

and

of

other

The

epithelial

molecules

mitochondria.

by

tnemelppuS

A

tnemelppuS

PRACTICAL PRACTICAL

Investigating

the

uptake

of

oxygen

by

respiring

seeds Investigating

The

apparatus

how

up

quickly

oxygen

which

is

in

Figure

12.1.1

germinating

during

seeds

aerobic

absorbed

by

is

the

a

respirometer

use

up

respiration

soda

lime.

oxygen.

and

The

and

The

release

it

can

seeds

carbon

decrease

in

measure

respiration

take

and

causes

the

red

liquid

to

move

along

the

capillary

tube.

of

movement

can

be

measured

by

the

scale

–

the

faster

of

rate

of

germinating

apparatus

shown

in

Figure

The 12.1.2

rate

of

effect

the

air The

pressure

the

on

seeds

dioxide,

volume

temperature

the

is

a

more

accurate

rate respirometer.

of

respiration,

to

keep

the

the

quicker

apparatus

at

the

a

liquid

will

constant

move.

Why

is

it

important

1

temperature?

Place

into

2 1 eye

2

3

4

5

6

7

Set

soda

Figure

the

germinating

boiling

rest

of

seeds

tube.

the

apparatus

8

protection

up

is

some

the

as

shown.

Be

very

careful

lime

corrosive

12.1.1

A

simple

not

to

it

corrosive.

is

touch

the

soda

lime

as

respirometer.

3

Close

the

much plastic

clip

the

and

nd

coloured

out

liquid

how

rises

in

capillar y

tubing

the

tube

capillary

tube

in

30

minutes.

clip

eye

is

This

protection

soda

water

lime

at

corrosive

a

investigation

works

on

the

bath

same

known

temperature

one.

principle

It

can

number germinating

of

the

previous

repeated

at

temperatures

a

by

seeds

changing wire

be

as

gauze

the

temperature

of

the

coloured

water

and

so

compare

the

rate

of

water

soda

Figure

12.1.2

A

respirometer

for

lime

respiration

investigating

the

effect

of

temperature

of

the

seeds.

on

respiration.

KEY

SUMMARY

1

1

Copy

POINTS

QUESTIONS

and

complete

the

sentences

using

these

In

is

words:

aerobic

broken

energy aerobic

glucose

oxygen

in

carbon

dioxide

takes

place

in

all

living

.

A

fuel

is

.

It

is

broken

down

to

release

is

water

and

the

waste

gas

.

and

Respiration

When

it

of

These

in

the

reactions

structures

2

a

presence

Write

take

of

place

called

down

we

in

every

call

it

living

equation

for

Energy

Make

is

a

released

list

of

ve

during

aerobic

processes

that

cell,

inside

3

tiny

The

word

aerobic

glucose

respiration.

a

Describe

b

What

how

a

simple

equation

+

the

function

use

respirometer

of

soda

this

4

energy.

The

lime

in

the

apparatus

balanced

H

O

12

+

6

do

the

you

think

will

happen

to

the

rate

of

for

or

chemical

aerobic

is:

6O

→

6CO

+

6H

2

O

2

Respirometers

germinating

ii

increases

seeds

to

if

the

temperature

i

can

be

used

to

respiration

decreases

the

rate

of

respiration

to under

5 °C

→

water

2

measure of

+

12.1.1?

5 What

oxygen

in

6

c

aerobic

works.

C

Figure

for

is:

respiration.

respiration

is

catalyse

cells.

dioxide

equation 3

the

to

respiration.

carbon b

in

respiration

word

involves

takes

.

the

water.

enzymes

reactions place

of

carbon

Also

action produced

presence

forming

for

2 respiration

glucose

release

cells

dioxide

Respiration

the

to

mitochondria

oxygen, energy

respiration,

down

different

conditions.

50 °C?

139

12.2

Anaerobic

Muscles LEARNING

Dene

anaerobic

for

in

the

muscle

exercise

•

word

anaerobic

State

and

that

exercise

equations

in

carry

vigorous

energy

glucose

much

out

tnemelppuS

the

is

possible

balanced

for

Describe

lactic

in

an

is

the

acid

in

oxygen

release

glucose

strenuous

build-up

muscle

and

during

the

of

to

cause

for

energy

in

is

the

this

from

the

get

enough

happens

glucose

release

absence

exercise,

aerobic

not

of

of

oxygen

your

to

muscles

your

start

to

a

without

little

using

energy

oxygen.

from

each

oxygen.

enough

respiration

how

it

tissue

respires

enzyme-catalysed

without

dioxide

oxygen.

and

to

oxygen

supply

all

may

the

reach

energy

the

the

body

muscles

As

water,

anaerobically

reactions

a

result

but

to

of

the

aerobic

glucose

lactic

to

acid

is

release

energy.

respiration

not

do

broken

Most

not

down

of

happen

to

carbon

instead:

recovery →

lactic

acid

+

energy

released

exercise

tissues,

respire

the

to

make

an

electron

microscope.

beating

lactic

is

alcohol

and

absent

C

→

H

O 12

if

Some

same

in

not

the

bacteria

way,

heart,

release

for

do

not

enough

also

respire

example

normally

energy

to

keep

anaerobically

those

that

we

use

energy

and

set

is

H

+

OH

in

respire

their

anaerobically

surroundings,

when

to

make

carbon

+

in

dioxide

2CO

+

+

energy

released

energy

released

2

water

released

alcohol

yeast,

anaerobically

to

broken

alcohol

as

supply

5

with

compared

in

such

from

so

the

land

or

of

a

is

no

molecule

respiration.

and

form

little

each

aerobic

down

when

lot

of

ooded

oxygen

of

This

energy

chemical

bond

is

and

glucose

is

soils

available.

in

because

remains

energy.

anaerobic

glucose

stored

Y ou

in

can

is

lactic

see

alight.

–1

energy

aerobic

respiration

fermentation

anaerobic

Hurdlers

140

build

up

lactic

acid

in

their

muscles.

to

dioxide:

2C

respire

completely

you

muscle

would

short

alcohol

saturated

respiration

acid

the

in

2

roots

less

or

6

become

not

in

carbon

→

Far

this

properly.

acid

glucose

Plant

cardiac

as

microorganisms,

oxygen

6

as

yoghurt.

Other

under

such

anaerobically

heart

make

cells

These

vigorous

respiration

to

Muscle

Other

Yeast

cannot

When

During

respiration.

respiration

of

glucose from

aerobically.

system.

yeast

debt

removed

respire

chemical

need.

•

to

blood

anaerobic muscles

respiration

lungs

your

respiration

During equation

glucose

by

molecule

molecule

State

and

enough.

anaerobic

Anaerobic

•

and

muscles

less It

aerobic

heart

quickly

Anaerobic

anaerobic

releases

than

oxygen

your

yeast

respiration

per

need

to

your

muscles

respiration

during

brought

tnemelppuS

State

muscles

respiration are

•

oxygen

OUTCOMES

Your •

without

respiration

by

(kJ

16.1

yeast

respiration

released

1.2

in

muscle

0.8

/

g

glucose)

this

tnemelppuS

Lactic

Lactic

be

acid

acid

can

removed

and

blood,

Our

oxygen

‘paid

after

After

to

by

the

build

in

up

after

we

carry

to

lactic

lactic

up

acid

acid.

to

blood

in

the

exercise

on

hard,

more

The

of

acid

oxygen

beat

at

a

the

and

fast

in

muscles.

They

has

for

is

in

to

to

be

deeper

aerobic

removed

the

rate

muscles

must

muscles

debt

and

debt

acid

it

the

it

faster

oxygen

lactic

so

in

oxygen

breathing

from

their

cramps,

lactic

causes

respiration

the

cause

of

supply

continues

in

and

build

exercise,

order

down

acid

muscles

The

We

aerobic

heart

lactic

up

away.

break

exercise

Sprinters

builds

exercise

recovery

transport

body.

vigorous

straight

vigorous

during

to

debt

poison

the

during

back’

respiration

slowly

from

liver.

order

the

often

liver.

hold

their

3

breath

of

during

oxygen

after

The

the

100

get

race

in

metres

rid

of

order

enzyme-catalysed

aerobic

respiration

function

glucose

acid

to

a

is

without

is

partly

the

to

in

supply

from

acid.

that

That

of

release

oxygen.

in

end

the

is

oxygen

mitochondria.

down

the

Afterwards

their

reactions

broken

produced

lactic

‘repay

occur

a

race.

they

need

why

they

most

These

breathe

of

the

cell

deeply

this

and

energy

structures

anaerobic

cytoplasm

of

7 dm

debt’.

During

product

about

not

respiration,

alcohol

partial

in

do

or

lactic

breakdown.

This

SUMMARY

1

QUESTIONS

a

Dene

the

b

Give

c

Compare

term

runner

breathing

anaerobic

during

examples

the

of

energy

aerobic

and

anaerobic

Describe

and

explain

released

from

anaerobic

the

in

aerobic

and

her

her

oxygen

debt

by

training.

POINTS

a

molecule

of

glucose

1

respiration.

Anaerobic

chemical

differences

between

the

anaerobic

respiration.

respiration

reaction

break

down

in

is

the

cells

glucose

to

energy release

released

after

respiration.

that 2

repaying

respiration

KEY two

is

deeply

(See

the

energy

without

using

table oxygen.

for

some

gures

to

use

in

your

answer.)

tnemelppuS

2 3

The

table

below

shows

the

units

of

lactic

acid

produced

in

In

anaerobic

glucose leg

muscles

of

an

athlete

during

a

of /

minutes

0

10

20

30

40

50

60

70

80

0

1

7

12

9

6

3

1

1

in units

of

lactic

acid

b

When

a

graph

using

the

the

lactic

Explain

why

the

Suggest

why

acid

muscles

the

tissue,

reach

a

end

of

the

produced

lactic

Explain

why

session

of

we

hard

Far

more

muscles

produced

less

lactic

acid

Explain

how

an

alcohol,

dioxide

in

yeast

energy

each

is

released

molecule

in

aerobic

of

than

in

towards respiration.

race.

carry

on

breathing

heavily

after

we

nish

a

exercise.

The

oxygen

debt

build

muscles

develops

and

how

it

is

has

up

of

during

produces

that 5

acid

acid.

4

4

or

lactic

maximum?

anaerobic

the

to

absence

plants.

glucose

d

down

the

forming

carbon

from c

in

data.

3 did

energy

muscle

and Draw

broken

oxygen,

plus

a

is

race: release

time

respiration,

the

an

to

lactic

hard

oxygen

be

paid

acid

in

exercise

debt

back

by

repaid. breathing

in

extra

oxygen.

141

tnemelppuS

opposite

PRACTICE

1

Which

QUESTIONS

process

does

not

require

energy

from

6

The

of A

equations

change

respiration?

diffusion

of

oxygen

across

the

alveolar

that

contraction

C

passage

D

synthesis

of

muscle

during

(Paper

2

When

nerve

of

to

enzyme-catalysed

show

glucose

as

reactions.

the

a

overall

result

the

role

of

glucose

Which

for

the

term

rst

exercise enzyme

of

respiration

wall

describes B

for

occurs

in

respiration?

impulses

protein

A

activator

B

active

C

product

D

substrate

molecules

1)

site

[1]

yeast

respires

without

oxygen,

the

cells

produce: (Paper

A

alcohol

B

carbon

C

lactic

acid

D

lactic

acid

7 dioxide

and

After

[1]

vigorous

high.

A

carbon

Which

carbon

1)

[1]

B

lactic

During

aerobic

chemical

respiration,

reactions

molecules

to

is

enzymes

breakdown

be

to

glucose

B

produce

lactic

C

produce

oxygen

D

release

student’s

heart

rate

reason

from

for

this?

anaerobic

from

anaerobic

removed

the

respiration

muscles

respiration

from

the

muscles

catalyse

C

nutrient

oxygen

to:

produce

a

removed

from

be

is

required

metabolism

A

not

dioxide

to

acid

needs 3

a

dioxide needs

(Paper

exercise,

alcohol is

and

2)

D

waste

of

in

lactic

products

of

the

liver

for

acid

respiration

need

to

be

removed acid

(Paper

energy

8

The

2)

oxygen

oxygen (Paper

1)

During

vigorous

without

is

the

exercise,

oxygen.

release

The

carbon

dioxide

B

carbon

dioxide

muscle

D

much

result

of

oxygen

this

additional

the

lungs

volume

after

of

exercise.

energy

and

from

energy

each

molecule

of

A

anaerobic

B

metabolism

C

removal

D

respiration

from

each

molecule

does

respiration

in

muscle

tissue

of

lactic

acid

in

the

liver

of

carbon

of

dioxide

for

muscle

tissue

to

release

contraction

2)

[1]

of

(a)

Write

for

Which

for

glucose

9

1)

required

water

glucose

(Paper

is

respiration

(Paper

out

and

aerobic

complete

the

word

equation

respiration:

[1]

+

5

the

by

respires

energy

little

is

of

A

C

debt

absorbed

[1] This

4

[1]

not

have

oxygen

→

+

+

mitochondria? [4]

A

ciliated

B

liver

epithelial

cell A

to

C

student

muscle

nd

red

the

blood

student

apparatus.

cell

opened (Paper

2)

the

of

for

took

After

apparatus

respiration

several

each

several

[1] sealed

142

up

rate

shown

of

opposite

crickets.

cell The

D

set

cell

again.

readings

reading

minutes

the

before

from

clip

the

was

being

spring

clip

time

/

0

5

10

15

20

25

30

35

0

0

0

31

65

95

130

162

minutes

position

of

liquid

/

droplet

mm

(a)

Explain

why

crickets

wire soda

lime

carbon

gauze

(i)

a

water

(ii)

the

apparatus

before

The

calculate the

direction

in

which

the

closing

diameter

0.8 mm.

State

was

used

was

left

the

clip.

for

ten

minutes

absorbs

dioxide

(b)

(b)

bath

Use

of

the

the

the

capillary

results

rate

of

[2]

in

tube

the

oxygen

is

table

to

uptake

coloured 3

in drop

will

move

apparatus.

as

the

Explain

crickets

your

respire

in

mm

per

hour.

answer.

(c)

[4]

Explain

how

the

investigation (c)

Explain

why

the

clip

is

opened

after

(d)

readings.

State

one

constant

10

Copy

factor

during

that

the

should

be

(Paper

kept

investigation.

complete

The

rst

(a)

the

row

table

has

with

been

ticks

an

completed.

sisehtnysotohp

negyxo

a

series

of

catalysed

reactions

produces

carbon

noitpmusnoc

✗

/

✓

oxygen

of

graph

athlete

short

shows

who

period

of

enzyme-

all

The

of

after

rest.

0.0

5

10

15

dioxide

time

the

time

20

/

25

30

35

minutes

Describe

the

change

in

oxygen

(night

3)

over

the

35

of

shown

the

apparatus

in

effect

respiration

of

was

question

of

Pinto

put

9

was

temperature

used

on

the

Explain

was

the

clip

minutes

taken.

that

[4]

closed

over

and

time.

the

The

changes

(i)

10

and

(ii)

20

to

in

oxygen

between

20

minutes

[6]

beans.

into

open.

the

consumption

a

water

bath

After

ten

position

results

of

are

minutes

the

as

30

minutes.

[5]

at (Paper

with

recorded

were

[5]

apparatus

27 °C

clip

minutes

day)

determine

rate

consumption

10

0.5

(c)

to

for

energy

place

(Paper

The

oxygen

[1]

1.0

recordings

11

cells

1.5

consumption and

the

exercised

animal

respiration.

2.0

(b) takes

inside

aerobic

2.5

0

releases

structures

out

md

cells

the

carry

3

plant

nim

consists

[4]

1–

produces

in

the

3.0

noitaripser

feature

only

if

and

4)

Name

The

and

a

occurs

differ

17 °C

[1]

3)

crosses.

at

50 °C.

that

and

would

repeated

[2]

12

(Paper

results

was

taking at

the

[3]

the

4)

the

droplet

follows.

143

13

Excretion

13.1

Excretion

LEARNING

OUTCOMES

Excretion

•

Dene

•

Name

the

term

is

the

metabolism,

and

•

the

Describe

in

excretory

excretory

the

the

removal

from

the

body

of

the

waste

products

of

excretion

The

organs

organs,

products

role

of

assimilation

the

of

waste

toxic

materials

substances

which

are

are

the

and

substances

removed

lungs,

liver

from

and

in

the

excess

body

kidneys

of

by

(see

requirements.

the

excretory

Figure

13.1.1).

liver

amino

Excretory

products

acids

Humans •

Dene

have

two

main

excretory

products.

deamination

•

Carbon

dioxide

transported

of

•

the

to

blood

page

130).

Urea

is

is

the

into

made

in

made

lungs

the

the

air

liver

in

in

in

body

the

blood

the

from

tissues

plasma.

alveoli

excess

during

and

is

amino

respiration.

Here,

it

diffuses

breathed

acids.

It

is

It

out

is

out

(see

carried

to

lungs

the excrete

kidneys

the

plasma

where

it

is

ltered

out

and

leaves

the

carbon

body

dioxide

dissolved

Excretion

liver

is

substances

processes

materials

a

in

vital

like

the

form

process

carbon

of

in

urine.

the

dioxide

metabolism

and

urea

of

would

the

be

body.

Without

allowed

to

it,

build

toxic

up

makes

in

in

the

tissues.

These

substances

would

reach

a

toxic

level

and

and

destroy

them

the

tissues.

harmless

Do

kidneys

excrete

not

are

13.1.1

The

excretory

are

egested

canal

with

‘egestion’.

body

cells

in

Substances

metabolism.

that

are

Substances

have

been

without

eaten

being

and

have

digested

passed

and

through

absorbed

into

the

the

organs.

bloodstream.

hepatic

by

salts

alimentary Figure

‘excretion’

produced

urea

that and

confuse

excreted

Fibre

is

an

example.

vein

Assimilation stomach

Assimilation

now

become

means

part

of

that

the

the

cells

food

or

molecules

are

used

by

that

the

have

been

absorbed

cells.

liver

portal

tnemelppuS

hepatic

vein

The

liver

carries

out

a

number

of

important

functions

as

part

of

assimilation:

•

stores

glucose

glycogen.

blood

by

This

(see

removing

helps

page

to

it

from

regulate

the

the

blood

and

concentration

storing

of

it

as

glucose

in

the

166)

large

intestine

•

uses

amino

brinogen,

acids

to

make

involved

with

proteins,

blood

such

as

plasma

proteins,

e.g.

clotting

small

intestine

appendix

anus

rectum

•

breaks

•

converts

body, Figure

13.1.2

The

position

portal

of

the

fatty

e.g.

excess

acids

under

amino

and

the

acids

glycerol

into

fat

which

skin

hepatic

vein.

•

144

down

produces

cholesterol

from

fats

(see

page

71).

is

stored

around

the

tnemelppuS

Roles

The

see

of

liver

the

carries

from

liver

out

Figure

over

13.1.2,

200

all

different

the

blood

roles

from

in

the

the

body.

digestive

As

you

system

STUD Y

can

TIP

ows

Deam inat ion to

the

liver

rst

before

going

into

the

rest

of

the

circulation.

breakd own amino

acids

produced

in

the

alimentary

canal

by

the

digestion

cannot

is

are

absorbed

store

broken

the

down

into

amino

into

the

acids

two

blood

that

parts.

it

in

the

small

cannot

One

of

use

these

intestine.

and

parts

so

is

Your

each

made

of

of

amin o protein

is

The

acid s

body

amm onia .

molecule

into

to

mak e

Urea

prod uctio n

urea.

the

excess

is

a

sepa rate

proces s. Other

it

roles

enters

breaks

and

of

the

the

liver

small

down

harmful

include

intestine,

hormones

that

substances,

making

and

have

such

bile,

emulsies

as

which

fat

circulated

alcohol

in

and

neutralises

(see

the

page

84).

blood

drugs

(see

for

acid

The

a

page

as

liver

while

178).

cells protein gut

some

acids

into

digestion

amino

are

built

protein

make

new

to

excess

cells

taken

amino

to

the

changed

acids

liver

into

are

and

urea

urea

KEY

1

POINTS

Excretion

is

the

removal

from

liver

the

amino

Figure

acids

13.1.3

made

This

shows

what

happens

to

amino

acids

in

the

body.

that

acids

are

not

cannot

be

required

stored

for

so

making

the

liver

breaks

proteins.

Each

down

amino

amino

acid

broken

down

into

two

by

the

process

of

is

converted

to

carbohydrate

or

deamination.

fat

and

used

as

carbon

acids

The

other

molecule

is

ammonia

(NH

)

which

chemicals

during

products

dioxide

include

and

urea.

The

lungs,

liver

and

kidneys

One

a

source

excretory

combines

organs.

Carbon

of dioxide

energy.

tissues

Excretory

are molecule

waste

molecule 3

is

in

of

metabolism.

2

Amino

body

is

excreted

by

the

lungs.

with

3

to

in

the

dioxide

kidneys

urine

(see

contains

to

in

form

the

page

nitrogen

the

146).

is

excretory

blood

where

The

known

part

as

it

of

the

product

is

ltered

the

urea.

out

amino

amino

acid

group

–

This

and

is

is

carried

molecule

this

is

4

is

called

deamination

because

this

group

is

why

liver

liver

breaks

down

toxins,

for

example

drugs

urea

acids.

excrete

from

The

urea

in

urine.

the The

liver

breaks

down

toxins

removed. such

The

makes

amino

kidneys

that

5 process

The

excess

excreted

such

as

alcohol

as

alcohol

and

drugs.

and 6

The

liver

uses

amino

acids

to

paracetamol. make

proteins

proteins

SUMMARY

QUESTIONS

7

Deamination

of

1

a

Explain

and

i

how

then

tnemelppuS

Distinguish

3

Describe

of

removed

carbon

2

each

what

from

dioxide

between

these

excretory

the

ii

excretion

happens

during

products

body:

are

produced

and

excess

liver

is

to

into

as

plasma

brinogen.

is

the

amino

form

made

such

breakdown

acids

in

ammonia,

the

which

urea.

urea

and

egestion.

deamination.

145

tnemelppuS

carbon

13.2

Kidney

The LEARNING

Describe

kidneys

OUTCOMES

The •

the

structure

of

kidneys

•

Describe

the

in

role

of

They

also

Describe

Your

control

kidneys

the

internal

of

the

of

urinary

urea

system.

and

excess

the

units

fat

the

water

at

the

They

that

top

are

and

ion

of

your

content

of

abdominal

protected

surrounds

chemicals

STUD Y

out

TIP

of

the

a

body

cons ists

subst ance s

water .

becaus e

It

one

pigm ent.

plasm a

of

is

the

a

in

yello w

in

If

by

the

been

then

the

of

are

in

blood

urin e.

At

or

the

it

a

As

to

form

tubule

the

lot

cavity

just

underneath

lower

ribcage

water

day

and

back

you

the

blood

a

ows

water

uid

of

are

ltrate.

are

the

ltering

these

urea,

substances

depends

will

much

water.

have

on

the

water)

exercise,

as

you

of

or

as

units

forced

As

the

(glucose

If

produce

because

you

not

body’s

perhaps

they

can

it

and

water

because

is

so

have

been

very

you

taken

you

hot,

produce

in

sweating,

dilute

of

and

at

each

to

the

intervals,

carries

the

tubule

the

bladder

through

blood

with

a

urine

where

a

shorter

low

is

it

released

is

stored.

tube

a

lot

the

of

kidneys

urine.

and

concentration

of

the

here

into

it

the

leaves

urethra.

waste

The

chemicals

the

renal

away

kidney.

renal

vein

blood

away

kidneys

and

ows

From

called

takes

from

‘cleaned’

the

remove

other

from

the

artery

brings

waste

to

kidneys the

kidneys

in

the

blood

urea

chemicals

blood

KNOW?

kidney

you

as

and

through

through

and

renal

YOU

blood

network

known

useful

the

kidneys

complex

salts,

(short

conserve

and

a

into

blood.

during

take

is

the

reabsorbed

and

cold

the

glucose,

into

a

will

urine

is

less

end

ureter

from

has

are

a

million

born,

decreases

but

with

tubules

the

age.

ureters

to

the

carry

urethra

out

Figure

of

carries

the

13.2.1

ring

urine

The

of

closed

body

urinary

system.

urine

down

bladder

bladder

146

body.

that

vein

number

the

blood.

backbone,

cells

enters

kidney

dehydrated

sweating

concentrated

reabsorb

the

water

kidneys

as

from

Blood

each

plasma

along

you

diffuse

tubules.

reabsorbed

have

body,

when

the

them.

kidneys.

such

blood

volume

water,

a

water ,

are

urea

Inside

kidney

passes

content.

wast e

compo und

and

The

yello w

Urea is

colou rless

disso lves

wast e

disso lved

is

subst ance s

of

salts)

uid

like

the

molecules,

ltrate

Urin e is

to

arteries.

called

small

Each

are

from

kidney

renal

DID

They

salts

structure

transported

in

are

diaphragm.

Waste

that

part

excretion

the

and the

up

the

excretion

the

of

for

system

kidneys

•

make

the responsible

urinary

structure

stores

urine

muscle

until

you

keeps

the

urinate

bladder

If

you

cut

cortex

and

the

–

the

kidneys

open

a

a

kidney

brown

pelvis

–

lengthways,

outer

a

area,

white

the

you

can

medulla

–

see

a

three

reddish

areas:

inner

the

area,

area.

medulla

cortex

medulla pelvis

renal

artery

brings

to

the

renal

takes

A

kidney

with

A

kidney

cut

part

of

the

ureter

attached.

vein

blood

away

the

blood

kidney

from

kidney

ureter

one

kidney

collecting

tubule

cortex

duct

Figure

13.2.2

A

vertical

of

Inside

which

each

you

the

kidney

can

see

section

kidney

are

of

(left

a

kidney

hand

thousands

only

with

a

(right

hand

side).

Detailed

view

of

part

side).

of

tiny

tubes

microscope.

called

The

kidney

function

of

tubules

the

medulla,

kidney

tubules

determine

is

how

the

cortex.

the

body

The

in

to

lter

much

water

waste

the

urine

the

blood

is

remove

excreted.

chemicals

which

and

and

ows

The

excess

from

waste

ltering

water

the

is

are

kidneys

chemicals

carried

out

removed

down

the

is

stored

in

the

with

POINTS

The

urinary

kidneys,

structure

of

the

artery

in

the

functions

stores

ureter

in

urinary

the

system

right

in

the

left

column

2

The

internal

kidney

column.

lters

kidney

urea

carries

bladder

carries

renal

carries

and

other

waste

chemicals

out

of

the

blood

3

The

vertical

A

cortex

B

blood

with

a

high

concentration

of

a

Distinguish

b

What

the

is

urine

blood

section

medulla

down

to

with

low

of

C

between

the

kidneys

c

Distinguish

d

Name

the

a

the

concentration

kidney

renal

and

artery

D

of

not

main

and

excretion

nitrogenous

where

between

is

the

substances

found

inner

of

a

outer

medulla.

the

it

and

renal

vein

E

in

in

the

urine

of

a

take

substances

back

into

the

and

the

product

glucose,

quantity

the

urine

the

urine.

of

and

control

water

excrete

The

ureters

bladder

excreted

by

5

The

carry

from

volume

the

lost

in

urea

in

depends

urethra.

blood

plasma

on

and

urine

to

the

kidneys.

and

concentration

the

health

e.g.

the

ureter

produced?

found

materials

label:

egestion.

waste

ureter

lter

blood,

urea

of

the

how

urine

intake

much

of

water

which

has are

an

bladder

water two

of

urea

4

3

an

kidneys

of

blood, vein

a

bladder

structure

consists

and

useful

Sketch

ureters,

of

urine

out

2

consists

urethra.

cortex renal

system

QUESTIONS

each

one

cortex,

bladder.

and

Match

the

from

the

1

show

ureter .

ureter

1

SUMMARY

to

and

in

KEY

and

open

pelvis

and

been

lost

in

sweat

during

person.

exercise

and

in

hot

weather.

147

tnemelppuS

tnemelppuS

Inside

13.3

Kidney

tnemelppuS

Structure LEARNING

Describe

the

structure

of

containing

Inside

Describe

the

role

of

the

in

ltration,

removal

and

excess

water

and

of

reabsorption

of

glucose

Each

of

chemicals

these

capillaries

the

ows

renal

into

artery

the

kidney

branches

in

many

the

renal

times

to

give

arterioles

called

a

supplies

blood

to

a

closely

packed

glomerulus

ltration,

blood

ows

out

of

the

glomerulus

into

another

the

arteriole.

Blood

then

ows

into

capillaries

around

the

rest

of

the

and

tubule, some

waste

kidney,

of

After urea

the

kidney group

tubule

tubule

tubule arterioles.

•

kidney

a artery.

kidney

a

OUTCOMES

Blood •

of

function

which

joins

to

form

the

renal

vein.

The

kidney

tubule

itself

salts

consists

of

the

The

of

a

Bowman’s

tubule

being

glomerulus

Figure

13.3.1

is

capsule

pushed

found

shows

in

like

inside

that

the

at

one

the

the

end.

This

nger

of

Bowman’s

tubule

forms

a

is

a

formed

rubber

by

the

end

glove.

capsule.

loop

which

goes

deeper

Bowman’s

into

the

medulla

and

back

to

the

cortex

(see

page

147).

The

end

of

capsule branch

renal

of

the

kidney

tubule

the

medulla

drains

into

a

collecting

duct

which

goes

through

vein

and

empties

urine

in

the

pelvis

and

then

ows

into

the

ureter.

DID

YOU

KNOW?

collecting

People

on

taught

to

survival

courses

are

duct

assess

dehydration

blood

capillaries

wrapped

colour

of

yellow

the

by

their

their

looking

urine.

urine,

dehydrated

level

the

the

at

The

of

the

darker

more

person.

round

tubule

Figure

blood

Kidney

tubule.

glomerulus

with

waste

e.g.

13.3.1

Filtration

Look

filter

reabsorption

Filtration

urea

small

and

chemicals,

at

Figure

13.3.2

showing

how

a

kidney

tubule

works.

molecules

through

The

kidneys

renal

are

close

artery

is

high.

glomerulus

is

wider

to

You

the

heart

can

see

so

the

blood

pressure

that

the

blood

vessel

in

the

entering

the

Bowman’s

capsule

blood

entering

pressure

to

situation). useful

the

than

is

this

one

glomerulus

increase

It

the

inside

the

pressure

leaving

than

it.

there

glomerulus

that

causes

is

So

leaving

(it’s

the

there

must

it.

rather

blood

to

be

This

like

be

a

more

causes

bottleneck

ltered.

substances

reabsorbed

into

The

lining

of

the

capillaries

is

like

a

net

with

tiny

holes

in

it.

Blood

blood

cells

and

through

filtrate

(urea,

some

like

large

the

urea,

molecules,

capillary

glucose,

like

lining

salts

blood

and

and

so

water,

proteins,

stay

pass

in

are

the

out

too

blood.

of

the

big

to

Small

pass

molecules,

glomerulus

and

‘cleaned’ salts

and

water) blood

Figure

148

13.3.2

Filtration

and

reabsorption.

into

the

Bowman’s

capsule.

It

is

in

this

space

that

the

ltrate

collects.

microvilli

All

of

the

the

body.

tubule.

If

you

will

•

glucose,

They

This

look

see

some

are

salts

reabsorbed

reabsorption

at

the

of

a

back

large

of

into

active

the

associated

provide

much

involves

structure

adaptations

microvilli

and

cells

with

surface

the

the

water

blood

transport

in

the

active

area

wall

are

needed

from

(see

of

the

page

the

mitochondrion

by

kidney

35).

tubule,

you

transport:

for

Figure

absorption.

13.3.3

An

epithelial

lining

•

numerous

After

the

dissolved

water

enters

and

the

The

process

in

may

the

then

mitochondria

be

reabsorption,

As

bladder.

the

leaving

of

uid

if

ducts

ureter

From

concentration

this

reabsorbed

collecting

to

blood

of

water.

provide

and

here

the

it

waste

is

It

in

the

for

active

left

is

low

in

Urine

through

renal

and

the

water.

down

vein

The

the

a

uid

that

and

is

at

much

duct

stored

STUD Y

TIP

in

Reabs orptio n

intervals.

and

lower

salts

diffus

chemicals.

ion

and

to

diagram

of

the

kidney

tubule

and

by

a

glomerulus

branch

2

Describe

3

The

of

b

the

what

table

body

activ e

is

osmos is.

explai n

Bowman’s

renal

happens

shows

the

capsule

vein

in

e

c

branch

kidney

collecting

of

the

tubules

concentrations

of

to

ve

in

label:

kidn ey

d

by

Wat er

reabso rptio n a

gluc ose

QUESTIONS

Expe ct

Sketch

of

occu rs

reabso rbed

1

the

tubule.

salts

tran sport.

SUMMARY

from

kidney

some

collecting

urethra

has

excess

tubule,

collects

the

cell

the

transport.

urea

through

ows

bladder.

expelled

kidney

is

on

body

urine.

the

is

what

ows

the

is

energy

of

duct

renal

form

to

artery

these

page

s

by

the

referr ing

proces ses

30

and

(see

34).

urine.

substances

in

three

uids.

–3

concentration

substance

blood

in

renal

ltrate

/

g

dm

in urine

artery

kidney

tubule

urea

0.2

0.2

20.0

glucose

0.9

0.9

0.0

amino

0.05

0.05

0.0

KEY

1

acids

POINTS

Blood

is

ltered

through

salts

8.0

8.0

removing

16.5

and protein

82

0

a

the

information

state

the

kidney

in

the

substances

table

that

to:

pass

The

explain

the

blood

into

of

the

the

into

tubule,

kidney

c

state

the

d

how

substances

you

have

named

pass

into

3

substances

kidney

tubule

the

that

and

results

are

reabsorbed

explain

for

why

passes

salts,

glucose

they

into

are

the

blood

reabsorbed,

materials

some

water

the

are

blood

the

salts

such

and

as

most

reabsorbed

capillaries

tubule.

the

tubule,

the

explain

the

urea,

useful

along b

it

water.

glucose,

from

as

glomerulus

0

2

Use

the

from

Urine,

some

out

consisting

salts

of

the

and

of

kidneys,

ureters,

to

bladder

until

be

urea,

water

passes

along

stored

in

the

the

protein. urination.

149

tnemelppuS

Reabsorption

13.4

Kidney

kidney

tnemelppuS

The LEARNING

Describe

the

process

and

person

explain

how

the

concentration

machine

urea

and

can

salt

in

or

survive

on

damaged,

one

it

kidney.

can

be

However,

fatal

unless

a

if

both

kidneys

medical

become

procedure

as

kidney

dialysis

is

available.

A

common

indicator

that

of the

glucose,

dialysis

it known

controls

transplants

of diseased

dialysis

and

OUTCOMES

A •

kidney

dialysis

kidney

is

damaged

is

the

presence

of

protein

in

the

urine.

This

the happens

when

the

glomeruli

are

damaged

so

that

large

molecules

of

blood protein

•

Describe

how

machine

works

a

kidney

pass

out

of

blood

plasma

into

the

ltrate.

dialysis

‘clean’

blood

passes

from

the

arter y machine

•

Describe

and

the

to

a

vein

advantages

disadvantages

of

vein

kidney

dialysis

transplants

compared

with

dialysis

fluid

blood

carr ying

fluid

blood

in

wastes

dialysis

dialysis

fluid

dissolved

useful

salt

Dialysis

This

machine.

cleaner

blood

fresh

back

body

fluid

to

is

what

•

A

tube

•

The

•

Inside

is

vein

has

a

in

the

sugar

machine

and

salts

it

the

diffuses

Renal

like

sugar

dialysis

thin

fluid

membrane

out

partially

blood

and

permeable

separating

from

dialysis

fluid

blood

into

dialysis

fluid

dialysis.

happens

when

connected

to

someone

one

of

the

has

dialysis

patient’s

treatment.

veins.

dialysis

flowing

dialysis

over

blood

ows

along

the

tube

and

into

the

machine.

membrane

•

•

the

machine

dialysis

membrane,

dialysis

uid.

Urea

into

The

no

diffuses

the

out

dialysis

dialysis

overall

the urea

13.4.1

to

from

substances

stay

waste

Figure

in

passes

blood

which

of

the

is

pumped

separates

blood,

the

across

over

the

patient’s

the

surface

blood

dialysis

of

and

a

the

membrane

and

uid.

uid

loss

the

of

already

has

glucose

glucose

and

salts

and

from

salts

the

in

it,

blood

so

by

there

will

diffusion

be

into

uid.

urea

•

Urea

and

other

waste

chemicals

leave

the

machine

in

the

dialysis

uid.

• dissolved

The

patient’s

‘cleaner’

blood

passes

back

into

the

vein.

protein

The blood

flow

dialysis

patient

times from

body

has

to

use

the

dialysis

machine

for

several

hours,

two

or

three

fluid

(dialysate)

a

week.

This

may

involve

attending

a

special

ward

in

hospital

or

it

to

can

be

done

at

home.

Between

visits

to

the

dialysis

ward

of

the

hospital,

waste

patients

eat

a

restricted

diet

without

too

much

protein

and

salt.

If

they

dialysis

membrane

Figure

150

13.4.2

Dialysis.

eat

too

toxic

much

and

protein,

would

mean

they

will

more

produce

frequent

too

much

dialysis

urea

which

treatment.

becomes

tnemelppuS

Dialysis KEY

Dialysis

involves

the

separation

of

two

solutions

by

a

partially

1 membrane.

This

dialysis

membrane

has

tiny

pores

in

it

POINTS

permeable

which

A

dialysis

small water

and

small

solutes

to

diffuse

through,

but

not

larger

molecules

proteins.

In

the

case

of

kidney

dialysis

the

blood

is

pumped

over

molecules

of

a

dialysis

membrane

which

contains

a

uid

(the

pores

water

has

the

normal

potential

as

concentrations

normal

of

salts

and

glucose

and

is

the

molecules

dialysis,

solute

molecules

2

such

as

salts

and

During

glucose

the

membrane.

As

the

dialysis

uid

has

the

as

normal

blood

plasma,

the

same

concentrations

of

into

as

blood

proteins,

reach

equilibrium

and

are

the

the

Excess

dialysis

salts,

membrane

Kidney

uid,

urea

into

so

and

the

they

other

diffuse

toxic

out

of

restored

chemicals

are

the

and

blood

person

not

is

no

net

since

failed

3

may

have

a

kidney

transplant.

This

the

diseased

kidney

with

a

healthy

one

from

a

donor .

the

Kidney

be

Before

type

a

a

of

close

relative

kidney

donor

or

friend

transplant

and

is

recipient

or

someone

carried

(the

out,

person

who

the

has

just

blood

receiving

typing

Blood

reduces

typing

the

is

the

chances

same

that

as

the

for

blood

attack

the

new

kidney

and

recipient’s

reject

it.

To

A

and

kidney)

immune

the

occuring,

drugs

are

given

to

the

patient

transplants

be

there

may

nding

a

there

suppress

means

those

they

the

immune

are

more

infections

for

system.

likely

to

They

catch

remain

certain

on

these

infections

the

problems

suitable

is

always

donor

the

risk

of

rejection.

must

be QUESTIONS

Tissue

system Explain

the

why

for

and

the

presence

of protein

in

the

urine

may

operation indicate

to

avoid

dialysis,

donor

chances

after

uid.

but

of rejection

same

blood

tissue

transfusion.

reduce

of

involves

1 will

the

died.

type

the

dialysis

SUMMARY matched.

in

the

of

tissue

may

in

inconvenience

and

replacing

is

the

dialysate.

kidneys

diffusion

it

present

across

transplants

with

the

to

in

A

of

uid.

solutes,

and in

urea

out

dialysis

concentration normal.

pass

water

glucose, such

dialysis,

salts

diffuse

There potential

kidney

some

blood through

from

through.

same

plasma.

and During

pass

prevents

dialysate)

diffusing which

to

but

the

large surface

allows

such

through as

membrane

allow

life,

to

kidney

damage.

which

2

have

Figure

13.4.3

version

longer.

of

a

shows

kidney

a

simple

dialysis

machine. After

recovering

normal

dialysis

life,

including

treatment

functions

of

a

continuously

They

in

a

also

bone

a

marrow.

match

a

a

operation

normal

not

urea

and

there

to

have

that

it

is

at

is

patient

and

does

home.

some

from

However,

the

diet,

or

just

hormone

people

kidney

the

hospital

remove

wealthy

donate

in

kidney,

make

suitable

Some

from

the

of

them

blood

always

resorted

to

the

to

able

not

as

with

rather

red

nd

danger

paying

to

at

cell

healthy,

all

The

uid

production

a

is

rejection.

poor

people

by

blood

from

a

the

partially

Name

the

which

urea

the

to

permeable

blood

process

by

passes

into

from

the

dialysis

them. Explain

how

concentrations

dialysis

fluid

and

Make

the

salts

returned

normal

while

on

a

table

to

advantages

show

and

fluid

disadvantages

dialysis

fluid partially

waste

of

are

dialysis.

fluid

3

dialysis

glucose

in

to

dialysis

and

kept

uid.

b

dialysis

is

dialysis

membrane.

intervals.

that

patient’s

separate

the

Kidneys

kidney

tissue

a

have

dialysis.

donor

of

lead

replace

than

blood

a

to

need

Transplants

stimulates

difcult

is

and

of

kidney

kidney

permeable

out

transplants. membrane

Figure

13.4.3

Simple

version

of

a

kidney

dialysis

machine.

151

PRACTICE

1

Which

QUESTIONS

substances

healthy

are

found

in

the

urine

of

a

7

person?

The

conversion

proteins,

occurs A

glucose

and

proteins

B

glucose

and

water

C

proteins

D

salts

(Paper

and

and

The

water

C

B

kidneys

D

(Paper

[1]

part

A

of

it

system

from

the

liver

lungs

8

As

part

makes

urine,

stores

it

the

urinary

body.

Which

organ

[1]

of

an

investigation,

collected

from

a

samples

person

of

urine

throughout

a

and

is

hour

period.

The

urine

sample

collected

not early

in

the

than

the

morning

was

more

concentrated

system?

kidney

C

liver

D

ureter

(Paper

1)

samples

Which

is

the

collected

used

to

make

less

urea

B

less

water

C

the

the

amino

was

later

in

the

blood

day.

B

excess

fatty

C

excess

glucose

the

D

excess

hormones

9

The

is

from

day

the

urine

night

concentration

decreased

day

concentration

at

of

the

blood

plasma

night

2)

[1]

diagram

blood

Which

the

this?

acids (Paper

1)

at

for

acids increased

(Paper

during

reabsorbed

tubules

glucose

the

explanation

produced

was

renal

likely

urea? D

excess

most

A

in

[1]

is

during

shows

the

urinary

system

and

its

supply.

[1] (a)

4

plasma

brinogen,

bladder

B

A

to

and

2)

Which

3

acids

organ?

heart

24 removes

which

amino

albumen

salts

1)

urinary

in

of

as

A

were 2

such

the

blood

concentration

of

A

aorta

B

renal

artery

C

renal

vein

C

vena

vessel

with

the

lowest

(i)

(ii)

urea?

Name

State

A

to

parts

the

A

to

D.

functions

[4]

of

structures

D.

[4]

B

5

A

cava

(Paper

1)

[1]

Which

process

ltrate

in

the

A

active

B

cohesion

C

diffusion

D

osmosis

reabsorbs

renal

glucose

from

the

C

tubules?

transport D

(b) (Paper

2)

(i)

The

of

6

Which

is

following

is

a

list

of

components

[1]

not

an

A

breakdown

B

deamination

excretory

of

function

of

the

liver?

the

found

alcohol

blood

blood.

in

the

Identify

urine

proteins,

platelets,

red

of

those

that

healthy

urea,

blood

are

people.

glucose,

cells,

salts,

water C

production

D

protein

of

(ii)

State

three

2)

[1]

(Paper

152

factors

that

affect

the

synthesis

volume

(Paper

[1]

urea

2)

and

concentration

of

urine.

[3]

10

Ammonia

waste

is

produced

product

of

by

their

all

animals

as

11

a

A

man

shows (a)

Ammonia

produced

by

humans

to

urea.

Explain

why

how

this

blood

table

in

shows

the

The

concentration

of

regular

graph

over

the

17

urea

days

in

of

and

for

10

days

his

afterwards.

the

renal

composition

artery,

of

ltrate

in

blood

3.0

Bowman’s

/

g

dm

urine

capsule

artery

aeru

renal

Bowman’s

in

eht

plasma

doolb

in

/

ltrate

blood substance

2.0

g

−3

concentration

2.5

md

noitartnecnoc

urine.

3–

and

received

days.

[3]

ni

capsule

17

is

necessary.

plasma

the

failure

for

changed

treatment

The

kidney

treatment

is

his converted

with

dialysis

metabolism.

1.5

1.0

0.5

urea

0.2

0.2

20.0

glucose

0.9

0.9

0.0

amino

0.05

0.05

0.0

8.0

8.0

0.0

0

5

10

15

time

acids

mineral

ions

82

0.0

0.0

State

Explain

four

of

table

the

are

protein

(ii)

glucose

present

(iii)

the

substances

present

is

is

shown

the

in

ltrate,

the

amino

the

higher

acids

are

not

the

in

of

the

blood

(i)

[2]

urea

urine

and

than

in

the

in

the

renal

concentration

in

how

the

renal

ltrate

is

artery

of

has

urea

(ii)

times

the

give

support

person

the

your

received

evidence

from

answer.

[2]

vein.

formed

a

(d)

the

of

decrease

urea

dialysis

in

until

in

the

day

the

concentration

blood

27.

from

Show

the

your

[2]

Describe

the

the

concentration

urea

in

Explain

Kidney

organ

[2]

in

the

man’s

changes

the

the

that

in

occur

the

in

blood

graph.

changes

[4]

that

you

have

described.

than

of

(e)

[3]

transplants

transplants.

having

with

kidney.

[4]

a

kidney

continuing

Before

living (Paper

to

shown

mineral

[3]

blood

higher

Explain

days

working.

(c)

urine

the

start

[2]

ltrate

(c)

many

treatment;

graph

Calculate

of

but

not

and

in

in

concentration

ions

(iv)

30

why (b)

(i)

how

dialysis

the

(b)

25

16.5 (a)

protein

/

20

a

kidney

donor,

it

are

is

most

Describe

the

transplant

with

is

the

dialysis

advantages

compared

treatment.

transplanted

important

common

from

that

the

[3]

a

donor

4)

and

the

types.

is

If

used

the

a

kidney

then

recipient

why

(Paper

recipient

these

it

is

as

have

from

also

compatible

a

deceased

tissue

closely

procedures

as

are

typed

blood

person

to

possible.

match

Explain

necessary.

[3]

4)

153

14

Coordination

14.1

All LEARNING

Describe

living

impulses

signals

nerve

that

as

pass

of

Describe

your

the

structure

of

that

nervous

tnemelppuS

Distinguish

are

sensitive

to

cells

are

changes

in

their

temperature,

called

that

detect

glands

speed,

environment;

stimuli

detect

the

chemicals

and

in

muscles,

movement,

the

(singular:

stimuli;

your

that

for

food.

bring

availability

stimulus).

example,

Effectors

about

cells

are

the

responses.

secrete

useful

substances

and

muscles

contract

to

bring

about

system

between

involuntary

the

as

wind

detect

buds

such

The

actions

they

take

as

a

result

are

called

responses.

voluntary Animals

and

they

taste

movement.

•

are

daylight,

the Glands

human

in

Receptors

in

cells

food

organs, •

organisms

OUTCOMES

nerve

electrical

control

humans

changes

along

response

Nervous

in

•

and

have

nervous

systems

which

at

their

simplest

are

networks

of

actions specialised

complex,

human

for

nerve

they

brain.

detecting

cells,

as

in

are

organs

T wo

organ

changes

in

jellysh

with

systems

our

and

sea

powerful

are

anemones.

processing

involved

environment

–

and

the

the

At

skills,

their

such

sensory

nervous

most

as

the

system

system

for

cranial

coordinating brain ner ves

central

our

responses

and

initiating

actions.

Here

we

discuss

the

peripheral

nervous

system.

The

nervous

system

is

involved

in

the

coordination

ner vous ner vous

spinal

and

spinal

regulation

sensory

system

Human

The

functions.

Topic

14.4.

The

the

spinal

by

You

will

nd

information

about

the

nerves

brain

and

to

spinal

main

parts

nervous

of

the

system.

Each

by

a

but

also

the

nerve

is

you

need

information

STUD Y

in

up

passing

Voluntary

actions

along

link

the

and

a

nerve

see

nerve

two

by

to

system

organs:

the

skull

different

side

(PNS).

the

and

legs.

cells

the

with

brain

the

impulses

all

or

of

the

Cranial

brain

the

Spinal

Spinal

the

visible

neurones.

parts

system.

of

brain

are

central

column.

between

Nerves

to

of

of

only

abdomen.

and

the

nervous

nervous

either

spaces

lots

microscopes

electricity

on

abdomen

of

parts:

protected

connected

thorax

tube.

form

is

of

vertebral

nerves

the

two

up

peripheral

through

brous

the

is

pairs

thorax,

made

in

the

of

peripheral

made

brain

the

in

the

is

by

Cranial

pairs

protective

up

are

some

arms,

in

The

system

make

nerves

consists

and

system

cord.

nervous

that

cord

system

protected

respectively.

head

human

is

spinal

cord

The

spinal

system

(CNS)

nervous

cord

central

and

14.1.1

nervous

system

central

and

The

nervous

human

nervous

and

nerves

spinal

organs

nerves

nerves

body

in

the

link

leave

the

the

vertebrae.

neurones

to

the

Neurones

which

are

surrounded

naked

eye,

transmit

like

pulses

of

wire.

TIP

Rem embe r:

trans mit

ner ve

cells

impu lses,

‘messa ges’.

not

decision

or

a

she

making.

kicks

voluntary

the

154

body

in

ner ves cord

Figure

of

system

system

brain.

a

are

A

ball.

action.

under

conscious

footballer

T urning

These

carries

over

the

actions

control

out

a

pages

are

and

involve

voluntary

of

under

a

the

book

the

action

is

an

conscious

brain

when

he

example

control

in

of

of

We

make

having

two

to

types

think

unconsciously .

heart

are

time,

but

the

four

we

ileum

other

the

When

does

This

can

person

it,

not

is

to

stimulus

The

effectors

to

is

to

a

you

have

them

very

of

on

breathing

are

and

in

the

in

sharp

the

that

are

our

(see

we

most

we

us

occur

of

of

of

page

can’t

those

that

beating

of

Movement

ureter

studied

without

actions

conscious

occasionally .

occur

a

not

actions

quick,

automatically

involuntary

the

the

food

146)

control

choose

in

are

by

to

make

brains.

object

automatic

such

as

a

response

pin

that

without

the

person

about.

a

simple

pin

the

happen

urine

Voluntary

think

the

are

we

control

of

actions

are

blinking,

down

is

Some

These

that

and

make

sits

example

The

82)

actions

there

need

an

choose

them.

decisions

a

actions

page

about

realising

action.

them.

Swallowing,

such

(see

voluntary

of

about

involuntary

thinking

and

and

and

reex

the

muscles

which

receptors

in

the

legs

is

are

an

involuntary

pain

that

sensors

cause

the

in

action.

the

person

skin.

to

get

Front

up

view

of

the

top

part

of

the

nervous

system.

quickly.

The

sequence

of

events

is:

STUD Y stimulus

The

→

coordinator

about

the

central

body

and

Some

for

from

page

→

the

to

brain

pain

part

the

system

the

reexes

(see

is

stimulus

nervous

neurones

eye

receptor

coordinator

of

effector.

to

allow

to

be

the

body

This

of

connect

brain

as

we

effector

that

will

other

Inside

neurones

see

in

the

inside

parts

the

to

Y ou

the

the

the

of

spinal

section

TIP

response

information

happens

with

stimuli.

with

→

connects

always

connections

aware

receptors

involve

the

→

cont ro l

the

cord,

on

muscles.

on

can

see

157 .

throug h SUMMARY

QUESTIONS

1

complete

and

cranial

the

sentences

peripheral

using

spinal

these

brain

neurones

and

nerves

spinal

of

the

cord

body

make

up

make

the

up

nervous

the

are

connected

to

the

brain

the

connected

to

the

spinal

cord.

The

and

nervous

The

human

of

many

specialised

cells

known

made

up

a

Put

the

following

coordinator

words

into

stimulus

the

system

as

correct

effector

tnemelppuS

3

Dene

a

Explain

each

the

voluntary

of

the

above

difference

system

spinal

receptor

(cranial

involuntary

Neurones

action

and

a

3

Some

(not

Give

two

examples

of

involuntary

c

Give

two

examples

of

voluntary

spinal

or

nerve

nerve

actions

under

control). b

and

nervous

and

transmit

an

(brain

cord)

the

system

nerves).

response

words.

between

system

central

.

sequence:

action.

the

is

2

b

of

nerves

peripheral

2

nervous

system.

and composed

CNS .

POINTS

nervous are

All

coordi nated

system.

nervous

is nerves

are

CNS .

central

1 the

the

words:

KEY

All

arcs

perip hera l

and

respon ses

The

are

reex

160).

ner ve s

Copy

reex es

T hey

into

invo lving

abou t

that

simpl e

page

arra nged

the

more

neur ones

cells

impulses.

are

involuntary

conscious

Other

actions

actions.

are

voluntary

and

involve

actions. conscious

control

by

the

brain.

155

tnemelppuS

tnemelppuS

Involuntary

14.2

Neurones

and

reex

arcs

Neurones LEARNING

OUTCOMES

Neurones

• Describe

and

transmit

between

the

three

types

found

in

a

reex

these

the

specialised

cells.

Their

structure

allows

them

to

functioning

neurones

in

a

information

contains

the

as

nerve

nucleus

impulses

and

almost

over

all

of

long

the

distances.

cytoplasm,

The

but

cell

there

arc are

• Describe

highly

of body

neurone

are

distinguish

thin

long

of

extensions

way

through

of

cytoplasm

the

that

may

be

quite

short

or

extend

a

body.

reex Sensory

neurones

transmit

impulses

from

sense

organs

to

the

brain

action and

spinal

cord.

cytoplasm

nucleus

cell

direction

ner ve

a

ending

sense

of

ner ve

body

impulse

in

organ axon

myelin

ner ve

ending

in

central

the

sheath ner vous

system

(insulation)

Figure

14.2.1

Motor

cord

A

sensory

neurones

to

effector

neurone.

transmit

organs

–

impulses

muscles

away

and

from

the

brain

and

spinal

glands.

dendrites

This

neurone

has

a

long

axon.

direction

cell

body

central

in

of

nerve

impulse

myelin

the

nervous

axon

sheath

(insulation)

system

neurone

effector

(as

Figure

The

by

diagrams

insulation.

that

Relay

neurones

bodies

with

in

their

the

brain.

Notice

the

cell

nuclei.

used

The

and

a

YOU

axons

KNOW?

of

motor

metre

neurones

whales!

neurones

long.

in

Think

giraffes

neurones

When

may

There

be

about

or

the

over

the

great

of

and

travel

reaches

a

synapse

impulse

rst

in

one

on

by

is

brain

one

side

through

acting

the

at

It

meet,

or

a

an

a

muscle

gland

the

layer

at

100

sensory

in

do

not

across

Since

synapse,

surrounded

by

fat.

separate

This

neurones,

metres

per

which

to

are

second.

neurone.

neurones

cells

insulation

These

motor

cord.

a

the

the

it

touch

synapse

ensures

is

and

an

released

impulses

drugs

other .

impulse

triggers

transmitter

that

Many

159).

each

When

substance

chemical

system.

page

actually

synapse.

transmitter

(see

rich

myelinated

called

nervous

neurones

formed

(connector)

from

diffuses

synapses

a

Some

they

motor

myelin,

impulses

them

the

form

spinal

neurone.

of

and

as

relay

and

chemical

second

to

quickly .

between

a

known

impulses

neurone.

the

direction

effects

gap

sensory

is

transmit

neurones

tiny

the

on

the

a

from

very

neurone

pass

two

the

neurones

reexes,

inside

any

show

the

here)

in

either

neurone.

insulation

is

produced

156

above

This

fast

type

short

motor

around

our

neurones

sensory

A

impulses

in

third

are

DID

grow

makes

A

14.2.2

ends

–

is

an

only

travel

produce

in

their

Reex

ner ve

pain

arcs

impulse

from

white

sensor

matter

sensor y

(axons

neurone

extend

of

myelinated

the

length

of

neurones

the

grey

that

spinal

matter

(neurone

cord)

cell

bodies)

spinal sensor y

cell

cord

neurone

body

pain

sensor

motor

neurone

synapse

inside

forms

muscle

motor

Figure

If

you

and

example

about

of

the

a

hot

object,

you

automatically

a

simple

pain

but

reex.

not

remove

without

Y our

until

brain

you

your

hand

thinking.

This

receives

have

already

very

is

stimulated

an

The

impulses

hand.

If

you

relied

on

the

brain

to

make

sensory

would

travel

be

to

burnt

the

in

brain

the

and

time

it

took

for

at

the

diagram

impulse

along

above

the

the

the

grey

across

pathway

is

called

stimulus

receptor

is

in

the

the

and

trace

the

pathway

a

reex

sensor

SUMMARY

QUESTIONS

1

complete

the

synapse

a

the

the

hot

ame.

skin.

sentences

grey

reex

cord

The

When

using

arc

it

the

to

a

spinal

relay

cord

the

impulse

(connector)

relay

to

neurone

a

motor

passes

the

impulse

across

a

neurone

in

neurone

impulses

neurones.

the

arm.

transmits

The

the

muscle

is

impulse

the

to

a

effector

This

Inside

to

action

remove

is

the

the

hand

from

the

hot

and

it

object.

response

is

these

reexes

so

are

you

do

protective;

not

harm

words:

relay

effectors

nerve

by

of

synapse

arc

is

in

sensory

In

The

motor

quickly,

and

a

of

Many

Copy

impulse.

along

neurones.

example

heat

matter

a

synapse

contracts

The

an

cord

impulses

muscle

This

generates

spinal

back.

The

the

the

decision

second

Look

sensor

to

neurone

neurone.

to

heat

travels

moved

a

passes

you

the

impulse

Inside

your

neurone

14.2.3

touch

quickly

relay

neurone

muscle

they

happen

very

yourself.

A

B

C

motor

transmitter

are

transmitted

the

to

matter

the

of

spinal

the D

spinal

The

go

cord

the

impulses

to

leave

.

where

the

impulse

impulses

the

There

is

are

passed

spinal

a

gap

cord

the

next

to

neurones.

along

between

chemical

to

on

neurones

two

substances

neurones

are

to

called

released

to

a

pass

KEY

1

2

Look

a

at

the

Name

diagram

the

parts

of

the

motor

labelled

A

neurone

to

to

the

right:

A

Give

the

functions

of

parts

B,

arc

and

relay

a

Dene

each

of

the

sensory

and

ii

chemical

iii

myelin

Explain

Make

a

of

neurone,

and

an

a

motor

effector .

Reex

actions

are

rapid,

synapse

transmitter

iv

substance

relay

a

the

function

drawing

of

a

of

relay

i

–

and

neurone

iv

in

the

(connector)

nervous

and

protective.

often

They

coordinate

responses

4

of

following:

automatic

b

up

types

D

2

i

a

made

three

neurone

neurone

3

is

and

neurone:

D

C

reex

receptor ,

a b

POINTS

neurone.

by

interpret

stimuli

with

effectors.

system.

neurone.

157

14.3

Synapses

tnemelppuS

LEARNING

Dene

the

term

The

neurotransmitter

Describe

•

Describe

nerve

how

an

how

impulse

many

transmission

passes

drugs,

at

across

e.g.

a

heroin,

synapse

and

a

affect

but

synapses

is

a

junction

between

two

the

The

binding

in

two

neurones

meet,

they

do

a

small

The

gap

that

gap

is

carries

the

presynaptic

the

between

called

impulse

the

them,

not

about

synaptic

impulse

to

neurone.

away

across

the

touch.

from

the

The

the

20 nm

gap.

The

synapse

neurone

synapse

is

only

the

These

to

the

receptor

on

sites

the

have

neurotransmitter,

temporary.

neurotransmitter

postsynaptic

triggers

neurone.

Once

is

the

neurotransmitter

is

broken

enzyme

in

the

synaptic

an

this

has

down

by

gap.

wide.

5

called

The

mitochondria

provide

energy

to

reform

the

neurotransmitter.

the

carries

called

the

axon

postsynaptic

synaptic

sites

There

neurone

that

is

of

the

shape

receptor

neurones.

an is

specic

membrane.

binding

happened Where

to

complementary

impulse synapse

attaches

postsynaptic

4

A

diffuses

synapse gap

•

drugs

OUTCOMES

3

•

and

of

presynaptic

neurone neurone

How

does

from

one

a

nerve

impulse

neurone

to

the

transfer

next?

across

the

Chemicals

synapse

known

impulse

as end

neurotransmitters

are

released

by

the

of

axon

presynaptic myelin

neurone

an

and

impulse

diffuse

in

the

across

the

postsynaptic

synaptic

gap

to

sheath

trigger

neurone.

mitochondrion

synaptic

Structure

of

the

synapse vesicle

The

axons

of

neurones

end

in

swellings

synaptic

called

containing

bulb

neuro-

synaptic

bulbs.

The

surface

of

the

synaptic

bulb

is transmitter

called

the

the

presynaptic

synaptic

gap

from

membrane.

the

It

is

postsynaptic

separated

by

substance

membrane synaptic

of

the

cell

body

or

axon

of

the

next

gap presynaptic

neurone.

membrane

If

you

the

look

at

synaptic

Figure

bulb

neurotransmitter

14.3.1

has

you

many

will

vesicles

molecules.

It

also

see

that

dendrite

containing

contains protein

many

mitochondria

which

suggests

that

energy

is

postsynaptic

receptor

membrane

required

in

synaptic

transmission.

The

postsynaptic

postsynaptic

neurone

membrane

on

its

has

surface

a

which

neurotransmitter

Synaptic

1

When

bulb

it

an

number

act

of

as

large

protein

receptor

sites

molecules

for

Figure

the

14.3.1

The

structure

of

a

synapse.

substance.

transmission

impulse

causes

arrives

vesicles

at

the

synaptic

containing

the neuro-

neurotransmitter

to

move

towards

neuro-

the

transmitter

transmitter

presynaptic

binds

membrane. released

2

The

vesicles

fuse

with

the

presynaptic

protein synaptic

membrane,

into

the

releasing

synaptic

the

neurotransmitter

gap

gap.

Figure

158

to

receptor

14.3.2

Action

of

a

neurotransmitter

at

a

synapse.

a

reex

direction

happens

arc

i.e.

synapses

from

because

presynaptic

bulb

ensure

presynaptic

vesicles

and

the

of

that

nerve

neurone

impulses

to

are

only

postsynaptic

neurotransmitter

receptors

can

only

are

only

found

on

travel

neurone.

present

the

in

in

tnemelppuS

In

one

This

the

postsynaptic

membrane.

The

effect

Most

drugs

synapses.

by

of

that

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inuencing

with

drugs

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drugs

the

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of

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by

are

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of

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of

system.

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have

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so

of

or

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interacting

that

brain

them.

increases

stimulate

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at

impulses

by

inhibiting

drug

Amphetamines

brain,

their

transmission

neurotransmitters

stimulating

type

in

transmission

the

the

release

activity

In

and

is

making

a

person

more

alert.

They

also

have

the

effect

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this

image

coloured

The

Heroin

between

and

the

beta-blockers

effects

of

are

examples

neurotransmitters.

of

inhibitory

Heroin

acts

on

drugs

and

to

reduce

sensation

of

the

pain.

neurotransmitters

heart

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release

of

neurotransmitters

Beta-blockers

and

are

taken

by

are

drugs

people

to

that

and

block

reduce

can

this

reduces

receptors

blood

at

presynaptic

neurone.

the

neurone

What

is

meant

by

b

the

each

of

these

terms?

neurotransmitter

function

with

a

synaptic

c

protein

c

receptor

of

an

of

each

impulse

of

the

vesicles

receptor

b

across

of

vesicles

left

of

clustered

the

presynaptic

following

is

meant

excitatory

in

reach

inhibitory

in

an

is

effect

for

of

research

d

b

the

number

far

of

greater:

(0.15

×

10

).

mitochondria

the

following

POINTS

terms?

A

synapse

of

each

different

type

of

is

a

two

junction

neurones.

An

impulse

i

heroin

nerve

and

ii

amphetamines

impulses

across

the

into

the

effects

that

the

have

on

of

c

a

the

neurotransmitter,

the diffuses

across

the

synapse?

following

receptor

drugs

gap

to

bind

molecules

postsynaptic

transmission:

ecstasy

triggers

drug.

trigger caffeine

each

drug

do

synaptic

the

As

15

synaptic

on

human

synapses

neurones,

quadrillion

which

some

many

of

drug

example

transmission

adult

billion.

therefore

release

What

number

the

2 Give

the

86

has

between

ii

the

neurotransmitter

molecules

by

for

synapses:

1 i

a

(below).

between

molecules

KEY

What

have

space

KNOW?

other

0.15

transmission

Do

lots

bottom

YOU

brain

QUESTIONS

synapse

Explain

c

neurone

for

these

b

tiny

pressure

estimate

a

the

(×14 000).

neurone

a

is

see

the

neurones

4

neurones

rate.

SUMMARY

3

a

postsynaptic

gap

Estimates

2

the

shows

that

DID

1

of

image

presynaptic together

neurones

a

synaptic

them.

reduce

and

The

appetite. (above)

the

cytoplasm

suppressing synapse

the

the

orange.

an

with

on

the

the

membrane

and

impulse.

cocaine

3

In

a

reex

ensure

only

4

one

Many

arc,

that

travel

in

direction.

drugs,

their

effects

with

the

at

synapses

impulses

e.g.

by

heroin,

have

interacting

receptor

molecules

synapses.

159

14.4

Sense

We LEARNING

are

Dene

of

sense

receptor

particular

•

organs

cells

as

groups

responding

to

the

function

of

Explain

structure

the

impulses

the

of

and

Some

eye

The

pupil

reex

to

and

also

light

intensity

light

central

are

the

have

as

receptor

stimulated

the

receptors

eye

and

have

other

and

and

use

that

our

sense

organs

These

impulses

concentrated

to

specialised

cells

travel

to

to

detect

generate

along

nerve

sensory

system.

receptors

tissues

are

chemicals.

these

nervous

found

ear

cells

in

groups

arranged

modify

the

in

in

certain

special

organs.

tissues.

information

from

the

in before

it

reaches

the

receptors.

In

the

eye

there

are

and structures

pupil

surroundings

have

such

when

environment terms

our

We

stimuli,

neurones

stimuli

Describe

stimuli.

certain

They •

of

OUTCOMES detect

•

aware

organs

for

focusing

light

rays;

in

the

ear

there

are

structures

for

diameter amplifying

Sense

sound.

organs

are

groups

of

receptor

cells

that

respond

to

specic

stimuli.

•

The

eyes

respond

•

The

nose

to

responds

light

to

rays

and

chemicals

in

give

the

us

air

our

sense

and

gives

food

and

of

us

sight.

our

sense

of

smell.

•

The

us

•

tongue

our

The

ears

use

a

variety

of

their

senses

of

The

to

chemicals

in

our

drink

and

gives

taste.

respond

hearing.

Musicians

responds

sense

ear

to

sound

also

vibrations

detects

and

movement

give

and

us

our

sense

position

of

of

the

body,

when

so

provides

information

about

our

balance.

performing.

•

The

It

socket

tear

also

responds

detects

to

pain

pressure

and

and

gives

temperature

us

(see

our

sense

page

of

touch.

168).

gland

Eye tear

skin

structure

ducts

Your

cornea

pupil

eye

three

sits

pairs

inside

of

eye

a

socket

muscles

in

as

the

you

skull

can

and

see

is

in

moved

Figure

about

14.4.1.

by

The

eye

iris

is

a

complex

brous

to

eye

brain

a

function

14.4.1

The

eye

in

its

socket.

At

the

the

front

the

chan ges

and

our

fo r

in

blood

the

also

inside

de tect ing

thin gs

tempe ratu re

tens

ion

mus cles.

info rm ation

hom eostas is.

160

syst em

recept ors

body

like

is

composed

tissue,

with

the

sensory

of

different

tissue

detection

of

and

light.

tissues,

blood.

Figure

such

Each

14.4.2

as

tissue

has

shows

in

of

the

eye.

of

the

eye

Light

the

eye

is

and

the

then

their

transparent

passes

pigmented

functions.

cornea,

through

iris,

the

through

through

pupil,

the

lens

which

which

to

the

is

a

light

hole

retina

at

in

the

TIP

sens ory

has

the

centre

back

T he

help

structures

enters

STUD Y

to

which

muscle

muscle

the

Figure

organ

tissue,

in

T his

helps

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of

the

tears

eye.

very

provides

front

wash

lysozyme,

In

humans,

opposed

views

the

an

the

to

your

shutting

The

of

retina

the

protection.

that

called

with

the

at

your

eyes

the

same

is

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is

set

moist

side

a

light-sensitive

transparent

the

time

tear

you

layer,

glands

blink.

receptor

which

that

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cells.

make

also

the

contain

bacteria.

by

eyes

side

at

What

are

from

to

by

every

rabbit.

but

alternately

with

delicate,

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the

eld

tissue

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kept

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a

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in

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head

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apart,

angle.

two

as

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accurately.

tree-dwelling

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it

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off.

lets

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a

When

you

simple

judge

and

you

light

into

such

as

which

vision

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monkeys,

distances

gives

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and

us

the

ability

essential

to

judge

adaptation

predators,

accurately

to

such

as

for

lions

and

survive.

reex

mirror

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less

light

must

vision

Stereoscopic

animals,

pupil

Look

stereoscopic

into

turn

the

the

your

the

eyes

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shine

turn

eyes

light

so

bright

on

and

off,

you

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a

light

cells

see

in

near

pupils

the

retina

eyes

decrease

retina

increase

clearly.

the

your

pupils

protects

your

can

light

your

This

is

send

and

in

from

in

size

impulses

turn

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damage.

to

another

then

size.

let

more

example

along

of

a

sensory When

neurones

pass

in

the

impulses

optic

to

the

nerve.

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muscles

in

connect

the

iris

to

motor

stimulate

ciliary

neurones

them

to

that

contract.

pupil

a

bright

light

constricts

to

is

shone

protect

into

the

the

retina

eye

the

from

damage.

muscle

changes

lens

with

thickness

when

of

the

focusing

retina

inner

rod

light-sensitive

cells

that

work

layer

in

which

dim

light,

contains

and

cornea cone refracts

cells

that

detect

colour

and

details

light

yellow

most

spot

or

sensitive

fovea

part

of

the

retina

pupil

blind

spot

lens point can

change

its

shape

to focus

light

onto

the

where

the

optic

nerve

attaches

to the

eye;

no

light-sensitive

cells

here

retina

iris

controls

light

the

intensity

entering

of

through optic

the

nerve

pupil carries suspensory

away hold

Figure

14.4.2

A

the

horizontal

lens

in

section

of

the

Sense

organs

are

groups

of

QUESTIONS

specic the

impulses

brain

POINTS

receptor

Give

the

eye.

1

1

to

place

KEY

SUMMARY

nerve

ligaments

name

in

each

case

for

the

part

of

the

eye

is

sensitive

b

controls

c

holds

d

refracts

to

that

stimuli:

respond

light,

to

sound,

that:

touch, a

cells

temperature

and

light chemicals.

the

intensity

of

light

entering

the

eye

2 the

lens

in

place

within

the

The

cornea,

retina,

the

light

after

it

has

entered

the

transmits

nerve

impulses

f

controls

the

shape

g

secretes

the

enzyme

h

allows

light

to

of

pass

the

to

the

brain

lysozyme

3

In

Describe

and

explain

the

changes

in

iris

pupil

the

diameter

of

the

the

surrounding

light

intensity

of

and

the

blind

eye

that

described

in

light,

the

diameter

decreases.

intensity

When

decreases

of

the

the

pupils diameter

when

lens,

14.4.2.

bright

the

light

2

nerve

parts

functions

Figure

the

optic

are

have

lens

through

pupil,

eye spot

e

iris,

eye

of

the

pupil

widens

changes. to

let

in

more

controlled

by

light.

a

This

simple

is

reex.

161

14.5

The

eye

tnemelppuS

Control LEARNING

The •

Explain

the

pupil

reex

of

light

size

intensity

the

antagonistic

action

Explain

on

in

the

how

near

the

and

State

are

that

light

the

The

pupil

is

controlled

circular

muscles

by

a

are

pair

of

antagonistic

arranged

around

muscles

the

pupil.

The

muscles

muscles

run

are

outwards

described

from

as

the

pupil

antagonistic

like

the

because

spokes

they

in

have

a

wheel.

opposite

iris

far

eye

focuses

while

rods

the

the

circular

radial

muscles

muscles

contract

contract

to

to

reduce

increase

the

the

size

size

of

of

the

the

pupils

pupils.

objects The

•

reex

of

effects:

•

pupil

and

These muscles

of

iris.

radial the

the

in in

terms

of

OUTCOMES

and

sensitive

cones

cells

in

the

diagrams

intensity

is

potential

show

low

to

and

what

in

damage

happens

bright

the

light

in

dim

when

light

it

is

when

much

the

light

higher

and

has

the

retina.

retina

In

dim

light

In

bright

light circular

•

•

Describe

the

distribution

rods

and

they

function

State

the

cones

and

position

the

of

of

circular muscles relax,

circular

radial muscles contract,

radial

pupil dilates

pupil

muscles

muscles

contract,

muscles

relax,

way constricts

the

fovea

radial

muscles

STUD Y

Here

is

a

way

remem ber

Cs:

Figure

TIP

cons tr

the

three

cont ract,

Figure

14.5.2

through

on

(upside

top

control

the

diameter

of

the

pupil.

how

light

the

transparent

is

focused

retina.

Notice

because

bottom

of

Information

cornea,

in

the

of

the

object

about

this

that

way

passes

the

eye.

the

image

the

enter

light

the

inverted

through

Light

eye

on

rays

and

image

the

the

enters

lens

retina

reected

cross

goes

to

the

be

inverted

from

over

the

is

to

the

behind

brain

the

where

TIP

it

Unit

T he

shows

the

down)

and

lens.

STUD Y

and

muscles

aint .

focused

cells ,

iris

Focusing

eye

In

The

to

this:

circul ar ,

14.5.1

2

we

dealt

tissu es,

is

few

interpreted

months

eye

is

right

way

up.

We

learn

how

to

do

this

in

the

rst

with

syst ems.

a

the

life.

orga ns light

orga n

of

very

from

rays

reflected

object

good retina

exam ple

wher e

you

tissu es

tissu e)

rod

eye

an

can

(e.g.

and

and

is

of

syst em :

cells

of

the

iden tify

mus cle

cone

part

orga n

(e.g.

cells ).

an

T he

Figure

14.5.2

This

shows

light

rays

refracted

by

the

cornea

and

the

lens.

orga n

sens ory

Rods

and

cones

syst em .

Rods

Rod

and

cells

when

night

162

it

cones

are

is

dark,

vision.

are

the

sensitive

for

Cone

light-sensitive

to

light

example

cells

are

of

at

low

night.

only

receptor

intensity

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sensitive

are

to

cells

and

in

the

send

responsible

light

of

retina.

impulses

high

for

only

our

intensity.

are

three

wavelengths

cells

to

give

contains

brain

so

This

The

light.

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our

cones

image.

area

gives

horizontal

of

as

in

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eye

enters

the

image

clearly.

the

eye

cornea

it

in

blind

is

the

when

must

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and

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our

retina

has

spot.

the

its

which

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of

own

is

in

from

of

cone

the

neurone

gives

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us

and

not

the

fovea

different

centre

eld

contains

centre

to

impulses

in

visual

vision

the

the

fovea

cone

of

the

is

sensitive

as

retina

your

a

retina

to

the

very

few

cones.

detailed.

on

right

the

same

eye

is

to

the

spot.

Accommodation

occur

The

peripheral

fovea

the

blind

of

each

interprets

vision.

middle

rest

our

cell,

brain

rods.

the

The

the

level

your

no

in

us

of

cone

colour

and

area

position

right

of

of

us

this

detailed

types

tnemelppuS

There

term

used

focusing

be

on

refracted

60%

of

the

rest

is

which

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be

the

done

to

far

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and

(bent)

so

refraction

by

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the

near

that

of

lens.

changes

objects.

we

the

The

can

light

lens

As

see

rays

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that

light

the

is

the

done

surrounded

by

and

ring

the

of

tissue

lens

controlled

is

If

you

•

the

•

the

(or

are

looking

ciliary

are

retina.

If

you

•

the

so

at

a

distant

the

lens

is

as

distant

looking

ciliary

and

can

recoil.

The

shape

of

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at

muscles

suspensory

14.5.3

tissue

spherical

when

eye

pulls

pulled

they

the

into

pass

is

a

object:

near

in

suspensory

an

elliptical

through

object

contract

ligaments

around

(fatter).

looking

at

the

ligaments

(thin)

A

distant

lens

and

focused

on

the

focus.

to

counteract

the

pressure

inside

the

ring

the

are

Light

the

lens

not

pulled

recoils

rays

distant

are

so

and

the

become

refracted

object.

The

lens

slack

becomes

so

more

near

than

object

the

in

ciliary

lens

muscle

becomes

When

the

14.5.4

A

near

KEY

POINTS

The

pupil

reex

the

eye

views

a

distant

object,

explain

what

happens

ciliary

muscles

ii

the

suspensory

circular

the

Explain

shape

what

of

the

views

a

lens

happens

near

to

to

the

each

of

these

a

State

what

muscles

control

structures

when

entering

the

the

muscles

size

of

to

each

of

the

following

in

bright

The

the

light:

of

the

iris

ii

radial

muscles

of

the

State

what

the

ciliary

muscles,

lens

ligaments

are

all

involved

to

c

Explain

d

Suggest

why

each

of

the

above

in

dim

In

the

pupil

they

unconscious.

reex

is

retina,

doctors

shine

a

Describe

the

distribution

of

light

in

people’s

eyes

when

of

low

and

cones

in

the

retina

their

cells

are

the

respond

to

detect

high

Cone

light

colour .

to

light

cells

intensity

The

fovea

is

and

made explain

and

intensity.

respond

rods

rod

around

controlled.

and 3

in

light.

periphery

are

in

(focusing)

eye.

distributed the

and

pupil

happens

how

of

through

iris

3 b

eye

the

the iii

the

object.

happens

circular

in

intensity

the

accommodation i

the

muscles

pupil.

suspensory

2

radial

ligaments

2 eye

of

to:

light

b

involves

QUESTIONS

the

iii

object.

were

focus.

iris i

contracts

rounder

more

they

is

of

eye,

and a

object.

Light

coordination

1

shape

tight

shape.

1 SUMMARY

thin

object:

Figure

elastic

a

muscles

and

•

relaxes

into

the

the

ciliary

muscle

pulled

relax,

inside

the

refracted

The

are

the

muscles

pressure

taut)

rays

by

stretched

is

by Figure

elastic

ciliary

lens

entirely

of

cones.

functions.

163

14.6

Hormones

The LEARNING

A

•

endocrine

Identify

on

adrenal

glands,

a

diagram

hormone

•

testes

State

by

the

each

and

the

the

these

Describe

the

adrenaline

released

four

the

and

than

a

glands

into

certain

it.

duct.

organs

These

produced

by

an

endocrine

in

that

the

are

blood.

Endocrine

secreted

into

the

means

that

the

bloodstream

gland

rather

are

of

Hormones

or

tissues

referred

its

target

to

travel

throughout

recognise

as

target

each

the

hormone

organs.

Each

body

and

but

only

respond

hormone

to

alters

the

organs.

of

heart,

lungs coordinate

the

activities

of

the

body

but

in

a

different

way

pupils to

tnemelppuS

•

transported

hormones

Hormones

and

substance

ovaries

effects

on

chemical

produces

activity •

a

pancreas,

hormone

of

is

the gland

the

system

OUTCOMES

Explain

that

increases

and

oxygen

that

adrenaline

supply

to

of

the

nervous

they

system.

secrete

and

The

the

main

actions

endocrine

are

show

glands,

in

the

Figure

hormones

14.6.1.

glucose

muscles

during

activity Pituitary

It

•

Compare

the

endocrine

makes

a

gland

at

the

hormones

base

and

of

the

controls

brain.

things

and like

nervous

is

many

growth,

and

sperm

and

egg

production.

systems

stomach lungs

STUD Y

TIP

heart

T he

term

Pancreas

‘secr e tion’

blood

means

a

that

cells

subs tanc e

mak e

Adrenal

glands

adrenaline

that

makes

glucagon.

make

glucose

Glucagon

insulin

Insulin

lowers

and

the

concentration.

increases

it.

when you

is are frightened or angry .

usef ul

relea

se

fo r

it

the

into

body

and

Adrenaline helps your

body cope with an

the

blood emergency

or

some

body ,

o ther

e.g.

conf use

the

part

gut.

secre tion

‘excr e tion’ ,

of

whic h

the

Do

no t

with

Testes

This

is

make

wast e

of

(see

me ta bo

page

development

in

males.

of

Ovaries

make

females.

These

oestrogen

control

the

and

progesterone

menstrual

cycle

in

and

the secondar y

remov al

testosterone

stimulates

features

during

puberty.

stimulate

lic

during

144).

Figure

14.6.1

The

organs

of

the

development

of

secondar y

sexual

features

puberty.

endocrine

system.

Adrenaline

Adrenaline

are

will

The

are

Adrenaline

is

excitement,

164

released

fear

or

during

stress.

times

of

in

a

is

secreted

situation

immediately

responses

that

by

puts

become

necessary

coordinated

by

the

you

much

to

increasing

the

breathing

•

increasing

the

heart

•

widening

pupils

risk

more

in

which

glands.

of

If

you

injury,

aware

these

gets

or

and

‘ght

you

realise

even

ready

or

that

for

rate

more

light

enters

the

take

ight’

ready

that

death,

to

rate

(pulse)

so

at

survive

adrenaline,

•

the

adrenal

eyes.

you

you

action.

situations

action

by:

levels

of

stimulates

within

activity,

the

an

body.

To

adrenaline

increase

provide

in

the

rate

enough

stimulates

cells

of

chemical

energy

in

the

for

liver

STUD Y

increased

to

convert

T he glycogen

to

glucose,

which

diffuses

into

the

blood.

This

increases

table

of

glucose

in

the

blood,

so

that

there

is

more

the

for

muscles

sudden

as

a

source

of

energy

for

muscle

contractions

needed

action.

coordinates

the

increased

uptake

of

oxygen

and

the

distribution

of

blood

so

that

oxygen

and

glucose

Setti ng

this

way

•

The

more

that

air

air

oxygen

need

them

passages

into

that

the

can

for

reach

be

in

bronchi

the

and

lungs.

bronchioles)

This

increases

widen

the

to

The

breathing

carbon

the

Arterioles

more

in

rate

increases

dioxide

glucose

the

and

Arterioles

to

divert

in

the

blood

to

at

a

to

increase

faster

the

uptake

of

oxygen

and Hormones

are

brain

and

oxygen

muscles

for

gut

the

and

dilate

respiration

other

too

much

in

(become

these

wider)

to

deliver

by

organs.

organs

constrict

(become

is

in

as

a

result

of

the

of

anxiety,

constant

high

blood

pressure

prolonged

and

heart

They

Beta-blockers

also

act

adrenaline

blood

on

and

pressure

endocrine

coordinate

the

drugs

surface

reduce

and

Comparing

The

cell

so

are

effects.

the

and

activities

the

of

at

the

synapses

to

block

disease

rate

and

nervous

(see

(see

the

Beta-blockers

heart

endocrine

system

act

membranes

its

decrease

the

that

Topic

nervous

system

act

to

Topic

to

nervous

structures

nerves

forms

for

3

reduce

14.3).

pulse

control

of

and

the

ight’

oxygen

stimulates

pupils

in

situations.

increases

and

supply

glucose

during

SUMMARY

and

system

endocrine

system

cells

in

impulses

hormones

neurones

in

the

What

glands

to

activity.

QUESTIONS

meant

by

the

terms?

a

endocrine

b

hormone

c

target

system

(chemicals)

organ

blood State

each

fast

is

following

of

information

rates

breathing

systems

2

speed

or

muscles

of

along

organs.

increases

Adrenaline

of

information

pathways

the

body.

secretory

electrical

alter

may

1

feature

and

to

14.3).

receptors

help

secreted

stress

‘ght result.

blood

target

Adrenaline

widening and/or

are

glands

narrower)

2

released,

that

endocrine

travel

muscles.

adrenaline

chemical

rate.

and If

system s.

POINTS

activity •

two

of

substances

•

you

absorbed.

1 excrete

tables

allow

volume

KEY

•

system s

out

compa rison s

the

respiration.

(trachea,

alveoli

the

ner vo us

ensu res

direc t

betw een muscles

the

changes

mak e in

which

horm onal

work .

in Adrenaline

in

available

and to

compa res

the

ways concentration

TIP

tnemelppuS

reactions

also

the

of

gland

the

which

secretes

following:

slow a

testosterone

c

oestrogen

b

insulin

transfer

short-lived, longevity

e.g.

of

usually muscle

contracts

slow

and

longer

3

lasting a

short

Suggest

four

in

which

the

only

the

area

at

whole of

a

tissue

or

organ 4

neurone

Explain

how

prepares e.g. muscle

of

contraction

response

conversion

by

of

glucose

adrenaline

the

body

for

action.

to

or glycogen,

secretion

increases.

the

area end

secretion

time

adrenaline

target

situations

for

action

protein

synthesis,

5

State

four

ways

in

which

the

glands rate

of

respiration

endocrine

the

system

nervous

differs

from

system.

165

tnemelppuS

tnemelppuS

Adrenaline

14.7

Controlling

in

the

Controlling LEARNING

the

term

tnemelppuS

Explain

the

metabolism,

concept

cells,

some

Describe

glucose

down,

the

control

of

work

see

concentration

how

STUD Y

The

maint aini ng

cond ition s

is

do

In

the

chan ge

to

It

say

hom eostas is

the

and

body.

some

are

Enzymes

are

and

the

such

kept

pH

control

these

temperature,

suitable

inuence

conditions

working.

as

reactions

in

and

in

the

constant.

enzyme

the

body,

so

is

and

See

Unit

5

to

activity.

body

Homeostasis

pH

can

the

that

slow

down

maintenance

enzymes

or

of

control

overall

is

control

an

of

our

example

body

of

processes.

The

control

of

homeostasis.

humans,

the

normal

temperature

of

the

blood

is

37 °C.

When

body , reaching

the

brain

is

warmer

than

this

temperature

it

sends

sligh tly

is

more

our

along

sweat

nerves

glands

to

the

produce

skin

sweat

to

promote

and

this

heat

helps

us

loss.

to

For

cool

example,

down,

that body

temperature

to

normal.

maint ains When

we

brain

or

keep s

feel

cold

our

blood

temperature

falls

below

37 °C.

Then

the

will

se t

stimulate

and

by

production

increasing

the

of

rate

more

of

heat

in

respiration

the

in

muscles

the

liver.

It

by

also

limits . stimulates

sweat

by

The

This

gets

control

is

falls

acts

the

to

body

to

conserve

heat

by

decreasing

the

production

of

glands.

feedback

of

body

same

temperature

temperature

thermostat

the

sweat

Negative

hot

the

them shivering

too

inside

proteins,

cons tant

cond ition s

oven

occur

as

efciently.

has

returning

with in

glycogen.

conditions

temperature

impulses

near ly

such

cons tant

in

time.

in

from

internal

brain

body

blood

the

reactions

up,

say

hom eostas is

precis e

built

conditions,

water,

change

metabolism

we

of

enzymes

constant

TIP

Alth ough

all

as

when

temperature

slight

stop

they

such

best

concentration

blood

Any

that

chemical

are

feedback and

•

molecules

of broken

negative

many

homeostasis In

•

conditions

temperature

sort

of

constant

ensure

that

control

at

the

the

is

an

system

pre-set

actual

example

as

in

an

of

oven

temperature.

temperature

is

negative

as

to

keep

Negative

close

to

the

feedback

the

feedback

pre-set

switches

temperature heater

possible.

In

our

body ,

if

the

temperature

increases

above

off

or

required

as

required

oven

oven

temperature

temperature

below

bring

be

it

close

glucose

oxygen

thermostat

the

back

to

normal

to

it,

37 °C,

normal.

within

set

concentration,

and

carbon

It

then

may

limits.

the

dioxide

it

responds

not

be

There

water

by

exactly

are

also

content

of

concentrations

taking

37 °C

control

the

of

actions

all

the

systems

blood,

the

that

time,

for

blood

will

but

will

blood

pH

and

the

blood.

switches oven

gets

temperature heater

too

Figure

on

cold

14.7.1

rises

Controlling

the

Controlling

an

oven

is

an

example

need

glucose

the

energy

and

therefore

need

a

constant

supply

blood.

feedback.

When

you

eat

concentration

stay

high

insulin

a

high

can

because

concentration

166

for

of

from negative

glucose

temperature

Cells of

blood

into

in

the

carbohydrate

increase

cells

the

in

the

blood.

blood.

by

a

meal

factor

pancreas

These

Insulin

cells

your

of

20.

blood

detect

secrete

stimulates

glucose

However,

liver

the

the

cells

it

high

does

hormone

to

not

glucose

convert

called

glucose

tnemelppuS

Dene

body

OUTCOMES

During •

conditions

tnemelppuS

glucose

concentration

glucose

increases

concentration

STUD Y

TIP

insulin causes (food

decreases

intake)

Insu lin

glucose in the liver to

change to glycogen

normal

blood

glucose

normal

level

blood

glucose

and

gluc agon

are

horm ones.

not

enzy mes.

say

that

T hey

So

insu lin

are

alwa ys

and

level

gluc agon

chan ges

stim ulate th e

to

gluc ose.

Do

glucagon causes

say

that

‘insu lin

glycogen in the liver

glucose

gluc ose

glucose

to change to glucose

concentration

concentration

decreases

to

enzy mes

such

as

14.7.2

mus cle

the

the

storage

liver

cells

When

you

muscles

you

a

race

up

Y our

the

cells

blood

Blood

lots

so

blood

glucose

the

instruct

of

and

out

glucose

cells

the

cells

to

from

to

other

the

the

so

of

•

liver

is

an

makes

makes

blood.

this

by

the

and

it

into

the

normal.

pancreas,

releases

molecules

not

and

stimulates

diffuses

to

does

decrease

Glucagon

which

increases

controlled

but

energy

which

hormones

from

the

blood

or

example

insulin

to

of

negative

stimulate

a

feedback

decrease

because

in

blood

the

tissue

in

the

centre

secretes

make

photo

of

the

glucagon

sure

the

decrease

too

to

stimulate

an

increase

in

blood

1

glucose

POINTS

Homeostasis

concentration

stays

within

limits

and

does

not

much

(see

treatment

of

T ype

1

diabetes

in

T opic

as

10.3).

Homeostasis

It

involves

operates

constant

negative

to

conditions

of

QUESTIONS

and Dene

the

term

Explain

why

is

it

water ,

oxygen

in

important

that

conditions

in

cells

are

its

tnemelppuS

the

as

3

term

an

The

pancreas

negative

feedback

using

controlling

example.

blood

in

the

the

blood

controls

the

roles

of

the

pancreas

and

the

liver

of

by

hormones

glucagon Explain

as

well

pH.

concentration

glucose

dioxide

blood

kept

constant.

Explain

carbon

the

homeostasis

as

b

such

temperature.

glucose,

a

constant

increase

maintain

b

the

of

conditions,

feedback.

a

is

maintenance

2

SUMMARY

glucagon.

glucose

body

2

this

and

or

internal

1

of

insulin

pancreas:

concentration,

or

and

your

the

KEY

to

cells

cells.

more.

concentration,

•

by

cells,

the

pancreas

This

inside

stimulates

exercise,

provide

decreases,

glucose,

glucose

to

detect

concentration

remove

This

blood

type

blood

concentration

is

the

38).

The

add

T he

normal.

pancreas

into

glycogen

glucose

page

concentration

in

concentration

liver

(see

to

some

from

glucagon

glucose

blood

glucose

returns

carry

down

blood

glycogen

glucose

Other

break

the

lots

or

of

hormone

to

monitors

to

absorb

decreases

decreasing.

secrete

liver

run

take

need.

keep

compound

to

concentration

done

the

glucose

producing

insulin

which

and

stimulate

the

in

liver. maintaining

a

constant

blood

glucose

concentration.

167

tnemelppuS

into

is

increases

(exercise)

Figure

conv erts

glyc ogen ’.

conv ersion

not

14.8

Controlling

body

temperature

Birds LEARNING

and

mammals

successful

•

Identify

on

•

a

different

diagram

Describe

of

how

temperature

ones

structures

the

and

ways

skin

to

animals

be

as

active

adjust

they

a

at

the

can

constant

night

body

as

live

in

body

well

cold

temperature.

as

temperature

environments

during

in

the

day .

different

as

They

The

well

skin

as

are

very

hot

provides

conditions.

body

is

kept

The

constant

The

STUD Y

maintain

OUTCOMES

skin

skin

is

the

largest

the

body

organ

in

the

body

and

has

several

important

TIP functions:

We

produ ce

respi ratio n

shiveri ng;

to

our

e.g.

we

and

we

by

lose

heat

evapor ation

swea t;

e.g.

bene ath

•

protects

from

damage

•

stops

•

prevents

•

detects

changes

in

•

detects

pressure

(touch)

•

loses

in

surrou ndin gs,

by

heat,

heat

when

pathogens

too

from

much

entering

water

loss

temperature

and

pain

we cons er ve

by

the

havin g

heat

by

conduction,

convection,

radiation

and

evaporation.

fat

skin .

oil

gland

hair

erector

muscle

hair

sweat

sense

–

receptors

detect

pore

blood

sweat

capillar y

gland

pain,

pressure,

cold arteriole

and

heat

sensor y

neurones

Figure

Polar

to

bears

conserve

have

their

a

thick

body

layer

of

insulating

fat

heat.

Many

fat

14.8.1

of

the

structure

structures

temperature.

by

The

radiation.

We

We

lose

use

of

in

the

and

our

human

skin.

diagram

absorb

skin

for

layer

help

heat

heat

in

controlling

through

loss

our

when

skin

we

are

body

–

mostly

hot

and

to

hot

conserve weather

hairs

lie

heat

Mammals

is hair

when

we

are

cold.

flat

a

poor

have

fur

or

conductor

hair ,

of

which

heat.

So

traps

air

a

layer

pockets

in

of

air

the

close

fur

or

to

hair

the

skin.

reduce

Air

the

muscles

loss

of

heat

to

the

atmosphere

by

keeping

convection

currents

of

air

away

relax

from

the

contract

warm

so

that

surface

hairs

of

the

stand

skin.

erect

When

to

trap

it

a

is

cold,

thick

hair

layer

of

erector

air

so

muscles

reducing

cold

heat hairs

weather

stand

loss.

up

When

is

hair

muscles

it

is

trapped

currents

hot,

hair

close

ow

to

erector

the

closer

skin

to

the

muscles

relax

so

so

heat

can

more

surface

of

the

that

be

hairs

lost

lie

as

at.

Less

air

convection

skin.

contract

Mammals Figure

14.8.2

Hairs

are

involved

maintaining

body

temperature.

168

also

have

a

layer

of

fatty

tissue

beneath

their

skin,

which

is

in

a

good

in

cold

insulator

as

it

environments

does

have

not

very

conduct

thick

heat

layers

well.

of

fat.

Mammals

that

live

Controlling

body

temperature

blood

gets

blood

temperature

brain

too

hot

falls switches

No

matter

what

the

weather

is

like,

your

body

temperature

stays on

very

close

to

37 °C

unless

you

have

a

fever.

There

are

receptors

in

cooling

the mechanisms

brain

that

detect

changes

in

the

temperature

of

the

blood.

When

the normal

brain

detects

action

of

any

change

effectors

to

in

the

restore

blood

the

temperature,

blood

it

temperature

coordinates

to

the

body

normal

temperature

body

temperature

normal.

brain

switches

In

the

heat,

the

brain

detects

an

increase

in

the

blood

temperature. on blood

The

brain

sends

impulses

to

the

skin

to

increase

the

rate

of

warming

gets

blood

temperature

sweating mechanisms too

so

that

more

heat

is

lost

by

evaporation

from

the

skin

cold

Figure

In

the

The

cold,

sweat

the

brain

glands

stop

detects

a

decrease

producing

sweat

in

the

and

blood

the

rises

surface.

hair

14.8.3

temperature.

erector sweat

muscles

contract

to

raise

the

hairs.

The

body

starts

to

shiver

as

evaporating hot

some

of

the

body

muscles

contract

spontaneously

and

release

cools

heat

heat

weather

from

by tnemelppuS

A

respiration.

this

very

much

the

Blood

ows

through

the

muscles

and

is

lost

skin

by

radiation

warmed

heat.

effective

blood

skin.

way

ows

to

regulate

through

Arterioles

supply

the

body

temperature

capillaries

these

near

capillaries

to

with

is

to

the

change

surface

blood.

The

change

the

how

of

muscle arterioles sweat

around

the

arterioles

can

contract

and

relax

to

blood

dilate gland

ow.

The

To

lose

vessels

heat,

widen

these

and

muscles

there

is

in

an

the

walls

increase

in

of

the

blood

arterioles

ow

relax.

through

the

Figure

capillaries.

the

In

This

is

surroundings

the

cold,

the

known

by

as

vasodilation.

convection

muscles

in

the

and

More

heat

is

now

lost

14.8.4

to

radiation.

walls

of

the

arterioles

contract

so

the

cold

little

weather

vessels

become

narrower.

This

reduces

the

blood

ow

through

lost

the

heat

by

sweating

radiation

capillaries

the

The

skin.

and

This

control

the

is

of

blood

known

body

is

as

diverted

to

stay

beneath

the

fat

layer

stops

in

vasoconstriction

temperature

is

by

negative

feedback

as

shown

arterioles sweat

in

Figure

14.8.3.

The

brain

coordinates

the

responses

by

effector

constrict gland

to

lose,

temperature

conserve

that

stays

or

gain

within

heat

set

in

order

to

maintain

a

body

limits. Figure

SUMMARY

QUESTIONS

KEY

1

Explain

2

Describe

14.8.5

how

the

brain

controls

body

temperature. 1

what

happens

a

to

lose

heat

b

to

conserve

when

heat

in

we

the

are

when

skin:

are

The

brain

cold.

2

How

do

we

produce

heat

in

the

body

if

we

are

Explain

how

fur

and

control

fat

in

tissue

cold

beneath

the

skin

Insulation

conserves

loses

tnemelppuS

Explain

how

maintaining

vasodilation

body

many

skin.

heat

help

generates

heat,

and

heat.

in Vasoconstriction

and

environments. vasodilation

5

the

the

cold?

3 temperature

body

using

in

shivering

4

by

structures

sweating 3

controls

temperature

hot,

we

POINTS

and

vasoconstriction

temperature.

are

involved

in

heat

the

is

lost

control

from

the

how

much

blood

in

skin.

169

tnemelppuS

organs

14.9

Tropic

responses

Tropisms LEARNING

OUTCOMES

Plants •

Dene

the

terms

the and

respond

plant

the

chemical

such

as

towards

light

or

and

away

gravity.

from

the

Different

different

parts

stimuli.

of

These

plant

Explain

plant

growth

the

by

effect

hormones

responses

are

much

slower

than

the

responses

coordinated

by

control the

•

stimuli

grow

nervous

systems

in

animals.

They

are

called

tropisms

auxins

of

synthetic

used

Gravitropism

as Whichever

way

a

seed

is

planted,

the

root

always

grows

downwards

weedkillers in

the

the

shoot

grows

A

direction

direction

growth

of

of

gravity.

The

shoot

always

grows

upwards

against

gravity.

response

to

gravity

is

called

a

gravitropism.

upwards

Roots

are

direction

to

absorb

Shoots, root

positively

as

the

water

on

the

gravitropic

stimulus,

and

gravity.

mineral

other

hand,

because

They

they

grow

grow

in

the

downwards

same

into

the

soil

ions.

are

negatively

gravitropic.

They

will

grows

always

grow

in

the

opposite

direction

to

the

direction

of

gravity.

This

downwards

ensures Figure

14.9.1

Which

way

is

that

shoots

grow

upwards

getting

the

leaves

into

sunlight.

up?

Auxin

STUD Y

TIP A

A

seed

plant

stimulates

germ inat es.

roo t

and

then

Gravi tro pi c

ensu re

the

seedlin g

itself

o ther

a

Whi ch

in

If

is

a

of

growth

seedling

the

side

of

causing

the

cells

this

to

growth.

elongate,

Auxin

but

in

in

shoots

by

slowing

down

cell

roots

auxin

elongation.

shoot

is

put

and

and

on

its

root.

side

stimulates

In

the

the

the

auxin

cells

shoot

builds

there

the

to

auxin

up

on

builds

the

elongate

and

up

lower

on

the

side

therefore

lower

to

grow

the more

on

the

lower

side.

This

causes

the

shoot

to

bend

upwards.

establ ishes

compe tition

plan ts

by

controls

up?

respon ses

it

growth

auxin

shoo t

way

sur vi val

as

called

A inhibits

appe ar .

hormone

with

In

the

down

near by.

on

root

the

side

upper

so

auxin

the

growth

the

made

auxin

in

side

root

by

a

root

also

root

of

the

bends

builds

by

up

on

inhibiting

root

the

cell

elongate

lower

side.

elongation.

more

than

But

As

a

those

auxin

slows

result,

on

the

cells

lower

downwards.

tip

auxin

builds

lower

up

on

auxin

side

causes

elongate

gravity

lower

less

cells

to

on

side

gravity

Figure

14.9.2

Auxin

controls

the

positive

gravitropism

of

roots.

Phototropism

The

cress

time

These

the

cress

light.

170

seedlings

have

grown

towards

This

and

sort

shoots

seedlings

their

of

growth

grow

in

shoots

the

photo

have

response

towards

the

have

grown

is

light

been

towards

called

they

a

are

put

the

in

a

window

for

some

light.

phototropism.

positively

Because

phototropic.

tnemelppuS

tnemelppuS

Explain

of

either

phototropism growth

•

to

gravitropism

advantage

maximum

efciently

of

this

surface

for

tropic

area

to

response

the

is

that

tnemelppuS

light.

They

auxin

made

the

can

leaves

then

expose

absorb

the

light

more

STUDY

Cells This

TIP

photosynthesis.

response

is

controlled

by

in

the

shoot

tip.

become

moves

away

from

the

shoot

tip

down

the

stem.

When

a

light

only

from

one

side

the

auxin

is

unequally

distributed

cells

in

is

on

found

the

direct

towards

on

the

shaded

light.

the

The

light.

shaded

side

to

shoot

side

the

elongate

grows

Roots

of

are

more

more

not

stem.

on

than

the

sensitive

The

to

auxin

the

cells

shaded

made

shoot

by

on

side

the

cells

and

pressure

bends

which

osmosis.

the

turgor

inside

causes

stretch.

the

the

cell

cell

Auxins

wall

work

makes

by

elongate

more

on

shaded

auxin

by

swells,

increasing

side

light.

auxin

tip

water

vacuole

stimulates

to auxin

they

so

T he most

when

shoot

absorb receives

or

The

elongate, auxin

longer ,

tnemelppuS

The

making

the

walls

to

it

easier

for

stretch.

side

passes

down

shaded

side

shoot

bends

towards

14.9.3

Synthetic

Synthetic

Auxin

plant

auxins

Important

controls

are

cereal

them

for

water ,

Herbicides

leaves

of

like

the

crops

effective

like

2,4-D

wheat

whereas

nutrients

cereal

positive

phototropism

of

shoots.

hormones

very

(monocotyledonous)

the

light

are

and

selective

and

most

light

sprayed

plants

as

the

are

on

because

barley

of

are

the

narrow

weeds

broad

they

weedkillers.

leaved

crop

are

that

but

thin

with

(dicotyledonous).

tend

and

leaved

compete

to

run

point

off

the

upwards.

The This

weedkillers

are

more

likely

to

be

absorbed

by

the

broad-leaved

weeds.

plant

weedkiller

fashion,

The

auxins

increasing

food

from

increase

the

rate

the

of

growth

cell

rate

division.

photosynthesis

to

of

The

the

affected

weeds

maintain

this

weeds,

cannot

rate

of

possibly

provide

growth

Dene

of

the

it

soon

die.

KEY

a

tropic

A

b

to

c

State

what

growth

response

will

happen

in

each

of

the

Some

seedlings

are

placed

in

a

window,

in

sunlight

for

6

A

Some

horizontally

for

a

seeds

few

are

placed

with

their

roots

tnemelppuS

the

observed

Auxins

the

growth

responses

in

question

2

in

action

of

Explain

how

growth

of

positively

shoots

are

is

the

a

growth

the

stimulus

are

and

of

positively

grow

light.

are

plant

hormones

growth.

Synthetic

terms

are

used

as

weedkillers

auxin.

by

4

to

control

auxins of

twisted

hours.

that Explain

a

gravitropic.

Shoots

towards

lying

3

3

are

and

phototropic

germinating

a

stimulus

phototropism

light.

hours.

b

hormone

in

following. response

a

a

gravitropism

2 2

is

the

Roots

gravitropic

phototropism

with

grow

die.

gravitropism

response

following:

response

to

it

POINTS

negatively a

sprayed

made

enough

and

QUESTIONS

each

has

causing

gravity.

1

been

that

by

1

SUMMARY

has

synthetic

auxins

are

able

to

act

as

weedkillers.

making

too

the

weeds

grow

fast.

171

tnemelppuS

Figure

the

PRACTICE

1

In

QUESTIONS

which

spinal

A

pathway

do

nerve

impulses

travel

in

a

6

reex?

effector

diagram

shoot

→

neurone

The

sensory

→

neurone

sensory

cell

→

→

to

shows

receiving

the

light

response

from

of

one

a

plant

side

only.

relay

light

motor

light

neurone

B

motor

C

neurone

→

sensory

neurone

sensory

cell

effector

→

→

relay

→

sensory

relay

neurone

→

effector

neurone

neurone

→

→

motor

neurone

D

sensory

relay

cell

→

neurone

sensory

→

neurone

motor

→

neurone

→

effector

(Paper

1)

[1]

Which 2

Where

are

relay

neurones

statement

explains

how

this

response

is

situated?

controlled? A

effector

C

B

spinal

D

(Paper

3

A

cord

spinal

nerve

1)

Auxins

stimulate

a

gravitropic

impulse

cord

metres.

in

The

travels

0.02 s.

speed

from

This

of

the

is

a

a

ngertip

distance

impulse

B

Auxins

stimulate

a

phototropic

to

C

Auxins

stimulate

cells

of

the

1.4

C

light

the

opposite

Auxins

from

70 m s

on

−1

7 m s

D

to

grow

on

faster

the

than

side

the

closest

cells

to

on

side.

stimulate

(Paper

1)

Which

shows

the

the

light

cells

to

on

opposite

grow

the

faster

side

away

than

the

cells

side.

170 m s

(Paper

2)

[1]

Which

are

[1]

7 4

the

−1

0.7 m s

−1

B

response.

is: D

−1

A

response.

[1]

nerve

spinal

A receptor

hormone

the

and

A

adrenaline

B

insulin

–

its

–

correct

match

between

effect?

decrease

increase

in

in

heart

blood

symptoms

of

Type

1

diabetes?

the

rate

glucose

A

bleeding

gums

B

constant

alertness

C

thirst

D

tiredness

and

and

poor

and

wound

healing

insomnia

unexplained

weight

loss

concentration

C

oestrogen

–

decrease

in

the

volume

and

unexplained

weight

gain.

of (Paper

2)

[1]

urine

8 D

testosterone

–

stimulates

development

A

man

injures

his

arm

in

an

accident.

of

Afterwards,

he

can

feel

objects

touching

his

sperm

hand,

(Paper

1)

Which

occur

when

in

a

hot

A

environment?

them.

all

in

sweat

hair

skin

glands

muscles

are

A

constrict

active

relax

B

constrict

not

contract

C

dilate

active

relax

D

dilate

active

contract

C

172

his

hand

away

active

cause

of

between

this

could

his

hand

his

spinal

be

and

that:

the

spinal

damaged

all

nerves

effectors

2)

move

erector

B

(Paper

cannot

The

nerves

cord

arterioles

the

he

[1] from

5

but

all

nerves

hand

D

all

(Paper

[1]

between

in

and

the

2)

his

arm

between

his

are

the

spinal

receptors

in

receptors

cord

his

cord

and

the

cut

are

hand

in

his

cut

are

damaged

[1]

9

The

the

diagram

shows

a

horizontal

section

of

11

eye.

A

scientist

and

investigated

cones

shown

in

across

the

distribution

the

diagram.

of

cones

the

distribution

retina

The

in

the

of

a

of

mammal

graph

shows

rods

as

the

retina.

D

C

B

B

A

E

X

Y

X

Y

A

sllec

the

(b)

Explain

(c)

A

parts

labelled

A

to

E.

[5]

fo

Name

enoc

(a)

person

brightly

(i)

the

walks

lit

eye

is

from

a

a

sense

dark

organ.

room

into

rebmuN

why

[2]

a

place.

Describe

the

change

that

you

would A

see

happening

to

the

person’s

B

pupils.

[1]

(a) (ii)

Suggest

the

advantage

of

the

Name

Give you

described

in

(i).

parts

reasons

(a)

the

retina

X

and

Y .

for

your

answers.

[4]

Copy

the

graph

and

show

on

it

the

3) distribution

10

of

[1]

(b) (Paper

the

change

Copy

that

and

complete

shows

part

concentration

of

of

the

the

ow

chart

control

glucose

in

of

the

(c)

(i)

the

State

the

of

an

rods

involuntary

blood

glucose

retina.

action

[3]

involving

eye.

[1]

Explain

how

involuntary

in

the

blood. (ii)

increase

in

the

control

action

of

differs

an

from

the

concentration control

of

a

voluntary

action.

[3]

↓ (d)

Explain

having detected

by

the

two

advantages

to

coordination

an

animal

systems:

of

the

…

nervous

system

and

the

endocrine

system.

[3]

↓

insulin

secreted

(Paper

↓

12

(a)

4)

Describe

when liver

cells

respond

by

[2]

(b)

sensory

There

spinal Write

out

a

similar

ow

chart

to

show

response

glucose

to

a

decrease

in

Explain

using

concentration.

as

(Paper

an

the

the

principle

control

example.

of

of

that

impulse

occur

arrives

at

at

a

synapse

the

end

are

neurone.

of

huge

cord

and

[4]

numbers

the

of

brain.

synapses

Explain

in

why

the

this

so.

[3]

blood

[3] (Paper

(c)

events

the

is body’s

the

nerve

…

a

(b)

a

negative

glucose

in

4)

feedback,

the

blood

[5]

4)

173

15

Drugs

15.1

Drugs

What LEARNING

A •

Dene

•

Describe

are

the

term

drug

is

any

the

use

of

antibiotics

treatment

of

bacterial

There the

substance

that

is

taken

into

the

body

that

alters

or

drug inuences

in

drugs?

OUTCOMES

are

chemical

several

ingredients

of

reactions

different

medicines

in

types

and

the

of

are

body.

drug.

used

Some

to

treat

are

the

and

active

cure

people

of

infection

disease.

•

State

that

some

bacteria

makes

to

antibiotics

them

less

State

that

paracetamol,

designed

to

antibiotics

but

do

which

alter

sensory

perception.

suppress

morphine

muscular

pain

pain,

and

antibiotics

counteract

the

are

medical

symptoms

of

drugs

‘u’,

soothe

useful

are

not

or

kill

socially

pathogenic

acceptable

bacteria.

drugs

Alcohol,

that

people

nicotine

take

for

and

their

kill

pleasurable bacteria

mood-enhancing

which

caffeine •

are

are Aspirin,

resistant

Others

effects,

to

help

them

relax

or

concentrate.

affect

viruses Drugs tnemelppuS

are •

Explain

the

strategies

that

be

used

to

reduce

of

Explain

why

Acid

user.

Diethylamide

Stimulants,

mood-enhancing

antibiotics

well-being

of

their

drugs.

more

severe

effects

Hallucinogens,

or

LSD,

cause

psychedelic

like

visions

like

cocaine,

ecstasy

and

for

amphetamines

the

are

but

do

not

and

drugs

energy.

which

Heroin,

give

the

user

although

it

a

short-lived

affects

the

feeling

body

in

a

kill different

bacteria

because

bacteria

of

•

illegal

recreational

antibiotic-

all resistant

be

the

drug development

to

called

that

Lysergic can

tend

sometimes

way,

also

gives

a

feeling

of

well-being.

affect

Drugs

act

upon

the

human

body

in

various

ways.

Some

drugs,

such

viruses

as

nicotine

system

and

works

heroin,

and

mood-enhancing

STUD Y

TIP

in

the

nervous

impulses.

T here

are

den e

the

term

ways

to

cell

the

top

of

this

the

liver

page ,

types

can

we

write

describ e,

it

the

abused

heroin

change

the

combining

way

by

and

way

with

that

the

people.

Many

nicotine,

in

which

protein

nervous

act

of

at

the

synapses

neurones

molecules

send

on

the

neurones.

from

is

are

the

site

broken

of

the

down

breakdown

in

the

body

of

by

alcohol

and

enzymes

other

and

the

toxins.

products

which excreted.

The

breakdown

products

can

be

detected

in

the

urine,

of and

drug s

of

by

as

the

at

are

all

this

often

such

and

with

‘drug ’.

den ition

Drugs

covers

are

drugs,

do

membranes

The

Lear n

the

man y

these

system

They

interfere

so

you

this

taking

mem ory.

who

have

Many

rely

it

drugs

why

the

in

have

drug,

regularly.

are

urine

tests

Athletes

been

drugs

on

take

is

drugs.

illegal

accidents

the

a

In

are

taking

many

and

are

potential

person

carried

part

can

in

out

routinely

to

be

possession

or

see

tested

addictive.

become

countries

to

if

competitions

addicted

some

or

dealing

all

in

of

people

and

for

If

the

them

been

drivers

drugs.

the

and

have

car

body

feel

comes

the

need

to

to

non-medicinal

results

in

severe

punishment.

The

body’s

produce

to

Many

in

an

on

medical

drugs

uncontrolled

prescription

174

are

way

from

a

dangerous

and

are

doctor.

if

taken

available

only

metabolism

more

increase

to

may

enzymes

have

the

to

become

break

effect

it

that

used

down

the

to

so

user

the

that

rst

drug.

the

The

dose

liver

of

experienced.

may

the

drug

has

Antibiotics

(bacteria

growth.

cure

are

and

a

group

fungi)

Antibiotics

human

Antibiotics

and

can

antibiotics

has

be

to

was

the

Penicillin

acts

on

a

breakdown

Some

are

be

over

the

stop

by

cell

made

to

kill

by

be

by

and

and

the

wall

cell

to

and

their

treat

and

fungi.

Usually

of

a

course

of

time.

and

mass-produced.

formation,

leakage

crossing

stop

vets

mouth.

period

cell

or

bacteria

discovered

inhibiting

wall

by

certain

substances

microorganisms

doctors

taken

to

by

pathogens

caused

a

antibiotic

bacteria

of

or

taken

rst

used

diseases

injected

be

antibiotics

chemicals

are

prescribed

animal

Penicillin

to

of

that

of

cell

leading

contents.

membranes

and

others MRSA

prevent

enzymes

proteins.

taking

A

big

Antibiotics

antibiotics

problem

resistant

to

to

tnemelppuS

Viruses

are

rely

viruses

for

viral

but

be

have

no

treat

viral

on

and

than

They

the

that

is

such

there

are

is

that

viruses.

many

vets

not

of

use

not

differently

on

such

There

as

is

making

no

point

are

in

and

being

antibacterial

need

bacteria

to

have

know

resistance

carry

their

host.

antibiotics

possible.

diseases

as

to

out

AZT

their

This

that

This

antibiotics

the

development

MRSA.

This

has

of

in

which

is

by

why

viruses.

used

There

that

our

to

are

such

has

hospitals.

deaths

as

number

recent

only

years

when

of

as

cases

a

of

result

in

those

necessary

MRSA

of

and

are

antibiotic

bacterial

treatment

been

caused

Overuse

resistance.

See

anti-viral

was

by

overuse

responsible

prescribing,

test

patients

have

had

with

organ

in

the

USA

and

strategies.

ensuring

that

UK

taking

more

all

on

their

pills

use

aureus

or

suppressed

has

decreased

antibiotic

a

to

against

patient.

contain

nd

the

The

out

white

the

for

a

hospital

discs

on

would

be

has

this

agar

Here,

effective

to

infected

plate

four

ways

resistance

bacteria,

whereas

because

two

they

would

have

not.

their

courses

to

on

POINTS

control

page

239. A

drug

is

the

a

substance

body,

which

chemical

taken

alters

or

reactions

QUESTIONS

a

Dene

b

Name

two

drugs

c

Name

two

mood-enhancing

the

term

drug

d

Name

two

drugs

that

2

are

used

as

body.

Antibiotics

by

medicines.

the

can

cell

pathogens

wall

inhibiting

protein

drugs.

synthesis that

destroy

disrupting

formation,

be

harmful,

but

are

not

illegal

and

metabolism

in

in the

pathogen

cell.

countries.

3 Explain

a

in

in

2

ask

in

antibiotic

that

antibiotics.

inuences

many

may

out

which

pathogen

different

into

1

doctor

carried

antibiotics

complete

are

a

be

transplants.

Prescribing

people

to

of

for

1

SUMMARY

of

using.

HIV/AIDS,

fewer

Staphylococcus

hospital

who

specic

by

is

anti-

KEY of

doctor

control

killed

The

this

bacteria

use

antibiotics

There

treat

far

to

Before

methicillin-resistant

caused

systems,

which

by

own

antibiotics

immune

hospitals

metabolism,

means

inhibit

explains

caused

antibiotics.

own

antibiotics.

to

especially

gels

in

antibiotic

laboratory

antibiotics,

antibiotic-resistant

become

which

sensitivity

Bacterial

other

controlled

disease.

cells

to

reactions,

diseases.

and

do

control

available,

work

doctors

have

to

effect

antibiotics

so

cells.

used

important

particular

would

drugs

they

drugs

a

not

metabolism

cannot

with

entirely

we

to

them,

prescribe

but

catalysing

how

antibiotics

act

to

kill

pathogens

like

bacteria

Antibiotics

cannot

kill

viruses

and since

they

have

no

cell

fungi.

tnemelppuS

wall

host 3

Explain

why

antibiotics

can

kill

bacteria

but

not

but

rather

cells,

live

taking

inside

over

their

viruses.

metabolic

processes.

175

tnemelppuS

Antibiotics

15.2

Heroin

LEARNING

Describe

of

heroin

the

effects

of

Morphine

and

codeine

poppies abuse

of

and

State

that

injecting

heroin

•

infections

Describe

the

addiction

such

as

problems

to

withdrawal

heroin,

is

Heroin

has

as

a

a

tnemelppuS

how

nervous

effect

a

opium

compound

so

is

Heroin

rarely

has

only

limited

medical

uses

as

it

is

used.

depressant

structure

that

that

slows

is

down

similar

to

the

nervous

endorphins,

system.

a

that

are

found

in

the

brain.

Endorphins

are

made

group

naturally

the

brain

and

provide

relief

when

the

body

experiences

pain

or

stress.

and

heroin

work

by

ooding

system,

on

the

limited

function

transmitting

relief.

affects

to

of

When

a

the

synapses

in

the

brain

and

preventing

neurons

blocking

nerve

for

and

alcoho l

depres sant s.

shou

ld

when

use

this

writi ng

effect s

more

rst

and

on

time

This

mimics

synapses

they

intense

post-synaptic

in

usually

the

T opic

feel

happiness.

a

This

so

producing

molecules

bind

membrane

function

14.3).

warm

state

When

rush

is

of

of

pain

to

the

the

synapse,

natural

people

and

known

a

take

feeling

as

of

euphoria

on

the

term

abou t

their

body .

shou ld

apply

be

these

to ler ance

depend ence

addict

Addiction

TIP

ideas

and

to

alcoho l.

injecting

to

heroin

into

a

vein.

heroin

becomes

part

of

the

body’s

metabolism

and

the

body

quickly

able gets

and

the

heroin

are

Heroin

Y ou

on

receptors,

the

Y ou

An

STUD Y

sites

pain

heroin,

transmission.

(see

the

from

takes

TIP

Heroi n

bo th

impulses

person

endorphin-receptor

endorphins

synapses

STUD Y

heroin

used

effect.

to

the

to

to

the

More

take

The

tolerance

People

in

who

dependent

three

the

to

on

weeks

are

of

reduce

the

order

but

This

body

feeling

to

start

experienced,

to

But

heroin

quantities

drug.

painkillers

brain.

painkillers.

a

176

and

chemical

contentment

of

from

is

and

crime

heroin

to

morphine.

powerful

chemicals

from

the

Heroin

infection

Explain

its

extracted

medicine.

severe

symptoms

such

from

addictive

Heroin

They

the

compounds

in

of

in problems

•

two

painkillers

HIV

of

HIV

as

can highly

cause

used

heroin modied

•

are

the

feel

taking

they

needed

does

pain

the

drug,

to

includes

it

heroin

drug.

This

of

misuse

of

produce

This

has

to

or

want

get

can

nerve

prevent

becomes

euphoria

quickly

the

to

not

pain.

and

the

them

more

how

be

the

taken

just

to

of

happen

or

its

and

body

in

the

ever

a

has

its

impulses

own

natural

addicts

have

develops

greater

the

pain.

feelings

addicted

within

it

sending

deaden

repeat

‘hooked’

heroin.

where

unbearable

is

to

cells

as

matter

they

they

of

rst

are

just

two

tnemelppuS

•

Biology OUTCOMES

is

taken

Injecting

is

highly

surrounding

known

places

The

as

to

by

smoking,

dangerous

injection

gangrene.

inject

danger

it.

page

as

virus

can

die,

it

into

a

collapse

and

tissues

giving

can

the

run

needles

and

is

the

transmission

and

the

virus

that

vein.

condition

out

share

this

(HIV)

to

injecting

addicts

addicts

with

or

veins

start

Long-term

associated

of

suitable

syringes.

of

the

causes

human

hepatitis

211).

Social

problems

Heroin

addiction

often

points

Some

immunodeciency

(see

snifng

is

dominates

a

the

serious

lives

problem

of

addicts

for

and

many

they

countries.

think

only

The

drug

about

how

Heroin

addiction

addiction,

they

can

get

their

next

‘x’.

The

drug

can

be

expensive,

which

at

many

often

people

to

become

turn

to

difcult

crime

to

in

keep

order

a

job,

to

fund

and

their

habit.

addiction

often

It

risk

from

and

breakdown

families,

and

homelessness.

preferring

the

Addicts

company

of

tend

other

to

shun

addicts,

isolated

from

a

nicotine

is

produced

in

and

so

heroin

in

the

and

America

smuggle

the

Afghanistan,

and

It

elsewhere.

drugs

Heroin

which

is

the

largest

is

a

highly

dealers

who

into

sell

in

the

Golden

Triangle

(Laos,

Heroin

is

then

trafcked

Networks

of

developed

illegally

criminal

countries

into

gangs

and

it

on

the

streets.

Most

of

Europe,

help

to

have

harsh

penalty,

to

penalties,

stop

such

trafcking.

A

as

life

user

drugs

their

next

have

resulted

include

happening

A

great

to

go

centre.

which

to

deal

overcome

is

very

unpleasant

sleeplessness

of

addiction.

countries

some

of

the

cramps,

and

stops

and

taking

This

addicts

same

the

from

only

may

are

effects

symptoms.

(imagining

sweating,

support

Often

rehabilitation.

some

gives

withdrawal

hallucinations

muscle

willpower

heroin

into

In

them),

and

way

involve

given

as

to

is

These

the

hepatitis

and

and

needed

staying

in

a

drug,

who

HIV

inject

Heroin

the

interacts

nervous

with

nausea.

to

the

habit

SUMMARY

QUESTIONS

treatment

methadone,

1

Dene

in

heroin.

each

relation

of

to

the

drug

b

dependence

c

addiction

d

rehabilitation

a

Why

a

is

heroin

highly

If

a

heroin

taking

what

Heroin

to

crime,

viral

the

drug

addicts

who

want

to

many

give

up

people

their

becoming

habit

is

involved

available

in

with

crime.

rehabilitation

Support

for

addict

drug,

happens

social

and

how

stops

describe

to

them.

can

and

the

lead

family

spread

of

these

consequences

of

drug?

diseases.

Explain

cause

described

addictive,

addiction

problems

the

use:

tolerance

b

3

following

a

depressant

often

synapses

system.

are

as

are

amongst

heroin.

can

2

Drugs

needles

spread

drug

things

overcome

another

Shared

in

the

the

terrible

vomiting

others

dose.

to

in experiences

to

for

heroin-producing

imprisonment

who

turn

money

and

3 death

may

obtain

North

process

distribute

the

addicts

Vietnam,

addicts

countries

addictive

drug.

producer

of

drug

lives

society.

world,

Thailand).

and

their

addiction.

POINTS

crime

Burma

of

put

they

2

of

form

people

to

depressant

Heroin

serious

more

friends

1

become

is

far

can

leads

KEY family

but

drives

society

in

a

can

affect

negative

way.

centres.

177

tnemelppuS

Heroin

15.3

Alcohol

of

drugs

Biology LEARNING

Describe

the

effects

of

sport

alcohol

a

socially

its

supply

acceptable

and

drug

in

consumption

many

are

countries

very

tightly

in

the

world.

regulated

and

in

consumption

Describe

the

long-term

alcohol

on

the

body

it

is

banned

entirely.

effects When

of

is

some,

others

•

misuse

excessive In

alcohol

of

in

the

OUTCOMES

Alcohol •

and

and

alcohol

is

consumed,

it

is

absorbed

into

the

blood

very

quickly

on since

it

is

a

small

molecule

that

does

not

need

to

be

digested.

It

is

society

tnemelppuS

also

•

Discuss

in

the

use

of

hormones

sport

soluble

the

wall

the

stomach

Alcohol type

of

volume

alcohol

of

in

cell

the

membranes,

stomach

slows

gets

and

down

distributed

its

so

it

small

is

absorbed

intestine.

very

The

quickly

presence

through

of

food

in

absorption.

throughout

the

body

in

the

blood.

Some

units

is

lost

through

the

lungs

and

the

kidneys.

It

is

absorbed

by

liver

3

drink

/

cm

by

cells

and

broken

down

by

enzymes

so

that

its

concentration

in

the

volume

blood /

men

alcopop

extra

decreases

gradually.

This

breakdown

happens

more

quickly

in

%

400

5

500

2

8

4

than

their

and

in

women

enzymes

less

fat

in

concentration

strong

because

tend

to

their

bodies

of

be

alcohol

men

more

active.

than

in

have

the

more

They

women,

blood

to

of

also

which

these

have

more

tends

decrease

enzymes

to

more

and

water

cause

the

quickly.

lager Like

cider

500

4

2

(glass)

heroin,

down

the

125

40

5

wine

175

12.5

2.2

spirit

35

40

1.4

(vodka)

of

others.

of

is

removing

With

depressant.

of

loss

•

slower

reaction

•

loss

self-control.

nerve

coordination,

It

affects

impulses.

inhibitions

larger

•

of

a

transmission

effect

with cocktail

the

alcohol

so

quantities

judgment

In

people

this

and

lack

the

brain

small

nd

of

control

by

quantities,

it

easier

to

inhibitions

of

slowing

ne

this

has

socialise

leads

to

movements

times

and Unlike

heroin,

alcohol

does

not

lead

to

addiction

as

quickly

if

at

mixer all.

Many

their

The

content

one

extra

strong

cider

drink

throughout

alcohol

8 grams

alcopop

people

of

hour.

lives

alcohol;

The

drink

more

page

200

UK

than

for

alcohol

in

without

of

drinks

this

is

to

advice

4

units

about

moderate

in

day

drinking

units.

broken

recommends

per

quantities

addicted.

measured

quantity

government

3

to

becoming

is

the

small

and

that

in

men

women

during

One

down

2

unit

the

is

liver

should

to

3

(but

in

not

see

pregnancy).

Addiction

lager

Some

people

referred

to

as

metabolise

greater

irritable

and

aggressive

wine

spirit

and

mixer

Figure

178

15.3.1

Some

alcoholic

drinks.

dependent

alcoholics.

alcohol

quantities

Alcoholics

cocktail

become

nd

can

are

of

it

after

alcohol

hard

cause

They

made

to

their

drinking

develop

in

to

the

get

cope

alcohol

a

the

spend

a

They

same

and

lot

of

are

as

effect.

sometimes

more

therefore

everyday

pain

and

tolerance

liver .

with

families

and

upon

enzymes

need

They

problems

misery.

They

money

on

to

feel

tense

without

can

drink.

that

take

a

and

drink.

become

Social

problems DID

The

misuse

of

alcohol

is

a

factor

in

crime,

family

disputes,

YOU

KNOW?

marital Researchers

breakdown,

child

neglect

and

abuse,

absenteeism

from

discovered vandalism,

assault

and

violent

crime

including

murder.

In

the

damage

done

by

alcohol

is

considerable

and

is

three

for

governments

to

has

and

adverse

making

to

other

effects

them

drink

drugs

feel

alcohol

on

involved

people’s

more

and

are

drive

in

many

road

concentration,

condent.

then

to

four

of

times

the

more

in

people

who

abuse

measure. alcohol

Alcohol

have

cirrhosis

often frequent

difcult

Finland

that

some liver

countries

in

work,

a

In

some

vehicle

accidents.

while

at

countries

or

operate

the

it

is

type

Alcohol

same

against

machinery.

of

and

time

defence

the

that

In

law

most

who

protein

system.

some

have

in

the

This

people

susceptible

to

a

specic

cells

of

their

suggests

are

genetically

cirrhosis

if

they

3

Europe

There

are

the

Long-term

Drinking

serious

and

large

builds

liver

on

is

The

of

the

blood

with

alcohol

It

can

liver

more

is

condition

is

the

to

is

50

than

part

a

mg

the

in

the

of

the

per

100

legal

so

fatty

by

of

cm

.

abuse

that

liver.

brous

If

fat

is

this

scar

have

disease

breaks

quantities

that

can

heart

of

alcohol

stored

and

continues

the

tissue.

Alcohol

the

If

heavy

is

drinking

able

the

continues

to

This

condition

then

carry

out

condition

drinking.

with

in

tnemelppuS

misuse

Anabolic

increased

of

They

hormone.

of

The

strength

as

the

liver

becomes

alcohol

drugs

are

and

by

result

is

the

is

The

full

and

in

liver

toxins

fatal

consumption

of

also

the

the

less

to

reaction

respond

use

of

a

number

anabolic

increased

of

similar

mimicking

the

to

the

male

sex

male

the

features,

facial

In

of

and

protein-building

growth,

which

gives

effects

the

to

times

stimuli,

Armstrong

side-effects

men,

use

of

resulting

these

baldness,

drugs

kidney

from

can

and

the

breasts.

body

In

hair

women,

and

there

irregular

is

a

life

for

was

banned

doping

from

offences

competitive

in

2012.

development

POINTS

of

periods. Alcohol

is

if

in

taken

a

depressant

excess,

it

reaction

and

can

times

and

QUESTIONS

a

Describe

b

What

how

effects

Explain

alcohol

does

reaches

alcohol

the

have

brain

on

the

after

it

is

about

why

a

person

who

has

drunk

2

brain?

alcohol

should

a

What

are

the

b

Summarise

long-term

effects

of

alcohol

on

the

not

effects

of

alcohol

on

society

and

Long-term

of

its

use

of

lack

effects

include

and

discuss

of

self-

of

alcohol

cirrhosis

brain

of

the

damage.

Performance

enhancing

drugs

the anabolic

steroids

can

have

use. serious

the

a

person.

body?

like banning

a

drive.

3 the

in

drunk.

liver

Discuss

to

lights.

and

abuse

3

longer

trafc

about

damage

control

2

takes

as

excessive

bring

liver

for

bring

c

it

of

lengthen

1

so

such

athlete

1

SUMMARY

be

endurance.

impotence,

development

to

Alcohol

hormone

KEY even

thought

sport

muscle

harmful

steroids.

aggression,

are

accidents.

damage,

cycling

are

road

stops

brain

Lance

There

drugs

many

blood.

person

leads

other

nodules.

becomes

from

unless

of

behaviour.

substances

work

and

cirrhosis.

removing

reversible

personality

steroids

testosterone.

this

job

not

Long-term

changes

The

its

is

known

and

cause

slows

This

alcohol.

limit.

years

ulcers,

body

large

liver

as

replaced

number

stomach

Drinking

known

and

over

lead

toxins.

metabolism

damaged

in

driving

alcohol

other

the

This

tissue

of

alcohol

for

health.

and

with

up.

of

quantities

damage.

alcohol

interferes

limit

penalties

effects

effects

brain

down

legal

severe

hormones

to

improve

performance

in

side

effects.

sports.

179

tnemelppuS

of

15.4

Smoking

Tobacco LEARNING

plants

It

is

structure

the Describe

gas

the

effects

exchange

carbon

and

tar

system

monoxide,

in

on

State

can

that

cause

lung

chronic

tnemelppuS

•

link

and

the

lung

obstructive

at

of

for

smoking

the

T ar

and

is

It

the

the

smok e

have

hear t

syst em

gas

Y ou

this

effect s

and

as

in

be

as

in

on

to

are

the

as

abou t

it

for

a

a

against

smoke

smaller

and

It

–

Bogart

by

have

nervous

died

smoking.

at

57

from

more

stop

bacteria

insect

a

molecular

system

and

so

ts

particularly

to

the

the

which

enter

the

nerve

cells

depressant.

arterioles,

stickiness

more

as

move

of

these

lining

mucus.

help

to

are

smoke

the

narrowing

There

Some

lungs

irritates

normally

in

material

tar.

a

the

the

T ar

produce

cough’.

gas.

volume

an

added

in

and

is

to

of

the

about

can

This

remove

the

back

of

4000

cause

cancer

with

hot

there

is

less

supply

may

not

Due

sometimes

heart

can

that

At

a

heart

be

to

may

by

the

the

If

it

blood

a

oxygen

baby

(see

by

already

when

muscle.

enough

this,

with

carry

time

delivered

premature

it

disease

tobacco

the

they

are

keep

but

means

in

may

page

not

where

the

on

the

lungs

the

mucus

removed

This

to

on

is

the

200).

clean.

the

stimulates

the

particles

the

places

settle

to

Tobacco

the

dust,

air

dirt

lungs.

the

of

is

cells

lining

where

out

given

and

airways

cells

and

from

term

bronchitis

Mucus-secreting

cilia

that

multiply.

(COPD)

chronic

smoke

airways.

phagocytes

bronchi

to

the

permanently

blood

nicotine.

there

properly.

response,

bacteria

send

to

including

which

of

This

to

on

that

smoking

diseases

lining

combines

strain

arteries

develop

of

It

oxygen

response

pulmonary

in

of

respiration,

by

stick

and

in

resulting

this

not

increases

to

with

clotting.

to

cilia

in

pregnancy

to

effect

mucus

system

the

alveoli

narrows

collects

them

make

the

its

beating.

that

and

bloodstream.

coronary

lung

the

the

interacts

stimulant,

also

poisonous

weight

efciency

accumulates

immune

for

the

caused

The

It

that

the

faster

obstructive

the

passages

a

fetus

of

to

a

‘smoker’s

puts

and

birth

irritates

produce

on

to

carcinogenic.

during

the

collection

reduce

Humphrey

our

that

blood

smoking,

to

is

This

is

faster

compounds

as

oxygen

for

by

cough

through

smokes

blood

into

because

rise

harder

emphysema.

180

protect

happens

through

drug

it

material

reduces

10%.

more

ows

woman

hum ans.

as

a

beat

stimulates

monoxide

so

is

promote

pass

and

giving

beating

needs

as

on

sticky

not

chemical

Chronic

brought

with

quickly

it

pressure.

that

described

much

be

blood

Smokers

Diseases

actor

to

smoke

heroin

heart

damaged

haemoglobin

have

cancer

way

drug.

very

unlike

accumulate

throat

and

the

The

interact

heroin,

the

black

are

Carbon

syst em .

aske d

ques tions

tran sport

on

circul atory

well

exchan ge

may

tobacc o

But

airways

different

in

Like

does

airways.

the

to

term

absorbed

platelets

the

mucus

TIP

is

increases

cools.

of

chem icals

the

it

tobacco

makes

blood

tends

T he

of

synapses.

which

coronary

cancer

STUD Y

of

bloodstream.

Nicotine

(COPD),

evidence

between

allows

denition

Biology

disease

Discuss

a

Nicotine

of

smoking

disease

cancer

heart

as

pesticide.

smoke

tobacco

pulmonary

natural

the

nicotine

tobacco

a

that

Nicotine

•

nicotine

health

OUTCOMES attack.

•

make

and

body’s

this

the

happens

air.

Large

amounts

bacteria

and

of

phlegm

white

blood

(a

mixture

cells)

are

of

200

mucus,

produced,

which 175

attempt

their

Chronic

nd

lungs

as

it

means

difcult

the

up.

to

bronchi

This

long

term.

move

are

condition

air

partly

is

chronic

People

into

and

with

out

this

of

000

condition

cough

blocked.

001

bacteria

the

Eventually

much

the

lining

this

that

of

cells

the

weakens

they

surface

blood

break

area

for

reach

alveoli

the

alveoli.

digest

a

to

walls

down

gas

the

and

pathway

reach

of

the

burst,

exchange.

100

of

them.

alveoli

the

lung

bronchitis

50 lung

so

cancer

25

reducing

This

tuberculosis

75

shtaed

through

white

tar

/

Phagocytic

and

125

rep

Particles,

150

rep

bronchitis.

to

raey

people

condition 0

is

emphysema,

which

leaves

people

gasping

for 1920

breath

as

remove

lung

have

the

control.

form

this

a

is

area

of

discovered,

the

still,

lung

a

and

part

of

cells

is

block

in

of

out

eventually

a

occupy

Deaths

from

lung

tnemelppuS

From

that

to

the

other

a

smoking

and

twentieth

low,

but

lung

these

cigarette

In

contrast,

you

deaths

increased

smoking

deaths

tuberculosis

In

see

the

the

from

blood

break

the

link

early

lung

more

other

falling,

a

and small

sort

of

care

and

better

cancerous

smoke

deposit

part

of

as

the

were

the

habit

diseases,

result

of

such

improved

showing

in

the

increases

the

wa lls

chan ce

the

of

ch ance s

arteries.

tha t

disease

the

(see

of

heart

As

1

risk

page

oxygen

in

X-ray

the

on

right

page

lung.

128.

th a t

blood

will

of

developing

108) .

to

th e

B lo cked

h eart

c lo t,

Dene

a rter ies

th is

the

following

words:

there

cor o na r y

and

QUESTIONS

nicotine

b

tar

c

carbon

monoxide

hear t

r edu c e

the

2

da ma g es

Explain

how

increased

cigarette

risk

of

smoking

is

linked

to

an

developing:

muscle. a

lung

cancer

a

What

b

Describe

is

the

b

bronchitis

function

of

the

c

heart

alveolus

disease

(air

sac)?

POINTS

T obacco

smoke

monoxide

and

consists

smoke

of

nicotine,

tar ,

alveolus

carbon

particles.

c

Smoking

is

bronchitis,

lung

associated

with

emphysema,

cancer.

diseases

heart

such

disease

two

is

Describe

who 2

cancer

the

nicotin e

3 KEY

with

fat

a increased

supply

a

housing.

1 increases

an

in

data

SUMMARY

is

alveoli

disease

Tobacco

will

between

between

Compare

Heart

tumour

lungs.

X-ray

medical

1920–60.

widespread.

lung

as

Wales

vessels.

off

cancer

dramatically

became

from

were

can

establish

and

If

the

cancer.

century,

of

as

above,

scientists

England

large

organs.

graph

helped

in

of

A

spread

diseases

may

tumour.

and

may

1960

cells

divide

to

airways

tumour

1950

cause

as

grow

1940

These

DNA

but

1930

or

long-term

The

tar.

and

known

may

the

Many

the

slow

cells

it

in

grow

very

oxygen

conditions.

carcinogens

The

group

enough

efciently.

these

changes

growth

small

of

the

airways.

not

Worse

is

of

promote

This

absorb

dioxide

both

cancer

substances

lining

cannot

carbon

smokers

of

they

ways

adapted

what

develop

in

to

which

carry

happens

to

a

healthy

out

its

alveoli

function.

in

people

emphysema.

as

and

d

Explain

how

functioning

emphysema

of

the

affects

the

lungs.

181

PRACTICE

QUESTIONS

1

denition

The

A

best

any

substance

inuences

of

the

taken

chemical

substance

that

term

into

drug

the

body

reactions

B

any

affects

C

substances

that

are

D

substances

that

may

the

in

6

is:

Which

statement

on

nervous

the

(Paper

to

body

nervous

treat

become

system

A

blocks

B

combines

The

effect

of

heroin

the

activity

with

of

all

sensory

receptors

information

on

about

neurones

nerves

that

pain

disease

C

prevents

the

D

stimulates

release

of

neurotransmitters

addictive

1)

neurones

to

send

impulses

[1] about

2

the

that

the

transmit taken

describes

system?

drug

in

tobacco

smoke

is: (Paper

A

carbon

dioxide

B

carbon

monoxide

7

Why

and

C

nicotine

D

tar

pain

A

2)

is

it

[1]

necessary

develop

all

new

viruses

for

drug

types

have

of

companies

to

nd

antibiotics?

become

resistant

to

antibiotics

3

(Paper

1)

Which

statement

of

A

[1]

is

not

related

to

the

taking

B

antibiotics

have

become

C

antibiotics

have

been

60

heroin?

The

drug

is

a

D

stimulant.

in

drugs

use

of

for

misuse

over

years

many

bacteria

are

resistant

to

some

antibiotics B

The

drug

is

C

Not

taking

addictive.

the

drug

may

withdrawal

symptoms.

The

a

lead

to

(Paper

severe

8

D

drug

is

depressant.

Tobacco

What

the (Paper

1)

Which

component

is

[1]

smoke

the

contains

effect

of

carbon

carbon

monoxide.

monoxide

on

body?

[1]

A

4

2)

in

tobacco

smoke

is

causes

mutations

in

the

epithelium

of

the

the bronchi

cause

of

lung

cancer? B

A

carbon

dioxide

B

carbon

monoxide

C

nicotine

D

tar

reduces

the

oxygen-carrying

capacity

of

haemoglobin

C

5

1)

Which

drug

muscle

goblet

[1]

increases

protein

synthesis

in

adrenaline

B

antibiotics

C

insulin

stops

(Paper

9

tissue?

A

Drugs

the

movement

make

more

of

cilia

may

[1]

be

classied

as

useful

and

harmful

drugs.

(a)

Explain

(i)

(b)

(i)

why

drugs,

antibiotics

and

Name

(ii)

one

are

useful

drug

classied

as

drugs.

that

is

[4]

classied

drug.

as

a

[1]

testosterone

(ii) (Paper

2)

Explain

briey

named

is

why

the

drug

you

have

[1]

(Paper

182

to

2)

harmful D

cells

mucus

D

(Paper

stimulates

3)

classied

as

a

harmful

drug.

[2]

10

The

graph

the

UK

in

between

shown

and

1991

as

per

shows

which

the

number

alcohol

and

number

100 000

was

2006.

of

of

deaths

the

The

deaths

major

death

per

in

12

cause

rates

100 000

The

graph

smoked

are

1910

men

to

number

women.

over

shows

by

men

1980.

of

the

the

The

deaths

same

number

each

year

in

dotted

of

men

of

the

line

cigarettes

UK

from

shows

from

lung

the

cancer

period.

deaths

per

year

20 from

lung

cancer

noitalupop

18

16 males 14

000 001

4000

12

number

10

of

cigarettes 20 000

females smoked

8

rep

3000

6

shtaed

4 2000

2

deaths

from

0

per

lung

year

10 000

cancer

5

3

1

9

7

5

3

1

1000

0

0

0

9

9

9

9

9

0

0

0

9

9

9

9

9

2

2

2

1

1

1

1

1

year

Source:

is

Ofce

of

reproduced

National

with

the

Statistics.

permission

Crown

of

Public

(a)

Use

the

deaths

graph

in

to

which

describe

alcohol

the

Copyright

Controller,

Sector

the

was

material

Ofce

Information

trends

the

Calculate

rates

(c)

for

Cirrhosis

the

of

cirrhosis

among

between

the

consumption

of

percentage

men

liver

of

has

young

is

increase

1991

often

alcohol.

(a)

cause.

State

(i)

people.

in

by

number

the

Explain

UK,

how

(ii)

[2]

heavy

of

the

the

year

of

nd

out

if

the

cases

of

cirrhosis

increase

in

alcohol

increase

is

likely

to

in

the

Explain

why

inuence

(Paper

11

In

(a)

countries

prescription

Explain

these

to

(b)

alcohol

car

is

under

1980

which

there

was:

highest

number

of

cigarettes,

(b)

Describe

of

deaths

from

cancer.

what

[2]

happened

to:

(i)

cigarette

(ii)

deaths

consumption,

and

from

lung

cancer

over

the

you shown

by

the

graph.

[5]

number

due

to

(c)

an

[2]

Discuss

whether

evidence

to

lung

the

support

cancer.

graph

the

provides

idea

that

any

smoking

[3]

the

dangerous.

[3]

(Paper

4)

3)

many

on

of

a

1970

cases

consumption.

driving

in

consumption

lung

causes (d)

1960

especially

the

be

1950

highest

period would

1940

and

death

2006.

caused

The

increased

in

and

1930

year

[3]

(b)

1920

(OPSI)

in

major

1910

of

antibiotics

from

why

a

antibiotics

countries

are

available

rather

are

prescribed

than

freely

buy.

Explain

only

doctor.

in

available

[2]

why

antibiotics

do

not

kill

viruses.

[3]

(c)

Discuss

the

antibiotics.

(Paper

dangers

of

overusing

[4]

4)

183

16

Reproduction

16.1

Asexual

and

sexual

reproduction

Reproduction LEARNING

plants

•

Dene

means

producing

new

living

organisms.

Animals

and

OUTCOMES

asexual

and

are

sexual

reproduce

two

types

of

to

make

new

reproduction:

individuals

asexual

of

the

and

same

sexual

species.

There

reproduction

reproduction

Asexual •

Identify

asexual

In from

descriptions,

asexual

tnemelppuS

•

reproduction

there

is

only

one

parent.

All

the

offspring

diagrams

are and

reproduction

reproduction

identical

to

the

parent

as

they

inherit

exactly

the

same

genetic

photographs

Discuss

the

advantages

disadvantages

sexual

of

information.

They

means

there

is

due

the

are

genetically

identical

to

the

parent,

which

and

asexual

little

variation

amongst

the

offspring.

Any

variation

is

and to

effect

of

the

environment,

for

example

the

availability

of

reproduction nutrients

fungi

Bacteria

not

and

and

are

have

a

asexually

water

plants

determine

reproduce

microscopic

nucleus,

the

DNA

but

loop

how

organisms

a

loop

is

well

organisms

grow.

Bacteria,

asexually.

of

copied

made

DNA.

so

up

of

When

that

one

cell.

bacteria

there

is

They

do

reproduce

some

for

each

new

cell

cell.

membrane

You

can

nd

some

information

about

how

DNA

is

copied

on

DNA

page

cell

218.

wall.

parent

This

because

cell

duplication

of

the

mould

is

reproduces

specks

a

of

the

of

damp

cell

asexual

parent

cell

a

fungus

asexually

dust,

and

surface,

hypha,

grows

called

produce

divides

into

reproduction

splits

it

which

by

into

two

is

by

making

called

a

binary

new

cell

ssion

two.

grows

making

they

splits

of

over

a

spore

hundreds

oat

open

on

bread

spores.

through

and

a

(see

These

the

air .

thread

pages

are

When

grows

6

small

a

and

and

spore

out.

This

7).

It

light,

like

lands

on

the

surface

mycelium.

cases

new

or

of

bread

Eventually ,

sporangia

spores

are

at

formed

forming

short

their

a

dense

thread

or

network

hyphae

of

tips.

asexually

grow

Inside

by

upwards

each

division

of

and

sporangium

the

nuclei.

into

Each two

of

growth

cell

threads

division

bacterial

type

DNA

Pin

continued

The

wall

nucleus

gains

a

small

quantity

of

cytoplasm

and

a

protective

daughter

spore

cells

case.

When

ready ,

the

sporangia

break

open

and

the

spores

are

dispersed.

Potatoes

Figure

Each

16.1.1

new

identical

Binary

bacterial

to

each

cell

other

ssion

is

in

bacteria.

genetically

and

to

the

are

reproduce

swollen

Sucrose

is

asexually

underground

transported

in

by

stems

the

means

that

of

stem

grow

phloem

from

tubers,

from

the

the

which

parent

leaves

into

plant.

these

parent

underground

stems

that

swell

as

they

convert

the

sucrose

into

cell.

starch.

leaving

The

the

However,

‘seed’

from

one

the

farmers

sexual

organs.

184

to

parent

new

potato

Sexual

In

tubers

potatoes

regrowing,

of

parent

plant

in

dig

plant

the

are

shoots

as

at

the

ground

them

plant

known

dies

the

up

and

next

end

to

sell

year.

genetically

and

roots

of

survive

the

them.

All

growing

over

the

Some

from

are

kept

as

produced

When

the

season

winter.

tubers

identical.

emerge

the

they

start

growing

points

‘eyes’.

reproduction

reproduction

The

sex

there

organs

are

make

two

sex

parents.

cells

or

The

parents

gametes.

In

have

animals

sex

the

male

gametes

are

nuclei

are

egg

inside

cells.

structures

fuse

At

an

contain

one

which

half

comes

the

from

set

of

In

grains.

During

may

animals

the

The

A

the

female

into

a

egg

new

comes

The

zygote

or

are

the

from

a

inside

zygote

the

in

gametes

gametes

individual

nuclei

has

male

gametes

gametes

reproduction

gamete.

chromosomes.

the

fertilised

material

female

plants

female

sexual

grow

genetic

the

owering

In

plants

fertilisation.

embryo

half

cells.

owering

ovules.

at

fertilisation,

and

sperm

pollen

In

called

together

form

are

nucleus

to

plant.

male

the

divides

gamete

gametes

that

underground

stem

contains

developing

two

sets

of

chromosomes

–

one

from

each

gamete. tuber

Unlike

asexual

genetically

reproduction,

identical

to

the

the

offspring

parents.

Each

produced

zygote

are

‘eyes’

not

receives

half

its

genes young old

from

its

male

parent

and

half

from

its

female

parent.

This

means

tuber

tuber

that swelling

sexual

reproduction

brings

about

variation

in

the

with

offspring.

stored

Advantages

and

reproduction

An

advantage

can

plants

If

left

grow.

in

place

Plants

There

in

may

is

very

little,

reproduction.

affected

none

by

may

a

more

be

if

of

rapidly

tubers

any,

is

much

for

from

grow

with

asexual

growth

be

a

disease.

resistance

to

into

each

are

so

as

a

Since

Figure

new

than

plants

for

could

spread

which

all

the

potato

plant.

are

of

if

and

the

same

to

new

areas

many

seeds

wasted.

asexual

these

all

in

parent

seeds.

methods

individuals

genetically

they

may

all

are

identical,

very

quickly

through

a

crop

be

killed.

plants

plants

are

genetically

identical.

reproduce

asexually

by

monoculture, producing

in

The

resources.

However,

are

the

from

Potato

Disease

16.1.2

Organisms

where

dispersed

result

disease

fast.

other

many

they

is

areas

tubers

disadvantage

the

it

competition.

variation

can

that

colonise

reproduction

as

places

This

and

compete

sexual

certain

have

spread

potato

but

not

unsuitable

reproduction

to

grow

parent,

there

in

asexual

ground,

the

disadvantages

plants

rapidly

produced

where

land

the

as

Seeds

of

of

reproduce

in

If

tubers,

as

well

as

sexually

with

environmental owers.

conditions

features

rise

to

change,

adapted

variation.

adapted

to

adapted

if

species

the

the

are

it

to

In

is

unlikely

the

the

new

wild,

existing

able

to

there

conditions.

many

conditions

environment

better

that

as

and

their

If

be

Sexual

individuals

changes.

survive

will

individuals

reproduction

may

not

parents,

there

is

with

be

but

plenty

as

may

of

gives

SUMMARY

be

well

1

Explain

each

Asexual

Sexual

nuclei

reproduction

offspring

to

form

Binary

in

in

one

involves

zygote,

different

ssion

formation

a

results

from

reproduction

genetically

3

a

gamete

b

fertilisation

c

zygote

d

embryo

Describe

each

the

bacteria,

the

each

spore

are

all

production

of

of

th ese

fusion

of

male

offspring

other

and

of

that

their

production

examples

in

and

female

are

a

binary

b

spore

production

c

tuber

formation

parents.

fungi

asexual

and

asexu a l

reproduction:

genetically

parent.

producing

from

potatoes

in

of

ssion

Asexual

does

reproduction

not

result

in

may

variation

produce

of

many

tuber

3

reproduction.

offspring

as

individuals

in

sexual

in

bacteria

in

fungi

in

potatoes

Make

the

a

table

to

advantages

disadvantages 4

following:

POINTS

identical

2

the

evolve.

examples

1

of

variation,

2 KEY

QUESTIONS

well

rapidly,

but

tnemelppuS

tnemelppuS

starch

compare

and

of

asexual

it reproduction

and

reproduction

in

sexual

reproduction. plants.

185

16.2

Flower

Flowering LEARNING

the

structure

insect-pollinated

of

to

an

the

grains

ower

functions

of

have

carry

part • State

petals,

is

and

• Describe

and

out

sexual

female

reproduction

gametes

pollination.

and

pollen

to

parts.

the

female

Female

grains

grow

The

parts.

gametes

a

tube

male

by

producing

to

parts

The

are

transfer

deep

reach

make

owers,

inside

them.

pollen

of

the

Each

grains

pollen

female

pollen

tube

the a

male

gamete

so

it

can

fuse

with

the

female

gamete

to

form

anthers, a

stigmas

male

male

delivers sepals,

carry

OUTCOMES which

• Describe

plants

structure

zygote.

Fusion

of

male

and

female

gametes

is

fertilisation

ovaries

the

structure

of

a petals

wind-pollinated

• Compare

the

ower

adaptations

of anther

stamen

different

types

of

pollen

grain filament

stigma sepal

carpel

style

ovar y

ovule nectar y

Figure

16.2.1

Flowers

vary

A

in

half

ower

structure

Insect-pollinated

The

spiky

pollen

pollinated

from

grains

owers

and

wind-pollinated

are

the

from

smooth

grains

are

Flower

parts

swollen

owers.

•

Sepals

•

Petals

•

stalk

in

ies

a

smell

jump

in,

of

rotting

slide

esh

down

the

of

covered

the

out

to

186

plant

visit

in

pollen;

change,

another

after

a

to

attract

sticky

few

allowing

ower

of

days

the

the

upon

their

ower.

method

of

pollination.

owers

sepals

rings

form

attached

the

outer

to

ring

the

end

and

the

of

a

carpels

that

coloured

and

on

the

full

the

style

are

sugary

protect

the

scented.

nectar.

ower

Many

Visiting

when

have

a

insects

it

is

a

bud.

nectary

land

on

at

the

nectar.

male

sex

where

the

organs.

the

Each

pollen

anther.

In

is

this

one

is

made,

ower

made

up

of

two

and

the

lament,

there

are

four

a

stamens

ower).

female

and

an

inside

sex

organs.

Each

carpel

is

made

up

of

a

ovary.

the

ovary.

Each

ovule

has

a

female

gamete

–

cell.

pollen

in

The

in

structures

holds

the

arranged

makes

anther,

ovules

grains

the

ies

walls

are

of

insect-pollinated

photograph,

above

left.

owers

They

are

are

often

also

spiky

often

like

sticky.

ies

the

to

same

adapted

to

attach

to

hairs

on

the

surfaces

of

insect

The

bodies.

–

grains

become

dislodged

onto

a

stigma

when

an

insect

enters

and

another are

depending

insect-pollinated

Indonesia

The the

are

the

egg

grains produces

feed

a

those

Sumatra

to

are

The

stalk.

brightly

stigma,

The

from

an

ring.

which

Carpels

the

arum

are

in

often

leaf-like

which

(eight

•

are

Stamens

parts:

•

inner

base,

petals

are

ower

the

the

Titan

of

insect-

form

The

drawing

ower

of

the

same

species.

The

ower

in

Figure

16.2.1

has

walls

climb

species.

stigma

its

way

in

the

centre

towards

the

of

the

ower

nectary.

which

an

insect

will

push

past

on

a

Wind-pollinated

owers

STUD Y inflorescence

inside

spikelet

(group

a

single

T here

single

of

TIP

flower

flower

are

type s

of

feather y

flowers)

some

stigma long

man y

ow er .

with

a

differ ent

Look

hand

filament

and

mak

e

sure

anther

you

can

stamen

iden tify

filament style anther

parts

ovar y

hinge

desc ribed

differ ent 16.2.2

Grasses

and

perenne,

The

are

so

anthers

that

chances

on

a

small,

the

are

hang

The

feathery

positioned

They

large

act

like

a

surface

pollen

grains

that

get

wind.

that

the

Rye

grass,

wind-pollinated

inconspicuous

no

wind-pollinated

scent

are

wind.

small,

These

no

Lolium

ower.

compared

and

ower.

with

nectar.

smooth

owers

and

light

make

huge

The

ower

the

are

ower .

providing

for

the

a

a

catching

blown

into

T wo

them.

Wind-pollination

can

owers

lot

of

pollen,

anthers

which

produce

so

is

why

that

and

cereals

another

plants

much.

such

grow

means

be

close

that

likely

to

were

separated

as

by

and

showing

feathery

large,

loosely

stigmas.

But

the POINTS

grasses

to

one

pollen

transferred

Bromus,

anthers

the

KEY fact

of

waste attached

a

in

the

stigmas

area

a

of

here

ow ers.

away

outside

net,

on

example

by

of

main

landing

the

blow

an

have

grains

as

small.

outside

can

and

They

carried

grains

very

is

typical

green

grains

grass

pollinated

pollen

easily

pollen

wind

pollen.

also

of

are

rye

all

owers.

pollen

stigma

anthers

so

of

of

features

produce

they

numbers

are

many

insect-pollinated

The

species

cereals

has

owers

This

four

with

mobile

Figure

the

at

lens

is

than

large

1

more

if

Insect-pollinated

have

they

sepals

ower

distances.

Long

anthers

hanging

out

of

rye

grass

petals

in

to

to

the

owers

protect

bud

attract

and

the

bright

insects.

The

owers.

stamens

SUMMARY

consist

laments.

up

1

Copy

use

and

some

of

complete

more

the

than

sentences

using

these

words

(you

of

a

Each

stigma,

carpel

style

2

once):

carpels

pollen

Wind-pollinated

ovary

parts

of

a

ower

are

called

the

.

Each

is

of

an

and

a

lament.

the

.

The

female

The

parts

grains

are

Each

is

made

up

of

Make

a

owers

table

and

of

a

to

compare

the

wind-pollinated

,

pollen

a

ower

are

called

Compare

the

structure

of

an

style

and

of

that

insect-pollinated

large

carried

owers

quantities

pollen

with

on

the

Insect-pollinated

produce

ower

ower.

that

of

is

.

owers.

insect-pollinated

the

smooth

smaller

and

spiky

wind.

owers

quantities

pollen

of

that

a attach

wind-pollinated

are

feathery

the

sticky 3

anthers

Wind-pollinated

easily

2

owers

with

made

light, .

and

outside

produce inside

ovary.

made 3

up

and

stamens hang

male

and

made

stigma stigmas

anther

is

may

inconspicuous,

The

anthers

QUESTIONS

to

insects.

ower.

187

16.3

Pollination

Pollination LEARNING

• Dene

the

the

term

pollination

agents

transfer

Pollination

owers

are

different

adaptations

insect-pollinated

pollinated

adapted

agents

When

the

structural

may

of

of

to

be

pollen

carried

grains

one

pollination;

of

out

these

there

are

by

from

the

insects

methods.

others

or

anther

by

Insects

such

as

the

to

a

wind,

and

birds

wind

and

and

are

bats.

of

pollination

• Compare

the

stigma.

two • Name

is

OUTCOMES

and

of

wind-

an

its

pollen

to

bring

gamete

anther

so

that

the

so

is

it

splits

pollination

male

that

ripe,

gamete

open

can

occur.

(inside

fertilisation

along

a

can

its

length

Pollination

pollen

grain)

is

and

releases

needed

near

to

the

in

order

female

occur.

owers

tnemelppuS

• Distinguish

between

self-

pollination

and

cross-

pollination

and

discuss

Insect

Look

at

pollination

the

diagram

of

the

ower

below.

It

has

a

number

of

their adaptations

for

insect

pollination.

signicance

The

ower

tongues

is

and

pollinated

are

able

anthers

brushing

–

by

to

ripe

onto

bees,

reach

with

the

which

the

land

nectaries

on

at

petals.

base

of

Bees

the

have

long

petals.

stigma

pollen

insect’s

the

the

back

insect’s

back

stigma

and

closed

style

ring

of

hairs

stop anthers

ovar y small

ovule

the

insects

reaching

petals

nectar

form

landing

–

dead

pad

nectar y

Figure

Honey

bee

with

pollen

on

its

legs.

The

16.3.1

bees

anthers

brush

STUD Y

of

TIP

Whe n

you

po lli nated

a

hand

how

to

insect s.

able

you

do

at

owe rs

lens,

their

them

look

shou ld

for

no t

bee’s

When

against

such

back

the

the

sugary

in

bee

ripe

pollination

Look

the

at

one

nectar

a

as

way

it

to

made

that

pushes

enters

stigma

ower

in

the

sticky

its

another

and

another

of

from

down

ower,

pollination

same

nectaries.

pollen

head

the

it

is

to

species.

The

them

the

brushes

will

base

some

of

achieved.

a

of

outside

wind

the

pollination

ower

so

that

on

the

they

next

release

page.

their

The

pollen

by

owe r

seen

diagram

hang

the

wind

blows

them.

be

The

stigmas

they

act

as

are

a

feathery

net

to

and

catch

are

pollen

also

found

grains

in

outside

the

air.

the

ower,

where

Wind-pollinated

before . owers

by

the

grains

the

188

the

from

helps

po lli nated

this

the

Wind

when

have

upon

pollen

iden tify

anthers

Y ou

transfers

positioned

petals.

pollen

bee

insect -

with

struct ure

be

feed

are

against

the

the

A

have

wind

so

same

light,

to

that

smooth

another

some,

species.

by

Most

pollen

ower.

chance,

of

the

grains

The

which

anthers

will

land

pollen

can

easily

produce

on

the

produced

stigma

will

be

many

be

of

carried

pollen

a

lost.

ower

of

The

structural

features

of

insect-

and

wind-pollinated

owers

are pollen

compared

in

the

feature

caught

table.

insect-pollinated

owers

wind-pollinated

owers

pollen

present

–

colourful

and

absent

or

very

small

and

carried

petals scented

present

nectaries

which

food

to

–

is

make

a

for

attract

insects

difcult

to

by

see

nectar

sugary

liquid

pollinating

absent

insects lots

present

–

usually

with

long

laments

so

of

pollen

stamens

laments;

attached

rmly

laments;

for

to

hang

to

inside

insects

small

anthers

quantities

anthers

the

rub

outside

ower

the

against

of

easily

pollen

grains

light easily

to

blown

attached

so

Wind

pollination.

pollen

to

is

away

quantities

of

smooth,

that

pollen stick

loosely

16.3.2

ower;

sticky, large

spiky

the

laments

made

anthers Figure

short

wind

pollen

that

can

easily

insects’ be

carried

by

the

wind

bodies

sticky,

carpels

small

usually

for

stigmas

inside

insects

to

the

rub

large,

ower

catch

against

air

feathery

pollen

stigmas

grains

in

to

the

tnemelppuS

Hazel

Pollination

and

the

Self-pollination

a

stigma

of

the

catkins

release

pollen

to

be

carried

by

variation

occurs

same

when

ower

pollen

or

to

a

is

transferred

different

from

ower

but

the

on

anther

the

wind.

to

same KEY

POINTS

plant.

1 occurs

when

pollen

is

transferred

to

a

stigma

Pollination

pollen another

benet

plant

to

material

a

of

the

species

between

same

of

species.

plant,

different

since

plants

Cross-pollination

it

ensures

and

is

of

exchange

results

in

a

of

which

natural

selection

can

operate

greater

(see

Unit

results

in

much

less

variation,

since

of

the

male

to

the

stigma

exchanged

with

different

is

advantage

plants

but

with

the

part

an

if

there

are

no

plants

growing

in

isolation

from

others

of

genetic

same

material

one.

pollinating

the

of

the

petals,

same

Give

is

b

two

ways

Write

to

down

pollinated

in

the

three

and

pollen

pollen

other

from

from

insect-pollinated

wind-pollinated

differences

wind-pollinated

between

owers

owers.

tnemelppuS

a

What

is

the

difference

between

owers

with

are

feathery

anthers

anthers

same

of

to

the

ower

on

involves

pollen

the

self-pollination

and

of

from

stigma

or

a

hang

the

the

of

the

different

same

Cross-pollination

owers.

that

ower .

Self-pollination

ower

insect-

and

the

transfer 2

have

nectar .

species.

3

which

and

and

QUESTIONS

different

owers

scent

However ,

insects,

transfer

a

ower

female

ower.

Insect-pollinated

outside

1

the

the

is

stigmas

SUMMARY

of

anther

variation

inconspicuous for

of

of

Wind-pollinated self-pollination

the

18).

bright not

transfer

from

genetic

2 Self-pollination

the

grains

greater

part upon

is

of

plant.

involves

pollen

tnemelppuS

Cross-pollination

from

the

the

crossanthers

of

one

ower

to

the

pollination? stigma

b

State

the

advantages

of

cross-pollination

over

self-pollination.

a

of

another

different

plant

ower

of

the

on

same

species.

189

16.4

Fertilisation

and

seed

formation

LEARNING

OUTCOMES

Fertilisation State

that

fertilisation

owering

a

pollen

nucleus

plants

occurs

nucleus

in

an

in

fuses

when

with

a

Pollination

the

starts

ovule

to

tnemelppuS

nucleus. •

Describe

the

events

that

•

complete

part

grow

of

a

a

when

ower.

pollen

Fertilisation

the

If

tube

a

to

pollen

pollen

take

grains

grain

the

land

lands

male

occurs

when

the

male

occurs

inside

the

ovule.

on

on

nucleus

nucleus

the

a

stigma

ripe

to

the

fuses

of

stigma

it

female

with

the

lead

female to

is

female

nucleus.

This

fertilisation

State

the

requirements

germination

of

Each

for

the

seeds

of

pollen

ovule.

the

style

carries

the

The

the

ovary.

male

grain

As

it

and

carries

male

It

grows

grows,

enters

fertilisation

in

the

a

pollen

ovule

tube

tube

from

nucleus

nucleus

which

pollen

nutrition

gamete

gamete

a

the

with

through

then

zygote

fuses

is

to

take

gains

the

it.

a

tissues

The

formed

male

the

–

egg

fusion

the

style

the

cell

of

nucleus

from

pollen

hole

the

by

of

rst

small

with

the

nutrition

and

tube

reaches

micropyle.

nucleus.

the

to

tissues

two

This

is

nuclei.

germinating

pollen

A

pollen

(left)

grain

with

its

and

a

pollen

germinated

tube

and

pollen

male

grain

pollen

down

gamete

grain

tube

grows

style

nuclei.

ovule

STUD Y

TIP

Rem embe r

male

the

po lle n

deliv ered

gam e te

tube .

no t

that

gam e te

the

the

to

and

gamete

fuse

with

nucleus

egg

cell

about

nucleus

is

femal e

pollen

tube

penetrates

micropyle

po lle n

po lle n

male

male

inside

grai n

to

by

T he

the

is

the

grai n

is

Figure

16.4.1

Fertilisation

occurs

within

the

ovule.

gam e te.

PRACTICAL

Growing

Find

pollen

some

owers

particularly

Cut

some

transfer

sucrose.

anthers

dish

of

Scanning

grains

190

electron

and

pollen

micrograph

tubes

of

lily,

of

pollen

Lilium

sp.

for

small

Use

to

squares

to

a

the

24

forceps,

with

anthers

covered

in

pollen.

Lily

owers

are

suitable.

them

to

tubes

lter

of

paintbrush

squares

48

put

of

hours.

on

a

damp

paper

to

Visking

soaked

in

transfer

dialysis

Remove

microscope

a

(dialysis)

nutrient

some

tubing.

the

pollen

Leave

squares

slide

and

tubing

and

solution

in

grains

a

covered

carefully

observe.

rich

from

with

in

the

Petri

a

pair

tnemelppuS

•

Seed

formation KEY

After

fertilisation,

the

zygote

divides

and

grows

into

the

embryo. 1

The

ovule

forms

the

seed

with

the

embryo

inside

POINTS

Fertilisation

male

The

of

ovary

the

forms

ower

sepals,

the

are

petals

fruit

not

and

with

needed

stamens

the

seeds

when

wither

inside

it.

fertilisation

and

fall

off.

Many

has

of

the

occured,

They

have

parts

so

gamete

pollen

when

the

fuses

gamete

nucleus

the

with

nucleus

the

from

the

female

inside

an

ovule.

completed 2

their

occurs

it.

A

fertilised

egg

grows

into

functions. an

ovary

the

embryo

which

becomes

inside

now

an

forms

ovule

the

seed.

fruit seed

thin

with

The

ovary

forms

the

fruit

testa

containing

3

many

Germinating

seeds.

seeds

require

stone

water,

warm

oxygen

and

a

temperature

suitably

for

growth

skin

and

the

becomes

seed

4

Figure

16.4.2

How

a

plum

ower

grows

into

a

plum

Pollen

that

Each

fertilised

ovule

grows

to

form

a

seed.

Each

seed

is

made

up

the

The

embryo

ovary

forms

Conditions

Three

•

•

the

for

is

energy

store

•

a

seed

coat

or

grows

are

needed

of

some

down

an

ovule

in

SUMMARY

needed

for

seeds

for

to

seeds

swell.

to

Cell

from

seeds.

Cells

expansion

the

absorb

This

swelling

water,

breaks

develop

the

vacuoles

seed.

made

these

a

makes

Water

is

the

also

radicle

needed

(embryonic

to

dissolve

root)

the

Oxygen

is

State

what

happens

by

enzymes

from

the

food

stores.

occurs

when

in

grow

Water

plants.

Describe

the

role

of

the

also tube.

enzymes.

needed

for

aerobic

respiration

to

provide

the

What

happens

to

each

embryo

of with

to

soluble

c •

style

ovary.

seed

pollen activates

the

and

b products

the

the

tube

germinate:

owering

out

on

pollen

QUESTIONS

fertilisation

expand.

land

fruit

1

coats

a

testa.

germination

conditions

Water

an

that

produce

of: reach

•

grains

stigma

fruit.

the

following

after

energy.

fertilisation? •

A

suitably

warm

temperature

is

needed

so

that

enzymes

can

work

efciently.

i

petals

ii

ovule

iii

ovary

PRACTICAL

Conditions

for

germination

2

a

State

the

three

environmental Y ou

can

investigate

the

A

conditions

necessary

B

C

conditions

D

that

germination germination

Set

up

and

the

leave

checking

with

tubes

them

them

mung

as

for

a

b

to

germination

has

In

each

explain

week,

day

affects

see damp

if

of

the

seeds.

beans.

shown

every

affect

for

started.

case

how

in

part

the

a,

condition

germination.

cotton 















warm

warm

warm

cold

wool

c

Explain

why

the

seeds

in

oxygen

Only

the

seeds

in

A

have

all

tubes

B,

C

and

D

in

the

absorber

the

conditions

germination.

needed

for

temperature

Practical

box

(left)

did

not

germinate.

191

tnemelppuS

ovule

development.

16.5

The

male

reproductive

system

The LEARNING

or

•

Identify

of

the

on

diagrams

male

system

testes

are

the

male

sex

organs.

They

produce

the

male

gametes

OUTCOMES

and

the

parts

sperm

This

reproductive

state

spermatozoa

cells.

stimulates

during

their

The

–

a

word

testes

also

changes

puberty.

This

that

in

is

make

a

the

boy’s

happens

usually

abbreviated

male

body

between

as

hormone

he

about

to

or

testosterone.

develops

10

sperm

and

into

16

an

years

adult

of

age.

functions tnemelppuS

The

•

Compare

male

and

female

testes

outside

gametes

sperm

and

are

the

cells

be

need

stored.

cells

which

they

mature.

these

located

body.

uids

sac

the

puberty,

much

to

in

a

keeps

temperature

stored

A

tubules

secrete

a

After

are

inside

This

the

in

urethra.

which

the

tubules

cells

to

outside

the

can

hangs

gland

develop

produce

the

sperm

swim.

which

temperature

37 ˚C

prostate

sperm

scrotum

cooler

constantly

just

called

The

a

than

testes

tube

the

at

cooler

the

small

wider

called

testes

and

The

sperm

testes

duct

as

properly

where

connects

other

glands

prostate

seminal

vesicle

secretes

as

a

mucus

source

together

of

and

other

energy

form

for

semen,

glands

their

also

secrete

sugars

respiration.

known

as

which

Sperm

seminal

cells

sperm

and

cells

the

use

uid

uid.

prostate

gland

The

of

two

the

time.

any

sperm

penis.

A

ring

urine

ducts

Urine

of

join

and

muscle

from

the

with

the

semen

around

bladder

urethra,

never

the

pass

urethra

during

sexual

which

down

runs

the

contracts

down

urethra

to

the

at

centre

the

prevent

the

sperm

and

same

loss

of

intercourse.

urethra

spongy

tissue

Male

and

female

gametes

penis

Gametes

testis

the

are

female

specialised

sex

cells.

gamete

cell

that

is

is

The

male

called

the

adapted

gamete

ovum

for

is

or

called

egg.

swimming

the

The

by

sperm

having

a

cell

is

a

agellum

that

foreskin

lashes

male

from

side

parent

to

to

side.

the

egg

Sperm

of

the

cells

carry

female

genetic

parent.

The

information

nucleus

from

contains

the

the

scrotum

father’s Figure

16.5.1

Male

reproductive

chromosomes.

provides front

An

egg

is

much

bigger

than

a

sperm

because

system:

the

food

store

that

supports

the

embryo

after

fertilisation.

view.

bone

rectum

acrosome

middle

the

piece

like

head

the

containing

flagellum

a

whip

sperm

(tail)

and

beats

drives

for ward

enzymes

a

sperm

cell

nucleus membrane

containing

chromosome

membrane

anus

cytoplasm sperm

an

egg

tube jelly

a

coat

sperm

same

this nucleus sperm

tubules

in

on

scale

the

as

egg

containing

testis chromosomes

Figure

16.5.2

Male

reproductive

system:

Figure side

192

view.

16.5.3

Structure

of

a

human

sperm

(top)

and

an

egg

(bottom).

it

Its

nucleus

half

the

haploid

are

contains

number

cells.

of

Body

described

as

the

mother’s

chromosomes.

chromosomes

cells

have

the

as

body

normal

cells.

Gametes

They

number

of

are

contain

described

chromosomes

as

STUD Y

Egg

diploid.

cells An

egg

is

fertilised

by

a

sperm

cell.

The

head

of

the

sperm

to

membrane

The

the

sperm

two

help

of

it

the

reach

sperm

nucleus

nuclei

fertilisation,

cell

moves

fuse

the

the

coat

fuses

to

of

the

with

through

together

jelly

surface

the

form

changes,

the

cell.

egg

zygote

that

no

The

cell

cytoplasm

a

so

egg

cell

func

membrane.

of

the

egg

(fertilised

more

cells

are

egg).

sperm

you

and

can

adap ted

tions

can

featur es

After

these

enter.

and

sperm

specia lised

contains

cells enzymes

TIP

and

.

fo r

Mak

state

and

adap t

their

e

sure

their

key

explai n

them

fo r

how

their

tnemelppuS

func tions .

Comparing

male

and

feature

sperm

size

small

female

gametes

cell

egg

cell

much

swims

using

agellum

(or

that

lashes

from

not

store

very

sugar

for

number

move

along

itself

the

–

is

oviduct

and

by

peristalsis

side

has

energy

cell

side cilia

to

sperm

tail) moved

(mobility)

than

its does

movement

larger

little

in

–

uses

seminal

protein

uid

and

cytoplasm

respiration

until

fat

–

in

enough

implantation

to

in

last

uterus

of 23

(haploid

number)

23

(haploid

number)

chromosomes

constantly

produced

produced

puberty)

sperm

swimming

pathway

cell

by

has

the

through

the

The

jelly

SUMMARY

QUESTIONS

1

complete

Copy

and

semen

urethra

sperm

The

male

the

cells

gametes

which

pregnant

releases

contains

surrounding

sentences

testes

penis

are

after

contraceptive

acrosome

coat

month

menopause,

when

life

mitochondria,

tail.

a

until

often

throughout

Each

one

(after

using

energy

called

these

duct

and

taking

a

to

that

power

digest

a

egg.

words:

ejaculation

sperm

or

pill

enzymes

the

puberty

except

are

prostate

Human

made

in

the

organs

the

.

from

to

or

each

tnemelppuS

a

tube

testis.

form

.

and

2

A

which

Give

out

three

called

an

adds

the

erect

differences

within

carries

gland

During

the

contained

the

The

of

are

the

uid

semen

to

a

sac

sperm

the

passes

cells

and

away

sperm

along

1

The

male

consist

cells

sperm

the

egg

cells.

2

The

Explain

how

sperm

cells

and

egg

cells

are

adapted

for

of

fertilising

reproductive

the

ducts,

and

sperm

smaller b

sperm

an

POINTS

urethra

sperm

and

called

.

between

(top)

male KEY

sex

sperm

egg.

scrotum

testes,

organs

scrotum,

prostate

gland,

penis.

cells

than

are

the

tnemelppuS

millions

number

much

female

egg

their cell.

They

are

produced

in

functions. huge

to

numbers

swim

using

and

a

are

able

tail.

193

16.6

The

female

reproductive

Ovaries LEARNING

Identify

of

the

on

diagrams

female

system

female

sex

organs

that

produce

the

female

gametes

OUTCOMES called

•

are

system

and

the

parts

or

oestrogen

between

reproductive

state

ova

eggs.

and

10

The

ovaries

also

progesterone,

and

15

years

of

make

which

age

the

starts

during

female

to

hormones

happen

with

girls

puberty.

their Oestrogen

stimulates

the

development

of

the

sex

organs

and

functions secondary

•

State

the

the

parts

functions

of

the

reproductive

of

develop

female

ready

sexual

into

to

an

characteristics

adult.

receive

an

in

a

Progesterone

embryo

in

the

girl’s

body

prepares

case

of

a

as

the

she

starts

uterus

so

to

that

it

is

pregnancy.

system The

ovaries

kidneys.

oviduct

28

The

ovaries

months.

The

egg

moves

lining

attached

puberty,

days.

openings

uterus

are

After

of

the

slowly

If

sperm

If

the

cells

egg

is

are

not

tend

passes

the

the

egg

to

out

oviduct

down

to

an

in

a

inside

is

release

of

the

present

in

fertilised

it

an

eggs)

into

just

ovary

the

uterus

egg

about

will

a

below

about

on

the

every

alternate

funnel-shaped

ovulation.

the

the

after

an

(or

and

called

oviduct

die

abdomen

from

egg

towards

the

will

the

ovary

process

oviduct

of

released

The

egg

(womb).

be

day.

If

fertilised.

the

egg

is

ovar y

fertilised uterus

of

will

divide

to

form

an

embryo

it

develops

which

may

attach

itself

to

wall

the

cer vix

it

lining

of

the

uterus

where

into

a

fetus.

(neck

uterus)

vagina oviduct

uterus

opening

of

Figure

vagina

16.6.1

Female

rectum

reproductive

system:

front

view.

bone

STUD Y

TIP

urethra

T he

are

testes

the

and

sex

gona ds

–

ovar ies

orga ns

the

or

orga ns clitoris

that

or

fo rm

gam e tes.

secre te

–

the

the

T hey

sex

testos terone ,

and

that

their

sex

can

also

ho rm

ones

oestro gen

prog estero ne.

you

cells

Be

anus

sure

compa re Figure

func

tions

The

It

lower

leads

to

outside

of

the

Above

vagina

birth

194

16.6.2

Female

reproductive

system:

side

view.

.

of

end

a

of

the

body.

urethra

the

is

the

as

tube

is

the

it

is

the

has

a

called

Above

through

urethra

called

canal,

uterus

muscular

the

which

The

through

of

urine

of

from

clitoris.

vagina

here

muscle

vagina

opening

sensitive

vulva.

ring

the

that

is

a

the

the

called

that

vagina

bladder

The

outer

sometimes

baby

the

opens

passes

is

cervix.

to

the

the

opening

passes

opening

known

at

as

birth.

out.

of

the

the

Sexual

During

is

intercourse

sexual

pumped

The

erect

made

by

penis

the

the

vagina.

the

sperm

towards

As

they

are

the

to

the

vagina

movement

move

to

secretions

form

females

in

the

vagina

cells

stimulate

penis

during

lubricates

stimulates

sperm

seminal

and

against

from

semen

uid

at

orgasm.

or

into

and

tissue

the

so

each

that

sexual

penis

the

and

other .

of

the

around

erect.

Fluid

penis

contractions

tubules

Blood

becomes

intercourse.

movements

from

it

within

begin

the

in

testes

penis.

ow,

an

clitoris

of

males

spongy

placed

walls

ejaculation

called

is

This

the

the

special

ducts

added

move

intercourse

into

or

the

through

this

time

vagina

the

the

Repeated

the

glands

seminal

including

uid.

penis

man

into

the

experiences

movements

walls

may

the

prostate

Contractions

of

also

the

of

vagina.

This

feelings

erect

produce

the

of

penis

gland

urethra

is

an

pleasure

against

orgasms

for

the

the

3

woman.

up

to

Each

500

ejaculation

million

SUMMARY

1

Copy

out

correct

contains

sperm

between

2

to

5 cm

of

semen

with

cells.

QUESTIONS

the

list

function

of

organs

from

ovary

carries

vagina

a

oviduct

receives

cervix

carries

uterus

produces

ring

the

urine

of

list

out

muscle

the

on

on

of

left

the

the

at

penis

the

the

and

match

each

with

its

right.

body

opening

during

sexual

of

the

uterus

intercourse An

the

egg

eggs

from

and

the

ovary

female

If

egg

the

hormones

cell

sexual

time

of

fertilisation

urethra

2

Look

a

the

at

the

Name

place

where

diagram

the

of

the

a

fetus

female

b

Where

reproductive

system

to

G

A

there

is

ovulation.

at

a

around

chance

that

occur.

POINTS

B

the

do

each

The

female

following

reproductive

of system

the

at

below:

1

diagram

ovulation

will

ovary

happens

parts

A

on

the

develops

KEY labelled

leaves

intercourse

consists

of

the

ovaries,

take oviducts,

uterus,

cervix

and

place? vagina.

i

the

production 2

G

of

The

ovaries

which

C

ii

fertilisation

iii

development

are

oviducts

F

of

an

3

The

the

released

eggs

at

into

ovulation.

oviduct

is

the

organ

embryo where

iv

produce

oestrogen

passage

D

The

fertilisation

uterus

is

the

occurs.

organ

in

E

of

the

baby which

during

Some

women’s

oviducts

can

get

blocked.

Explain

why

with

blocked

oviducts

would

be

unable

to

fetus

have

able

whereas

to

have

a

later

a

woman

with

only

one

blocked

develops.

The

oviduct

cervix

is

a

ring

of

muscle

a that

baby,

and

a 4

woman

embryo

birth the

3

the

may

separates

the

uterus

be from

the

vagina,

birth

canal.

which

is

the

baby.

195

16.7

Fertilisation

and

implantation

Human LEARNING

There •

Describe

fertilisation

in

Describe

the

are

millions

an

egg

muscular

of

the

a

ball

of

cells

that

sperm

swim

in

a

man’s

from

the

semen.

vagina

to

If

one

the

of

them

oviduct

–

is

to

the

into

the

tube

that

links

the

ovary

to

the

uterus.

uterus

intercourse,

sperm

cells

swim

through

the

mucus

in

the

cervix

into

is

the implanted

must

zygote

After form

it

early

development

to

of

humans meet

•

fertilisation

OUTCOMES

uterus

and

then

all

the

way

to

the

oviduct.

Many

sperm

cells

do

wall

not

survive

produced

this

–

to

difcult

increase

journey ,

the

which

chance

of

is

why

some

so

of

many

them

a

sperm

reaching

fertilisation

cells

the

are

oviduct.

forms

sperm

head

of

one

penetrates

sperm

egg

membrane

jelly

coat

changes nucleus

of

other sperm

stop

fuses

sperm

with entering

egg

to

successful

the

egg

b

nucleus

at

ovulation

an

egg

into

tail

ovar y

sperm

Figure 16.7.2

STUD Y

Events

at

16.7.1

If

TIP

the

time

nucle us

rst .

T he

divisi on

durin g

T his

of

divide

nucle ar

is

there

the

that

the

same

chrom osom es

See

page

abou t

this.

sperm

After

is

an

218

the

in

a

in

fertilisation.

egg

nucleus

contains

readiness

oviduct,

is

46

for

through

has

fuses

with

as

and

it

rst

the

the

egg

division

the

succeed

the

egg

to

sets

start

which

the

in

head

surrounding

father.

these

on

is

left

form

of

the

of

the

membrane

agellum

nucleus

two

the

and

may

coat

with

and

from

cell

acrosome

jelly

contains

one

cell

the

fused

chromosomes

the

sperm

by

cytoplasm

diploid

mother

a

released

membrane

the

which

the

the

pathway

sperm

from

now

the

outside.

zygote

chromosomes

The

zygote

being

occurs

the

egg.

–

nucleus

copied

shortly

after

fertilisation.

This

to

So

stops

fertilise

can

take

if

other

the

sperm

egg.

place.

an

egg

If

cells

there

However,

intercourse

fertilise

196

and

Enzymes

enters

sperm

nucleus

one

egg

it.

digest

nucleus

The

mito sis.

gene tical ly

iden tical .

more

divide s

occu rs

sure

have

num ber

for

that

of

grow th

all

are

cell

mus t

type

mak es

cells

and

a

Ovulation

fertilisation.

penetrating

Every

released

oviduct

of

successful

Figure

is

the

if

the

happened

it

is

from

is

no

entering

egg

sperm

just

released

in

can

before

during

so

the

only

stay

alive

ovulation,

this

one

oviduct,

time.

sperm

no

for

the

2

is

able

fertilisation

or

3

sperm

days.

can

Implantation

Fertilisation

zygote

Then

while

to

it

this

a

place

to

continues

divide

After

takes

begins

cycle

while

few

oviduct,

beating

of

to

of

to

give

or

along

ciliated

by

four

slow

embryo

is

a

to

less

this,

form

cells

the

a

and

hollow

the

of

lining

the

at

of

cells

which

cells.

contractions

cells

eight,

Some

rate

ball

fertilised

two-celled

then

regular .

down

peristaltic

epithelial

After

once

becomes

stop

the

oviduct.

divides

divisions

hours

the

the

It

divide

others

pushed

in

divide.

It

egg

but

after

a

continue

they

moves

the

or

embryo.

divide.

down

oviduct

and

the

the

oviduct.

cell

divisions

form

an

embryo

a

ball

of

cells

forms

zygote

divides

zygote oviduct

implantation

of muscular

of

uterus

lining

of

Figure

16.7.3

Implantation

of

the

embryo

wall

developing

ovary

placenta

uterus

embryo.

DID It

may

The

take

a

embryo

number

embeds

implantation.

contains

oxygen

these

wastes

days

into

the

uterus

numerous

from

chemical

The

of

blood

blood

diffuse

for

the

soft

lining

lining

has

vessels.

vessels

out

in

embryo

the

the

embryo

diffusion.

opposite

reach

the

uterus.

thickened

The

by

of

to

in

This

is

called

preparation

obtains

Carbon

YOU

and

nutrients

dioxide

and

and

Eggs

cell

than

a

to

QUESTIONS

1

complete

and

zygote

sperm

Sperm

cells

The

through

the

one

of

cells

and

these

the

swim

then

words:

implants

fertilisation

the

sperm

using

ovaries

vagina

enter

made

sentences

sexual

cells

intercourse.

the

weeks

female

through

of

the

enter

about

the

every

eggs

ostrich

into

the

present.

oviduct

The

where

which

lining

2

a

of

the

How

fertilised

the

cervix

An

four

passes

down

or

to

and

egg

.

take

were

the

uterus

up

KEY

cells

are

needed

where

to

Why

does

a

membrane

form

around

to

State

the

following

a

an

human

egg

b

a

of

chromosomes

in

it

fertilise

the

the

sperm

cell

c

a

long

equivalent

Fertilisation

of

the

in

the

2

For

an

egg

nuclei

occurs

a

and

of

seven

when

sperm

nucleus

fertilisation

place

egg?

and

must

a

cell

of

to

an

the

fuses

egg

cell.

occur,

have

sperm

reached

the

taken

cell

must

oviduct.

after

of

the

The

a

zygote

ball

of

embryo,

cells:

Aepyornis

bigger .

an

3

number

60 cm

the

if

form

fertilisation?

3

bird,

of

POINTS

have b

eggs

even

bigger

weighs

eggs.

ovulation

sperm

times

and

egg

uterus.

many

largest

the

is

The

place

divides

the

were

is

during

oviduct.

may

egg

24

The

elephant

with are

is

egg

1.36 kg.

nucleus passes

It

The

today

embryo

1 in

egg.

weighed

uterus

cells.

world

hen’s

maximus,

Its

Copy

single

the

ostrich

up

direction.

are

in

extinct

SUMMARY

KNOW?

uterus.

divides

cells

which

the

oviduct

the

lining

to

called

form

the

passes

and

down

implants

in

zygote of

the

uterus.

197

16.8

Pregnancy

Pregnancy LEARNING

OUTCOMES

Pregnancy •

Outline

the

growth

humans development

of

the

State

the

functions

of

cord,

sac

the

and

tnemelppuS

Describe

the

placenta

and

embryo

its

functions

of

umbilical

that

some

support

toxins

can

and

cross

affect

The

its

The

so

has

and

orga ns

the

featur es

is

know n

have

embr yo

that

The

The

the

hum an,

a

One

is

It

•

are

it

as

the

the

food

area

and

a

a

fetal

there

and

supp lies

is

why

featu res

large

are

the

These

site

the

to

lining

gain

projections

cord

of

other

cord

grows

sac

of

the

or

attaches

makes

the

attach

which

of

to

the

and

grow

fetus

surrounds

oxygen

they

fetus

blood

to

amniotic

mechanical

it

oxygen

into

to

the

the

it.

and

diffuse

nutrients

between

fetal

for

blood

to

and

uid

damage,

for

the

placenta

from

to

the

surround

example

and

contains

placenta.

and

when

protect

the

the

mother

movements.

in

the

development

are

after

into

summarised

fertilisation,

tadpole.

where

months

toes

The

Three

are

a

as

human

embryo

a

baby

ready

to

be

born

at

follows.

does

embryo

not

yet

looks

have

a

bit

arms

like

or

a

legs,

sh

but

months

the

the

mother

Seven

the

It

the

is

The

heart

embryo

now

has

has

called

a

a

started

face,

fetus.

and

other

to

beat.

limbs,

Most

ngers

of

the

and

for

carries

fertilisation

the

nerves

and

muscles

fertilisation,

has

perfectly

body

the

hair.

last

after

carbon

wastes

of

the

fetus

rapidly.

after

months

arter y

human.

after

fetus

ngerprints

•

develop.

formed.

months

length,

will

fertilisation

looks

developing

Five

these

after

and

Its

although

formed

only

about

eyebrows,

movements

may

180

from

mm

in

ngernails,

have

been

felt

by

month.

fertilisation

development

is

almost

complete.

dioxide

the

dioxide

and

wastes

fetus

smal l

diffuse

into

from

the

the

fetal

mother ’s

blood

blood

distan ce

the

betw een

blood

blood

maint ain

grad ients

vein

from

the

brings

oxygen

placenta

to

and

the

food

fetus

28).

oxygen direction

of

blood

oxygenated

into

Figure

16.8.1

blood

blood

The

role

the

food

diffuse

mother ’s

blood

mother ’s

blood

deoxygenated

and

flow from

198

in

period

uterus,

nutrients

continue

to

exchange

wastes;

transport

pregnancy

month

T wo

the

page

into

tissue

surfa ce

Sinc e

good

conc entra tion

(see

soft

carbon

the

matern al

to

•

the

subst ance s

short

are tw o

gas

for

where

and

diffus ion.

exchan ges

the

T his

same

lung

intes tine:

for

also

absorb ed.

has

is

surfa ce

is

the

amniotic

and

to

stages

of

clear

are

fetus.

which

fe tus.

TIP

disso lved

birth,

gestation

blood.

sudden

organs

placen ta

the

sac

against

main

and

T he

and

the

it

•

exchan ge

is

vessels

amnion

end

it

STUD Y

lls

dioxide

embryo

as

called

are •

recogn isably

it

umbilical

makes

the

implanted

into

umbilical

maternal

fetus

TIP

all

is

fetus

•

Once

has

growth.

An

placenta

blood

fo rm ed

fertilisation

time

the

the

•

STUD Y

of

and

and placenta

between

the

carbon pathogens

time

period

cord

• State

of

This

uid

placenta

•

period

projections

placenta. •

the

months.

placenta,

to amniotic

9

the

grows umbilical

is

fetus

After •

is

and

of

the

placenta.

the

fetal

blood

placenta

dissolved

features

a

short

and

is

food

as

fetus

amino

excreted

an

some

umbilical

placenta

and

Amniotic

similar

sac

into

to

the

should

Young

be

the

HIV

with

can

fetus

returns

from

from

to

and

the

the

has

also

the

surface

are

to

including

water.

where

same

area

between

supplies

and

fetal

maintain

glucose,

The

mother’s

it.

placenta.

blood

oxygenated

ltered

the

have

blood

fetus’

skin

developed

the

The

barrier

a

uid

fetus

blood

The

from

and

are

the

uid

to

has

shed

fetus

to

be The

fetus

at

26

days.

a

The

fetus

at

8

weeks.

The

fetus

at

5

months.

contains

fetus

the

to

the

fetus.

composition

into

the

carries

lungs.

does

cord

the

blood

the

into

amniotic

and

disease.

that

be

causes

positive

if

management

to

a

child

the

is

The

not

amnion

out

some

fetus

provide

may

during

who

the

This

before

vaccinated

mother

pathogens.

since

cross

is

is

the

carry

a

why

they

urinates

any

is

However,

still

virus

all

can

young

act

with

a

the

mother

the

virus.

even

susceptible

that

become

placenta,

infected

not

by

they

pregnancy

does

fetus

caused

fetus.

rubella

AIDS

the

and

environment,

harm

also

toxins

measles)

against

for

the

to

sterile

(German

should

birth

into

deoxygenated

taking

a

is

placenta

careful

give

as

vaccinated

HIV

mother,

it

is

fetus.

acts

virus

born

why

large

blood

vitamins

diffuses

the

that

drinks

womb

men

its

organs

Rubella

infection

The

be

the

disease.

across

of

for

from

is

a

It

kidneys.

Cells

the

This

fetus.

exchanges

good

food

formed

and

placenta

though

is

two

the

28).

joins

vein

Since

ions,

the

intestine:

page

which

her

movements

uid

nutrients

The

a

when

the

urea

for

absorbed.

small

are

mineral

plasma.

breathing

its

surface

(see

transports

uid

to

and

all

cord

that

there

gradients

fats,

are

the

diffusion.

blood

through

artery

exchange

and

for

obtains

acids,

produces

The

lung

distance

maternal

gas

substances

the

concentration

The

the

can

get

women

pregnant.

as

so

a

a

baby

virus.

who

reservoir

may

However,

is

HIV+

Nicotine

can SUMMARY

also

pass

across

the

placenta

(see

Topic

1

a

How

to

b

is

the

List

two

in

1

The

fetus

size

and

grows

and

develops

inside

the

uterus.

It

increases

all

the

major

The

umbilical

the

site

of

the

amnion

cord

attaches

exchange

of

the

fetus

substances

amniotic

the

What

is

to

the

between

placenta,

fetus

which

and

is

in

tnemelppuS

The

uid

to

protect

the

fetus

the

has

diffusion

of

mother’s

blood.

What

a

large

surface

area

for

gas

exchange

long

does

it

last

are

the

and

functions

amniotic

of

the

uid?

Describe

nutrients

and

waste

between

fetal

blood

structure

and

pathogens

cross

the

placenta

into

efcient

the

acts

as

a

barrier

to

many

in

the

which

placenta

fetal

diffusion

blood

and

fetus; mother’s

placenta

ways

of

and

between

toxins

two

and

helps

the

gestation

How

damage.

placenta

Some

pass

direction.

from

the

4

opposite

and

that

mother;

4 3

fetus

humans?

amnion mechanical

the

that

mother’s

organs.

3 makes

to

the

substances

period?

2

connected

in 2

develops

fetus

substances

from

blood

POINTS

the

placenta?

two

pass

KEY

QUESTIONS

16.9).

blood.

others.

199

tnemelppuS

tnemelppuS

The

16.9

Ante-natal

care

and

birth

Ante-natal LEARNING

Ante-natal •

Describe

the

ante-natal

pregnant

Describe

the

while

in

labour

and

tnemelppuS

Describe

the

she

advantages

disadvantages

provides

of

the

is

breast

important

so

iron

the

and

•

calcium,

•

iron,

so

carry

blood

that

right

the

nutrition

mother

obtains

all

Particularly

calcium.

vital

and

has

the

for

also

the

health

needs

protection

a

balanced

nutrients

important

as

the

that

•

to

of

the

make

sure

for

the

fetus

it

diet

needs

during

for

this

growth

are

vitamins

and

and

minerals,

•

her

protein,

new

They

to

preparation

therefore

amnion

at

7

to

8

weeks

that

provide

for

need

body

in

are

the

Her

the

the

the

birth.

will

need

to

ensure

such

that

she

growing

extra

growing

extra

red

iron

blood

pregnant

red

blood

fetus

in

is

the

cells

mother

diet

that

has

cells

also

needed

making

to

make

carries

enough

red

more

oxygen

energy

to

around

amino

mother

making

fetus

make

substance

so

The

the

fetus.

both

the

heavier

tissues.

of

can

the

woman

of:

body

to

carbohydrate,

move

pregnant

bones

her

oxygen

cells.

A

quantities

haemoglobin,

the

the

fetus

adequate

to

inside

is

mother

milk

gets

fetus

birth,

The

milk

as

A

before

womb.

pregnancy.

development. formula

care

the

and time

and

or

in

birth

It •

is

processes during

involved

it

women that

•

care,

care fetus

of

care

OUTCOMES

The

many

acids

makes

fetus

new

that

muscle

is

also

they

tissue

both

in

growing

the

and

need

to

uterus

make

in

developing

and

cells.

of

The

mother

should

not

smoke

since

nicotine

and

carbon

monoxide

pregnancy.

cross

the

babies.

also

placenta

She

crosses

birth

should

the

defects

placenta

so

and

can

drink

no

placenta

and

in

premature

alcohol,

and

mental

some

result

can

or

retardation.

babies

are

very

cause

born

a

small

variety

Drugs,

with

or

an

underweight

quantities,

of

such

effects

as

addiction

heroin,

to

as

alcohol

including

cross

the

heroin.

Birth

A

placenta

the

born

pregnancy

prematurely,

takes

about

perhaps

9

months.

because

there

In

has

some

been

a

cases

babies

problem

are

during

amniotic

cavity

the

normal

pregnancy.

An

early

fetus

most

breaking

of

the

membrane

(amnion)

around

the

fills

uterus

A

is

few

the

weeks

common

before

This

positions

and

the

its

birth,

head

build-up

of

reason.

the

above

fetus

the

pressure

in

usually

cervix.

the

turns

over

Hormones

uterus

inside

released

stimulate

the

by

hormonal

uterus.

the

fetus

changes

in

fetus

(50 cm)

the

mother .

A

hormone,

oxytocin,

is

released

from

her

pituitary

gland

that

uterus

stimulates

cer vix

small

16.9.1

Position

before

200

of

the

birth.

baby

just

muscles

contractions

These

Figure

the

of

contractions

contractions

breaks,

slowly

allowing

of

the

the

uterus

become

stretch

the

uterus

to

wall.

This

stronger

the

amniotic

contract.

and

opening

uid

is

to

the

The

beginning

more

of

mother

the

escape.

of

frequent.

cervix

starts

and

to

feel

labour

Stronger

the

amnion

The

to

muscles

push

the

the

baby’s

takes

the

and

The

baby

It

umbilical

attaches

navel.

wall.

The

to

After

It

is

a

for

of

is

contract

cervix.

through

As

tied

baby.

few

the

now

soon

that

The

the

as

it

the

very

cervix

widens

vagina.

is

born

baby

strongly

This

the

has

and

or

part

baby

airways

start

dilates

of

the

breathes

clear

of

and

birth

for

mucus

easily.

pushed

process

painful

the

important

cord

the

wall

pushed

quickly.

is

breathe

uterus

towards

is

quite

time.

can

the

head

place

rst

of

and

The

minutes

out

labour

of

the

the

with

mother .

cut

just

remains

above

the

placenta

vagina

the

She

of

as

help

the

point

heal

comes

the

muscular

can

the

cord

to

away

where

form

from

it

the

the

baby’s

uterus

afterbirth

contractions

process

by

A

of

the

gentle

uterus

newborn

body

before

Pain-killing

may

the

be

drugs

given

space

labour

by

can

an

between

and

also

by

be

epidural.

the

spine

breathing

given

This

and

to

in

ease

involves

the

a

special

the

pain

inserting

spinal

cord.

way

during

during

a

of

impulses

from

pain

receptors

to

The

the

drugs

umbilical

cord.

of

These

(tube)

prevent

1

into

POINTS

During

the

labour

uterus

the

wall

muscles

in

contract.

the 2

transmission

its

labour .

birth.

catheter

with

is

exercises

KEY

the

baby

At

birth,

the

baby

passes

out

brain. of

the

breath.

and

The

takes

its

umbilical

cord

Breast-feeding is

This

is

her

so

Breast

pregnancy

that

milk

soon

the

after

contains

glands

birth

in

she

the

is

mother’s

able

antibodies

which

the

that

to

breasts

produce

pass

to

the

will

enlarge.

detaches

milk.

baby

passes

and

give

immunity

to

diseases

the

mother

has

had

immunity

(see

Topic

10.3)

means

that

the

child

antibodies

in

the

blood,

but

is

unable

to

The

antibodies

remain

in

the

child’s

blood

has

produce

while

it

for

a

short

time

afterwards.

Breast-feeding

also

to

form

between

mother

and

baby

that

is

is

a

research

has

shown

that

breast-feeding

is

to

and

develop

mothers.

certain

Mothers

are

Children

diseases

less

likely

such

to

who

as

are

benecial

breast-fed

childhood

develop

cancers

cancers

of

breast,

are

less

and

iron,

protein

it

women

difcult

Formula

or

milk

convenient,

comes

it

in

needs

with

to

to

may

but

be

water

do

not

be

In

to

breast-feed

They

their

therefore

rely

to

avoid

Breast

milk

likely

not

with

be

the

that

it

contains

Formula

and

that

protect

or

they

it

form

SUMMARY

1

Describe

places

each

able

the

risk

milk

milk

QUESTIONS

of

what

the

birth

happens

following

of

a

to

during

baby:

of the

muscles

b

in

the

the

uterus

cervix

or the

amnion

and

amniotic

also d

the

placenta

whereas

does

not.

sometimes

Make

a

table

simply

to

show

the

Of

and

disadvantages

breast-

of feeding

from

nd

advantages course,

baby

infections.

bottle-feeding.

2 milk

the

ovaries.

uid

money,

notably

antibodies

infections

non-sterile

breast

advantages

milk,

to

c

costs

drugs

more

sterile

some

getting

bottles.

smoking,

has

formula

wall

from

She

both

a

babies

diet.

diabetes.

womb

babies

on

her

mixed

under

may

this,

able

since

powdered

conditions.

women

are

embarrassing.

in

alcohol.

common

Some

enough

carbohydrate

both.

over children

involves

having

close

4 Medical

and

breast-fed

enables

benecial

uterus

afterbirth.

them

and

bond

placenta

the

should

and

the

the

care

mother

and

itself.

as

Ante-natal

calcium,

mother’s

from

out

The

recently. the

Passive

cut.

it 3

passive

and

tnemelppuS

During

tied

isn’t

breast-feeding

and

bottle-

an

feeding. option

at

all!

201

tnemelppuS

tnemelppuS

rst

vagina

16.10

Sex

hormones

Puberty LEARNING

You •

Describe

the

testosterone

developing

roles

and

oestrogen

secondary

characteristics

are

at

the

only

ovary

testes

start

time

uterus

the

lining

from

the

Whe

n

Paper

you

4 ,

mak e

no te s

they

10

become

and

14,

the

follicles

your

life

start

is

to

called

develop

in

the

ovaries.

puberty

than

person.

boys.

The

The

actual

changes

that

age

take

of

puberty

place

by

hormones.

At

the

beginning

of

puberty

the

are

all

pituitary

the

base

the

testes

of

the

make

the

sex

which

in

testes

brain

the

starts

to

make

hormones

that

organs

develop

ovaries.

active.

our

The

sex

organs

secondary

sexual

start

to

produce

sex

characteristics.

boys

start

•

the

growth

•

the

testes

•

growth

•

the

•

development

making

of

to

of

the

hair

on

in

of

of

testosterone,

male

make

deepening

ovaries

and

sex

sperm

the

the

which

stimulates:

organs

cells

face

voice

muscles

in

the

body.

girls

start

making

oestrogen,

which

stimulates:

•

the

growth

the

ho rm

ones

T o pic

to

a

table

ro les

here

16.1 1.

referr ing

•

the

start

•

growth

of

•

growth

and

•

widening

of

all

and

Keep

your

A

person

nishes

read

and

the

rst

sex

organs

menstrual

cycle

and

the

rst

period

intera ct

to

men strual

mood

parts

of

development

the

of

body

breasts

of

the

hips.

becomes

you

can

changes

an

adolescent

stop

be

and

an

growing

emotional

increased

when

at

puberty

about

time.

sexual

18

starts.

years

of

Hormones

Adolescence

age.

can

bring

about

urges.

table

3

how

you

they

cont ro l

cycl e

so

the

them

cont racept ion

A

cycles

are

complete

hormones

This

to

which

the

changes

receive

an

cycle

lasts

coordinate

coordination

is

for

that

occur

the

important

embryo

so

that

28

activity

so

it

about

in

the

that

can

of

the

start

days

ovary

the

ovary

lining

its

and

of

is

and

the

controlled

and

the

the

by

uterus.

uterus

is

ready

development.

and Girls

use

on

T o pics

16.1

unde rstand

treatin g

female

hair

Adolescence

uterus.

we

of

when

Menstrual

you

2

of

your

fo r

includ e

lists

when

start

to

have

periods

between

the

ages

of

about

10

to

15

years

in

and

infert ility .

old.

During

and

cells

this

a

period,

pass

happens

menstrual

202

But

about

TIP

revisi on

fo r

of

adolescents.

STUD Y

how

and

in

earlier

to

at

The

16.1

sperm

develop

person

stimulate

Puberty

the

organs.

the

The

in

sex

ages

cycle

Puberty

that

of

the

of

hormones

of

make

development

usually

These

group

set

Between

in

gland

A

complete

life.

puberty

during

menstrual

to

of

controlled the

a

in

sexual

changes

and

with

later

in

varies the

born

active

Girls Describe

adolescence

of

This

•

and

OUTCOMES

out

for

cycle.

of

the

the

the

rst

lining

of

vagina.

time,

it

the

This

uterus

is

shows

breaks

called

that

a

down

and

menstruation.

girl

has

had

her

blood

When

rst

Stages

Girls

are

ovaries.

in

the

born

They

potential

menstrual

with

do

egg

is

a

not

very

large

produce

surrounded

cycle

number

any

by

a

of

more

small

potential

during

group

egg

their

of

cells

in

lifetime.

cells

and

their

Each

together

they ovulation

form

At

a

follicle.

puberty,

involves

some

the

egg

chromosomes

food.

Each

follicle

as

in

by

the

starts

uid

the

to

and

follicle

the

thousands

follicles

by

or

a

develop

moves

bursts,

start

by

in

As

to

by

the

The

the

ovary

This

to

at

the

of

number

lls

with

develop.

gland

it

the

(see

ovary.

is

page

of

the

and

After

cells

of

stored

This

enlarges

follicle

ovary .

development

beginning

grows

some

each

the

cytoplasm

pituitary

edge

egg,

in

reduces

start

follicle

the

the

follicles

develop.

follicles

the

towards

releasing

these

which

half.

few

released

nishes.

of

meiosis

nucleus

one

hormones

menstruation

with

of

are

dividing

month

stimulated

A

There

2

and

164).

cycle

lls

weeks,

the

uid

uterus

ready

into

the

oviduct.

This

is

called

ovulation.

The

follicle

cells

left

for

behind implantation

in

the

ovary

weeks.

If

implantation

While

to

If

form

2

the

egg

thicken.

In

vessels

and

form

ball

the

a

the

yellow

implantation

occurs

is

week

glands.

woman

cells

If

not

remains

developing

the

of

it

body

does

in

after

active

the

becomes

it

it

the

has

occurs,

implants

remains

will

during

ovary

ovulation

fertilisation

which

which

occur,

into

the

the

for

then

the

next

decrease

in

size.

pregnancy.

lining

a

of

thick

the

fertilised

thick

uterus

lining

of

egg

uterus

starts

blood

divides

lining

to

and

pregnant.

menstruation

If

fertilisation

vagina

of

the

now

If

a

and

does

the

uterus

begins

not

yellow

breaks

occur,

body

down

the

in

egg

the

and

is

dies

ovary

lost

and

passes

breaks

during

out

down.

of

The

the

thick

menstruation.

The

lining

cycle

again.

pregnancy

does

occur,

the

embryo

releases

a

hormone

that

Figure

stimulates

the

yellow

body

to

remain

active

which

in

turn

16.10.1

During

cycle

the

lining

of

the

uterus

to

continue

to

thicken.

This

supplies

the

with

ensures

that

Between

the

menstrual

food

and

oxygen

menstruation

ages

cycles

of

45

have

will

and

as

it

not

55

stopped.

continues

its

development.

It

also

are

years

This

a

is

woman’s

called

the

Explain

periods

stop

as

her

KEY

role

development

of

and

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testes

regulation

and

of

the

ovaries

secondary

in

Testosterone

males

the

sexual

males

and

females

at

in

a

List

at

b

the

effects

that

stimulates

the

Oestrogen

testosterone

has

on

the

body

of

a

that

oestrogen

has

on

the

body

of

a

girl

at

puberty.

3

During

follicle

ovary 3

Explain

the

meaning

of

the

following

menstruation

b

ovulation

c

Draw

and

a

in

timeline

the

to

uterus

show

during

the

a

in

stimulates

the

secondary

that

during

a

and

the

in

puberty.

menstrual

develops

sexual

occur

cycle

inside

lining

a

the

thickens.

If

of

the

implantation

implantation does

4

in

terms:

uterus a

occur

puberty.

characteristics

boy

females

effects

that

the

sexual

puberty.

puberty.

List

synchronised.

secondary

during

changes

2

the

characteristics 2

in

of

uterus

POINTS

changes

QUESTIONS

the

the

menopause

characteristics

1

and

occur.

1

SUMMARY

menstrual

activities

the ovaries

embryo

the

stimulates

changes

menstrual

that

occur

cycle.

in

the

ovary

the

not

occur ,

uterus

down.

and

This

is

the

lining

vagina

of

break

menstruation.

203

16.11

tnemelppuS

LEARNING

The

There

OUTCOMES

The •

Describe

the

production

sites

of

progesterone

cycle

and

in

pituitary

the

Explain

the

hormones

and

gland

at

that

the

control

base

of

the

the

menstrual

brain

cycle.

secretes:

and •

Follicle

Stimulating

•

Luteinising

Hormone

(FSH)

Hormone

(LH)

pregnancy

role

FSH,

of

the

ovary

secretes:

the

LH,

progesterone

controlling

hormones

menstrual

The •

four

cycle

of

oestrogen

in

are

menstrual

•

oestrogen

in

oestrogen

Each

menstrual

cycle

cycle

pituitary

it

starts

gland.

stimulates

follicle

there

beginning

FSH

and

progesterone

with

This

the

secretion

hormone

the

development

is

cell

of

a

the

stimulates

that

cycle

other

has

each

cells

is

of

in

one

the

of

into

carried

or

more

cells

follicle

blood

the

potential

these

the

the

in

to

FSH

to

follicles.

grow

starts

to

of

blood

to

into

the

ovary

Inside

grow

secrete

from

the

an

egg.

and

where

each

At

the

divide.

oestrogen

into

the

bloodstream.

Oestrogen

•

In

the

centre

enlarges

in

is

the

a

yellow

second

body

half

of

It

has

stimulates

three

the

main

repair

effects.

and

thickening

of

release

cycle

to

produce

lining

of

the

uterus.

which

the

LH menstrual

the

released;

and

yellow

progesterone.

body

forms

ovary

relative

concentration luteinising

in

the

blood

hormones

the

pituitary

hormone

(LH)

of

follicle

from

stimulating

hormone

gland

(FSH)

relative

progesterone oestrogen

concentration

in

the

blood

hormones

the

of

from

ovary

Lining

shed

Oestrogen

(menstruation)

by

ovary;

uterus

released

lining

starts

Progesterone

yellow

of

uterus

to

body;

released

lining

continues

Lining

by

down

of

to

pregnancy

thicken

does

thicken

lining

breaks

if

not

of

uterus

0

days

7

days

14

days

time

Figure

204

16.11.1

Control

of

the

menstrual

cycle

by

21

/

hormones

days

28

days

days

from

the

pituitary

gland.

occur

It

stops

the

secretion

•

It

stimulates

the

of

FSH

pituitary

from

gland

the

to

pituitary

secrete

DID

gland.

LH.

YOU

Nobody

The

lining

of

the

uterus

thickens

in

preparation

to

receive

an

you

are

can

the

cycle

see

from

important

from

increases

day

in

0

size

the

graphs

hormones

to

day

within

14.

the

in

Figure

during

During

the

this

16.11.1,

rst

half

time

the

FSH

of

and

the

egg

oestrogen

menstrual

develops

and

follicle.

of

of

stimulates

around

day

the

14

follicle

of

the

to

burst

release

its

egg.

This

happens

is

is

certain

about

of

of

In

top

the

part

of

follicle

the

Figure

second

half

of

the

the

shows

yellow

cycle,

that

body

after

which

ovulation

secretes

progesterone

the

by

the

ovary

have

these

stimulate

•

maintain

further

growth

lining

in

its

20%,

has

stop

the

of

secretion

shows

the

eventually

As

the

cycle.

it

of

that

This

stops

for

together

with

the

FSH

the

of

the

lining

state

and

LH

of

and

from

concentration

secreting

the

of

the

the

then

begins.

this

the

gradually

this

role.

the

it

If

secreted

by

They

menstrual

of

it

of

progesterone

of

the

around

may

LH

pituitary

decreases

of

and

the

the

yellow

also

stop

cycle

the

and

middle

in

the

in

the

there

is

second

body

in

early

body

the

part

the

hormone

the

uterus.

This

prevents

occurring

of

the

cycle

and

lining

so

This

and

tests.

use

and

SUMMARY

the

egg

If

pregnancy

there

body

is

excreted

a

that

the

lining

of

occurring

uterus

and

no

in

woman

to

LH

the

the

embryo

continue

stop

from

the

urine

misses

a

secretes

secreting

pituitary

and

this

period

is

she

to

QUESTIONS

Name

four

a

a

pregnancy

testing

kit

to

nd

coordinating

2

cycle

each

Describe

is

The

pituitary

the

hormone

ovary

Oestrogen

the

roles

in

menstrual

cycle.

3

Explain

that

Some

of

why

the

thick

state

of

these

controlling

the

at

it

is

lining

the

important

of

time

the

of

uterus

is

ovulation.

pregnant. State

what

happens

as

a

out. of

the

decrease

of

in

oestrogen

and

progesterone

end

of

and

FSH

the

stimulates

secretion

of

the

development

of

a

follicle

5

oestrogen.

stimulates

the

thickening

of

the

that

uterus

inhibits

FSH

production

and

causes

and

the

the

pituitary

towards

from

the

ovulation

remains

of

the

follicle.

formation

The

of

to

yellow

the

body

release

the

which

maintains

the

lining

of

the

why

it

is

important

progesterone

pregnancy

cycle.

is

occurs,

secreted

but

FSH

yellow

not.

LH.

Suggest

why

nd

what

it

difcult

to

proportion

is

of

body out

secretes a

progesterone

menstrual

lining,

6 stimulates

the

Explain

is

LH

and

secreted.

hormones

if

3

the

hormone

basis

be

hormones

in

remains

the

gland.

the

a

be

progesterone.

may

as

pregnancy

continue

the

known

is

again.

yellow

as

is

of

so

menstruation

is

POINTS

inside

2

during

happen

occurs.

that

oestrogen

does

concentration

1

of

size.

result

KEY

continues

lining

miscarriage.

4

can

takes

so

less

menstruation

uterine

progesterone

starting

important

pregnancy

She

placenta

Progesterone

gland.

yellow

decreases

decreases

uterus

the

implant

happens,

stimulates

this

oestrogen,

breaking

where

is

yellow

secrete

placenta

maintain

menstrual

This

an

not.

uterus,

prevent

the

stimulation

progesterone

lining

occurs

fertilised,

that

or

the

to

but

involved

During

no

oestrogen

1

intercourse

thick.

is

effects:

thickened

reduces

concentration

stimulation

If

one

and

graph

half

that

whether

pregnancy,

sometimes

The

out

continues

pregnancy.

•

no

there

implanted

menstruation down,

but

because

and

the the

estimated

progesterone

to they

the

group

remains

from

•

in

One

progesterone.

over

secreted

uterus.

nding

During

16.11.1

become

many

implant

at

cycle.

body The

the

it

way

and

how

not

researchers

embryo LH

do

embryo.

lining

As

KNOW?

knows

embryos

tnemelppuS

•

woman’s

embryos

never

uterus. implant

in

the

uterus.

205

16.12

Methods

of

birth

control

Birth LEARNING

if

•

Describe

the

methods

natural,

control

lets

couples

decide

whether

or

not

to

have

children

and

OUTCOMES

of

how

should

following

birth

so,

many.

To

prevent

pregnancy,

the

method

of

birth

control

either:

control:

chemical,

barrier

•

stop

the

sperm

•

stop

the

eggs

•

stop

from

reaching

the

egg,

and from

being

made,

or

surgical the

Barrier

fertilised

egg

from

implanting

and

developing

in

the

uterus.

methods

IUD

The

uterus

cap

cervix

or

diaphragm

before

uterus.

It

is

intercourse.

should

be

used

a

It

rubber

dome.

prevents

with

the

The

man’s

sperm-killing

woman

sperm

cream

or

places

from

it

over

entering

her

the

foam.

strings

The

condom

is

a

thin

rubber

tube.

It

is

rolled

over

the

man’s

erect

penis

vagina

before

It

also

intercourse.

gives

common Figure

16.12.1

Intra-uterine

It

stops

protection

form

of

the

against

birth

control

sperm

from

sexually

and

is

entering

transmitted

easy

to

the

woman’s

diseases.

It

is

body .

the

most

use.

device

A

femidom

is

the

female

equivalent

of

a

condom

and

is

inserted

uterus

into

the

vagina.

vagina

Chemical

The

IUD

methods

(Intra-Uterine

wrapped

in

woman’s

copper

uterus

or

and

Device)

contains

it

is

is

a

small

hormones.

thought

to

work

plastic

It

is

by

device

tted

that

inside

preventing

is

the

sperm

rectum

passing cap

for

Figure

folded

cap

insertion

16.12.2

through

the

uterus.

It

may

also

prevent

an

embryo

from

fitted

over

cer vix

implanting

in

the

uterus

should

conception

occur.

Cap

IUS

is

penis

(Intra-uterine

placed

slowly

and

making

The

in

it

pill’

different

the

causes

unlikely

is

an

types

system)

uterus.

the

is

a

in

sperm

available.

T-shaped

progesterone

the

will

contraceptive

pill

small

contains

mucus

that

oral

of

It

cervix

swim

as

They

it

is

to

plastic

that

is

become

device

that

released

thick

and

sticky,

through.

taken

contain

by

the

mouth.

There

hormones

are

oestrogen

and

condom

progesterone

pills.

by

These

Figure

16.12.3

to

the

be

by

concentrations.

preventing

production

released

by

of

the

the

There

ovary

FSH

by

ovaries

are

releasing

the

and

also

eggs.

pituitary .)

so

progesterone-only

As

pregnancy

(They

a

do

result,

cannot

this

no

eggs

occur .

Condom

The

For

woman

many

has

vagina

result

uterus

in

a

heart

In

and

take

the

and

a

a

pill

pill

is

Drawbacks

pregnancy.

depression

effects.

to

couples

contraception.

applicator

varying

work

inhibiting

mature

in

The

painful

very

small

circulation

every

a

day .

very

are

reliable

that

side

failure

effects

periods

number

–

of

each

are

and

to

sore

pill

has

women,

convenient

take

the

the

pill

breasts,

its

own

pill

weight

set

can

method

regularly

be

of

of

can

gain,

side

the

cause

problems.

spermicide rectum

A

contraceptive

under

Figure

16.12.4

the

of

implant

the

upper

is

a

small

arm.

It

exible

releases

rod

ovulation

and

works

for

up

to

3

that

is

placed

progesterone

Spermicide

prevents

206

skin

years.

just

which

of

Contraceptive

different

types

Spermicides

cream

or

should

be

they

To

avoid

also

woman

with

contain

between

chemicals

The

that

puts

are

kill

the

not

another

8

progesterone.

and

13

sperm.

cream

very

They

into

such

are

weeks.

effective

method

There

as

are

her

on

sold

vagina

their

the

as

cap

foam,

before

own

or

and

the

condom.

methods

couples

may

work

Spermicides

used

Natural

Some

that

are

jelly.

intercourse.

injections

may

have

not

be

religious

becoming

able

or

to

moral

pregnant

use

the

methods

objections

they

may

to

described

using

abstain

here

or

Figure

16.12.5

from

having

sex

Calendar

for

rhythm

method

contraception.

at sperm

times

when

rhythm

likely

after

and

is

to

fertilisation

method.

occur

that

then

about

date.

A

This

most

relies

weeks

each

after

especially

in

likely

on

abstaining

woman

predicts

2

method,

and

is

month

having

women

happen.

determining

from

keeps

to

a

sex

record

when

her

in

days

when

ovulation

period.

who

when

the

of

do

This

not

They

may

ovulation

just

she

is

not

a

very

regular

cut

tube

and

ends

tied

most

and

her

occur.

the

is

before

has

should

have

use

just

periods

This

reliable

sperm

periods.

tube

testis

A

better

method

ovulation.

For

is

to

follow

example,

changes

checking

for

in

the

symptoms

increase

associated

in

body

with

temperature Figure

and

changes

just

before

It

useful

in

cervical

ovulation.

mucus

This

which

becomes

symptoms-based

wetter

method

and

is

less

more

for

people

who

do

not

have

access

to

family

top

and

the

Surgical

other

methods

of

contraception

is

described

end

of

cut oviduct

planning and

clinics

Vasectomy

effective. oviduct

is

16.12.6

sticky

blocked

here.

ovar y

methods

vagina

A

sperm

them

is

tubes

must

a

are

be

duct

also

known

vasectomy

cut

sure

ejaculate

is

but

and

tied.

that

he

there

Sterilisation

is

a

and

The

does

are

no

minor

as

is

a

a

vas

minor

operation

not

deferens.

want

sperm

in

is

operation

not

any

the

operation

The

a

a

man.

reversible,

children.

semen,

for

for

usually

more

operation

just

woman.

The

to

His

so

cut

the

man

uterus

sperm

man

can

still

rectum

uid.

Her

oviducts

are

cut Figure

and

sure

blocked.

that

she

The

operation

does

not

want

is

not

any

reversible,

more

so

the

woman

must

POINTS

QUESTIONS 1

Barrier

methods

condom, 1

Sterilisation

children.

KEY

SUMMARY

16.12.7

be

a

What

is

b

Under

meant

by

the

term

include

femidom,

IUD

the

and

contraception? IUS.

what

circumstances

would

a

couple

choose

to

use

2 birth

control

Chemical

methods

contraceptive

2

Explain

how

the

following

birth

control

methods

cap

or

d

vasectomy

diaphragm

b

condom

c

Methods

can

be

rhythm a

Explain

how

oral

contraceptives

pill,

and

implants,

spermicides.

spermicides 3

3

the

work: injections

a

include

methods?

(‘the

pill’)

act

to

of

birth

natural

control

(abstinence,

method).

prevent

pregnancy. 4

b

What

birth

are

the

control?

disadvantages

associated

with

this

form

of

Surgical

methods

vasectomy

and

involve

female

sterilisation.

207

16.13

tnemelppuS

LEARNING

Control

Outline

in

the

use

of

contraception

hormones

and

fertility

drugs

Some

had

Describe

vitro

the

process

fertilisation

of

Discuss

of

the

is

regular,

social

implications

and

fertility

the

release

cause

of

to

in

you

n

read

mak

func tion

a

cannot

sexual

as

because

being

intercourse

for

the

infertile

12

if

months

man

they

or

have

without

pregnant.

infertility

may

be

for

in

due

this

fertility

women

to

a

type

drug

is

lack

of

that

of

FSH

infertility

containing

the

do

production

may

FSH.

ovaries

involve

The

FSH

not

by

the

regular

stimulates

the

eggs.

treatments

involve

Remember

if

the

effect

then

the

pituitary

of

Unfortunately,

of

reasons

tablets

that

that

make

oestrogen

the

inhibits

pituitary

the

insensitive

production

of

to

FSH.

oestrogen

continues

on

to

the

pituitary

release

FSH

is

blocked

and

by

ovulation

the

drug,

occurs.

fertility

that

may

treatment

not

be

easy

does

for

not

always

doctors

to

work

for

discover.

a

On

variety

the

other

how hand,

it

can

work

too

well;

too

many

eggs

may

be

released,

resulting

cycl e in

twins,

triplets,

quadruplets

or

even

more!

and

of

FSH

stim ulatin g

the

but

regarded

this

sure

men strual

deve lo pm ent

in

e

unde rstand

cont ro lle d

the

children

are

TIP So

is

This

release

oestrogen.

the

of

Treatment

injections

Other

you

unprotected

becoming

eggs.

pituitary.

ovaries

Befo re

have

in

treatments

sectio

to

Couples

(IVF)

contraception

STUD Y

want

infertile.

woman

Often

•

drugs

couples

woman

the •

fertility

OUTCOMES

Fertility

•

of

of

Articial

the

fo lli cles

ovary.

Some

may

couples

be

the

uterus.

If

the

are

man

man

remains

vitro

does

the

placed

is

not

then

a

child’s

It

via

called

is

possible

a

ne

donor

donor

father

is

the

man

sperm

semen

tube

sperm

lead

a

to

for

there

the

this,

or

of

father

be

This

are

collected

woman’s

(AI).

if

the

semen

problems

biological

infertile.

may

into

sample

is

or

insemination

provide

can

not

that

plastic

enough

may

the

enough

articial

produce

by

because

produce

later

who

sperm

for

in

AI.

life

probably

unknown.

fertilisation

fertilisation

‘in

parents

children

not

ejaculation.

and

infertility

means

have

does

insemination

vitro

treat

he

process

defective,

because

In

with

The

Articial

In

cannot

because

problems

from

insemination

glass’.

and

(IVF)

when

Eggs

mixed

is

other

another

technique

methods

and

sperm

together

in

a

have

are

that

been

collected

laboratory

can

be

used

unsuccessful.

from

dish

the

where

to

In

vitro

potential

fertilisation

occurs.

To

increase

FSH

to

eggs

can

body

A

couple

with

treatment.

208

triplets

resulting

from

fertility

be

wall

follicles

that

the

chances

stimulate

the

contains

a

ne

of

success,

development

collected

and

on

the

from

plastic

surface

nutrients

of

her

woman

several

ovaries.

tube

the

and

the

of

A

inserted

ovaries.

oxygen.

The

small

to

is

often

follicles

incision

collect

eggs

so

are

the

kept

injected

that

is

made

eggs

in

a

with

several

in

from

the

the

solution

and

to

is

mixed

the

the

the

A

with

solution

woman’s

is

into

also

inject

it

from

the

and

If

left

to

days

the

(or

that

started

few

uterus.

a

is

used

for

up

from

to

24

fertilisation

divide

and

into

then

procedure

a

is

a

sperm

hours

has

for

fertilisation

occurred

embryos.

doctor

donor)

places

successful,

and

These

the

are

them

kept

into

embryo

will

fetus.

possible

into

a

man

checks

have

for

the

eggs

technician

zygotes

develop

It

collected

occur.

that

in

is

tnemelppuS

Semen

an

to

take

egg.

the

The

nucleus

zygote

is

from

then

a

defective

cultured

for

sperm

several

cell

and

days

so

it

A

grows

into

an

embryo

and

is

then

transferred

into

the

woman

in

technician

with

hope

that

it

The

social

fertility

The

implants

for

the

a

sperm

also

not

had

to

implications

of

couples

It

a

IVF

clinic

also

a

to

safe

plan

gave

great

put

of

contraception

their

and

contraceptive

their

families

pill

and

in

1960

decide

made

when

it

to

been

of

the

of

7

The

women

effect

on

health

infants

ability

at

at

more

control

women’s

risk

by

over

health,

their

giving

pregnancy

and

around

the

is

an

IVF

countries

have

per

plan

to

and

sexually

often

be

a

in

and

has

the

and

time

1970s

of

to

30%

are

to

own

them

birth.

much

fertility.

the

TIP

It

opportunity

Death

birth

have

falling

rates

T he

use

of

ho rm

ones

in

is

not

can

available

national

receives

in

make

an

treatments

they

may

have

if

the

parts

of

the

world

childless

couples

choices

changed

a

all.

steep

Success

of

service,

and

proves

are

not

how

age.

rates

In

decisions

KEY

POINTS

many

unsuccessful.

Infertile

able

to

afford

A

problem

is

what

to

do

with

‘spare’

embryos

that

implanted.

Some

people

maintain

that

it

is

not

drugs

of

them

or

use

them

for

medical

acceptable

to

to

stimulate

eggs

and

a

QUESTIONS

Explain

how

pregnancy

b

Explain

fertility

in

If

the

of

male

couples

how

drugs

infertile

articial

can

increase

the

chance

of

a

sperm

women.

when

the

insemination

man

is

is

are

can

help

bring

about

Explain

a

nutrients

why

and

eggs

to

oxygen,

be

used

before

and

implanting

b

them

Discuss

that

what

are

possible

not

should

happen

implanted.

in

why

into

future

use

or

to

Should

used

for

for

where

used

to

articial

donor

fertilise

a

eggs.

a IVF

is

a

IVF

are

kept

embryos

are

in

a

solution

kept

for

a

of

a

the

Petri

technique

in

which

place

inside

few Oral

contraceptives

allow

uterus.

embryos

they

takes

dish.

women

3

opt

infertile.

4 days

infertile,

fertile

fertilisation

2

the

pregnancy.

may

woman’s

3 pregnancy

release

research.

insemination

1

the

increase

just

2

SUMMARY

take

are

chances dispose

can

containing

this

of not

females

In

FSH treatment.

16.1 2.

parts

fertility many

T o pic

16.14).

years

health

rst

is

average

1 repeat

in

control

many

also

with

to

35

treatment

birth

from

has

Topic

under

pills

2013.

promiscuity

(see

in

for

decreased

of

steeply

fallen

1.6

women

women

funded

have

just

infections

and

Methods

Contraception

greater

for

who

pill.

they

that

careers.

procedure

about

the

rates

means

led

publically

of

example,

transmitted

about

made

birth

for

families

education

with

that

woman

expensive

are

introduction

Thailand,

behaviour

in

the

successful

In

to

their

increase

for

so

children

sexual

IVF

since

world.

about

egg

have

desc ribed considerably

have

an

and

cont racept ive mothers

injects

uterus.

STUD Y children.

an

nucleus.

treatments

introduction

easier

in

at

the

be

from

IVF

destroyed,

treatments

frozen

for

they

to

wish

pregnant

decide

to

or

whether

become

not.

research?

209

16.14

Sexually

transmitted

infections

A LEARNING

sexually

Dene

sexually

infection

body

uids

gonorrhoea

transmitted

State

•

Describe

that

HIV

is

an

amongst

sexual

(STI)

is

the

contact.

a

disease

major

STIs

that

include

is

infections

that

HIV ,

transmitted

can

be

syphillis

and

transmitted.

the

methods

of

HIV

and

its

spread

(HIV)

human

immunodeciency

virus

(HIV)

is

a

human

pathogen

that

can

rst

identied

in

the

early

1980s.

Like

all

viruses

it

is

composed

of

ways

a which

virus

of

was transmission

immunodeciency

STI

The

in

during

(STI)

Human •

infection

OUTCOMES via

•

transmitted

(STIs)

few

genes

and

a

protein

coat.

It

enters

human

cells

and

uses

each

be

cell

to

make

more

viruses

which

then

enter

even

more

cells.

The

main

prevented

type State

lead

that

to

HIV

infection

cell

that

it

infects

tnemelppuS

Describe

how

HIV

HIV

infection

affects

with

virus

who

(TB)

HIV

is

may

lead

is

a

HIV

is

no t

a

negative

and

infection

whic h

number

of

of

If

Acquired

someone

they

are

described

as

being

HIV

has

positive

been

(HIV+).

the

be

body’s

infected

immune

by

People

other

who

system.

diseases,

do

not

It

is

easier

such

have

HIV

as

for

a

person

tuberculosis

are

described

as

and

destroys

an

important

type

of

lymphocyte

that

the

the

of

Eventually

syst em .

wo rd

Of te n

is

T his

immune

system.

lymphocytes

number

of

T

to

During

produce

lymphocytes

an

infection

antibodies.

decreases

these

T

During

and

so

lymphocytes

an

HIV

fewer

every

time

there

is

another

infection.

By

reducing

antibodies

the

T

lymphocytes,

the

person

HIV

infected

weakens

with

HIV

the

will

body’s

ability

succumb

to

to

ght

any

disease.

number

of

is infections

because

of

their

weakened

immune

system.

‘synd rome’

the

term

used .

a

The

(acquired

a

patient

with

AIDS

weight

of

with

HIV

immune

diseases

virus

(yellow)

deciency

brought

(×5000).

syndrome)

on

by

the

is

the

name

weakening

of

given

the

to

body’s

system.

early

glands

treating

infected

collection

immune

worker

the

the

AIDS

health

to

other

Lymphocyte

in

AIDS.

resu lt

weak enin g

HIV/A IDS

A

or

(HIV–).

produced

other

what

development

of are

imm une

means .

the

lymphocytes

attacks

stimulate

diseas e;

co lle ction

a

lymphocyte.

TIP

diseas es

from

to

Syndrome

pneumonia.

coordinates

it

HIV

weakens

HIV+

and

HIV

AIDS

of

system

The

STUD Y

type

the

infected immune

a

may

AIDS

Immunodeciency •

is

symptoms

and

a

loss,

high

of

AIDS

are

temperature.

various

types

of

very

much

Later,

cancer

like

u,

symptoms

and

a

with

might

decrease

in

swollen

include

brain

function.

Cambodia.

Not

all

HIV+

without

210

any

people

develop

symptoms

at

all.

AIDS.

Some

people

remain

HIV+,

but

tnemelppuS

•

of

How

HIV

is

is

one

HIV

transmitted?

transmitted

person

to

in

the

another

blood

during

and

semen.

unprotected

The

virus

sexual

can

pass

from

STUD Y

T here Either

partner

may

infect

the

other.

The

virus

can

also

be

passed

are

needles

contaminated

with

infected

blood.

In

this

has

spread

very

quickly

amongst

drug

addicts

who

share

needles.

T hey Unborn

babies

are

also

at

risk

from

HIV .

This

is

because

the

virus

can

the

placenta

to

the

fetus.

Even

more

likely

is

its

passage

from

blood

to

the

baby’s

blood

at

birth

when

the

two

into

for

close

contact.

transfusions

is

HIV

can

another

also

way

be

in

transmitted

which

HIV

in

has

HIV

only

breast

been

milk.

For

not

can

There

are

is

no

trying

that

the

drugs,

HIV/AIDS

cure

to

viruses,

fungal

Since

may

inside

but

that

infection

the

(AZT),

body

with

and

that

damage

the

people

infections

HIV

drugs

zidovudine

multiplying

prevented?

HIV/AIDS

develop

drugs

e.g.

for

be

they

will

by

yet

no

vaccine

inactivate

host

and

cells.

AIDS

as

take

HIV ,

some

of

them

to

these

do

the

There

are

work

the

Scientists

problem

prevent

not

treat

HIV .

but

lymphocytes.

Antibiotics

for

is

be

cups

of

the

virus.

the

cured,

it

is

important

tracing

is

bacterial

to

of

the

spread

of

HIV

in

the

UK.

person

Any

in

positive

either

as

people

a

are

antibodies

several

is

asked

result

then

in

of

identify

offered

their

weeks

to

sexual

an

blood.

after

the

people

intercourse

HIV

test

has

by

which

However,

person

who

or

diagnosed

these

been

they

may

sharing

reveals

have

the A

sexually

antibodies

at

be

passed

of

appear

during

2

The

spread

controlled

HIV

condoms,

only

sharing

methods

to

reduce

its

spread

on

via

sexual

infected.

of

by

body

contact.

STIs

the

can

use

be

of

preventing

of

needles, Other

infection

risk,

These

presence

will

transmitted

with

put

needles.

the

them .

the

uids HIV

food,

with

POINTS

can control

glasse s

who

and

prevent

important

someo ne

sharin g

virus

KEY

Contact

or

or

against

1 transmission

touchi ng

HIV+

by

insect s,

anti-viral

have.

cannot

is

HIV

trans mitt ed

bloodsuck ing How

throug h

exam ple,

Blood

transmitted.

AIDS .

infec ted

describ ed

bloodstreams

is used

becom e

meth ods

here. come

may

AIDS .

catch

the

the mother’s

and

cann ot

myt hs

pass

with across

HIV

way,

Peopl e HIV

man y

via

abou t hypodermic

TIP

intercourse.

the

hypodermic

and

education

include: programmes.

the

use

of

condoms

to

provide

a

physical

barrier

to

the

transmission 3

of

the

virus

during

sexual

HIV

in

•

setting

inject

free

drugs;

shared

•

up

this

needles

screening

education

the

exchange

reduces

and

donated

contaminated

•

needle

blood

of

risk

of

for

those

transmission

people

from

the

the

to

HIV

used

antibodies

for

make

HIV

the

a

virus

transmitted

use

or

of

in

a

What

the

known

AIDS.

What

c

Why

a

State

exactly

is

and

aware

how

it

of

can

the

be

methods

of

4

as

The

spread

reduced

prevented.

between

AIDS

and

use

an

the

HIV

ways

infection

not

be

treated

by

State

the

a

is

by

be

sexual

reducing

shared

drug

can

needles

users

of

and

by

donated

in

which

HIV

is

measures

that

can

be

in

transfusions.

HIV

destroys

lymphocytes

transmitted.

taken

to

reduce

the

spread

to

a

weakening

of

the

of system.

This

makes

infection.

tnemelppuS

Describe

the

effect

of

HIV

on

the

immune

system

and

susceptible

HIV

infection

leads

to

the

development

of

to

many

explain diseases,

how

to

which

using

during

used

people

3

HIV

men

screening

immune HIV

lead

antibiotics?

leading b

time,

HIV?

5 2

With

diseases

of

by

of

between

HIV?

blood can

is

semen

may

of

intercourse,

difference

the

blood.

infection

careful b

cells

It

eliminating

QUESTIONS

is

in

collection

the

1

infects

system.

transfusion.

people

virus

and

the

condoms

SUMMARY

that

immune

who

HIV

for

being

programmes

transmission

the

schemes

syringes

blood

is

intercourse

such

as

TB.

AIDS.

211

tnemelppuS

•

PRACTICE

1

The

the

QUESTIONS

drawing

correct

shows

a

half

identication

ower.

of

the

Which

labels

1

row

to

is

3

4?

The

diagram

system.

the

shows

Which

events

row

the

female

identies

reproductive

the

places

where

occur?

1

2

3

2

1

3

4

1

1

2

3

2

3

4

A

anther

stigma

petal

sepal

B

petal

stigma

sepal

anther

C

sepal

petal

anther

stigma

D

stigma

anther

sepal

petal

A

fertilisation

implantation

ovulation

B

implantation

ovulation

fertilisation

C

ovulation

production fertilisation of

production D

fertilisation of

2

(Paper

1)

Which

row

eggs

implantation

eggs

[1]

shows

the

correct

functions

of

4 insect-pollinated

(Paper

1)

[1]

Which

organ

an secretes

testosterone?

ower?

A

ovary

B

pituitary

C

placenta

D

testis

sepals anthers

gland

carpels provide

A

produce

contain landing

pollen

grains

ovules for

sepals

site

insects

anthers

carpels

produce

contain

pollen

ovules

(Paper

B

5

insects grains

The

stigmas

ovaries

anthers

receive

contain

produce

ovules

pollen

pollen

[1]

following

sexual

C

1)

attract

grains

four

processes

reproduction

1

Pollen

2

The

grains

male

in

lands

gamete

occur

owering

on

the

fuses

during

plants.

stigma.

with

the

female

grains gamete.

petals stigmas protect D

are ower

3

anthers

The

male

gamete

travels

down

the

pollen

a

in

site

of

tube.

produce

the pollination

ovules

4

The

pollen

tube

grows

out

from

the

pollen

bud

grain.

(Paper

1)

[1]

In

which

A

3,

4,

1,

2

B

4,

3,

2,

1

C

1,

4,

3,

2

D

4,

2,

1,

3

(Paper

212

order

2)

do

these

processes

occur?

[1]

6

Which

in

the

hormone

second

is

half

A

follicle

B

luteinising

C

oestrogen

D

progesterone

secreted

of

the

stimulating

by

the

hormone

hormone

yellow

menstrual

body

9

The

diagram

before

cycle?

shows

a

fetus

in

the

womb

just

birth.

(FSH)

A

(LH) B

C

(Paper

2)

[1] D

7

The

diagram

occur

to

the

below

uterus

shows

the

changes

that

during

the

menstrual

cycle.

E

day

2 2 lining

of

1

8

2 3

7

4

6 2

(a)

Name

body

(b)

Describe

parts

A

to

E.

[5]

5

uterus

4 2

the

2

7

3

structures

8

22

use

the

changes

to

letters

E

that

during

rather

happen

birth.

than

the

You

to

the

may

names

in

answer.

[5]

0

of

uterus

(Paper

0

2

lining

1

2

9

1

your

A

thicker

3)

1

1

1

9

gets

10

8 1

(a)

Dene

the

(b)

Explain

term

sexual

reproduction.

[3]

1 2

7

1

6

3

1

51

4

1

1

the

following

ovary, Which

row

events

during

shows

the

times

(in

days)

when

difference

pairs

and

(ii)

of

between

terms:

pollination

(i)

the

ovule

and

and

fertilisation.

the [4]

the

cycle

occur?

(c)

State

likely

factors

germination

ovulation

is

three

menstruation

uterus

occurs

gets

of

required

for

the

seeds.

[3]

lining

to

(Paper

thicker

3)

occur

11 A

10–27

25–28

Clomiphene

infertility

B

13–15

1–4

6–25

C

22–25

1–4

7–14

D

10–27

13–15

25–28

an

in

increase

pituitary

(a)

2)

in

Explain

Outline

fertility Potato

and

plants

stem

variation

A

drug

that

It

is

works

used

production

of

by

to

treat

causing

FSH

from

the

how

to

a

be

deciency

in

FSH

causes

infertile.

a

[2]

[1] (b)

8

a

women.

gland.

woman

(Paper

is

4–10

reproduce

tubers.

among

Which

by

results

offspring

cross-pollinating

means

in

plants

in

of

the

potato

of

the

social

issues

involved

with

treatment.

[4]

owers

least

(c)

plants?

Describe

the

roles

progesterone

in

of

oestrogen

pregnancy.

and

[3]

different (Paper

4)

varieties

B

cross-pollinating

C

production

D

self-pollination

(Paper

2)

of

plants

stem

of

the

same

variety

tubers

[1]

213

17

Inheritance

17.1

Chromosomes,

and

People LEARNING

Dene

•

State

who

capabilities meaning

of

to

the

chromosome,

at

closely;

same

or

traits

such

in

the

family

such

things

case

often

as

as

of

resemble

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other

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closely.

personality

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in

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families.

the We

terms

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Characteristics

inheritance

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DNA

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•

genes

gene

say

that

someone

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features

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parents.

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transfer

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genes

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as

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called

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cells,

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deer

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chromosomes

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female.

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chromosomes

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of

two

Figure

one

strands

17.1.1

in

the

joined

at

chromosome

the

in

photo

on

together

top

two

of

the

the

left

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next

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at

page

colours.

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thread

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chromosome,

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up

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it

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would

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form

chain

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molecule

called

long

DNA

stands

for

deoxyribonucleic

acid.

The

DNA

is

wound

around

tongue of

protein.

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cell

division

the

DNA

and

protein

are

this

over

each

that

record

very

tightly

together

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the

chromosomes

are

coiled

up.

1400 At

chromosomes

other

times

cell! the

214

we

chromosomes.

only

packed

species

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chromosomes

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stranded.

molecules

fern

genetic

through

the

so

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23

microscope,

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chromosomes

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light

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the

a

have

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the

cell

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is

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are

gene?

lengths

of

chromosome

actual

number

chromosomes

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the

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of

DNA

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that

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along

length.

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than

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in

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some

below.

the

of

our

chromosomes

have

Figure

genes.

17.1.1

A

double-stranded

chromosome.

Each

It

is

gene

a

is

a

unit

chemical

of

code

inheritance

that

the

cell

in

that

it

codes

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as

an

for

a

specic

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to

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STUD Y a

protein

amylase

molecule.

and

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lipase

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many

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for

know

about

example.

more.

several

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to

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proteins

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features

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environment.

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example

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determined

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each

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strand

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and

of

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the

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called

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called

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cells.

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1

to

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relationship

chromosome,

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pack ed

cells

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in

gene s.

POINTS

Inheritance

genetic

is

the

transfer

information

gene,

to

from

the

diploid

numbers

of

generation.

between

2

by

so

proteins.

sentences

meant

other

inform ation

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chromosome

DNA

is

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genetic

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At

is

chromosome

following:

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.

of

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cell

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generation

c

is

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DNA

DNA

structures

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the

KEY found

mad e

resemble

less

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information

times

them

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are

words:

tight ly chromosomes

of

molec ules

QUESTIONS

pro tei n Copy

pro tei n.

arou nd

divisi on,

1

one

chrom osom e.

(deoxy ribon uclei c

chromosome.

woun d

SUMMARY

of

se t

fath er .

TIP

DNA

acid) 17.1.2

o ther

the

chrom osom e

protein

of

Figure

of

the

DNA

Each of

the

from

type

STUD Y

core

one

from

both

mo th er genes

–

control

se t are

of

the

chrom osom es body

that

25 000

there different

TIP

haemoglobin,

number?

three

non-human

in

the

form

of

genes.

species. 3

A

gene

that

is

a

codes

length

for

a

of

DNA

protein.

215

17.2

Protein

tnemelppuS

Each LEARNING

chromosome

Explain

bases

that

in

a

the

gene

sequence

code

for

of

order

of

amino

Each

called

genes.

a

length

up

of

A

gene

divided

a

long,

is

a

into

super-coiled

small

thousands

part

of

the

of

molecule

DNA

shorter

of

sections

strand.

to

of

DNA,

make

a

making

up

particular

a

particular

protein.

gene,

Remember

carries

that

the

inside

information

every

cell

protein there

•

made

is

acids needed

in

molecule

the The

correct

is

OUTCOMES DNA.

•

synthesis

Explain

how

a

protein

is

are

thousands

of

different

chemical

reactions

taking

place.

made Enzymes

that

all

control

enzymes

determines

which

all

are

which

chemical

these

chemical

proteins.

enzymes

reactions

reactions.

Because

are

take

DNA

produced

place

in

inside

You

codes

each

should

for

cell

remember

proteins,

and

it

therefore

cells.

DNA

gene

1

gene

2

nucleus

Figure

mRNA

The

17.2.1

A

structure

gene

of

is

DNA

a

short

(see

section

Unit

4)

of

DNA.

contains

bases.

The

information

nuclear

is pore

found

in

the

sequence

of

bases

along

the

length

of

DNA.

nuclear

These

membrane

also

determine

controls

the

the

sequence

production

of

of

amino

other

acids

in

important

the

protein.

proteins,

DNA

including

mRNA

antibodies

+

and

receptors

for

neurotransmitters.

ribosomes cytoplasm

DNA

carries

information

information

ribosomes

protein

is Figure

17.2.2

The

vital

role

of

given

the

ribosomes.

code

to

the

a

kind

name

of

build

the

proteins

DNA

to

’messenger

messenger

the

from

site

molecule’.

RNA

amino

of

(mRNA).

acids.

protein

This

The

molecule

role

The

synthesis

of

is

in

RNA

mRNA

is

the

and

to

a

copy

of

the

base

sequence

on

DNA

out

of

the

nucleus

to

the

the

ribosomes

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are

letters

three

and

A,

of

copies

on

four

T ,

is

the

instance

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the

the

C

C

different

G.

bases

code

will

will

on

–

bases

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on

for

protein

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this

code

for

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it

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so

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replaced

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on

in

acid

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different

and

is

found

amino

DNA.

DNA

copy

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where

synthesis

occurs.

code

coded

base

DNA

cytoplasm

and

these

each

have

in

genetic

There

216

by

to

from

mRNA

carry carrying

moves

is

are

coded

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on

of

by

base

to

a

them

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base

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by

sequence

different

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another

mRNA.

refer

for ,

20

triplet

the

copy

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about

base

by

by

DNA.

amino

When

pairing’,

mRNA

does

(uracil).

their

of

acids

mRNA

so

for

not

Therefore,

double

strand

DNA

mRNA

tnemelppuS

DNA

DNA

unwinds

makes

mRNA

amino

methionine

acid

Figure

17.2.3

How

DNA

alanine

base

triplets

code

tyrosine

for

amino

nucleus

arginine

acids.

mRNA

The

coded

information

on

mRNA

is

used

to

assemble

amino

acids

in ribosome

the

correct

sequence

for

each

protein. nuclear

pore

•

The

mRNA

arrives

•

The

mRNA

strand

amino

•

The

acid

mRNA

assembles

in

at

the

from

base

the

triplets

nucleus.

for

each

particular

protein.

passes

amino

ribosomes

contains

the

then

the

acids

through

into

the

protein

ribosomes

and

each

ribosome

mRNA

molecules.

ribosome

•

The

amino

•

The

specic

bases

in

acids

bond

order

the

of

mRNA

together

amino

and

forming

acids

each

is

a

long

chain

determined

amino

acid

is

by

joined

–

the

to

the

protein.

sequence

the

next

of

amino

one

acid

passed

by

a

peptide

to

bond. ribosome

All

a

body

cells

particular

in

an

cell

organism

many

genes

contain

may

not

the

be

same

genes.

expressed

However,

because

the

in

cell amino

makes

only

the

specic

proteins

it

needs.

acid

added

to

growing

protein

Figure

SUMMARY

17.2.4

How

DNA

controls

protein

QUESTIONS synthesis.

1

2

What

is

the

function

a

DNA

b

mRNA

c

ribosomes

Look

at

the

part

of

of

a

each

of

the

molecule

of

following

in

messenger

protein

RNA

synthesis?

here:

AUGACGCAUGCAGUCCGA.

a

How

many

b

What

is

base

the

triplets

role

of

are

each

of

shown

these

in

this

base

section

triplets

in

of

mRNA?

protein

KEY

synthesis?

c

Write

down

the

DNA

base

triplets

that

coded

for

this

mRNA. 1

3

Indicate

if

these

statements

are

true

or

The

DNA

is

a

b

DNA

has

sequence

codes

false.

of a

POINTS

amino

DNA

d

The

the

a

double

contains

acids

2

helix

The

role

four

bases:

A,

G,

C

and

of

code

bases

in

shape

between

of

DNA

is

a

on

DNA

sequence

protein.

base

is

carry

to

it

copy

to

the

the

U

maintained

complementary

mRNA

and

ribosomes molecular

bonds

of

correct

protein

DNA c

for

pairs.

by

in

the

cytoplasm.

hydrogen

3

The

ribosomes

acids

into

assemble

protein

amino

molecules.

217

17.3

Mitosis

New

cells

below

•

Dene

its

mitosis

roles

in

•

Dene

role

in

and

of

into

state

growth,

replacement

asexual

As

repair,

cells

In

and

reproduction

meiosis

and

gamete

state

tnemelppuS

State

that

before

are

Outline

what

Describe

the

the

nucleus

cell

cells

into

are

is

a

during

role

of

to

that

is

the

rise

stem

cells

The

a

cell

DNA

of

in

the

The

new

urchin

You

can

has

see

just

that

divided

each

old

ones.

new

is

In

into

two,

wall

nuclei

the

divides,

between

cell

in

the

photograph

is

the

the

the

process

of

nucleus

cytoplasm

two

formed

nuclei

dividing

must

divides.

to

between

divide.

divide

the

nuclei.

divide.

of

nuclear

The

division

daughter

that

cells

occurs

are

during

genetically

growth

and

identical.

organs

to

cells

form

that

gametes.

are

not

It

is

the

genetically

nuclear

division

identical.

divide,

new

copies

chromosomes

exact

is

see

mitosis

copies

divides.

uncoiled

are

of

DNA

of

begins,

thicker.

They

staining

in

is

is

the

This

going

nuclei

coils

visible

up

This

is

the

is

so

a

very

in

this

is

attached

that

the

in

the

each

in

reliable

process

DNA

loosely

when

under

information

copying

on,

very

chromosome

DNA

become

technique

it

genetic

made.

arranged

each

the

the

be

made.

While

and

chromosomes

mitosis

of

must

occurs

the

nucleus.

going

to

on.

the

original

chromosome

microscope

when

a

used.

in

cell

has

During a

a

cell

division

which

sex

of

can

the

copy

As

suitable sea

of

urchin

the

occurs

daughter

nucleus

cannot

becomes

a

in

to

which

You

copy.

of

in

type

process

chromosomes

mitosis.

its

plants

ways

sea

mitosis

before

by

In

a

Before

nishing

occurs

gives

process

zygote

cells.

reproduction.

Meiosis

the

two

division

of

constriction

two.

two

Mitosis

Before

A

the

egg

mitosis

happens

chromosomes

•

by

fertilised

daughter

asexual

•

•

produced

the

production

chromosomes

duplicated

two

There

its

left,

animal

the

•

•

are

OUTCOMES

mitosis

the

two

copies

separate

so

each

new

cell

gets

a

copy

nucleus.

of

each

chromosome.

The

diagram

shows

what

happens

to

one

chromosome.

As a

a

result

of

mitosis,

each

daughter

cell

has

the

same

chromosome

chromosome

number

copied

two

the

a

original

reliable

parent

system,

cell.

they

As

are

the

chromosomes

genetically

identical

have

to

been

each

identical

other copies

a

as

by

of

and

to

the

parent

cell.

If

they

were

genetically

different

they

the

would

chromosome

be

rejected

by

the

body’s

immune

system.

chromosome

after

is

it

copied

The

nucleus

to

two

starts

copies

of

chromosome

divide

separate

pulled

and

signicance

are

Mitosis

produces

daughter

cells

following

•

•

daughter

chromosome

of

this

cell

has

17.3.1

This

is

each

cells

218

that

the

are

same

an

exact

number

copy

of

of

the

parent

chromosomes

cell.

and

These

are

growth

repair

identical

–

in

in

of

damaged

a

to

the

parent

cell.

Mitosis

is

important

for

the

animals

special

wounds

tissues

this

happens

growing

–

your

and

areas

skin

all

over

such

cells

as

the

the

divide

body,

tips

by

of

in

plants

stems

mitosis

to

it

and

roots

repair

wounds

type

•

Figure

cells

have

processes:

happens

divides–each

mitosis

apart

genetically

cell

of

the

what

happens

chromosome

divide

by

to

when

mitosis.

replacement

which

only

of

live

cells

for

a

that

short

wear

time

out

and

die,

such

as

red

blood

cells

tnemelppuS

LEARNING

reproduction

–

this

occurs

in

fungi

and

in

plants,

but

is KEY

rare

in

the

animal

reproduction

on

kingdom.

page

There

are

some

examples

of

POINTS

asexual

184.

1

Mitosis

cells Growth:

As

multicellular

organisms

grow,

the

number

of

produces

that

up

their

tissues

increases.

The

new

cells

must

be

the

existing

ones.

Growth

by

mitosis

takes

place

over

the

in

animals.

In

plants,

group

is

conned

to

certain

areas

2

parent

Stem

cells and

replacement

of

cells:

Damaged

cells

identical

new

cells.

Your

skin

cells

and

the

cells

must

be

dying

and

being

replaced

by

identical

lining

cells.

your

Red

cells

gut

need

live

to

Asexual

are

only

be

reproduce,

tnemelppuS

Some

a

short

by

to

the

such

as

time

will

wear

away

and

die.

of

the

cells

produce

blood

become

keep

dividing

They

do

cells.

and

Asexual

parent.

yeast

reproduction

Mitosis

and

occurs

potato

results

when

tubers

in

offspring

unicellular

die.

cells.

(see

T opic

16.1).

that

not

form

by

develop

from

mitosis

into

an

to

any

embryo

type

provide

the

of

remain

as

specialised

unspecialised

body

with

a

cell.

These

These

cells

are

needed

to

replace

cells

constant

that

get

QUESTIONS

cells

supply a

Which

type

There

is

a

layer

of

stem

cells

just

under

the

These

stem

cells

continually

divide

to

outer

make

toughened

for

protection.

They

get

rubbed

off

constantly

replaced.

When

skin

is

wounded,

cells

and

these

in

as

the

more

bone

cells

to

marrow

repair

to

the

produce

damage.

new

red

There

blood

are

and

cell

division

that

to

the

are

parent

cell?

that

Give

two

examples

of

need

stem

many

cells

cells

layer

mitosis

occurs

i

in

cells

plants produce

of

worn

when be

for

that

b become

to

cells

organisms

identical skin

daughter

specialised

functions.

produces

of

mitosis.

also

1

out

by

cells

SUMMARY They

new

unspecialised

cells

cells.

of

are

mitosis.

reproduction:

identical

Stem

for

replaced

as

are

specic which

same

replaced

that constantly

the

cell.

produced

They by

have

chromosomes

called

meristems

Repair

of

whole

the body

and

identical

number to

daughter

genetically

cells

identical making

are

tnemelppuS

asexual

stem

and

ii

in

animals.

cells

phagocytes

2

Describe

the

role

of

stem

cells.

replacements.

Each

time

a

specialised

remains

cells

in

Mitosis

stem

for

cell

some

divides,

specic

unspecialised

meristems

takes

place

in

in

the

to

go

plants

one

daughter

function

through

have

meristem

the

behind

and

the

starts

other

process

same

the

cell

the

root

role

tip.

as

of

to

become

daughter

mitosis

stem

cells

cell

again.

in

Cells

The

animals.

at

various

stages

of

mitosis.

219

tnemelppuS

•

17.4

Meiosis

Meiosis LEARNING

OUTCOMES

Meiosis •

Dene

meiosis

as

a

is

a

type

reproduction. division

in

which

number

resulting

formation

in

is

known

Explain

how

meiosis

variation

by

forming

human

of

of

paternal

essential

the

the

with

haploid

number,

sperm

the

sort

of

This

type

46

which

half

the

normal

number.

is

would

of

after

the

(As

and

results

chromosome

opposed

diploid

cells

both

would

in

to

the

number.

full

number).

had

have

generation

every

father,

nuclear

the

have

in

owering

In

meiosis

different

raw

to eggs

result

contain

of

the

material

changing

23

23

46

92

chromosomes

chromosomes.

the

number

generation.

in

for

In

a

of

This

This

is

of

If

the

this

chromosomes

does

reduction

not

happen.

selection

humans

are

to

and

in

in

–

the

the

not

the

allows

called

egg

a

different

and

has

23

from

number

of

generation.

ovaries

anthers

gametes.

meiosis

cells

and

the

to

and

and

They

variation

organisms

is

zygote

egg,

identical.

genetic

there

producing

The

generation

occurs

cells

so

reproduction

from

in

in

division

each.

mother,

sexual

contributes

because

involved

chromosomes

the

organs

meiosis

daughter

this

is

constant

sex

46.

life-cycle

chromosomes

from

sperm.

stays

at

the

number

plants

and

in

division

only

the

occurs

In

remains

division

halves

cells

Meiosis

a

egg

double

number

nuclear

chromosomes

as

and

fertilisation

chromosomes,

the

in

are

that

to

testes.

the

ovules.

genetically

provides

evolve

in

the

response

environments.

23

meiosis.

Figure

17.4.2

meiosis.

four

As

cells.

been

shows

you

Each

halved

to

can

of

what

see

these

give

a

happens

there

cells

are

has

haploid

to

one

two

one

pair

of

divisions

chromosomes

of

chromosome,

the

so

cell

the

during

resulting

number

in

has

gamete.

cell

46

46

from

with

in

sexual

chromosomes

sperm

and

cells

at

generation

nuclei

Meiosis

diploid

for

organs

new

Instead,

chromosomes

is

reproductive

maternal

in

sperms

gametes

as

formed

continued combinations

Human

that

the

produces

zygote

and

in

cells

If •

division

place

genetically chromosome

different

cell

takes

is This

halved,

It

the the

chromosome

of

reduction

the

one

testis

pair

of

chromosomes

cell

diploid

ovar y

in

cell

testis first

of

division

the

cell

23

fertilisation 23 haploid second

division

sperm

haploid

of

the

cell

egg

46 diploid

zygote

Figure

17.4.1

chromosomes

haploid

the

220

in

number.

diploid

The

number

gametes

is

The

number

in

number.

four

of

the

called

a

the

zygote

is

Figure

17.4.2

This

There

one

haploid

shows

are

what

two

cells

which

happens

divisions

chromosome

so

of

the

become

to

the

one

cell

number

sperm

pair

to

of

give

has

cells

chromosomes

four

been

cells.

halved.

during

Each

of

meiosis.

these

has

17.4.2

meiosis.

In

inherited

mother .

of

each

what

pair ,

one

from

the

father ,

When

the

23

meiosis,

and

shows

the

maternal

produced

in

happens

and

Differences

are

one

of

cells

chromosomes.

meiosis

one

chromosome

pairs

daughter

to

is

is

pair

gain

different

is

genetically

between

one

as

in

it

origin

was

separate

different

in

in

which

from

the

and

the

one

as

it

of

during

was

inherited

combinations

way

mitosis

chromosomes

paternal

maternal

chromosomes

This

of

rst

from

the

division

paternal

haploid

cells

another .

meiosis

A

The

differences

between

mitosis

and

meiosis

are

summarised

in

the

fertilised

of

and

in

Figure

17.4.3.

One

The

to

sperm

give

division

T wo

number

the

of

chromosomes

The

same

daughter

cells

number

of

chromosomes

a

are

genetically

The

daughter

cells

from

the

are

cell

STUD Y

genetically

parent

cells

are

formed

Four

daughter

cells

are

Meiosis

46

the

of

the

chromosomes.

Mitosis

diploid

shou

ld

haploid

haploid

Meiosis

SUMMARY

and

mitosis

diploid

a

compared.

many

pairs

of

body

chromosomes

are

there

in

the

an

iii

a

the

egg

number

POINTS

nucleus Meiosis

of

chromosomes

cell

in

ii

a

sperm

iv

a

red

these

human

cells:

which

number

to

cell

blood

three

tnemelppuS

b

Explain

ways

in

which

meiosis

are

differs

from

Meiosis

meiosis

produces

the

advantage

of

is

halved

from

resulting

genetically

in

diploid

cells

different.

produces

variation

by

new

combinations

variation. of

Explain

division

chromosome

mitosis. forming

how

reduction

cell

2 State

a

the

haploid

that zygote

a

is

cell? in

i

spell

co rrec tly.

QUESTIONS

human

State

to

you

haploid

1

of

how

diploid

KEY

How

learn

are

and

diploid

haploid

17.4.3

T hey

conf used

duplication

diploid

haploid

you

mito sis

diploid

DNA

haploid

when

wo rd s

meio sis.

them

c

nuleus

TIP

carefu l

easily

2

The

nucleus

formed

and

b

with

the

cells

write

a

zygote.

is

Be

1

or

with

divisions

different

daughter

Figure

egg

fusing

halved

identical

T wo

is

Meiosis

remains

The

the

egg

Mitosis

human

table

genetic

variation

among

gametes.

maternal

and

paternal

chromosomes.

221

tnemelppuS

tnemelppuS

Figure

17.5

Inheritance

Cat LEARNING

breeders

Use

to

pedigree

show

cats

diagrams

how

features

the

are

terminology

hair,

bred

all

the

if

they

kittens

features

kittens

together

short-haired

haired

the Use

long

some

are

inherited

•

that

breed

genes

together

two

cats

which

both

OUTCOMES have

•

know

and

at

kittens

all.

that

then

have

there

in

the

Breeders

appear

will

within

may

litter,

can

long

be

or

make

a

hair.

some

there

If

short-haired

long-haired

may

pedigree

family

two

be

no

long-

diagrams

of

cats

as

in

looks

very

like

and

to

Figure

show

17.5.1.

of You

will

see

that

a

pedigree

diagram

a

family

tree,

but

inheritance symbols

•

Distinguish

and

between

are

used

to

indicate

the

gender

of

individuals.

genes

alleles I

1

Symbols

2

for II

pedigree

square

=

diagrams:

male;

circle

=

female

III

shaded

circle

individual

or

with

square

the

=

condition

shading

=

long

hair

no

shading

=

short

1

hair

studied Figure

17.5.1

A

pedigree

family

unshaded

individual

circle

not

or

square

showing

of

diagram

showing

the

inheritance

of

hair

length

in

a

cats.

=

the

Genes

and

alleles

condition

A individuals

may

be

identied

gene

is

a

molecule. generation

and

I

–

2,

II

–

5

Each

of

gene

DNA

is

that

always

is

the

and

III

–

the

chromosomes.

genes

from

vary

versions

of

of

a

gene

In

Figure

the

Each

same

between

each

(see

species

gene

17.5.2,

you

You

species

individuals

are

below),

chromosomes.

has

known

but

can

can

has

from

as

usually

see

also

of

Nancy

the

gene

the

three

see

the

father

for

Mary

all

disease,

a

Soto

disease

in

who

these

the

early

from

1800s.

descendants

Maracaibo

in

different

be

two

more.

pair

are

of

and

d/d

different,

heterozygous

The

dominant

expressed

in

the

allele

phenotype.

two

alleles

individual

is

are

the

same,

homozygous

d

These

live

two

alleles

individual

is

are

the

same,

homozygous

of recessive

and

d

expressed

the

recessive

allele

the will

be

in

the

phenotype.

Many from

around of

mother

Venezuela. Figure

222

gene.

be

is

may

B/B

alleles

However,

The

serious

by

egg

Lake

one

every

dominant.

chromosome

of

one

A/a

two

this

will

the

descendants

died

many

individual

These

of

for

disorder ,

the

on

B

B

Wexler

position

There

on

alleles

the

studying

protein

and

genes.

species.

are

genes

the

a

d

neurological

a

place

genes

same

alleles.

A

responsible

Huntington’s

making

same

own

each

there

KNOW?

discovered

its

These

sperm A

Professor

for

the

the

within

chromosome

YOU

in

1. individual

DID

code

located

number, of

e.g.

length

by

17.5.2

This

shows

three

genes

that

are

on

the

same

chromosome.

alleles

Sometimes

is

only

one

an

organism

type

metabolism.

of

But

gains

instruction

many

two

to

copies

use

organisms

of

during

contain

the

same

growth:

two

allele

so

there

development

different

alleles.

If

STUD Y

or

an

Notic e is

expressed

and

affects

the

appearance

of

the

individual,

it

is

said

to

dominant

allele.

If

it

is

not,

then

it

is

said

to

be

a

recessive

the

the

1850s,

Gregor

Mendel

investigated

inheritance

in

pea

noticed

that

amongst

garden

pea

plants

one

variety

grew

to

while

another

remained

short,

or

dwarf.

He

used

pea

plants

bred

true

–

from

generation

to

generation

they

were

a

plants

or

dwarf

capita l

recess ive

smal l

letter .

differ ent

letter

allel e

allel es

of

the

plants.

Never

letter s

either

the tall

the

that

use always

a

be

as tall

as

alwa ys

plants.

and He

we

dom inan t

allele

allel e

In

that

be

show a

TIP

allele

for

sam e

gene .

When

tall.

he

plants

of

been

tall

give

Using

T

these

were

plants

on

about

letters

This

A

for

it

and

has

the

had

allele

the

is

all

when

He

he

there

he

a

the

a

generation

generation

next

that

his

gene

that

pea

consisted

dwarfness

He

did

knowledge

‘factors’

were

of

generation

generation.

used

called

is

next

new

reasoned

‘skipped’

but

the

this

seeds,

dwarf.

what

two

letter

But

DNA,

terminology

capital

letter

some

represent

gene

varieties,

produced

although

represent

dwarf.

and

two

dwarf.

and

genes

to

modern

plants.

case

them

passed

anything

Let

of

self-pollinated

many

to

cross-bred

None

that

had

not

of

controlled

controls

know

algebra

height

height.

in

pea

alleles.

for

tall,

used

recessive

and

for

the

let

t

represent

dominant

the

allele

allele

and

a

for

lower

allele. Mendel

The

a

genotype

pea

tt,

plant

the

(TT)

or

they

The

of

an

could

plant

is

be

organism

TT,

two

or

alleles

phenotype

is

the

are

way

If

They

recessive

that

the

tt.

homozygous.

homozygous

have

Tt

is

alleles

the

alleles

be

has.

alleles

for

are

So

the

are

genotype

the

homozygous

Individuals

different,

the

two

can

(tt).

it

are

example

expressed

same,

of

TT

refers

to

all

the

aspects

of

an

organism’s

biology

shape

the

of

will

apply

the

term

to

one

feature

of

an

organism,

for

round

of

seven

including

and

the

wrinkled.

POINTS

individual.

its

Pedigree

diagrams

show

genes. how

We

–

plants

if

KEY

an

seeds

pea

dominant

heterozygous

in

inheritance

in

or

Tt

except

the

features

1

It

studied

different

features

are

inherited

in

example families.

height

in

pea

plants.

The

genotypes

TT

and

Tt

result

in

plants

with 2

the

tall

phenotype,

whereas

the

genotype

tt

results

in

dwarf

An

allele

is

a

Most

3

The

genes

of

of

an

is

an

phenotype

QUESTIONS

have

genotype

makeup

SUMMARY

version

of

a

gene.

plants.

is

many

the

alleles.

genetic

organism;

all

organism

the

the

features

other

than

its

genotype.

1

Chromosomes

occur

in

pairs

in

all

cells

except

the

gametes. 4

Explain

why

they

are

not

in

pairs

in

A

dominant

expressed

2

a

What

are

b

Explain

5

3

Explain

is

meant

by

the

terms

dominant

allele

and

of

the

following

genetic

terms:

a

homozygous

b

heterozygous

c

genotype

d

phenotype

A

recessive

only

allele

each

6

seed

how

shape

you

is

would

dominant

nd

or

out

whether

is

always

phenotype.

allele

for

wrinkled

allele

no

homozygous

identical

a

is

expressed

dominant

A

two

the

when

present.

has

Explain

the

is

and

4

in

alleles?

what

recessive

allele

gametes.

individual

alleles

heterozygous

two

allele

different

of

a

has

gene

individual

alleles

of

a

gene.

recessive.

223

17.6

Monohybrid

inheritance

Monohybrid LEARNING

inheritance

characteristic,

•

Dene

•

Explain

concerns

the

inheritance

of

a

single

OUTCOMES

monohybrid

inheritance

It

involves

the

such

as

plant

inheritance

height

of

or

ower

the

parental

examples

alleles

of

of

one

gene.

We

will

colour

tall

×

dwar f

use phenotype

monohybrid

the

crosses

example

of

Mendel’s

peas. parental

There

pea

is

one

plants.

gene

The

for

height

gene

for

in

TT

tt

T

t

genotype

plant genotypes

height

has

two

alleles:

tall,

T, of

and

dwarf,

gametes

t.

gametes

There

are

three

genotypes

for

t

possible

plant

height: T

TT

=

homozygous

Tt

tall F

generation:

genotype

–

all

heterozygous

(Tt)

1

Tt

tt

=

=

The

STUD Y

The

TIP

tall

Whe n

you

gene tic

the

on

them

this

simpl e

hom ozyg ous

only

one

mak e

write

this

As

–

so

once

parental

result

plants

of

phenotype

dwarf.

Figure

a

above

shows

homozygous

plants

that

a

all

tall

plants

17.6.1

cross

dwarf

Mendel

used

between

plant,

in

his

tt.

a

homozygous

These

crosses.

represent

This

is

the

called

cross.

of

meiosis,

allele,

all

T,

recessive

the

and

allele,

t.

receive

one

dominant

and

all

because

the

have

allele,

T,

gametes

all

heterozygous

tall,

–

cross

and

dominant

the

tall

diagram

T T,

breeding

contain

only

in

parental

genetic

a

the

orga nism s

gam e tes

geno type

the

like

page ,

homozygous

plant,

pure

out

diag ram s

ones

mak e

write

heterozygous

the

When

allele

the

is

from

gametes

the

tall

from

fertilisation

and

one

genotype,

dominant

to

plant

the

occurs,

recessive

Tt.

Their

the

contain

dwarf

the

allele

plant

new

so

phenotype

recessive

allele,

will

be

will

be

t

the

diag ram .

The

rst

generation

is

known

as

the

F

generation,

and

in

this

particular

1

genetic

cross,

all

the

plants

in

the

F

generation

are

heterozygous

tall

(Tt).

1

Crossing F

tall

×

the

F

tall

generation

(3:1

ratio)

1

1

phenotype

The

F

plants

are

allowed

to

self-pollinate

(see

genetic

diagram,

1

F

Tt

left).

Tt

1

When

meiosis

occurs,

half

of

the

gametes

of

each

plant

will

genotype

have

genotypes

t

T

T

allele,

T,

and

half

will

have

the

recessive

allele,

t

time

when

fertilisation

occurs,

there

are

three

possible

gametes

combinations

gametes

T

t

TT

the

F

,

or

second

generation:

(homozygous

tall)

(heterozygous

tall)

Tt

tt

genotypes

in

2

Tt

generation:

alleles

tt

Tt

T

of

t

TT

F

dominant

t

This of

the

(homozygous

dwarf).

phenotypes

2

Amongst 25%

homozygous

dominant

75% 50%

heterozygous

tall

homozygous

generation

¼

(or

25%)

will

be

homozygous

½

recessive

(tt)

25%

(or

50%)

be

will

be

heterozygous

homozygous

dwarf.

and

Since

the

therefore

tall;

phenotypes

are

the

same,

¾

of

the

F

plants

will

be

tall

and

2

224

17.6.2

75%

:

25%

is

a

3:1

ratio.

of

¼

(or

TT

25%)

and

dwarf

Tt

Figure

tall;

(Tt)

will 25%

this

(TT)

dwarf.

This

can

also

be

written

as

3

tall :

1

dwarf.

¼

will

be

tnemelppuS

A

If

test

you

allele

cross

look

is

at

not

the

last

two

expressed

in

crosses,

the

F

you

will

generation

see

but

that

is

the

recessive

expressed

in

the

F

1

generation.

plant

have

just

the

plant

This

by

means

looking

same

because

that

at

it

can

only

do

because

phenotype.

it

We

be

STUD Y

2

we

not

know

plants

do

know

the

with

the

genotype

genotypes

genotype

of

of

TT

a

a

and

G en e tic

Tt

shou ld

dwarf

test

cross

whether

If

our

plant

it

tall

is

is

used

gives

heterozygous

half

tall

determine

homozygous

plant

(tt)

to

is

tall

plants

then

(Tt)

and

the

genotype

heterozygous

homozygous

all

(Tt),

plants

or

(T T),

(Tt).

crossing

half

If,

it

(see

then

an

individual

genetic

crossing

however,

with

dwarf

of

a

plants

our

dwarf

(tt)

in

it

diagrams

with

tall

a

the

unknown

tall

phenotype

plant

is

(tt)

ratio

of

nd

out

the

below).

squa re

possib le

be tw een

includ e

the

to

a

show

fusi ons

gam e tes.

is

will

give

1:1.

the

unknown

tall

plant

is

heterozygous:

homozygous:

×

tall

phenotype

tall

‘unknown’

Tt

dwarf

×

dwarf tt

genotype

TT

‘unknown’

alwa ys

dwarf

plant

plant

a

to

if

if

diag ram s

Punn e tt

tt

all A

TIP

tall

tt

genotype genotypes T

of

genotypes

t

t

gametes

T t of

gametes t

gametes

t

gametes

T

Tt

genotypes

test

cross

Figure

offspring:

17.6.3

100%

diagrams

SUMMARY

QUESTIONS

1

Complete

these

inside

brackets.

the

(Tt)

like

100%

these

by

test

tall

show

the

ratios

expected

cross

in

the

offspring:

offspring,

50%

heterozygous

50%

homozygous

not

the

actual

choosing

the

correct

word

from

1

A

pea

plant

with

a

tall

(genotype/phenotype)

TT

or

could

A

tall

pea

plant

with

genotype

A

tall

pea

tall

50%

dwarf

offspring.

the

inheritance

inheritance

characteristic

height

TT

is

of

such

a

as

or

ower

colour.

Crossing

a

homozygous

tall

(homozygous/

with

a

homozygous

dominant.

dwarf c

50%

have

plant heterozygous)

( tt)

Tt.

2 b

of

Monohybrid

involves

(genotype/phenotype)

(Tt)

recessive

POINTS

plant the

phenotypes

numbers

single a

Tt

genotypes

KEY

sentences

tt

T

phenotypes

heterozygous

Genetic

t

plant

with

genotype

Tt

is

plant

produces

all

(homozygous/ heterozygous

tall

plants.

heterozygous).

3 d

A

dwarf

pea

plant

heterozygous)

2

Fruit

a

ies

have

Using

the

a

with

genotype

tt

is

gene

that

symbols

State

for

the

this

Give

W

determines

=

long

the

wing

length

and

w

=

of

their

short

wings.

gives

tall

plants

to

(3:1

genotype

of

a

fruit

y

which

is

genotypes

heterozygous

Crossing

plant

its

tall

A

fruit

which

to

y

is

heterozygous

homozygous

predict

the

ratio

of

3

for

for

wing

short

proportions

of

plant

a

heterozygous

with

a

plant

plant

tall

homozygous

gives

to

1

a

ratio

dwarf

of

plant

gametes.

(1:1 b

a

dwarf

ratio).

dwarf

of

1

wing:

characteristic.

the

heterozygous

plants

1 ii

two

tall recessive.

4

i

Crossing

(homozygous/

length

wing.

each

is

Use

wing

mated

a

with

genetic

type

in

ratio).

one

diagram

their

offspring.

225

17.7

Codominance

tnemelppuS

Codominance LEARNING

OUTCOMES

Up •

Explain

the

term

to

either

•

Describe

the

now

the

inheritance

dominant

blood

or

we

have

recessive.

looked

The

at

recessive

involve

allele

is

alleles

not

that

are

expressed

in

the

of phenotype

ABO

examples

codominance

of

individuals

with

the

heterozygous

genotype.

Sometimes,

groups however ,

both

So

alleles

the

are

expressed

phenotype

is

a

and

neither

mixture

of

the

is

dominant.

effects

of

each

allele.

× parental

This

condition

is

known

as

codominance

and

the

alleles

phenotype

are

called

can R

parental

C

R

W

C

C

have

codominant

red

owers

alleles.

or

The

white

four

owers.

o’clock

Flower

plant

colour

is

W

C

determined

by

one

gene.

However,

if

you

cross

homozygous

genotype

red-owered F

plants

with

homozygous

white-owered

phenotype 1

× all

pink

plants,

the

offspring

are

all

pink.

The

two

parents

produce

flowers

heterozygous

offspring

(the

F

generation)

in

which

both

1

alleles R

F

genotype

C

1

W

R

C

C

are

R

W

pink

–

an

intermediate

colour.

can

see

are

in

Figure

pollinated

17.7.1

what

amongst

happens

themselves.

when

There

the

are

pink

red-,

W

C

C

give

W

plants R

to

C

You

C

expressed

C

pink-

and

white-owered

plants

in

the

F

generation

in

a

2

ratio

the

the

Notice R

W

C

:

50%

phenotypes

when

C

C

C

25%

is

:

25%

the

or

same

1:2:1.

as

the

Notice

ratio

W

W

C

C

of

alleles

also

that

are

R

C

R

R

C

C

genotypes

generation:

of

genotypes

each

allele

is

represented

as

a

capital

letter,

W

red

ower

neither

W

=

allele

is

C

W

and

white

recessive

and

ower

that

=

they

C

.

This

both

shows

exert

an

that

equal

C

effect

F

ratio

codominant.

R

C

the

the

C

so

R

that

W

R

gametes

of

on

the

phenotype.

phenotypes

2

R

25%

homozygous

C

R

C

R

50%

heterozygous

25%

homozygous

C

W

C

25%

red

50%

pink

25%

white

W

C

Multiple

So Figure

alleles

W

C

far,

we

have

looked

at

examples

where

a

gene

has

only

17.7.1

two

alternative

may

The

four

have

groups

of

alleles.

three

the

or

There

more

are

examples

where

blood

group

determined

human

by

system

one

gene,

I,

A

different

alleles:

I

B

I

O

and

I

I

A

O

I B

A

I

A

B

I

B

I

B

O

I

B

A A

The

alleles

I

B

and

I

I

are

B

I

O

I

codominant

slightly

and

different

code

group

A

I

A

three

Blood

are

I

with

gene

alleles.

Genotype

ABO

a

AB

O

I

O

for

molecules

on

O

the

surface

A

I

and

the

four

different

groups

I

at

group. of

and

anti-sera

anti-sera

clump

the

A

226

A

A

together

or

B

(blue),

and

if

B

the

molecules

anti-sera

(white).

anti-sera

on

their

B

Red

blood

reacts

cells

with

surfaces.

blood

does

table.

Remember

tested

(yellow)

and

the

diploid. with

red

cells.

The

allele

I

is

recessive

to

both

B

Look

Blood

of

not

You

any

code

can

for

see

person

one

the

can

of

these

possible

only

molecules.

genotypes

have

two

for

alleles

each

as

we

blood

are

all

phenotype:

parental

genotype:

blood

A

I

group

blood

group

O

B

I

I

A

gametes

×

AB

parental

phenotype:

parental

genotype:

A

O

I

blood

O

I

B

I

O

I

group

blood

×

O

I

O

I

B

I

A

Figure

Look

and

at

O.

B

O

O

I

A

I

I

phenotype

O

1

blood

group

A

1

blood

group

B

O

I

A

I

I

B

I

ratio:

O

I

I

B

O

I

A

I

I

phenotype

the

genetic

The

the

diagrams.

children

same

parents

all

will

have

T wo

parents

blood

have

groups

A

blood

or

B.

groups

None

of

STUD Y

AB

them

blood

have

four

group

blood

blood

as

their

A

1

blood

group

B

1

blood

group

AB

1

blood

group

O

TIP

ABO

parents.

groups

A

and

B.

They

could

have

blood

is

an

groups

–

A,

B,

AB

and

grou p

exam ple

children

and

O.

Y ou SUMMARY

can

QUESTIONS

aske d

in There

are

varieties

results

in

group

will

discon tinuo us

1

blood

O

I

codo min ance with

ratio:

1

17.7.2

syst em T wo

O

I

A

I

T he have

O

I

I

B

I

O

I

I

B

I

B

I

O

gametes

group

B

I

A

gametes

I

A

tnemelppuS

parental

the

red-owered,

of

of

the

a

four

o’clock

number

table.

white-owered

of

Explain

plant

crosses

the

of

of

the

each

plants

pink-owered

photo

between

results

number

(see

and

on

right).

varieties

the

expect

abou t

sam e

of

also

of

varia tion.

to

bo th

be

to pics

ques tion.

The

are

shown

cross.

of

each

colour

crosses

red

×

pink

white

red

×

pink

2

Use

of

a

The

of

126

131

pink

39

and

diagram

as

coat

If

white

a

83

work

the

mother

of

codominance.

known

to

where

the

inheritance

homozygous

88

115

offspring

A

white

92

pink

genetic

the

pink

white

×

group

3

×

red

out

father

is

blood

colour

in

all

the

possible

blood

heterozygous

group

some

homozygous

bull,

the

is

43

red

calves

for

groups

blood

O.

cattle

cow

have

is

is

an

example

crossed

coats

with

with

a

allele

causes

Flowers

R

W

causes

white

hairs.

red

hairs

to

be

Heterozygous

produced

cattle

have

and

the

coats

allele

the

that

are

KEY

of

of

red

genetic

the

o’clock

plant.

and

white

hairs

giving

POINTS

a Codominance

diagrams

offspring

in

to

the

show

the

following

a

a

roan

bull

and

a

roan

cow

b

a

roan

bull

and

a

red

c

a

roan

bull

and

a

white

cow

occurs

when

roan. both

Use

four

R

1 mixture

of

‘roan’.

R

The

a

colour

genotypes

and

the

phenotypes

alleles

2

The

over

as

neither

the

other.

inheritance

groups

A

I

expressed

phenotype,

dominant

crosses:

are

involves

B

I

of

ABO

three

in

is

blood

alleles:

o

and

I

cow

227

17.8

Sex

Sex LEARNING

Describe

how

sex

is

inherited

in

chromosomes

46

chromosomes

Dene

a

and

which

these

sex

occur

in

you

23

are.

In

pairs.

humans

In

there

females

all

46

humans chromosomes

•

determine

determined are

and

determination

OUTCOMES

Y our •

linkage

can

be

matched

together

into

pairs.

This

is

done

by

taking

sex-linked images

of

the

chromosomes

and

matching

them

for

size

and

shape.

characteristic In

•

Describe

an

•

colour

example

Use

of

genetic

blindness

sex

the

the

results

of

and

have

sex

X

Figure

the

the

you

sex

egg

an

X

can

of

and

a

are

have

Y

not

two

alike.

X

These

are

chromosomes

known

and

chromosome.

see

how

individuals.

sex

chromosomes

Remember

that

in

the

the

gametes

number

of

cells

contain

fertilisation,

of

and

Sex

As

XX

the

diploid

in

meiosis

so

each

gamete

can

have

only

one

egg

is

chromosome.

of

may

with

there

child

X

half

fuse

with

the

an

being

the

X

a

with

Y

Half

sperm

female

either

chance

or

the

a

of

sperm

Y

contain

chromosome.

with

Since

and

the

a

sperm

chromosome.

chromosome

equal

of

contain

sperm

zygote

an

there

X

are

with

equal

the

inheriting

Y

XX

or

male.

inheritance

you

can

see

is

in

the

very

electron

small

micrograph

and

much

opposite,

smaller

than

the

the

X.

Y

Therefore

cell

the testis

in

sperm

sperm

chromosome cell

a

an

and

the

or

chromosome,

XY

halved

chromosomes.

chromosome

numbers

XY

is

sex

chromosome

Y

chromosome

has

far

fewer

genes

than

the

other

chromosomes

ovar y

and

the

has

X

chromosome

17.8.1

two

All

At

Gametes:

that

Females

linkage

of

in

chromosomes

crosses

chromosomes

diploid

two

chromosomes.

an

determine

involving

are

Y

to In

predict

there

X

males

linkage

diagrams

males

as

as

far

fewer

than

development

mutated)

the

of

then

X.

One

testes

the

in

body

gene

the

on

the

embryo.

that

Y

If

develops

chromosome

it

is

is

not

stimulates

present

(or

if

it

female.

Y

Sex all

X

eggs

have

of

an

chromosome,

X

50%

sperm

have

a

linkage

an

chromosome

The 50%

tnemelppuS

X

genes

that

are

located

on

the

X

chromosome

are

described

as

have

Y

sex-linked

even

gender

controlling

or

though

they

have

sexual

nothing

to

characteristics.

do

with

Among

determining

the

genes

on

the

X

X

chromosome

are

genes

involved

with

controlling

vision

and

blood

clotting.

X

50%

XX

female

Males

if

any

only

of

have

them

one

are

copy

of

recessive,

the

then

genes

the

that

effect

are

on

will

be

X

chromosomes,

seen.

Because

Y

women

50%

XY

male

linked

have

common

Figure

17.8.1

The

diagram

shows

X

and

Y .

only

Do

not

of

the

forget

sex

(egg

and

that

sperm)

each

of

contain

to

give

the

228

than

in

this

girls.

is

they

why

T wo

are

less

affected

sex-linked

examples

are

by

sex-

conditions

discussed

are

more

here.

blindness

haploid

of

the

genes

on

the

X

chromosome

controls

the

ability

to

see

known

as

cones,

red

other

number

green

colours.

The

gene

works

in

the

receptors,

of

in 23.

boys

and

the

22

and chromosomes

chromosomes

chromosomes,

One gametes

in

X

alleles

the

Colour inheritance

two

recessive

the

retina

of

the

eye.

There

is

an

allele

of

this

gene

which

does

not

tnemelppuS

produce

so

any

protein

girl

vision.

the

a

or

woman

Males

allele

r

necessary

only

they

who

have

will

is

one

be

for

colour

vision.

heterozygous,

X

Rr,

chromosome

colour

The

so

allele

has

if

is

recessive,

normal

they

have

colour

inherited

blind.

colour-blind

normal-sighted ×

parents

male

female

r R

X

R

X

X

Y

meiosis

meiosis

r R

gametes

X

X

Y

Figure

r

gametes

17.8.2

What

can

cannot

see

familiar r

R

R

X

X

you

Figure

1

female

carrier

:

1

If

you

something

then

you

may

have

R

X

X

Y red-green

ratio:

see?

Y

X

normal-sighted

colour

blindness.

male

17.8.3

carrier

normal-sighted

parents

× female

male

r

R

X

R

X

X

Y

meiosis

meiosis

r

R

gametes

X

R

X

X

Y

R

gametes

Y

X

r

X

X

X

X

R

R

X

r

r

R

X

Y

R

R

Y

X

X

An F

X

chromosome

on

the

left

and

a

Y

ratio:

1

chromosome normal-sighted

female

:

1

carrier

female

:

1

normal-sighted

male

:

1

colour-blind

electron

17.8.3

shows

what

to

expect

if

the

mother

is

and

the

father

is

colour

blind.

Notice

POINTS

that

none

of

Sex

is

determined

children

can

expect

to

be

colour

blind,

but

the

girls

will

inherit

colour

have

this

blindness

allele,

but

on

it

the

does

X

chromosome

not

affect

their

from

their

who

are

heterozygous

are

carriers

of

phenotype.

colour

XY

and

females

17.8.4

shows

what

to

expect

if

the

mother

has

normal

colour

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this

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sex

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characteristic

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a

1

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in

4

the

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located

on

a

sex

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chromosome, father

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blindness.

responsible Figure

the

and

father.

2

females

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the

are for

by

the

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in

microscope.

homozygous

1 dominant

allele

photographed

17.8.4

KEY

Figure

right,

male an

Figure

the

usually

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chance

chromosome. that

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in

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2

of

the

chance

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colour

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that

there

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SUMMARY

QUESTIONS

are

in

tnemelppuS

1

Explain

how

2

Explain

the

sex

is

determined

in

a

sex

linkage

b

terms:

carrier

males

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linked

c

likely

than

to

in

X

re-issue

be

alleles

expressed

females.

humans.

4

following

more

one

so

colour

blindness

green

are

carriers

disorders,

colour

of

such

sex-

as

red-

blindness.

229

tnemelppuS

1

on

PRACTICE

1

Which

QUESTIONS

explains

occurring

in

a

the

life

advantage

of

6

meiosis

The

of

cycle?

cell A

meiosis

allows

sexual

reproduction

Indian

6.

How

and

muntjac

many

in

a

deer

has

a

diploid

chromosomes

sperm

cell

of

this

are

number

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species

of

in

a

skin

deer?

to

occur skin

B

meiosis

as

four

times

C

meiosis

produces

haploid

D

meiosis

produces

sperm

A

many

A

6

6

B

12

6

and

C

6

3

D

3

6

eggs

discover

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albinism

in

are

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What

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(Paper

2)

child

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A

0%

B

25%

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50%

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100%

(Paper

have

this

that

Which

feature

inuenced

controlled

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only

by

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gene

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environment?

condition?

1)

A

blood

group

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concentration

C

heart

D

lung

of

glucose

in

the

blood

disease

cancer

(Paper

2)

[1]

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describes

[1]

recessive

causes

the

genetic

code?

allele:

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is

their

8 A

[1]

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3

cell

[1]

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rst

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gametes

7 is

cell

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1)

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mitosis

(Paper

2

produces

a

harmful

the

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bases

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feature

DNA B

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never

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the

phenotype

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genotype

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in a

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produces

mRNA

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cell

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leave

the

nucleus

proteins

allele

the

homozygous

same

as

phenotype

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C

the

sequence

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the

triplet

of

bases

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a

gene

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of

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in

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and

RNA

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heterozygous

code

(Paper

molecules

with

1)

for

the

different

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acids

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4

Which

is

meiosis

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asexual

reproduction

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growth

of

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9

stems

of

and

egg

2)

(a)

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Explain

[1]

the

repair

(Paper

5

A

man

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sons

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blind.

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25%

B

50%

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75%

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(Paper

230

[1]

has

2)

[2]

the

difference

pairs

of

between

the

terms:

tissues

1)

have

colour

of

inheritance.

cells following

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term

roots

colour

vision.

blindness

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colour

is

the

but

His

her

wife

father

probability

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their

blind?

[1]

(i)

genotype

and

(ii)

gene

allele

(Paper

3)

and

phenotype

[2]

[2]

10

Brachydactyly

is

which

with

people

ngers

drawn

and

for

a

toes.

this

rare

genetic

the

A

rare

condition

condition

pedigree

have

diagram

in

(a)

short

Use

genetic

was

patterns

condition:

(i)

without

female

with

the

condition

(ii) the

in

following

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diagrams

proportions

of

cats

the

to

predict

with

next

the

different

generation

coat

in

the

crosses:

homozygous

dominant

homozygous

recessive,

heterozygous

×

×

[4]

homozygous

condition

recessive.

male

without

male

with

the

(b)

the

[4]

condition

condition

Explain

why

genotype

(c)

stripes,

but

Explain

why

with

Use

is

a

not

with

the

possible

tabby

one

male

blotched

kitten

(d)

it

of

cat

with

and

stripes

parallel

example

to

state

with

parallel

female

cannot

the

blotched

stripes. [3]

tabby

cats

produce

a

stripes.

of

[2]

inheritance

in

this

3

question

to

explain

the

terms

gene

and

allele.

11

12

13

14

(Paper

15

12 (a)

(i)

State

whether

brachydactyly

is

(a)

a

dominant

or

a

recessive

3)

Explain

allele.

nd

Give

evidence

from

the

family

the

you

would

genotype

use

of

an

a

test

cross

organism

that

[1]

could (ii)

how

caused

to by

[3]

either

be

homozygous

dominant

or

tree heterozygous.

that

supports

your

answer

to

part

The Refer

to

the

people

shown

in

the

four

numbers.

red-owered

What

are

the

chances

of

parents

3

and

another

child

with

this

a

genetic

diagram

to

explain

When

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have

(i)

pink

Explain

(ii)

[3]

Show,

the

In

is

has

are

cross-bred

the

owers.

why

by

this

is

so.

[3]

means

result

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of

cross

a

genetic

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3) owered

11

jalapa,

white-owered

your

answer.

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a

condition?

(b) Draw

Mirabilis

and

4 offspring

having

plant,

variety

[3]

variety. (b)

o’clock

tree

a by

[3]

(i).

tabby

cats

controlled

stripes

(T)

blotched

is

the

by

pattern

a

gene.

dominant

of

The

to

stripes

allele

the

in

for

allele

the

coat

parallel

(t)

pattern.

for

a

(c)

Plants

plants

with

64

of

(i)

(ii)

genetic

why

owered

(Paper

parallel

of

the

were

The

When

pink

crossed

seeds

they

[5]

with

were

owered,

variety

and

diagram

to

78

explain

results.

Explain

in

owers

owers.

themselves.

variety.

a

these

among

grown.

were

red

Use

red

and

plants

the

pink

with

collected

plants

this

there

plants

cross.

[5]

were

among

no

white-

the

offspring

[3]

4)

blotched

231

18

Variation

18.1

and

Variation

T ypes LEARNING

Distinguish

between

variation

humans

and

have

many

features

in

common

as

we

are

all

members

of

the

genetic same

variation

of

OUTCOMES

All •

selection

species.

Now

think

about

the

similarities

and

differences

between

phenotypic ourselves

and

monkeys

and

apes.

We

have

many

features

in

common,

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•

State

the

differences

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and

signicant

differences

species.

Biology,

which

we

use

to

categorise

animals

between into

continuous

are

different

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the

term

variation

means:

discontinuous

•

differences

between

•

differences

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is

species

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variation

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Identify

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differences

tnemelppuS

Although •

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that

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species.

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within

all

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the

that

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same

are

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are

with

in

many

this

unit.

differences

discontinuous

between variation

within

examples

is

caused

by

us

–

even

between

identical

twins.

Some

people

are

taller

genes

or

heavier ,

others

have

different

coloured

hair ,

skin

and

eyes.

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is

alone

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we

occurs

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of

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all

variation.

17,

variation

genotypes

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that

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haemoglobin

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types

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at

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genetic

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year

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the

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the

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type

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histogram.

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type

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18.1.1

the

range

class

range

people.

Figure

a

height

frequency

height

variation

measured

would

232

between

phenotypic

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are

in

see

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the

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the

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intermediates.

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eht

Discontinuous

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egatnecerP

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25

20

15

10

5

Some

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lobes.

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type

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Figure

plot

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chart

(see

question

11

on

page

18.1.2

percentage

variation,

groups

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B

(A,

of

B,

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bar

people

AB

and

O

AB

Blood

phenotypes

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with

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the

in

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the

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Maharashtra,

243).

tnemelppuS

India.

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no

at

to

birth,

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in

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genetically

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slightly

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the

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hat

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be tw een

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aske d

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KEY

of

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us.

plantlets

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the

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STUD Y personality,

on

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two

could

distin guis h

two

type s

of

varia tion.

1

Variation

is

the

difference

between

individuals

of

the

same

species.

2

Genetic

variation

individuals;

and

is

the

phenotypic

internal

differences

in

variation

the

is

the

genotypes

differences

of

in

external

SUMMARY

appearance.

1

3

Continuous

resulting

in

variation

a

range

is

of

inuenced

by

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genes

e.g.

and

height

the

in

Distinguish

between

continuous

and

environment

Discontinuous

phenotypes

variation

with

no

results

in

a

small

number

tnemelppuS

Discontinuous

blood

groups.

and

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of

give

three

each.

intermediates. 2

5

discontinuous

humans. variation

4

QUESTIONS

variation

is

cause

by

genes

alone,

e.g.

human

Describe

how

investigate

you

the

environmental

growth

share

of

the

would

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same

that

of

an

on

the

all

genotype.

233

18.2

Mutations

A

mutation

change

•

Dene

•

State

the

term

the

mutation

in

base

a

way

in

mutation

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Describe

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rate

of

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tnemelppuS

Describe

an

•

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of

the

of

cell

anaemia

as

of

the

of

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to

cell

to

a

rst

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malaria

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versus

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234

DNA.

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18.2.1

a

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18.2.2

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to

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anaemia

18.2.2

235

tnemelppuS

tnemelppuS

•

18.3

Adaptive

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to

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and

stems

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hydrophytes

236

in

present,

leaves

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air

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b

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how

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camel

to

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to

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arctic

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the

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pond

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in

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2

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1

shade

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KEY

SUMMARY

some

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ions

concentration.

are

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State

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the

the

stomata

day

dioxide

and

at

close

absorb

during

carbon

night.

237

tnemelppuS

water

stems

18.4

Natural

Natural LEARNING

selection

tnemelppuS

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18.4.1

Selection

for

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239

tnemelppuS

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18.5

Selective

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Figure

240

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241

tnemelppuS

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242

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how

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4)

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Pakistan

31.0

36.2

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2.6

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group

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mm

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resistance

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overcome.

[3]

4)

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by

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answer

to

part

(i).

[2]

243

19

Organisms

19.1

this

State

that

main

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253).

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form

fats

almost

of

and

all

energy-rich

proteins.

food

carbon

Sunlight

chains.

The

is

compounds,

the

major

ultimate

exceptions

such

as

source

are

the

of

vent

secondar y

communities

in

the

deep

ocean

that

rely

on

chemical

energy

rather

consumer

than

Figure

19.1.1

A

food

light

energy.

chain.

Consumers

plants

make

or

their

primary

own

eat

and

other

Sunlight

things

244

in

is

the

this

source

of

ecosystem.

energy

for

all

food,

as

they

energy

both.

so

are

organic

material

eat

Each

of

these

from

a

feeding

word

by

they

have

eat

and

and

pages

6

groups

meaning

eating

animals

the

to

are

is

a

‘to

other

7

eat

(consume)

T ertiary

that

for

it.

called

gain

their

of

can

top

(The

put

are

are

they

word

each

carnivores

from

into

a

trophic

level

as

you

will

see

in

these

trophic

organism

food

waste

feed).

living

ecosystem

are

secondary

carnivores.

energy

how

either

cannot

Herbivores

Carnivores

level.

Y ou

They

consumers

details

trophic

feed’.)

organisms,

consumers.

sometimes

bacteria

and

are

producers.

herbivores.

fungi

(see

All

they

carnivores,

Decomposers

Greek

their

or

consumers

consumers

that

obtain

animals

chains.

comes

in

an

tnemelppuS

tnemelppuS

Dene

an

Sun

known

•

recycling

Light

to •

looking

systems

transfer

one

are

for The

•

we

ow

the There

biological

unit

environment

OUTCOMES and

•

their

Energy

In LEARNING

and

Food

Food

They

next.

chains

chains

show

show

the

Look

at

ecosystem.

ow

the

The

the

ingests

the

This

can

food

one

living

food

in

show

and

always

energy

Figure

the

organism

grass

chain

organisms

and

chain

arrows

from

that

of

food

transferred

gazelle

what

feed

from

19.1.2

direction

to

that

the

the

begins

in

next.

lion

with

on

a

in

one

an

which

to

food

tells

gazelle.

often

a

the

African

in

chain

the

producer ,

East

energy

food

ingests

community.

organism

from

This

a

us

is

that

Notice

green

KEY

plant. 1

include

parts

of

a

plant,

such

as

seeds,

fruits

or

even

POINTS

Sunlight

energy leaves.

the

Food

ow

energy

of

chains

not

energy.

chain

only

show

Producers

would

look

like

the

gain

ow

their

of

food,

energy

they

from

the

is

also

for

→

producers

→

Sun,

so

an

2

this:

primary

A

food

chain

transfer

consumers

→

secondary

we

Food

do

not

chains

include

start

the

with

Sun

in

food

chains,

as

it

is

not

a

‘food’.

food

simple

ows

food

to

decomposers,

but

they

are

rarely

included

in

these

of

in

chains.

the

from

another.

one

Food

show

interconnecting

chains.

the

provide

form

of

compounds

energy

carbon

for

consumers

decomposers.

webs

4 In

shows

energy

to

Producers

and Food

of

systems.

producers. 3

Energy

source

consumers webs

But

main

biological

show

organism Sun

the

dead

most

communities,

animals

will

eat

more

than

one

type

of

Energy

is

animals organism.

A

food

web

gives

a

more

complete

picture

of

the

transferred

to

living

when

they

ingest

feeding

food. in

an

ecosystem.

5

grey

kestrel

lizard

praying

A

trophic

level

of

organisms

or

a

food

is

in

the

a

position

food

chain

web.

tnemelppuS

relationships

mantis

SUMMARY

QUESTIONS

spider

1

Look

at

the

woodland

moth

a

grasshopper

grasses

Christmas

Give

food

web

ecosystem

one

example

the

food

web

of

the

following:

for

from

each

i

a

producer

ii

a

primary

iii

a

secondary

the

here:

of

consumer

bush

consumer

b

Name

the 19.1.2

A

food

web

for

a

West

African

forest

Draw

four

over-harvesting

manner

e.g.

can

result

overshing.

of

in

food

a

Also,

species

decrease

the

in

by

humans

their

introduction

in

numbers

of

foreign

an

the

unsustainable

and

native

organisms

due

to

predation

and

(alien)

species

competition

e.g

food.

Both

of

these

result

in

disruption

of

webs,

due

to

the

removal

of

a

species

or

a

decrease

food

in

chain

organisms.

with

Indicate

levels

on

the

chain.

can Dene

the

term

explain

trophic

how

energy

level

is

chains transferred

and

food

for and

resources,

a

trophic

food

extinction,

2 displace

in

ecosystem.

c

The

carnivores

web.

between

trophic

their levels.

numbers.

245

tnemelppuS

Figure

the

food

19.2

Pyramids

and

describe

and

pyramids

of

numbers

pyramids

of

biomass

chains

plants

pyramids

food

they

webs

do

show

not

feeding

show

how

relationships

many

living

in

a

organisms

are

For

and

instance,

many

grasshoppers

grasshoppers

and

feed

on

lizards

many

are

grasses

eaten

by

and

grey

other

kestrels.

of Food

and

and

but

and involved.

numbers

numbers

interpret community,

• Compare

of

OUTCOMES

Food • Draw,

numbers

biomass

Pyramids LEARNING

of

pyramids

chains

and

food

webs

do

not

show

this.

of

Look

at

Figure

19.2.1.

There

are

far

more

plants

than

caterpillars

biomass

because

fewer

Look

one

This

The

at

caterpillar

than

the

600

shrews

numbers

→

of

in

eats

can

each

this

be

box

organisms

in

there

leaves

because

are

owl

→

in

a

plants.

eats

each

mice

many

10

pyramid

pyramid

at

many

There

are

far

shrews.

chain:

100

shown

the

from

each

food

caterpillars

information

area

living ten

owls

plants

owl

each

shows

trophic

→

of

owl

1

numbers.

roughly

how

many

level.

shrews

hundreds

of

caterpillars

The

producers

and

are

carnivores

consumers

than

than

primary

primary

the

are

rst

the

level,

third.

producers.

consumers.

consumers

as

There

But

they

herbivores

Notice

that

are

also

secondary

have

to

eat

tertiary

1

are

there

the

are

fewer

second

fewer

level

primary

secondary

consumers

are

consumers

bigger

than

them!

consumers

thousands secondary

90 000 of

primary

200 000

Figure

19.2.1

This

shows

the

and

consumers

consumers

leaves

consumers

producers

producers

1 500 000

an

owl

for

that

several

support

days.

number of

Figure

A

19.2.2

problem

Pyramid

with

of

numbers

pyramids

of

for

a

grassland

numbers

is

community

that

they

do

in

0.1

not

hectare.

take

into

tertiar y individuals

account

consumers

the

size

of

organisms

at

each

trophic

level.

decreases secondar y

consumers

buzzard

primar y

consumers size of blackbirds

individuals

producers

decreases

Figure

19.2.3

Pyramids

of

numbers

caterpillars

and

mahogany biomass

show

these

tree

trends.

Figure

19.2.4

A

pyramid

of

numbers

for

the

organisms

living

in

a

mahogany

tree.

parasites

For

instance,

a

mahogany

tree

and

a

grass

plant

each

count

as

one

ladybirds

organism.

greenfly

than

one

unusual rose

19.2.5

An

inverted

numbers.

246

one

grass

mahogany

plant.

As

a

tree

result

can

some

support

many

pyramids

of

more

herbivores

numbers

can

have

shapes.

bush

In Figure

But

pyramid

Figure

19.2.5

the

tertiary

consumers

are

parasites.

Many

of

them

feed

of

on

a

single

ladybird

so

this

pyramid

is

inverted

and

it

looks

top

heavy .

way

instead

biomass

each

to

of

biomass

overcome

numbers.

pyramid

trophic

the

problem

Biomass

shows

the

is

of

the

actual

size

mass

is

of

weight

to

measure

living

or

mass

of

STUD Y

biomass

material.

So

living

things

Prod ucer s

at

plan ts)

level.

the To

A

draw

a

sample

weighed.

mass

is

dry

it

mass

this

much

and

The

is

does

fats

as

constant

for

the

rst

each

the

needs

trophic

sample

estimated

is

to

be

level

is

calculated.

number

of

not

food

for

in

for

the

mass.

change

as

it

It

plant

is

the

recorded

is

is

in

in

at

by

beca use

and

The

inpu t

their

as

to

body

Dry

it

mass

mass

tells

carbohydrates,

community.

in

an

estimate

instance,

do

not

grass

take

often

into

such

as

The

is

time

will

be

grows

This

us

over

a

period

into

the

the

how

proteins

data

is

instant

at

a

how

fast

fast

in

rate,

an

time.

Biomass

but

organism

because

it

grows.

and

cattle,

its

biomass

at

is

grazed

any

POINTS

For

by Pyramids

means

it

is

better

to

calculate

the

of

time,

e.g.

over

a

year

or

a

of

numbers

show

instant many

individuals

there

are

biomass at

produced

provid e

metre.

one

account

grasshoppers

low.

and

energy

water

how in

level

abso rb

oven

1 animals,

tro ph ic

green

on

the

KEY pyramids

of

as

alwa ys

they

sunl igh t

average

organisms

drying

possible

plants.

the

square

taken

of

present

organisms

per

matter

usually

65%

does

material

grams

rst

collected.

taken

(suc h

are

ecosys tem .

approximately

biological

mass

by

data

from

mass

determined

a

expressed

dry

the

community.

animals:

useful

usually

organisms

multiplied

the

of

pyramid,

average

reaches

mass

and

The

in

dry

until

the

then

present

The

biomass

of

TIP

a

growing

each

trophic

level

but

give

no

season. indication

2

of

their

size.

Pyramids

of

biomass

the

of

living

indicate

2

5.8

g

per

m

dog-whelks

mass

each

trophic

material

level,

but

at

give

2

71

g

per

periwinkles

m

no

indication

of

the

rate

of

tnemelppuS

One

of

growth. algae

2

3987

g

per

on

m

and

Figure

19.2.6

A

Phytoplankton

in

water

–

pyramid

consists

both

of

biomass

of

tiny

freshwater

for

a

rocky

seashore

photosynthetic

(lakes

and

ponds)

growing

seaweeds

the

rocks

community.

organisms

and

in

the

that

sea.

oat

The SUMMARY

plankton

and

the

grow

sea

is

quickly

warm

at

times

with

of

plenty

the

of

year

light.

when

They

there

live

for

are

only

a

few

days 1

as

they

are

grazed

by

animal

plankton.

So

their

biomass

at

any

Draw

two

is

small.

But

over

say

a

year,

their

biomass

is

huge.

This

records

only

a

few

days’

growth

and

so

is

of

with

different

biomass shapes.

pyramid

pyramids

one numbers

time

QUESTIONS

nutrients

Explain

their

shapes.

inverted:

2

Draw

for

a

an

pyramid

of

ecosystem

biomass

and

explain

2

21

g

per

m

its

zooplankton

shape.

you

Make

include

the

measurement

4

g

phytoplankton

your

sure

unit

for

that

of

biomass

on

pyramid.

2

per

m

3

Figure

19.2.7

Biomass

pyramid

for

the

English

What

criticisms

made

about

numbers Biomass

can

vary

with

the

seasons.

In

have

been

Channel.

temperate

latitudes,

pyramids

and

of

pyramids

of

deciduous biomass?

trees

than

shed

it

is

their

in

leaves

winter

as

in

winter.

they

will

Their

have

biomass

leaves,

is

greater

owers,

fruits

in

summer

and

seeds.

247

tnemelppuS

tnemelppuS

Pyramids

19.3

Shortening

the

food

chain

tnemelppuS

The LEARNING

The • Explain

energy

losses

of

energy

transfer

levels

in

efciency

of

energy

transfer

between

trophic

levels

can

be

seen

between by

trophic

efciency

OUTCOMES

food

using

energy

pyramids.

These

show

the

energy

transferred

from

chains one

trophic

level

to

the

next.

The

energy

pyramid

in

Figure

19.3.1

2

• Explain

the

shows

increased

that

87 000 kJ

per

m

per

year

is

passed

to

the

tadpoles

from

2

efciency

green

in

supplying

plants

compared

plants

to

as

to

human

feeding

food

the

plant

plankton.

the

small

sh,

and

The

so

tadpoles

pass

on

to

a

tran sfer

char ts

consumers

in 14 000

primar y

87 000

producers

consumers

Ano ther water

char t

o ppos ite.

the

as

to

T his

energy

respira tion

able

tertiar y

energy

ow

decom posers .

be

67

weeds

show n

show s

to

1600

of

energy

is

year

TIP

ecosys tem .

way

per

crop

tadpoles

an

m

animals

Pyram ids

show

per

on.

pike

STUD Y

14 000 kJ

Figure

19.3.1

An

energy

pyramid

for

a

lake.

Figures

are

in

kJ

per

m

per

year.

and

Y ou

shou ld

interp re t

that

2

losses

2

The

tadpoles

obtain

87 000 kJ

per

m

per

year

from

the

water

plants

2

but

ow

only

pass

on

14 000 kJ

per

m

per

year

of

this

to

the

small

sh.

2

show

energy

ow.

The

remaining

chain.

they

The

will

energy

it

tadpoles

have

that

biomass

–

is

they

a

will

passed

their

swallows

Energy

73 000 kJ

do

per

m

have

out

pass

muscles

per

used

some

on

in

to

and

year

a

lot

of

waste

the

other

has

small

–

been

energy

urine

sh

organs

lost

is

that

in

the

the

swimming

and

the

from

faeces.

energy

sh

and

The

in

eats

food

only

their

every

time

tadpole.

always

‘lost’

in

this

way

as

it

passes

from

one

trophic

level

to

2

STUD Y

the

TIP

next.

Of

the

87 000 kJ

per

m

per

year

of

energy

in

the

producers

2

only

As

you

will

Phys ics,

proce sses

efc ient.

‘lost’

is

no

as

energy

are

page

per

m

carnivore,

the

pike.

trophic

is

not

heat.

energy

the

by

next

the

of

it

only

an

size

becomes

some

energy

of

the

of

energy

the

in

energy

pyramid

organisms

is

the

is

never

or

how

esh

of

passed

inverted.

many

the

from

of

Its

top

one

shape

them

there

since

it

simply

looks

at

the

energy

that

is

passed

on.

is

Birds

re tain

a

and

this

heat

cons tant

tempe rature

(see

Energy

Energy

plants

it

is

losses

ow

through

absorb

leaves.

Much

reected

them,

Plants

or

is

use

only

of

green

As

2

this

from

much

respiration.

248

to

year

Since

Resp iratio n

except ion.

168) .

level

affected

per

100% are

maint ain

body

from

trans fer

neve r

Muc h

mam mals

to

know

67 kJ

5%

energy

the

light

of

an

ecosystems

to

the

of

is

not

surface

which

energy

energy

is

the

of

they

in

leaves,

cannot

trap

inefcient.

energy

trapped

the

they

transfer

relatively

light

in

process,

that

At

strikes

best,

their

photosynthesis

passes

straight

because

through

absorb.

photosynthesis

respiration

is

in

their

about

own

40%

so

about

60%

of

the

energy

is

lost

tnemelppuS

efcient

as

released

heat

to

the

plant

and

then

to

the

atmosphere. in

Much

of

the

plant’s

biomass

is

lost

respiration

to tertiar y

decomposers

in

the

form

of

dead

leaves,

twigs,

consumers dead

remains,

released

fruits,

etc.

About

10%

of

the

energy

trapped

by

faeces, in

the

plant

Much

is

of

available

what

they

to

eat

secondary

consumers.

is

edible

not

very

or

etc.

respiration

secondar y

easy

production

digest.

So

primary

consumers

make

dead

available

released

only

about

10%

of

what

they

have

eaten

remains,

faeces,

etc.

to in

secondary

sresopmoced

consumers

to

respiration

consumers.

primar y

However ,

the

animal

esh

in

primary

for

example

heat

consumers dead

consumers,

of

grasshoppers

remains,

and faeces,

etc.

released

gazelles,

is

easier

to

digest

and

carnivores

may in

obtain

slightly

more

than

10%

of

the

respiration

energy.

producers

At

each

trophic

level,

energy

is

lost

as

heat

to dead

the

environment

and

consumers

lose

energy remains,

in

their

faeces

and

urine

to

decomposers

etc. energy

which

means

trophic

level.

that

there

Food

is

chains

less

on

for

the

land

input

next

rarely

have sun

more

than

When

four

farmers

trophic

grow

crops,

human

consumption,

grain

available

is

farmers

They

grow

may

to

or

buy

levels.

all

us

buy

as

the

as

such

food

as

rice,

energy

primary

plant

cereals

such

of

for

in

Figure

consumers.

to

feed

barley

19.3.2

Energy

their

Livestock

level,

animals.

or

maize

or

grass,

alfalfa

and

used

i.e.

in

grow

fodder

crops,

such

as

consist clover ,

for

grazing.

Animals,

such

as

pigs,

cattle

use

up

much

of

the

energy

in

their

that

there

is

not

as

much

energy

food.

vegetarian

diet

can

support

far

more

available

to

cut

down

the

number

of

links

in

people.

the

food

individuals

This

is

at

the

because

end

we

are

of

the

food

cutting

chain

down

the

of

energy

that

occurs

between

in

of

many

food

countries

of

plant

developed

diet

which

poultry,

human

can

provide

tend

origin

to

includes

sh,

lamb,

population

enough

a

and

is

b

Give

to

change

each

and

less

to

one

food

sh.

of

a

meat

pork.

If

farmers

our

diet

are

may

of

that

includes

animal

more

plant

origin.

trophic

POINTS

Energy

losses

occur

between

QUESTIONS

is

the

ultimate

form

of

energy

input

in

a

food

levels

two

ways

in

which

energy

is

‘lost’

from

food

why

food

chains

usually

have

fewer

than

ve

as

and

a

result

in

of

waste

chain?

produced.

chains.

2 Explain

mainly

or

be

materials

2

or

have

proportion

everyone,

respiration, What

that

meat

people

increasing.

for

trophic

a

diets

some

many

higher

beef

food

1

1

undigested

have

with

countries

KEY

SUMMARY

uneaten,

level.

90% foods

‘wastage’

is

each

chain

have fed.

that

at

If

to more

energy

us.

The we

ecosystem.

This

from

A

the

respiration

Western

varied means

an

and In

chickens,

in

they People

may

losses

the

More

energy

is

available

in

trophic foods

for

human

consumption

levels. if

3

a

Explain

supply

b

Explain

why

it

green

why

inefcient

in

is

efcient,

plants

a

diet

terms

as

rich

of

in

terms

human

in

energy

transfer,

to

products

loss.

feed

secondary

food.

meat

energy

of

we

is

relatively

as

consumers

3

A

more

that

than

as

consumers.

vegetarian

far

primary

rather

diet

people

includes

can

than

meat

support

one

products.

249

19.4

Nutrient

Nutrient LEARNING

Describe

the

carbon

far

we

Describe

the

role

ow

(fungi

in

recycling

Describe

the

different

the

water

with

food

ecosystems

and

from

energy.

the

There

Sun,

and

is

a

energy

through

the

This

different

topic

trophic

and

the

levels

next

are

and

is

about

then

lost

some

of

to

the

the

elements

comprise

living

organisms

and

how

they

are

cycled

in

nature.

stages Most

of

into

carbon that

•

concerned

energy

and atmosphere.

bacteria)

been

of

of ows

decomposers

have

cycle constant

•

cycling

OUTCOMES

So •

cycles

living

matter

(95%)

is

made

up

of

six

elements:

carbon,

cycle hydrogen,

have

a

oxygen,

constant

carbohydrates,

a

nite

source

nitrogen,

supply

fats

of

and

phosphorus

these

other

of

these

to

continue,

elements

organic

nutrients.

Life

and

if

sulfur .

they

are

materials.

has

Living

to

Unlike

existed

on

things

make

energy,

Earth

must

proteins,

for

there

is

millions

faeces consumers and

of

urine

years.

become

For

it

locked

up

in

dead

these

elements

bodies

and

life

must

will

be

recycled

become

or

they

will

extinct.

feeding

death

and

Bacteria

decay

feed

producers

decomposers

on

breaking

that

and

the

down

they

water

a

aerobic

Many

warm

are

feed

on

matter

of

dead

of

fats

these

temperature

catalysed

by

and

animals

carbohydrates,

absorb.

and

respiration

nutrients

fungi

waste

and

are

as

decaying

(urine

and

proteins

respired.

the

enzymes.

matter.

into

To

do

processes

They

They

faeces).

also

of

They

small

this

by

molecules

they

digestion

need

also

feed

oxygen

require

and

for

respiration.

in

environment

Decomposers

Figure

19.4.1

The

role

of

decomposers

in

They

also

release

break

carbon

down

as

amino

carbon

acids

dioxide

releasing

when

they

ammonia

respire.

into

their

ecosystems.

surroundings.

the

most

absorbed

These

in

by

this

plants

nutrients

plants. carbon

In

important

We

say

are

that

way

they

elements

and

recycle

for

converted

then

passed

nutrients

carbon

organisms.

into

on

are

to

and

nitrogen

Simple

complex

animals

–

two

compounds

of

are

compounds.

when

they

eat

the

cycled

dioxide

air

The

carbon

cycle

respiration photosynthesis and

decay

Carbon

is

used

important carbon

in

to

make

biological

carbohydrates,

molecules.

The

proteins,

carbon

fats,

comes

DNA

from

and

other

carbon

compounds

dioxide

animals

and

in

use

the

it

in

compounds

air.

Plants

absorb

photosynthesis

by

eating

to

carbon

make

dioxide

food.

from

Animals

the

get

atmosphere

the

carbon

plants.

feeding

Carbon

• carbon

in

Plants

and

carbon

plants

• formed

of

years

dead

ago

animals

fuels:

peat,

dioxide

Decomposers

of

dioxide

the

250

carbon

(as

some

use

well

dead

decaying

Fossil

(plus

fuels

water

like

dioxide

in

of

the

their

following

food

as

water

plants

and

for

ways:

respiration,

releasing

and

energy).

material

for

animals

for

food.

They

respiration,

releasing

oil,

and

also

use

natural

contain

carbon

energy).

is

peat,

one

of

coal,

the

and

gases

gas

released

gas

combustion

The

air

carbon.

oil,

Carbon

19.4.2

use

the

from

vegetation

•

Figure

into

millions

some

coal,

gets

compounds

burning

fossil

dioxide

cycle.

when

these

fuels

are

burnt.

into

the

air

during

STUD Y

TIP

Durin g These

processes

release

carbon

dioxide

into

the

air

and

this

carb on the

uptake

by

photosynthesis

so

the

concentration

of

pho to synt hesis

balances

carbon

is

suga rs. in

the

atmosphere

remains

constant.

Sometimes,

dead

plants

do

not

decompose.

Their

dead

bodies

become

fossilised

coal,

oil

and

gas

–

fossil

The

effects

of

combustion

concentration

Topics

21.2

of

and

carbon

of

fossil

dioxide

fuels

in

the

and

deforestation

atmosphere

are

on

the

discussed

sam e

in

cycl e,

The

water

water

cycle

cycle

water

Follow

moves

demonstrates

the

on

how

important

water

is

to

life

arrows

between

on

the

living

diagram

organisms

to

see

and

how

their

the

world’s

from

the

the

nitrog en

no t

muc h

than

as

use

carb

on

more

nitrog en

).

2

gets

More

powers

is

T he

–

environment.

It

Energy

(N

into

xatio n

beca

is

reactiv e

on

–

the

but

dioxid e

gas Earth.

in

a

of

compo und.

idea

occu rs

21.5.

simpl e

conv erted

compl ex

comm

The

is

fuels.

a

as

means

compo und

to

carb on form

T his

and

simpl e animals

xed

dioxide

colder

water

as

the

air

condenses

rises.

out.

Sun

water

cycle.

The

droplets

heavier

or

condensation

to

form

from

clouds

tiny

of

and

snow.

get

fall

This

is

bigger

as

rain,

and

hail

precipitation.

water

made

water

droplets

animals

water

some

breathe

out

vapour

water

evaporates

from

evaporation

from

the

of

the

soil

and

19.4.3

The

SUMMARY

water

(especially

vapour

through

returns

streams

to

the

and

sea

via

a

Describe

what

and

two

living

c

is

meant

living

by

the

term

cycle,

in

the

context

the

organisms.

substances

six

POINTS

of

that

are

absorbed

and

recycled

by

Carbon

of

elements

that

make

up

95%

of

living

is

cycled

ecosystems

organisms.

Name

water

cycle.

1

State

feeding,

matter.

by

State

the

roles

of

the

following

in

nutrient

3

Look

decomposers

at

the

diagram

b

of

green

the

plants

water

cycle

c

State

three

b

Explain

ways

in

which

water

c

State

the

it

rains

source

of

when

the

clouds

energy

respiration,

decomposition,

and

combustion.

Decomposers,

like

and

important

fungi,

are

bacteria

in

above.

gets

into

the

recycling

of

nutrients.

atmosphere. 3

why

processes

animals

the

a

the

cycles:

2 a

through

photosynthesis,

fossilisation 2

water

QUESTIONS

nutrients

b

lose

rivers

underground

KEY 1

trees)

transpiration

sea

water

Figure

plants

water

Evaporation,

condensation

precipitation

are

and

rise.

that

powers

the

water

cycle.

processes

in

the

important

water

cycle.

251

19.5

The

nitrogen

cycle

tnemelppuS

Nitrogen LEARNING

OUTCOMES

Nitrogen

•

Describe

the

roles

is

molecules.

microorganisms

an

element

required

for

many

biologically

important

of

in

Amino

acids,

proteins,

DNA

and

chlorophyll

contain

the nitrogen.

Approximately

inert

very

80%

of

the

air

is

nitrogen

gas

(N

)

but

it

is

2

nitrogen

•

cycle

Describe

the

stages

nitrogen

cycle

in

and

most

the

to

The

as

and

xed

nitrogen

and

below

changes

that

in

cannot

nitrogen

proteins,

diagram

the

organisms

microorganisms

them

acids

few

the

in

as

shows

happen

can

use

the

ions

the

to

make

it

in

form

such

use

this

of

as

Plants,

It

has

compounds

cycle

as

it.

form.

nitrate

nitrogen

nitrogen

of

it

is

and

animals

to

be

such

available

as

amino

ammonium

which

and

ions.

summarises

all

recycled.

air

lightning

animal

protein

fertilisers plant

animal

proteins

wastes

death

and

decay

nitrogen-fixing denitrifying

bacteria in

nitrogen-fixing

bacteria

decay

soil

bacteria

nitrate

act

ions

the on

dead

plants

and

remains

and

up

of

by

in

bacteria

in

taken soil

root

nodules

roots

animals

animal

wastes

nitrifying

bacteria

nitrate

Figure

19.5.1

The

nitrogen

in

the

soil

cycle.

Most

STUD Y

ions

of

nitrate

TIP

the

ions

nitrogen

(NO

).

that

They

plants

use

this

obtain

to

they

make

absorb

amino

in

acids

the

in

form

their

of

leaves.

3

The

Be

carefu l

‘plan ts

when

you

abso rb

Also

do

the

they

eat

plants

Any

the

no t

add

and

so

process

of

used

obtain

amino

acids

to

form

their

are

proteins,

nitrogen

broken

deamination.

in

the

down

Animals

such

by

that

as

form

enzymes.

of

animals

live

on

plant

to

land,

Animals

protein.

ammonia

such

as

by

the

‘plan ts cow

in

the

cycle

above,

convert

ammonia

to

urea

and

excrete

it

in

urine.

that

nitrog en

Decomposers

(bacteria

and

fungi)

break

down

dead

remains

and

+

T hey

don’ t,

fertili sers

nitrat e

animal

wastes

releasing

ammonium

ions

(NH

)

into

the

soil.

Bacteria

4

also

break

down

urea

in

urine

to

ammonium

ions.

This

process

that is

sometimes

called

ammonication.

Deamination

results

in

the

ions . production

urine

252

are

ions ’.

write

add

acids

excess

their

soil ’.

provid e

writi ng

nitrog en’

mean

nitrat e

‘farm ers

to

abou t

abso rb

amino

(see

of

the

Topic

excretory

13.1).

product

urea,

which

passes

out

in

animal

ions.

These

reaction

If

you

bacteria

instead

are

where

T wo

bacteria

of

tracing

we

Nitrogen-xing

nitrogen

gas

themselves.

available

The

These

a

can

suitable

all

the

cycle

in

source

light

the

of

or

air

they

are

into

die

energy

feeding

of

help

found

in

the

compounds

and

are

a

by

soil.

this

we

are

back

plants.

nitrogen.

These

nitrogen

decomposed,

nitrate

oxidation

realise

recycle

of

into

decomposer.

will

ions

to

ions

from

as

you

nitrate

microorganisms

the

ammonium

diagram

absorption

bacteria

alfalfa

bacteria

bacteria

plants

their

change

this

can

convert

that

they

xed

use

nitrogen

is

plants.

beans,

trees.

soil

bacteria

from

Nitrogen-xing

peas,

of

When

to

gain

with

groups

the

absorbing

the

started

other

in

tnemelppuS

Nitrifying

and

are

to

that

clover

and

they

amino

for

found

need.

gas

the

In

the

the

legume

trees,

ammonia

(in

of

roots

return

bacteria

Nitrogen

roots

tropical

on

into

acids.

the

in

many

swellings

nitrogen

make

environment

sugars

also

inside

change

use

are

the

that

requires

the

like

ame

nodules.

legume

plants

and

a

as

root

legume

nodules)

xation

such

called

plants

also

lot

of

provide

provide

energy.

The

Denitrifying

bacteria

live

in

water-logged

soil.

They

change

nitrate

top

root

to

nitrogen

gas.

It

is

thought

that

they

balance

the

uptake

of

by

nitrogen-xing

nodules.

the

cells

reveal

bacteria

causes

temperatures.

washed

into

nitrogen

Nitrogen

the

soil

ions

can

washed

be

are

lost

by

and

oxides

rain

from

out

of

oxygen

are

to

formed

where

they

react

in

together

the

form

at

reactions.

nitrate

of

the

the

soil

soil

before

by

plants

rainwater .

can

This

is

the

some

nitrogen-xing

bottom

a

root

photo

nodule

thousands

that

you

broken

can

open

live

of

nitrogen-xing

inside.

high

These

are

ions. KEY

Nitrate

the

bacteria. to

Lightning

shows

In

nitrogen see

gas

photo

ions

absorb

called

them

as

POINTS

they

1

leaching

Nitrogen

as

a

gas

is

in

(N

)

the

but

atmosphere

is

not

2

Farmers

add

fertilisers

containing

nitrogen,

e.g.

ammonium

nitrate. available

These

are

manufactured

from

ammonia

made

in

the

Haber

add

replace

Some

extra

the

sources

nitrate

farmers

do

of

nitrate

absorbed

not

use

by

ions

the

inorganic

for

crop

plants

plants.

and

fertilisers,

The

removed

but

most

organisms

process as

and

to

it

is

not

reactive.

fertilisers

at

instead

harvest.

use

2

Some

(N

natural

)

bacteria

x

converting

nitrogen

it

to

2

fertilisers

nitrogen

such

cycle

as

at

manure.

the

This

point

provides

where

the

dead

material

decomposers

that

enters

ammonia.

the

live

act.

inside

legumes.

Some

root

3

Bacteria

and

QUESTIONS

are

to

List

the

four

substances

element

present

in

living

organisms

that

Describe

the

the

protein

ammonia.

to

convert

nitrate

ions.

nitrogen. 4

2

bacteria.

bacteria

ammonia

contain

of

called

decompose

urea

Nitrifying

1

these

nodules

They

nitrogen-xing

SUMMARY

of

roles

following

of

microorganisms

(bacteria

and

fungi)

Denitrifying

nitrate

in

(N

processes:

bacteria

ions

to

convert

nitrogen

gas

).

2

a

decomposition

b

nitrication

c

nitrogen

d

denitrication

xation

5

Plants

and

acids 3

Explain

how

nitrogen

in

the

protein

of

dead

animals

absorb

convert

which

4

is

Explain

made

how

available

to

available

farmers

crop

to

can

plants.

plants

increase

in

the

the

form

of

quantity

nitrate

of

they

to

use

ions

amino

to

make

and proteins.

plants

nitrate

them

Animals

obtain

the

ions.

nitrate

amino

acids

eating

and

animal

they

need

digesting

by

plant

or

protein.

253

19.6

Populations,

and

ecosystems

Population LEARNING

Dene

the

term

population

State

the

factors

affecting

same

of

growth

of

a

Identify

of

growth

growth

•

the

State

different

in

a

phases

interbreed.

that

of

food

disease

are

factors

that

affect

and

population

the

of

the

the

same

species

individuals

in

a

living

in

population

Sometimes

such

or

on

like

This

it

as

a

on

is

is

difcult

easiest

to

tell

an

island,

mountain,

wildebeest

where

the

in

like

the

like

the

geographical

organisms

Komodo

Protea

game

kilimanjaro,

parks

live

dragons

of

East

or

in

on

a

islands

they

are

Africa.

species

into

terms

are

very

separate

widely

distributed

populations.

and

However,

it

is

there

difcult

are

to

usually

divide

barriers

reproduction,

such

as

rivers

and

mountains,

that

divide

them

into

growth

community

so

there

populations.

is

Some

interbreeding

individuals

between

migrate

across

these

barriers,

populations.

ecosystem The

•

All

Describe

and

different

phases

population

explain

of

growth

table

shows

some

animal

and

plant

examples.

the

the

population

habitat

creole

coral

place

curve reefs wrasse

around

Tobago

in

the

reef Caribbean

wildebeest

grassland

dry Komodo

Nepenthes

Komodo

rajah

carnivorous

A

community

organisms

Wildebeest

in

East

a

Africa.

–

An

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19.6.2

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mortality

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(2014).

257

PRACTICE

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The

for

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plants

large

State

over

the

years.

The

Only

dry

three

as

about

shows

square

the

metre

total

of

biomass

grassland

formed

during

in

one

plant

gures

mass

were

and

obtained

not

the

by

fresh

measuring

mass

of

the

State

uses

the

to

living

(ii)

2

organisms

in

are

produced

sugars.

which

adapted

to

[2]

the

trap

leaves

as

much

[3]

of

the

energy

dry

mass

/

g

m

photosynthesis

plants

trapped

by

carnivores

0.1

the

biomass

percentage

between

Show

decrease

green

(c)

Name

(d)

Suggest

in

plants

your

the

plant

available

how

antelopes

[2]

much

each

energy

year.

reaches

Express

your

as

kJ

m

.

Show

your

working.

process

the

advantage

rather

than

of

trophic

mass

as

antelope

faeces

loses

more

compared

of

with

its

the

[2]

This

food

chain

has

three

trophic

levels

it.

Explain

why

there

are

no

more.

[4]

during

4)

levels.

12

The

following

substances

measuring

fresh

the

intake

[1]

[2]

formed

between

why

X.

cheetah.

working.

biomass

decreases

mass

the

not

and

[3]

dry

is

–2

(Paper

Explain

which

that

–1

in

why

year

in

herbivores.

year

(e) herbivores.

the

ways

energy

Calculate

energy

Explain

to

[3]

0.9

the

passed

480

herbivores

Calculate

is

antelopes.

two

the

answer

green

(c)

that

simple

possible.

like

the

the

(b)

the

ways

are

10%

in

herbivores

material.

(a)

sugars.

year . (i)

The

in

3)

table

one

it

[4]

the

10

the

past

(b) (Paper

compounds

from

plants

light 250

simple

of

uses

increase

of in

make

1%

and

[3]

(ii) (e)

about

plant

rate

in of

to

the

[3]

(i) three

only

strikes

when

urea,

are

that

ammonia

biologically

contain

(NH

),

the

important

element

amino

acids,

nitrogen:

nitrite

3

investigating

different

biomass

production

in

ions,

ecosystems.

Choose

match

4)

may 11

The

diagram

shows

the

passage

of

a

food

light

chain

energy

in

that

a

grassland

strikes

the

each

year

is

400 000 kJ

m

of

of

each

the

the

one

substances

statements

once,

more

from

(i)

the

to

than

(v).

list

to

Y ou

once

or

all.

ecosystem.

leaves

of

the

main

nitrogen-containing

the

excretory

2

grass

each

use

at

(i) The

one

energy not

along

ions

[3] (a)

(Paper

nitrate

product

of

animals

.

(ii)

absorbed

by

(iii)

a

(iv)

synthesised

(v)

the

plants

33%

process

radiant

from

X

70%

energy

process

product

of

deamination

X

into

proteins

sun

400 000

kJ

(b)

10%

end

Nitrogen

product

gas

(N

)

in

of

nitrication

the

atmosphere

[5]

is

2

inert.

very

12%

in

10%

in

Unlike

few

carbon

organisms

Describe

how

dioxide

are

nitrogen

able

gas

body

of

body

antelope

(N

)

oxygen,

use

it.

present

in

of

the

faeces

faeces

to

2

20%

55%

and

atmosphere

is

made

available

to

be

cheetah

used

(Paper

by

organisms.

[4]

4)

259

20

Biotechnology

and

genetic

engineering

20.1

Microorganisms

and

biotechnology

The LEARNING

use

of

microorganisms

Biotechnology •

State

how

bacteria

are

biotechnology

biotechnology

and

is

the

use

of

microorganisms,

such

as

bacteria

and

useful fungi,

in

and

OUTCOMES

to

make

useful

products

or

to

carry

out

services

for

us,

such

as

genetic making

wastes

harmless.

engineering

The •

Describe

the

role

of

yeast

of

anaerobic

breadmaking

•

Describe

the

respiration

in

production

•

role

yeast

of

in

the

ethanol

use

of

both

bacteria

and

fungi

are

in

various

processes

is

widespread.

in

Bacteria

taken

•

for

Unlike

the

biofuels

or

•

reproduce

for

numbers

animals

nished

quickly

double)

plants,

product

very

with

that

microbes

quickly,

a

is

generation

often

can

i.e.

as

convert

in

time

little

hours

as

raw

(the

30

time

minutes.

materials

rather

than

into

months

weeks.

The

use

of

bacteria

independent

•

or

very

to

Bacteria

can

antibiotics)

harvested.

of

means

that

food

production

can

be

climate.

produce

that

pass

Enzymes

complex

out

into

made

by

proteins

the

(like

enzymes

surrounding

microorganisms

and

medium

are

used

and

in

can

the

be

food

industry.

Examples

food

•

of

enzymes

industry

amylase

that

are

produced

by

bacteria

for

use

in

the

are:

for

breaking

down

starch

in

the

production

of

glucose

syrup

of

the

products

of

pectinase

•

sucrase

•

protease

for

for

extracting

breaking

for

making

juice

down

meat

from

fruit

sucrose

more

in

(see

page

making

263)

confectionery

tender

traditional

biotechnology.

With

the

aid

microbes

of

In

plants

and

addition

with,

since

In

copies

The

of

use

people

have

concerns

about

the

of

and

health

of

chickens

260

the

and

and

contrast,

long

bacteria

the

the

bacterial

the

same

cells

are

alter

new

multiply

gene

can

can

be

rapidly,

(see

varieties

of

concerns

contain

to

be

work

cut

spliced

making

page

manufacture

ethical

also

easy

Plasmids

organism

inserted

in

breeding

Plasmids

quickly.

another

quickly

time.

DNA,

very

fungi

raise

In

can

open

into

many

267).

complex

over

their

the

kept

in

and

growth

as

would

be

the

case

in

the

use

of

other

these

living conditions.

not

of

from

media

a

scientists

plasmids.

replicate

plasmid

does

take

loop

called

gene

bacteria

manipulation welfare

a

nutrient

chemicals

Many

can

and

products.

can

single

DNA

they

enzymes

them.

the

of

engineering,

modify

animals

to

circles

genetic

so

and

small

by

of

organisms,

for

example

keeping

chickens

in

battery

farms.

tnemelppuS

Some

•

Biofuels

Many

and

microbes

respire

When

with

or

yeast

breadmaking

can

respire

without

respires

successfully

without

oxygen.

Yeasts

can

oxygen.

without

oxygen

(anaerobically)

it

is

called

fermentation.

Glucose

→

alcohol

+

carbon

dioxide

+

energy

released

Biofuels Some

Biofuels

are

fuels

made

from

biological

material.

Sugar-rich

products

This

biofuels

biobus

cooking

from

sugar

cane

and

maize

can

be

fermented

anaerobically

own

uses

to

produce

and

have

fermenters

sugar

cane

to

juice

maize

starch

starch

with

ethanol.

developed

is

another

is

and

when

as

fuel

ethanol

dioxide

Car

Oil

a

in

called

good

a

the

engines

seed

raw

burned

need

is

to

a

be

for

raw

oil

supplies

for

material

is

obtained

other

from

waste

made

waste

from

material.

used

of

food

products

from

industry.

their

example,

often

carbohydrates.

This

petrol

that

not

there

As

a

that

because

produce

is

no

result

modied

crop

of

material.

does

atmosphere.

rape

The

lot

no

Brazil,

fuel

used

Glucose

by

is

from

treating

the

enzymes.

substitute

means

a

have

substitute.

ethanol.

contains

carbohydrase

content

countries

biofuel

produce

which

Ethanol

Some

a

and

made

on

with the

yeast

oil

are

runs

to

overall

this

be

provides

it

fuel

able

oil

has

toxic

high

increase

is

to

that

a

gases.

in

carbon

use

is

pure

energy

Using

carbon

neutral

ethanol.

converted

into

fuel

biodiesel

Bread-making Yeast

Baking

is

another

Bread

is

made

yeast.

This

the

Bubbles

of

rise.

gas

sugar,

carbon

When

make

the

the

evaporate,

from

mixture

ferment

it

example

dough,

is

kept

at

using

dioxide

bread

is

mixture

a

warm

are

behind

in

a

our,

inside

hot

texture.

the

of

help

dioxide

trapped

in

to

produce

water,

temperature.

carbon

baked

‘light’

yeast

a

producing

bread

leaving

of

gas

the

oven

The

traditional

taste

of

sugar

the

and

starts

produced

bread

their

light

carbon

dough

to

dioxide

rise

and

the

of

the

alcohol

to

bread.

POINTS

Bacteria

are

useful

reproduce

2

a

Write

b

In

ways

in

which

bacteria

are

useful

in

a

word

equation

for

anaerobic

respiration

in

why

is

yeast

mixed

to

our

and

with

sugar

before

it

to

Make

of

a

table

ethanol

as

the

ethanol

summarising

a

fuel

for

make

Yeast

carries

out

anaerobic

in

the

production

water?

made

by

yeast

in

the

cars.

advantages

and

ethanol

for

biofuels.

bread-making? 3

3

and

is

of

happens

rapidly

molecules.

respiration

added

What

genetic

they

yeast. 2

bread-making,

as

biotechnology. complex

c

in

and

QUESTIONS engineering

four

loaves

texture.

biotechnology

List

caused

these

make

1

1

which

give

to

KEY

SUMMARY

and

alcohol.

bubbles

causes

food.

yeast

dough

the

heat

salt,

The

and

a

disadvantages

Yeast

carries

respiration

out

anaerobic

during

bread-

making.

261

20.2

Enzymes

and

biotechnology

Enzymes LEARNING

•

have

Investigate

pectinase

the

in

use

the

of

Biological

production

Investigate

enzymes

washing tnemelppuS

•

Explain

the

important

in

industry.

washing

powders

washing

powders

may

contain

one

or

more

of

the

juice

following •

very

of

Biological fruit

become

OUTCOMES

in

the

use

biological

powders

the

types

of

enzymes:

of

•

proteases

•

lipases

–

–

break

break

down

down

protein

fats

in

stains,

grease

e.g.

stains,

blood,

e.g.

grass

butter,

and

egg

lipstick

and

mayonnaise

use

of

lactase

production

of

lactose-free

in

•

amylases

–

•

cellulases

break

down

starch,

e.g.

food

stains

containing

starch

milk

fabrics

The

the

to

–

enzymes

high

water

listed

down

the

powders.

the

and

are

of

removed

been

alkaline

a

the

bres

attached

have

and

During

products

cellulose

dirt

above

temperatures

washing

stains;

break

remove

to

reactions

the

the

modied

so

conditions

washing

when

on

outside

of

cotton

them

cycle,

the

dissolve

washing

that

they

required

for

enzymes

or

are

withstand

some

break

suspended

machine

empties.

down

in

For

BIOLOGICAL

example,

Washing

proteins

cellulose



Contains



Works



More



Avoid



Do

protease

best

at

effective

using

not

use

low

and

boiling

are

broken

down

into

into

amino

acids

and

starch

and

glucose.

(40°C)

detergent

water

PRACTICAL

silk

Comparing

Figure

broken

down

lipase

temperatures

thanordinary

with

are

Powder

20.2.1

Biological

washing

the

action

of

biological

and

non-biological

powder.

washing

powder

1

what

Decide

soya

2

sauce,

Decide

linen

3

Add

you

what

or

sort

sort

wool.

the

put

of

Also,

same

it

of

stain

mustard,

fabric

the

are

you

decide

amount

into

you

going

to

have,

e.g.

egg,

etc.

of

are

what

stain

beakers

to

going

size

to

of

the

to

use,

fabric

fabric

e.g.

to

and

cotton,

use.

let

it

dry

before

‘wash’.

3

4

Granules

of

biological

washing

Weight

out

water

at

5

Add

piece

6

Decide

a

30 °C

Inside

as

of

the

these

cleansing

granules

granules

are

are

partially

enzymes

each

a

the

powder

dissolve

each

in

500 cm

which

act

7

Decide

you

fabric

are

with

going

the

to

same

stir

the

stain

to

each

‘washing’

beaker .

over

a

period.

how

to

compare

the

cleanliness

of

each

fabric

after

agents.

8

Repeat

Safety:

into

You

your

Wear

contact

could

tests

to

gloves

with

of

beaker.

same

often

and

opened.

washing.

262

in

of

how

of

powder.

10-minute Some

5 g

produce

see

and

your

if

do

skin

a

you

not

to

scale

get

let

avoid

of

the

the

a

cleanliness.

same

results.

washing

possible

powders

allergic

come

reaction.

Extracting

Pectinases

molecules

for

fruit

are

that

extracting

juice

enzymes

act

like

fruit

a

apples

that

break

‘glue’

juices

and

in

for

down

plant

pectins,

cell

walls.

softening

which

are

Pectinases

are

used

vegetables.

PRACTICAL

juices

Extracting

juice

from

apples

with

pectinase

Figure

1

Cut

an

apple

in

B

A

20.2.2

Extracting

apple

juice

using

half. pectinase.

2

Chop

each

half

into

small

pieces

and

put

them

into

separate

the

juice

in

from

a

apple

water

each

of

in

bath

the

in

beaker

beaker

at

of

and

10 cm

of

B.

40 °C

beakers

A

for

20

apple

minutes.

31

30

20

eciuj

Filter

beakers

the

apple

emuloV

5

both

over

the

fo

Place

solution

over

decudorp

4

water

/

3

of

10 cm

pectinase

elppa

Pour

mc

3

3

40

3

beakers.

10

2

pieces. 0

water

•

Explain

the

results

shown

in

the

pectinase

graph. A

•

How

does

the

pectinase

release

this

juice

from

the

apple

cells?

Figure

20.2.3

Why

was

10 cm

of

water

added

to

beaker

tnemelppuS

SUMMARY

use

Some

people

problems

get

lactase

do

not

digesting

diarrhoea,

milk

be

of

broken

into

enough

lactose,

and

Lactose

down

making

produce

and

wind

products.

in

the

stomach

is

a

sugar

cramps,

complex

simple

lactose-free

lactase

sugars

sugar,

by

the

and

found

if

to

from

extract

the

juice

A? from

The

results

practical

3

•

B

Sample

milk.

to

enzyme

or

that

Describe

what

following

may

milk

sucrose

1

have

They

consume

similar

QUESTIONS

milk

therefore

in

they

apples.

each

enzymes

a

amylase

c

lipase

b

of

the

do.

protease

can d

pectinase

lactase.

2

Explain

the

advantages

of

lactase

using glucose

+

sugar)

(2

simple

can

using

investigate

test

strips

the

test

use

Benedict’s

strips

reducing

the

that

that

test

sugars

detect

are

as

and

effect

used

all

of

the

lactase

in

breaking

concentration

to

detect

glucose

three

sugars

in

give

a

positive

powders.

sugars)

3 You

biological

galactose

washing (complex

in

the

of

in

down

glucose.

urine.

equation

lactose

These

You

Explain:

by

a

are

water

beaker

cannot

above

why

are

b

result.

the

was

added

to

A,

results

in

the

graph

above,

c

4

a

how

pectinase

juice

from

How

is

releases

apple

tissue.

lactose-free

tnemelppuS

lactose

enzymes

milk

produced?

KEY

POINTS b

Why

for 1

Biological

wash

washing

powders

temperatures

and

in

contain

alkaline

enzymes

that

work

at

is

there

Pectinase

conditions.

c

Outline

an

in

is

used

the

cell

to

extract

walls

in

fruit

fruits

juice

such

by

as

breaking

down

tnemelppuS

Lactase

breaks

down

lactose

to

is

the

to

best

the to

produce

apple. lactose-free

3

milk?

experiment

which

temperature pectin

demand

low

discover 2

a

lactose-free

produce

lactose-free

milk.

milk.

263

20.3

Fermenters

tnemelppuS

You LEARNING

may

without

•

Describe

the

Penicillium

of

•

the

role

in

it

of

the

antibiotic

how

fermenters

used

penicillin

refers

useful

production

oxygen

to

any

may

Industrial

production

inoculated

•

Adding

for

Penicillium

Fungi

are

growing

cultured

on

like

whether

they

are

suitable

as

that

carry

uses

out

with

However,

as

or

a

in

meaning

an

respiration

industrial

microorganisms

useful

without

process

to

for

context

produce

us.

The

agar

this

to

organisms

of

in

a

of

such

culture

This

inside

then

the

nutrients,

penicillin

large-scale

antibiotics

a

of

of

industrial

as

a

penicillin.

suitable

proceeds

fermenter.

such

as

fermentation

to

grow

These

sugar

or

The

fungus,

fermenter

in

under

this

the

conditions

starch,

as

is

a

is

case

Penicillium

conditions

should

source

include:

of

Ammonia

or

•

Vitamin

complex

•

Maintaining

a

constant

temperature

•

Maintaining

a

constant

pH

Batch

B

urea

is

added

is

as

added

a

source

for

of

of

nitrogen

to

make

proteins

respiration

about

of

about

30 °C

6.5

culture

sources

takes

about

30

hours

for

penicillin

production

to

start.

of

is

biomass

secreted

into

the

surrounding

liquid

100

of

by

the

10

fungus.

yield

of

penicillin

Penicillium 90

9 –3

–3

/

g

/

dm

80

g

dm

8

penicillin

70

7

60

6

50

5

TIP 40

4

biomass

Ferm enters

suita ble

of

carbon

respiration

Penicillin

grow th

the

nd

antibiotics.

STUD Y

a

oxygen.

•

It out

to

use

with

maintained

dish.

fermentation

140).

production

chrysogenum.

fungus

or

respire

important

production

Petri

word

page

are

One

The

the

(see

process

product

involved

penicillin

Explain

in

recognise

OUTCOMES

30

me ta bo

fo r

lism

micro orga nism s,

3

Penicillium

provid e

cond ition s

and

of

20

2

10

1

such 0

as

If

bacter ia

the

high ,

fung i.

tempe ratu re

enzy mes

micro bes

the

0

and

60

80

in

/

100

120

140

160

hours

too

the

Figure

20.3.1

This

graph

production

and

140

and

shows

of

160

the

growth

penicillin

of

during

a

the

fungus

Penicillium

fermentation

that

and

lasts

the

between

hours.

die.

Look

264

40

time

is

dena ture

orga nism s

20

at

the

graph

production.

This

a

which

substance

is

above.

You

because

is

not

should

penicillin

necessary

see

is

for

a

that

there

is

secondary

the

growth

of

a

delay

in

metabolite,

the

fungus.

production

starts

after

the

exponential

growth

phase

in

motor

response

in

is

the

one

or

fermenter

then

as

to

puried

batch

cleaned

more

is

ltered,

into

culture.

and

limiting

a

the

penicillin

crystalline

After

sterilised

the

ready

6

factors.

salt.

day

for

After

is

This

extracted

type

period,

the

next

about

the

of

6

days,

using

a

is

mixture

solvent

production

fermenter

the

is

and steam for

foam breaker

sterilisation

reduces

known

emptied,

foaming of

the culture

batch.

culture broth

Industrial

Industrial

fermentation

fermenters

are

large

tanks

(see

right)

that

can

hold

as

much

probes for

monitoring pH,

3

as

500 000 dm

of

fermenting

mixture.

Conditions

inside

these

huge oxygen and

tanks

are

carefully

controlled.

We

will

use

the

production

of

the temperature

antibiotic

penicillin

to

show

how

these

fermenters

work.

large stirrer to

•

The

fermentation

with

a

medium

sugars

and

vessel

containing

ammonium

is

made

the

salts.

of

stainless

required

To

this

steel

nutrients.

some

of

the

and

These

fungus

is

lled

mix contents

include

Penicillium

water-cooled

jacket removes

is

added. excess heat

•

The

fungus

grows

well

in

the

conditions

inside

the

fermenter. sterile air –

Sugars

provide

energy

for

respiration

and

ammonium

salts

are

used provides

by

the

fungus

to

make

proteins

and

nucleic

acids

(DNA

and

RNA).

oxygen for

diffuser – sends

After

a

few

days

the

fungus

starts

to

produce

penicillin,

respiration

bubbles of air

which

through the

accumulates

in

the

fermenter. mixture har vesting

•

A

stirrer

keeps

the

microorganisms

suspended

so

they

always

have drain

access

even

•

An

to

temperature

air

supply

fungus.

to

•

A

nutrients

(No

make

at

alcohol.

6.5

to

See

oxygen

page

a

Stirring

the

supplied

jacket

the

adding

Explain

is

give

monitor

by

SUMMARY

1

provides

water-cooled

Probes

oxygen.

throughout

oxygen

fermentation

•

and

for

to

maintain

an

Figure

the

the

aerobic

yeasts

respiration

respire

of

without

20.3.2

Large

industrial

fermenter.

the

oxygen

261.)

removes

the

heat

produced

temperature

temperature

if

helps

fermenter.

as

constant

alkalis

also

and

make

of

by

24°C.

sure

the

pH

is

constant

necessary.

QUESTIONS

the

function

of

each

of

the

following

in

an

industrial Industrial

fermenters.

fermenter:

a

a

stirrer

b

an

d

temperature

air

supply

c

a

water-cooled

jacket KEY

and

pH

1 2

Explain

3

State

in

a

the

the

role

of

Penicillium

conditions

POINTS

probes

in

necessary

the

for

production

the

of

production

Microorganisms

reproduce

quickly

conditions

penicillin.

of

found

penicillin

the

fermenters

fermenter.

products 4

Explain

how

and

fermentation

why

these

factors

change

during

ideal

inside

large,

such

temperature

b

2

oxygen

concentration

c

The

What

is

meant

ideal

conditions

batch

for

include

adding

correct

nutrients

and

by: maintaining

a

useful

penicillin.

pH

the

5

as

a

process:

fermentation a

industrial

producing

culture

b

secondary

metabolite?

and

a

constant

pH

temperature.

265

tnemelppuS

Penicillin

20.4

Genetic

Genetic LEARNING

engineering

Dene

the

term

is

genetic

engineering

•

State

can

of

that

be

human

and

tnemelppuS

•

in

Outline

engineering

the

production

medicines,

insect

providing

vitamins

in

how

herbicide

resistant

plants,

species

never

the

of

DNA

changing

the

DNA

achieved

one

of

humans

is

of

by

species

transfer

codes

the

the

genetic

material

of

a

gene

This

selection,

another.

between

totally

from

individual

production

species.

with

and

inserting

the

transfer

articial

bacteria

or

for

another

breed

genes

to

changing

that

engineering

to

be

would

removing,

of

from

is

a

because

specic

the

DNA

an

only

in

species,

A

one

can

rare

for

gene

protein.

of

that

engineering

unrelated

to

a

process

Genetic

bacteria

of

genes.

cases

allows

example

plants.

plants

Examples

genetic

is

by

section

from

additional

crop

engineering

a

Genetic

genetic

used

resistant,

involves

OUTCOMES organism

•

engineering

used

to

of

genetic

engineering

make Human

medicines

insulin

Many •

Discuss

the

advantages

and disadvantages

of

human

blood

clotting

modied

are

Herbicide

A

a

makes

with

the

the

affected

weeds

insulin,

human

produced

by

appropriate

reduce

the

can

be

sprayed

competition

of

variety

growth

bacteria

hormones

that

human

genes.

have

been

These

the

herbicide

of

to

from

medicines.

so

rape

a

has

soil

herbicide

this

itself.

and

as

oilseed

it

the

rape

crop

used

plants

into

resistant

oilseed

also

the

and

crop

transferred

rape

but

by

are

Insect

soya

is

elds

weeds,

in

modied

gene

to

produced

resistance

oilseed

applied

Herbicide-resistant

mass

genetically

which

to

are

crops proteins

herbicides

including

agents,

genetically genetically

modifying

proteins,

and

the

would

GM

continues

developed

This

glufosinate.

herbicide

But

been

bacterium.

to

not

oilseed

grow

When

only

rape

while

in

gene

kill

is

not

only

the

destroyed.

resistance

in

crop

plants

with

from

Maize

and

attacked

weeds

maize

and

cotton

by

are

are

insects

root

cotton

worm

boll

both

which

important

reduce

larvae

weevils

are

and

cash

their

crops,

yields.

The

stem-boring

pests

of

cotton

but

both

major

can

pests

caterpillars.

be

of

Caterpillars

plants.

th

At

the

beginning

produced

for

this

The

a

toxin

toxin

that

pesticides,

people

giving

to

it

available

disease

glasshouse

266

resistance

conditions.

in

GM

rice

under

on

it.

only

genes

make

its

to

people

who

reduce

the

grow

eat

high

has

the

in

crop

A.

on

it.

a

to

In

their

feeding

own

on

was

the

maize

environmental

rice

scale

be

rates

have

a

soil

resultant

Rice™.

will

mortality

caterpillars.

and

The

large

They

bacterium

1990s

and

toxin

crop

that

the

cotton

than

gene

plants.

which

impact

the

found

kills

insect

spraying

plants

are

killed.

plants

of

maize

Golden

soil

produce

less

insects

varieties

from

a

transferred

plants

vitamin

name,

certain

and

This

vitamins

century

kills

isolated

modied

transferring

20

which

because

Genetically

the

modied

feed

Additional

Assessing

was

genetically

larvae

of

If,

it

able

as

a

or

will

to

been

developed

bacterium,

rice

is

when,

pale

this

improve

make

result

of

that

yellow

rice

the

vitamin

poor

by

enables

diets

A.

in

colour

becomes

of

This

immune

the

will

systems.

production

Genetic

engineering

cheaply

on

a

large

makes

scale.

it

The

of

tnemelppuS

Industrial

insulin

possible

human

to

make

gene

insulin

that

codes

quickly

for

the

and

production enzymes

used

to

cut

bacterium

of

insulin

cut

A

the

is

identied.

human

circular

insulin-making

piece

bacterium.

Restriction

of

The

DNA

same

enzymes

gene

called

a

from

the

plasmid

restriction

enzymes

is

act

as

rest

chemical

of

the

removed

are

then

scissors

to

open

DNA.

from

used

a

to

cut

the

open

is

the

plasmid.

The

two

ends

of

the

DNA

of

the

plasmid

insulin-making

gene

new

put

human

plasmid

into

a

put

new

insulin

into

gene

plasmid

are bacterium

an

exact

called

match

‘sticky

Another

with

called

insulin-making

gene

now

a

bacteria.

as

The

two

DNA

ends

and

the

plasmid.

These

are

ends.’

enzyme

known

the

ligase

to

the

is

used

sticky

recombinant

bacteria

now

has

to

ends

attach

and

plasmid

the

gene

the

sticky

plasmid.

and

code

is

The

ends

back

insulin.

The

cell

the

plasmid

inserted

for

of

is

into

the

bacteria each

multiply

very

rapidly

inside

an

industrial

fermenter

and

produce

insulin.

modied

The

•

and

disadvantages

of

bacterium

make

has

Advantages

division

insulin

the

can

now

because

insulin

it

gene

genetically

crops

benets:

Solving

global

hunger

–

genetic

modication

could

feed

more

insulin

people

as

climate

the

crops

conditions

marginal

that

and

are

produced

soils.

Food

are

able

production

to

tolerate

could

be

increased

in

Figure

areas.

20.4.1

Human

by

•

Environmentally

friendly

can

be

insects,

less

use

–

GM

crops,

like

soya,

maize

purified

extreme

and

insulin

genetically

is

made

engineered

rice, bacteria.

would

resistant

of

pesticides.

mean

less

environmental

Consumer

an

avour

and

require

for

that

benets

improved

produce

Also,

need

threat

weeds

–

genes

improve

fertilisers

so

there

would

nitrogen

and

be

uptake

lessen

the

cause.

crops

better

fewer

diseases

that

chemical

they

GM

and

and

have

already

keeping

been

qualities.

produced

They

are

with

easier

to

additives. SUMMARY

The

concerns: 1

•

Environmental

become

safety

successful

–

weeds.

there

are

Pollen

concerns

from

GM

that

crops

new

that

GM

are

plants

will

Food

may

safety

–

be

transferred

new

gene

to

other

plants

combinations

may

by

insects

resistant

have

or

effects

the

Explain

what

genetic

unknown.

They

may

result

in

harmful

substances

that

being

Describe

three

in

crops

are

which

Biodiversity

reduce

the

–

increasing

number

of

use

plant

of

herbicides

varieties

and

and

wild

plant

breeding

ways

been

engineered

to

them.

will 3

What

4

List

is

the

meant

by

stages

a

plasmid?

involved

bacteria

human

insulin.

Discuss

the

in

that

make

POINTS

Genetic

engineering

involves

taking

a

gene

from

one

and

putting

it

into

another

and

human

plasmid.

insulin

The

gene

bacteria

can

grow

the

of

GM

concerns

species. people

The

benets

species crops

2

have

relatives.

5 1

different

so

producing

KEY

by

produced. improve

•

meant

wind.

genetically

far

is

engineering

to 2

weedkillers

•

QUESTIONS

be

to

transferred

produce

lots

into

of

a

bacterial

human

have

about

their

safety.

insulin.

267

tnemelppuS

•

to

PRACTICE

1

In

QUESTIONS

order

to

to

transfer

another

it

is

a

feature

necessary

to

A

a

chromosome

C

B

a

gene

D

from

one

species

6

a

a

Which

is

the

best

temperature

transfer:

genotype

nucleus

in

a

reason

1)

Yeast

high

temperatures

enzymes

B

at

high

temperatures

the

is

used

biofuels.

in

the

production

of

too

denature

of

much

at

low

This

is

yeast

cells

yeast

bacteria

reproduce

fast

because:

are

cells

a

good

produce

source

oils

that

of

are

at

low

of

nutrients

temperatures

there

is

no

diffusion

energy

added

into

bacteria

to (Paper

petrol

temperatures

some

D

B

increases

rate

bacteria?

[1]

too

A

contains

at

C

2

controlling

that

A

fermentation (Paper

for

fermenter

2)

[1]

(gasoline)

7 C

yeast

cells

respire

D

yeast

cells

to

produce

carbon

The

following

modication respire

without

oxygen

processes

occur

in

the

genetic

dioxide

of

bacteria

to

produce

a

human

to protein:

produce

(Paper

3

A

to

alcohol

1)

student

is

planning

compare

powders

1

a

gene

is

at

the

a

laboratory

2

a

plasmid

3

bacteria

divide

4

bacteria

are

effectiveness

removing

controlled

stains.

of

three

a

human

cell

factors

during

the

Which

inuences

washing

is

cut

open

by

restriction

enzymes

the

by

binary

ssion

washing grown

in

a

fermenter

to

combination

activity

of

human

protein

the

5 enzymes

from

investigation

produce of

isolated

[1]

recombinant

plasmids

are

taken

up

by

process?

bacteria A

size

of

container,

frequency

of

stirring,

6 type

of

washing

type

of

fabric,

bacteria

make

recombinant B

length

of

washing

of

type

of

stain,

appearance

D

washing

pH

4

of

size

of

of

fabric,

plasmids

Which

temperature,

1)

Which

substance

volume

of

water,

[1]

A

carbon

B

ethanol

Which

causes

dioxide

bread

C

dough

lactic

D

to

sequence

used

not

bacteria

5,

7,

6,

3,

4

B

2,

1,

7,

6,

4,

5,

3

C

1,

2,

3,

7,

6,

5,

4

D

1,

2,

7,

5,

6,

3,

4

(Paper

acid

a

in

many

reason

do

their

bacteria

not

An

for

industrial

268

events?

is

of

growing

herbicide-resistant

that:

A

less

herbicide

B

there

have

needs

to

be

sprayed

on

the

crop

processes.

is

less

competition

between

weeds

this?

complex

soya

plants

requirements

have

many

enzymes

so

can

there

is

less

risk

of

disease

attacking

the

sets

of

reactions

to

plants

carry

the

soya

plants

grow

faster

make

reproduce

slowly

under

optimum

conditions

are

fewer

safety

the

genes

of

bacteria

the

genes

of

crop

2)

of

products

bacteria

(Paper

order

[1]

advantage

(Paper

there

correct

environment

complex

useful

D

to

oxygen

D

C

combine

2)

soya

out

the

1,

C

B

genes

plasmids

[1]

are

from

is

2,

and A

human

rise?

1)

is

and

recombinant

A

soya

Bacteria

plasmid

mixture

8

5

the

nal

fabric

washing

(Paper

(Paper

of

fabric

form C

copies

time,

7 size

multiple

powder

concerns

with

compared

plants

and

modifying

with

modifying

livestock

[1]

2)

[1]

9

A

student

on

the

were

pulp

investigated

extraction

cut

up

was

and

of

crushed

divided

Sample

A

Sample

B

was

the

apple

into

mixed

effect

juice.

to

two

with

of

pectinase

Several

make

a

pulp.

samples,

A

pectinase

12

apples

growth

growth

and

treatment

The

and

Human

made

B.

used

as

a

for

188

to

reduced

amino

(HGH)

young

promotes

people

growth.

It

is

as

a

a

protein

acids.

(i)

State

how

many

bases

in

DNA

code

control. for

(a)

hormone

given

powder. (a)

was

of

is

this

protein.

[1]

your

[2]

Suggest: (ii)

(i)

what

should

be

added

to

sample

B

Explain

Genetically it

is

being

used

as

a

control,

three

variables

that

the

student

hormone

and

bacteria

a

similar

make

human

hormone

found

should in

keep

engineered

[1] growth

(ii)

answer.

as

constant.

cattle.

HGH

is

used

to

treat

children

who

[3] do

not

grow

properly.

There

may

be

a

genetic

3

(b)

The

student

obtained

35

cm

of

juice

reason

from

for

this

or

they

may

have

received

3

sample

A

noticed

and

that

appealing

15

cm

juice

than

from

from

the

sample

sample

juice

from

A

B.

looked

sample

radiation

She

a

more

brain

Explain

juice

why

from

there

sample

was

much

Suggest

the

why

juice

the

from

A.

student

sample

A

thought

was

Suggest

in

which

the

effective

of

fruit

the

investigation

to

nd

Many

pectinase

is

at

increasing

such

modied

as

HGH.[5]

advantages

to

of

produce

using

genetic

HGH.

[3]

may

children,

suffer

who

from

do

not

blindness

have

a

caused

a

lack

of

vitamin

A.

Lack

of

this

vitamin

in

the

juice.

diet

also

harms

their

immune

system.

[3]

Explain

the

consequences

of

an

ineffective

3)

organisms

can

be

genetically

that

they

can

be

used

in

but

bacteria

are

[4]

is

the

main

foodstuff

in

many

parts

of

biotechnological the

processes,

system.

engineered Rice

so

the

especially

diet

immune

10

genetically

out

(a) (Paper

are

protein,

4)

People,

their yield

human

student

by how

had

[2]

ways

improve

bacteria

a

engineering

that

varied could

have

more

13 three

how

produce

(Paper

State

or

[3]

appealing.

(c)

leukaemia

tumour.

Outline

to

more

(c)

(ii)

for

B. (b)

(i)

treatment

one

of

the

world.

Researchers

have

used

genetic

most engineering

to

produce

a

strain

of

rice

that

has

common. seeds

(a)

Dene

(b)

State

the

the

term

genetic

advantages

industrial

engineering.

of

using

rich

in

the

State

bacteria

the

human

(b)

Suggest

examples

of

body

selective

genetic

converts

why

(d) at

265.

Penicillium

rice

and

had

not

State

three

other

crop

the

produce

an

Name

diagram

of

the

fermenter

on

State

is

grown

in

fermenters

the

Discuss

(Paper

antibiotic

by

[2]

reasons

for

genetically

[3]

the

arguments

produced

conditions

the

each

condition,

maintained

inside

from

the

and

against

food.

[3]

4)

by

that

are

maintained

fermenter.

and

Describe

for

[1]

maintained

(Paper

genetically

produced

to

antibiotic.

ve

inside

(d)

be

page

Penicillium.

For

to

simply

plants.

genetically-modied

(c)

A.

3)

Look

(b)

vitamin

breeding.

modifying

(a)

into

[3] (c)

11

which

[2]

engineering.

(Paper

carotene

in

processes.

three

beta

[2]

engineered

(c)

chemical

how

[5]

describe

explain

the

the

it

is

it

is

must

fermenter.

antibiotic

fermenter.

how

why

be

[5 + 5]

obtained

[2]

4)

269

21

H uman

on

in f l u e n c e s

e co s y s t e m s

21.1

Food

Increased LEARNING

Describe

ways

in

modern

technology

resulted

in

increased

60

Arable

food

elds.

years

farms

negative

ecosystems

of

monocultures

and

resulted

in

advances

in

agriculture

over

the

improved

food

supplies

in

many

parts

of

the

world.

large

are

and

agricultural

tractors

combine

and

machines

ploughs

harvesters

for

for

to

work

preparing

harvesting

very

land

crops.

large

for

Chemical

impacts

of

the

encourage

crop.

the

Pesticides

growth

intensive

kill

pests

of

crop

like

plants,

insects

increasing

that

feed

on

the

yield

crops.

crop

Herbicides plants

has

large-

of scale

use

seeds

fertilisers on

and

Examples

sowing the

technology

has

production

Describe

production

which past

•

food

OUTCOMES

Modern •

supply

kill

weeds

that

compete

with

crop

plants

for

water,

light

livestock

and

nutrients.

Selective

breeding

has

increased

yield

and

made

production

crops •

Discuss

the

has and

implications

of

food

transferred

human

an

Intensive

global

yields

over

of

In

large

many

by

intensive

especially

and

this

gas

Mongolian

surroundings

farmer’s

of

his

farm.

such

waste

sh,

A

as

High

engineering

There

has

to

crop

plants

soya

are

and

even

their

pests Thailand.

and

some

and

plant

often

high

crop

in

plants

large

restricting

their

and

of

indoors

the

faeces,

the

sea

large

numbers.

environment.

methane

and

in

which

often

where

it

is

a

known

can

cause

have

mean

using

growing

of

and

that

of

of

parasites

and

crop

allowing

specic

effects

on

on

the

such

to

as

large

cages

The

surrounding

pathogens

these

large

in

controlled.

and

to

farmers

crops,

kept

antibiotics

resistance

same

are

carefully

serious

pesticides

the

tilapia,

to

treat

can

the

chemicals.

areas,

year

concentrate

wheat,

after

on

barley,

rice.

that

inside

lots

on

conditions

problems

effects

pesticides

agents,

achieve

livestock

and

reared

Urine

bass

can

sh

quantities

and

sea

advantage

negative

eggs

selective

is

the

to

growing

21.4).

farms

come

keeping

effects

21.5).

growing

of

involves

supply

are

generate

trout,

means

this

food

waterways

and

sh

This

large

Herbicides

in

resistance,

indoors.

negative

Topic

densities

with

This

maize,

farming

food

monoculture

growing

270

Genetic

technology

This

and

animals

Topic

lakes,

modern

their

them

cattle,

(see

from

easily.

and

year.

sh

diseases.

herbicide

densities

have

salmon,

their

food

waters.

high

(see

pollutes

have

spread

Intensive

as

livestock.

systems

Animals,

slurry,

using

and

keeping

methods

Fish,

the

such

supplementing

eutrophication

from

at

Intensive

as

is

plants

areas

greenhouse

pollutes

and

species.

farming

crop

movement

waste

features,

unrelated

numbers,

cows

drought

providing

for

population

The

to

economic from

increasing

resistant

social,

environmental

sufcient

more

may

pest

of

kill

plant

help

species.

resulting

in

pathogens

monoculture

the

and

insect

crop,

such

Continuous

the

(see

evolution

T opic

on

18.4).

environment.

species

as

use

of

the

that

parasitic

of

these

resistance

are

harmless

wasps

that

chemicals

among

act

lay

as

weeds,

The

the

large

soil

scale

so

that

organisms

matter,

not

such

the

as

manure,

food

to

in

from

starvation

and

their

or

of

to

food

is

Many

ooding,

most

places

Social,

Food

that

most

often

have

pests

production

of

where

is

the

The

the

structure

biodiversity

addition

good

the

also

but

caused

enough

to

and

soil

of

of

of

soil

organic

structure

ability

of

increased.

every

requires

year

politics,

the

but

is

world’s

There

many

is

enough

people

to

do

may

die

because

of

have

plantations

and

lived

political

land.

for

to

to

to

food

wars Machinery

like

farmers

grow

sell

to

for

for

food

damage

that

is

pressures

in

labour

increasingly

force

so

rural

mechanised,

there

unemployment

is

or

war.

Often

this

has

meant

forcibly,

from

years.

has

resulted

in

T opic

21.2.

As

has

not

the

farming

driven

demand

the

of

oil

palm

South-East

cover

Asia.

huge

Here

a

areas

lorry

of

from

a

in

for

movement

a

in

Indonesia

carries

away

the

fruits

has these

trees

to

be

processed

into

palm

oil.

large

of

people KEY

to

allows

elds.

at

of

become

large

implications

sometimes

ranching

described

harvester

very

to

plantation

environmental

in

but

those

land

clearance

combine

crops

food

Plantations

Land

this

feed

fail,

to

transporting

displaced,

ancestors

have

crops

economic

areas

been

of

but

food

currency.

supply

problems

and

so,

cause

to

economics,

enough

foreign

failure

are

large

have

land

gain

a

by

produce

diseases

by

there

famine

people

their

has

countries

caused

Often

there

increased,

everyone,

environmental

groups

places

feed

often

starvation.

where

supports

growth.

maintain

food

cash-crops

famine

of

to

has

poorer

Drought,

risk

crop

reduce

malnutrition.

or

non-food

is

helps

enough

and

populations

grow

longer

can

supply

world

poverty.

no

good

population

food

Shortage

it

fertilisers

out.

produce

the

time

supports

carried

world’s

farmers

chemical

POINTS

cities.

Intensive

fossil

who

agriculture

fuels.

own

does

not

It

also

farms

reach

requires

requires

and

local

large

much

inputs

of

investment

plantations,

often

energy

by

taking

from

large

prots

burning

1

that

use

of

breeding

corporations

so

The

and

chemicals

money

increase

people.

2

negative

crop

How

have

the

following

increased

food

Famine

improved

use

of

production?

agricultural

machinery

b

articial

Describe

fertilisers

d

use

of

the

negative

monoculture

tnemelppuS

Describe

on

impacts

of

the

reasons

result

transport,

of

intensive

livestock

the

people.

from

lack

of

and

drought,

an

ever

human

population.

production Intensive

agriculture

has

crops social,

3

on

pesticides

4 and

and

selection

increasing

2

livestock

many

problems,

ooding c

and

impacts

can

political

food a

an

QUESTIONS

3

1

in

production.

have

environment SUMMARY

resulted

food

production

selective

agricultural

has

in

Intensive

machinery,

tnemelppuS

tnemelppuS

As

of

over

that

always

World

use

for

food

shortages

in

the

world.

environmental

economic

and

implications.

271

21.2

Habitat

The LEARNING

pressure

Describe

habitat

the

reasons

natural

for

is

destruction

State

that

humans

have

losses

deliberately

by

altering

food

•

impact

List

food

on

the

chains

on

Reasons

negative

effects

has

the

on

effects

on

on

been

for

a

natural

and

variety

are

has

resulted

continues

of

to

reasons,

ecosystems,

such

many

in

be

but

as

reasons

why

destroyed.

we

have

pollution.

the

Land

many

There

Earth

that

is

unaffected

by

human

is

no

activity.

for

habitat

destruction

that natural

habitats

of

plants,

animals

and

microorganisms

are

habitats for

a

number

of

different

reasons:

of •

deforestation

has

There

and

destroyed

Explain

population

habitats

The

•

world

habitats.

a

webs

deforestation

natural

cleared

effects

ecosystem negative

increasing

of

environment

indirect •

an

OUTCOMES signicant

•

of

destruction

The

clearance

of

land

for

crop

production

(see

Topic

21.1)

and

for

the the

production

of

biofuels

(see

Topic

20.1).

environment

•

Space

of

•

as

More

build

for

Digging

such

•

to

land

mines

iron

people

The

human

needed

(see

•

Marine

which

wells Open

of

cast

coal

mining

destroys

large

for

Topic

and

At

high

coral

If

we

or

•

•

•

otters

or

and

latter

of

half

being

have

preyed

less

their

the

upon

prey

to

numbers

20th

by

hunt

killer

but

because

of

in

now

whales

Killing

Killing

to

and

and

this

coal

the

and

is

mineral

ores,

produced.

associated

etc.

huge

of

of

aluminium

shops,

pollutants

cause

algal

industrial

destruction

In

the

been

quantities

waste

and

of

for

waste.

Space

recycling

is

it

of

the

blooms

sea

in

include

the

sea,

fertilisers,

oil

from

oil

chemicals.

by

pollution

Caribbean

destroyed

cleared

them

of

large

they

of

on

areas

by

it

and

of

the

is

are

are

chains

natural

we

coral

reefs

estimated

many

food

pollution,

of

predators

were

large

from

has

species

in

an

–

have

humans

dangerous

herbivores

these

Overshing

that

which

over

considered

and

at

very

of

high

risk.

webs

environment

removed

have

23%

completely

organisms

either

huge

for

food

numbers.

estimated

had

(see

60

signicant

results

in

have

also

–

killed

Topic

there

The

many

were

many

population

million

in

of

these

21.9).

1492

of

to

different

American

750

in

bison

1890.

effects.

that

that

are

further

unbalanced

at

risk

of

food

damage

webs

by

and

other

unbalanced

factors.

the

they

are

Top

predators

control

the

populations

of

primary

consumers.

Their

may

removal

means

so

is

that

populations

of

herbivorous

animals

increases

overshing.

there

The

272

clearance

are

increased

century,

and

indirectly:

ecosystems protected

housing

storage

inuences

haven’t

Removing

Sea

extraction

which

produces

Major

thought

of

decreased

crab.

production

21.8).

destroyed

species

a

long-term

the

from

industries,

population

have

because

eating

more

roads,

ships,

risk

reefs

directly

otter

for

bauxite

require

biodiversity.

Human

sea

livestock

areas

land.

high

A

intensive

quarries

and

pollution.

are

for

rearing.

and

ore

infrastructure:

•

units

cattle

effect

increased

can

be

competition

overgrazing

for

and

the

plant

habitat

food

that

destruction.

they

eat.

and

The

Pacic

sea

otter,

Enhydra

lutris,

is

a

secondary

consumer

that KEY

feeds

on

invertebrates,

century

the

change

to

animals

such

were

as

sea

hunted

urchins

for

their

and

fur

crabs.

and

In

there

the

was

a

striking 1

the

whole

of

the

food

web

as

urchins

exploded

POINTS

19th

in

Habitats

by

and

ate

many

of

the

giant

seaweeds

that

provided

a

habitat

have

and

clearance

many

the

other

species.

catastrophic

web,

such

as

loss

many

The

of

loss

many

small

of

one

other

species,

animal

invertebrates,

the

species

sh,

sea

otter,

from

octopus

the

and

of

destroyed

land

for

food farming,

for

been

numbers

led

extraction

of

to resources,

such

and

ores,

as

fossil

fuels

food metal

housing

and

scallops. industry.

2

Pollution

has

destroyed

many

Deforestation marine

Humans

food

have

and

been

provide

clearing

land

for

forests

for

settlements

over

and

10

000

provide

years

to

grow

transport

are

now

very

few

forests

in

temperate

regions

that

have

cleared

at

some

time

in

the

past.

Tropical

forests

in

Humans

and

South

America

have

been

cut

down

over

the

of

these

forests

are

rainforests

rich

in

past

100

food

has

resulted

in

a

number

of

the

extinction

of

impacts

removing

chains

and

species

webs.

Deforestation

leads

to

biodiversity.

environmental

of

species,

loss

of

problems: soil,

•

negative

by

years.

extinction

Deforestation

coral

South-East

4 Many

have

habitats

from

Asia

as

not on

been

such

links. 3

There

habitats,

reefs.

of

species

ooding

carbon

and

dioxide

increase

in

the

atmosphere. •

the

•

an

•

the

of

soil

increase

in

increase

in

removed

degraded

Local

of

tropical

formation

the

of

ooding

carbon

rainforests

soil

is

gullies

after

weather

dioxide

all

are

easily

and

the

the

very

of

are

change

and

away

plant

cut

atmosphere.

thin

washed

loss

trees

patterns

in

when

causing

nutrients.

the

soil

The

vegetation

erosion,

land

is

rapidly

SUMMARY

down.

with

more

frequent

and

severe 1

storms.

much

Flooding

quicker

happens

and

is

not

more

frequently

absorbed

by

as

plants

water

and

QUESTIONS

runs

off

transpired

the

into

Outline

some

Forests

act

as

‘stores’

of

water,

their

leaves

slow

the

that

increasing

effects

an

human

the population

atmosphere.

of

land

has

had

on

the

down environment.

the

rate

water

of

evaporation

reaches

the

from

the

soil

and

decrease

the

rate

at

which

2

soil.

It

is

estimated

1880 Carbon

dioxide

is

added

to

the

atmosphere

because

vegetation

There

is

increased

decomposition

that

also

releases

that

1980

between

about

40%

is of

burned.

and

all

tropical

rainforest

was

more destroyed.

carbon

dioxide

which

is

not

absorbed

by

plants.

a

Rainforests

have

no

effect

on

maintaining

the

correct

balance

Give

three

large-scale

carbon

dioxide

and

oxygen

in

our

atmosphere.

They

produce

much

such

a

carbon

huge

produced

oxygen

that

of

all

of

plants

rainforests

of

other

rainforests

many

be

reserve

by

concentration

the

plenty

dioxide

species.

identied,

of

reasons

There

the

to

are

in

the

photosynthesis

atmosphere

makes

little

atmosphere.

‘lungs’

stop

loss

of

many

and

use

in

Earth

the

the

studied

they

oxygen

on

are

means

as

of

the

cutting

many

species

that

the

difference

There

earth.

down

is

no

There

forests.

habitats

in

and

and

rainforests

to

there

this

Outline

some

of

the

is effects

that

has

the

deforestation

quantity

the

on

environment.

overall

3

evidence

are

for

deforestation.

about b

as

reasons

of

however

Explain

the

negative

effects

of

deforestation.

Destruction

the

extinction

that

have

yet

of

to

classied.

273

tnemelppuS

tnemelppuS

Soils

is

loss

21.3

Pollution

Anything LEARNING

that

•

State

of

the

sources

pollution

of

and

land

tnemelppuS

Discuss

the

effects

of

the

chemical

effects

and

has

material

power

the

biodegradable

plastics

in

environment

in

both

as

and

as

harm

is

as

a

a

result

of

fertilisers,

animal

noise

and

from

pollutant.

human

activity

oil

and

human

Pollutants

carbon

wastes;

industrial

and

are

monoxide;

heat

released

domestic

is

sources.

the

of

substances

aquatic from

terrestrial

such

such

stations;

cause

the release

environment,

to

nonPollution

and

into

potential

substances,

biological

water

from •

released

OUTCOMES

human

activities

ecosystems that

are

harmful

to

the

environment.

We

expect

natural

ecosystems

and

absorb

breakdown

these

substances.

Topics

we

to

21.3

will

look

examples

of

to

In

21.5

at

some

pollution

We

of

land,

sea

and

throw

away

mountains

places

a

this

visual

rubbish

pollutant

is

as

undesirable pollutant

of

rubbish

every

day.

In

many

air. taken

well

to

as

a

effects

rubbish

danger

of

dumps,

to

the

becoming

environment.

pollutant

on

the

sources environment

carbon

dioxide

burning

cattle;

fossil

paddy

fuels

elds

for

coal

human

sewage

and

and

contains

oil

industrial

–

chemical

includes

a

variety

waste

ammonia,

carbohydrates,

effect

(see

page

278)

enhances

greenhouse

effect

(see

page

278)

extraction

livestock

urea,

greenhouse

growing

methane rice;

enhances

fats

and

protein,

pathogens

reduces

oxygen

destruction

(see

page

of

concentration

freshwater

in

rivers;

communities

276)

waste

of

toxic

can

be

fatal

to

wildlife

and

humans;

can

factories substances

mercury

such

and

fertilisers

as

lead,

accumulate

N

and

P)

arable

agriculture

arable

agriculture

eutrophication

spray for

killing

weeds

the

pesticides

for

killing

pests

and

and

livestock

waste

(non-pest)

(biodegradable

non-biodegradable

buried

domestic

and

industrial

waste

rubbish)

nuclear

(beta

274

gamma

atomic

radiation)

power

bomb;

accidents

stations;

nuclear

at

nuclear

tests

in

rubbish

toxic

fall-out

and

kills

fresh

water

harmless

(rivers,

plants;

lakes)

persist

in

in

food

chains;

kills

harmless

agriculture

diseases

solid

drift

in

environment

accumulates arable

and

organisms

cyanide

(mostly

herbicides

in

species

ground

tips;

liquids;

death

with

humans;

(landll)

health

release

high

hazard;

of

in

left

on

leakage

of

methane

exposure;

mutations

or

cancers

non-human

in

species

pollution

STUD Y Rubbish

is

chemicals

not

that

only

a

leach

visual

from

pollutant,

rubbish

but

dumps

it

contains

into

the

many

ground.

Examples

are

T he heavy

metals

that

enter

water

courses

and

the

drinking

water

table

applied

such

as

chemicals,

correctly

DDT

can

and

such

affect

dieldrin

as

areas

have

herbicides

locally

been

and

and

also

detected

in

pesticides,

far

the

away.

body

if

not

you

Insecticides

fat

sum

need

Paper

3.

mammals

and

birds,

many

thousands

of

miles

the

mar

to

If

where

away

used

of

they

would

in

aircraft

disease,

forests,

can

such

have

destroy

drift

onto

as

been

used

mosquitoes.

to

control

the

habitats

areas

of

of

natural

Herbicides,

crop

animals

pests

especially

and

vegetation

when

and

kill

you

Paper

by

materials

are

because

a

we

called

they

problem

into

this

sprayed

from

POINTS

–

throw

these

away

are

are

called

broken

when

a

it

long

time

comes

to

and

in

the

biodegradable.

non-biodegradable.

last

down

do

Plastics

not

disposing

are

decay

of

Some

used

easily.

plastics.

environment

are

for

But

Most

not

1

to

and

landll

sites

or

rubbish

dumps

where

they

take

up

a

is

the

Biodegradable

conventional

plastics

are

designed

non-biodegradable

to

break

plastics

once

down

they

release

of

by

example,

structures

some

which

is

plastics

now

digested

by

have

starch

bacteria

in

incorporated

the

lot

can

recycle

many

thermoplastics

that

we

by

into

Pollutants

affect

them

into

new

shapes.

Burning

plastics

in

they

the

volume

of

waste,

but

many

plastics

them

the

Nuclear

fall-out

testing

and

threats

to

produce

aquatic

and

toxic

gases

are

threatened

jellysh.

discarded

United

try

to

Fish

and

if

they

plastic

Arab

reduce

other

swallow

nets

Emirates

and

aquatic

plastic

other

banned

animals

bags

forms

of

can

life

too.

plastic

Some

plastics

are

In

plastic

others

but

are

some

non-

can

them

entangled

waste.

non-biodegradable

from

Sea

mistaking

get

from

nuclear

as

be

for

of

leakages

biodegradable

turtles

comes

use

reactors.

biodegradable;

pose

rivers,

incinerators

4

plastics

like

sea.

and

burn.

Non-biodegradable

air,

and

their

nuclear

reduces

the

land

ecosystems

and

weapons

remoulding

on

quickly

3

melting

activities.

dumped.

soil.

use

substances

human

of

the

We

done

by

waste

more

are

harm

environment

produced

becomes

plastic

the

the

packaging

this

Pollution

lakes

For

an

rest

plants.

aquatic

than

is

the

unit.

ecosystems

space.

to

and

2

goes

it

plastics

decomposers

these

4 ,

recycled.

in

2014,

the

products

to

pollution.

SUMMARY

1

List

of

2

three

the

QUESTIONS

pollutants

of

each

following:

a

the

atmosphere

b

aquatic

c

the

a

State

ecosystems

land

the

main

sources

of

radiation.

b

Describe

effects

3

Explain

to Most

plastic

bottles

have

a

recycling

symbol

with

a

category

number.

These

bottles

the

the

of

the

problems

environment

be

category

recycled

1

as

to

they

make

are

made

products

of

polyethylene

such

as

terephthalate

packaging

materials

(PET

and

or

PETE)

which

fall-out.

caused

by

non-

are

biodegradable in

undesirable

nuclear

plastics.

can

carpets.

275

tnemelppuS

tnemelppuS

Some

fo r

are

when

KEY

Waste

what

from

of vectors

ises

know

introd uctio n places

previo us

of

taki ng Antarctic

on

supply.

page

Agricultural

TIP

harmful

tnemelppuS

Land

21.4

Water

tnemelppuS

Pollution LEARNING

Describe

water

pollution

and

toxic

Describe

rivers

the

and

sewage

seas

pollution

lakes

and

due

the

and

and

industrial

into

the

pollutants

are

often

discharged

straight

into

sea.

chemicals

Rivers •

and

by rivers

sewage

rivers

OUTCOMES

Domestic •

of

pollution

empty

toxic

wastes

into

the

sea,

resulting

in

the

following:

of

to

over-use

•

of

Fertilisers

and

sewage

encourage

the

growth

of

algae

that

release

toxins.

fertilisers

•

Describe

of

the

female

negative

•

Pesticides

•

Radioactive

hormones

in

water

the

effects

Toxic

and

pesticides

metals,

Sewage

environment

algae

The

As

is

and

of

water

found

the

in

in

higher

is

molluscs

(shellsh).

concentrations

and

and

river ,

not

lead,

are

around

found

in

tissues

know

the

and

farmer

wrong

The

how

result

pollution

enriched

•

sewage

of

is

much

too

e.g.

of

in

can

be

land

to

to

of

that

use

washed

This

of

sh

in

a

organic

and

river

it

matter.

organisms

add.

the

rivers

oxygen

is

as

more

treated

suspended

sewage

is

concentration

so

that

raw

lakes.

We

But

have

particular

Problems

is

seen

farmers

can

soil

occur

added

at

need

and

if

the

rain.

can

cause

means

sequence

soil

may

no

crops.

which

the

If

fertiliser

heavy

is

improves

their

fertilisers

through

The

growth

284).

for

the

eutrophication,

leaching.

the

the

and

yield

if

as

sewage

rivers

or

period

nutrients.

on

bacteria.

page

the

fertiliser

is

killing

dumped

freshwater

recovers

into

fertiliser

these

is

gradually

by

(see

fertiliser

a

oxygen,

feed

many

countries

rivers

the

before

plant

called

of

that

water

increase

of

much

either

with

the

can

type

resulting

Fertiliser

this

best

uses

time,

from

into

of

the

away.

community

many

encourages

sewage

decomposed

In

deposited

drain

using

the

It

lots

that

migrate

are

the

up

bacteria

means

or

increases.

pollutant.

use

downstream,

out

fertilisers

a

raw

die

how

crop

world

copper

untreated

of

oxygen

so

the

water

raw

growth

of

travels

single

which

If

Fertilisers

to

into

ow

of

rivers

into

a

water

that

the

water

is

events:

and

streams

–

lake.

rivers.

•

Once

in

the

Nutrients

water

•

•

in

and

Animals

their

water,

the

so

that

this

stimulates

fertilisers

limit

eat

the

the

are

growth

algae

population

usually

do

of

the

not

in

low

growth

of

algae.

concentration

in

the

algae.

multiply

fast

enough

to

control

growth.

Algae

plants

cover

at

the

the

•

These

plants

•

Algae

also

shaded

276

some

stations.

mercury,

biggest

the

settle

sewage

the

as

bacteria

survive

dumped

of

such

the

shortage

wastes

parts

are

power

invertebrates.

cannot

into

of

organisms.

encourages

many

chemicals

nuclear

marine

small

drains

tissues

on

of

In

the

of of

herbicides

the

in

courses

• Describe

concentrated

contraception coastal

•

are

impact

by

surface

bottom

of

eventually

die

the

as

there

algae

layers

the

die

is

on

of

water,

and

rot

on

competition

the

reducing

the

light

reaching

lake.

surface.

the

for

river

bed.

resources

and

many

are

Decomposers,

•

Bacteria

respire

dissolved

•

The

chain

of

multiply

result

the

The

they

ions

act

added

of

are

as

in

feed

multiply

a

the

oxygen

cannot

events

quickly,

death

problems

These

of

that

Bacteria

in

bacteria,

aerobically,

concentration

same

as

on

dead

rapidly

plants

and

use

and

up

algae.

a

lot

of

oxygen.

invertebrates

The

such

tnemelppuS

•

of

decreases

respire

can

use

happen

up

short

limiting

form

this

kills

sh

and

if

sewage

oxygen

in

gets

into

respiration,

waterways.

which

can

sh.

eutrophication

in

and

properly.

supply

factor

of

are

in

to

the

fertilisers,

caused

most

growth

plant

by

natural

of

nitrate

plants.

growth

and

aquatic

phosphate.

ecosystems,

When

they

so

are

increases. Fertilisers

Farmers

make

up.

are

sure

encouraged

that

Phosphate

they

are

tends

to

to

reduce

applied

remain

the

at

in

a

fertilisers

time

soils

they

when

and

apply

crops

much

of

will

the

and

take

water

to

water

comes

detergents

has

from

domestic

helped

to

sources.

reduce

this

Removing

in

the

sea

–

nitrate

in

the

type

sea

of

pollution.

causes

growth

which

produce

toxins

and

kill

other

marine

algae,

of

contraceptive

Water

pollutants

women

Topics

16.12

therefore

in

take

and

nds

its

contraceptive

contraceptive

16.13).

way

pills

The

into

is

a

pills

human

containing

is

oestrogen

excreted

sewage.

The

oestrogen

in

urine

If

excess

are

not

broken

down

in

fertilisers

active

known

pass

through

unchanged

to

all

sewage

nutrients

amphibians

respond

to

this

leached

nutrients

for

enter

rivers

treatment

and

oestrogen

in

lakes.

the

they

causing

by

supplying

algae.

EE2.

plants

Female

contraceptive

so

Male

are

water

by

causing

the

sh feminisation

and

are

lakes

eutrophication

ingredient

as

and

hormones they

pesticides

metals.

rivers

provide

(see

and

3 Oestrogens

fertilisers,

toxic

hormones

hormone

synthetic

include

life.

into

Many

this

events

2

effects

turn

many

and

The

and

POINTS

sewage, of

grow

from

Similar

of

to

phosphate

phosphate

1 happen

algae

them

KEY in

caused

green.

of

aquatic

gaining organisms.

certain

female

characteristics

‘feminisation’,

testes,

having

protein

found

as

it

is

some

in

also

yolk

a

condition

called,

female

egg

–

involves

reproductive

which

is

known

producing

structures

carried

as

in

their

intersex.

eggs

and

This

inside

making

blood.

In

their

a

addition, SUMMARY

their

sperm

Drinking

rivers

water

water

works.

the

cells

An

do

is

may

often

be

increase

decrease

in

not

develop

taken

taken

in

from

downstream

oestrogens

sperm

rivers,

counts

in

of

and

the

drinking

recorded

in

in

the

case

efuent

water

men

in

of

from

has

long

been

some

1

a

sewage

parts

linked

over

the

past

20

of

Dene

the

pesticide,

to

terms

insecticide

and

herbicide

the b

world

QUESTIONS

properly.

Explain

why

they

are

years. used.

This

in

is

the

the

only

same

from

part

of

the

environment

effects.

agriculture

story

and

These

and

as

many

there

other

chemicals

industry,

are

other

synthetic

are

in

including

the

sources

plastics

food

of

chemicals

oestrogens

that

and

processing

in

c

have

the

can

waste

those

There

no

that

deal

with

implicated.

works

so

easy

EE2

the

is

rest

solutions

removed

could

be

to

of

the

drinking

effective

water

ways

this

from

problem

the

waste

upgraded.

treatment

to

the

a

Explain

the

negative

soya.

The

as

many

water

use

of

chemicals

from

some

charcoal

are

do

this.

works

will

Upgrading

be

sewage

sewage

lters

works

of

female

contaceptive

water

hormones

in

courses.

is b

one

pesticides

environment.

effects

are

how

damage

plants 2

especially

Explain

What

steps

taken

to

could

be

and rectify

the

expensive. problem?

277

21.5

The

greenhouse

Greenhouse LEARNING

Describe

the

contribution

atmosphere

greenhouse

gases

and

methane

tnemelppuS

change

Explain

how

in

greenhouse

climate

air

pollution

gases

heat

like

the

that

so-called

vapour

•

of

a

blanket

gases

in

surrounding

the

atmosphere

the

act

Earth

like

a

keeping

it

greenhouse

to

otherwise

would

be

radiated

into

space.

These

are

to the

climate

Some

carbon keep

dioxide

is

of warm.

the

gases

OUTCOMES

The •

effect

and

greenhouse

methane.

Some

(chlorouorocarbons),

by

causes

other

problems.

These

greenhouse

gases

are

which

man-made

greenhouse

are

air

carbon

dioxide,

pollutants,

gases

as

well

such

as

the

water

as

CFCs

cause

of

change

surface.

Some

atmosphere

Some

heat

gases

energy

as

heat,

energy

allow

enters

which

is

escapes

solar

food

energy

chains

radiated

into

to

and

away

pass

is

from

space,

but

gases

keep

through

eventually

the

much

to

lost

Earth’s

is

the

to

Earth’s

the

surface.

reected

back

greenhouse

towards

the

Earth.

Greenhouse

our

atmosphere

at

the

gases

temperatures

It

is

important

process

be

that

and

about

build-up

Power

to

it

the

to

exist.

that

the

average

However,

greenhouse

stations,

life

understand

without

–17 °C.

of

allow

over

greenhouse

temperature

the

last

100

effect

on

years,

the

is

a

natural

Earth

there

has

would

been

a

gases.

factories,

domestic

heating

and

transport

use

fossil

fuels

solar

and

release

huge

amounts

of

carbon

dioxide

into

the

atmosphere.

As

radiation

we Figure

21.5.1

The

greenhouse

have

seen,

removed.

are

In

burned,

and

other

South

even

There

also

the

has

release

the

oil

huge

reneries

and

quantities

atmosphere

when

of

power

carbon

they

burn

fossil

into

Of

all

the

severa l

areas

a

due

of

forest

to

the

is

and

into

the

decomposed

farming

being

and

atmosphere.

by

microbes

in

they

Roots

the

soil,

dioxide.

signicant

increase

expansion

released

found

material

oil

are

dioxide

for

in

in

by

of

sites

gas,

are

methane

rice

cattle

ooded

landll

natural

in

(another

cultivation

and

rice

and

also

elds

by

and

rubbish

other

and

bacteria

tips,

sources

of

in

natural

as

well

as

methane.

greenhouse

and

has

gases

CFCs

risen

by

the

cannot

greenhouse

gases

10%

largest

be

in

the

increase

ignored

than

last

as

carbon

30

has

they

years.

been

in

carbon

are

However,

much

more

dioxide.

know .

table

that

Look

on

you

back

page

your self

change

air Human

pollu tants

need

to

274

of

causing

to

these .

activities

greenhouse

has

the

the

the

is

are

gases

by

so

the

0.7 °C

an

increase

atmosphere

greenhouse

over

the

past

is

in

the

getting

effect.

century.

concentration

warmer.

The

This

surface

There

are

of

fears

of

is

the

Earth

that

this

0 °C

then

increasing.

temperature

polar

causing

enhanced

warmed

warming

If

278

large

cleared

TIP

are

remin d

of

carbon

carbon

conditions

which

Climate

the

in

are

fuels.

effective

to

resulted

trees

stations

dioxide

methane

T here

has

the

parts

Methane

Rotting

extraction

dioxide,

STUD Y

more

gas)

anaerobic

tree

been

rearing.

wetlands.

the

releases

remaining

producing

cattle

America

which

greenhouse

Factories,

deforestation

effect.

ice

of

would

the

start

Arctic

to

and

melt.

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This

would

was

to

cause

a

rise

above

rise

in

sea

level

ooding

would

of

include

many

some

low-lying

of

the

areas,

capital

for

cities

example

of

the

in

Bangladesh.

These

KEY

world.

1

There

could

rainfall

leading

become

as

very

parts

mean

also

of

a

be

to

dry.

the

change

more

Some

USA

massive

a

in

wind

extreme

of

and

these

Asia,

reduction

in

patterns

weather.

are

so

and

Some

important

that

the

crops

the

parts

distribution

are

expected

agricultural

warming

grain

of

of

the

areas,

climate

Central

Asia

of

America.

The

pattern

of

the

world’s

food

The

naturally

greenhouse

to

such

could

blanket

around

prevent

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escaping

distribution

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with

economic

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political

carbon

to

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emissions.

using

energy

cattle

to

the

This

more

effects

may

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of

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change

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pollution

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them

releasing

a

method

combined

domestic

is

to

heat

use

and

fossil

fuels

power

and

more

plant

in

efciently

which

the

as

happens

heat

is

used

in

and

tnemelppuS

The

diagram

in

for

of

in

effect

more

detail

possible

Earth

how

the

greenhouse

effect

cools

heat

down

back

into

in

sea

and

from

the

level,

low-lying

the

some

in

be

changes

climate

crop

and

a

production

areas.

QUESTIONS

radiates

Sun

Copy

and

complete:

and

carbon

radiate

part

energy

into

of

the

dioxide

absorbed

energy

space

atmosphere

space

Solar

passes

the

Space

water

and

absorb

air

radiates

absorbed

infra-red Earth

carbon

radiation

Earth’s

dioxide

and

through

and

radiate

surface.

heat

the

The

energy

Earth

back

into

CO

O

H

could

ooding

areas,

world’s

warms

the

consequences

space

water

warms

contributing

works.

1 some

radiation

is

change

SUMMARY

the

has

greenhouse

change.

climate

rise

in

shows

carbon

methane

this

climate

The

a

heating.

greenhouse

space.

by

the

reduction

The

and

energy

methane.

of

One

a

of

3 stop

as

Earth

consequences.

climate

done

heat

into

increased

Measures

act

the

be

dioxide affected

occurring

gases

and

2 North

POINTS

tnemelppuS

and

some

2

2

H

2

CO

of

the

energy

back

O to

Earth

CO 2

2

CO

This

is

mainly

radiation.

2

CO 2

CO

Some

2

H

the

heat

energy

is

O

H

O

of

2

2

by

the

greenhouse

atmosphere

H

Earth

gases.

O

How

the

to

CO 2

21.5.2

effect

radiation

List

passes

through

the

atmosphere

and

warms

the

the

The

red

Earth

radiates

heat

energy

back

into

space.

This

is

mainly

infra-

as

Some

and

in

each

a

human

source

of

this

causes

vapour

Human

the

the

heat

air

heat

activity

dioxide

and

greater

impact

energy

is

absorbed

by

the

greenhouse

is

give

the

that

acts

gas.

a

Describe

the

likely

gases.

to

warm

energy

is

other

up.

would

causing

a

carbon

pass

large

greenhouse

than

Without

carbon

straight

increase

gases

dioxide

such

(see

in

as

dioxide

back

the

out

and

into

space.

atmosphere

methane,

question

12

of

which

on

page

b

carbon

has

a

291).

the

increases

in

these

gases

in

the

atmosphere

that

Describe

which

for

the

enhanced

greenhouse

the

global

ways

people

governments

the

emission

and

and

can

of

in

their

reduce

greenhouse

attempt

to

are

reduce responsible

of

warming.

water

gases It

case

activity

of

consequences

This

contribute

greenhouse

radiation. 3

•

that

surface. one

•

gases

enhanced

the effect

Earth’s

the

up.

works.

to

Solar

warm

2

greenhouse

2

•

causes

2

CO

Figure

This

the

effects

of

global

effect.

warming.

279

21.6

Acid

tnemelppuS

Sulfur LEARNING

rain

dioxide

(SO

)

is

released

when

fossil

fuels

are

burned.

2

OUTCOMES T ogether

with

nitrogen

oxides

(NO

)

from

exhaust

fumes,

they

cause

x

• Describe

effects

the

of

causes

acid

acid

and

dioxide.

rain

in •

State

the

measures

that

taken

to

reduce

acid

Rain

in

the

nitric

when

acidic

sulfur

atmosphere

acids

as

be

as

low

acid

in

clouds

dioxide

and

react

acid

which

lower

the

pH.

and

as

and

dissolves

nitrogen

with

oxygen

carbon

oxides

they

dissolve

produce

In

some

places

the

pH

of

sulfuric

the

rain

3.0.

polluted

by

the

air

wind

nitric

be

water

considerable

and

droplets

become

polluted

acid distances)

dixoxide

water

produces (may

sulfur

the

rain

blown

sulfuric

naturally

can

may

oxidation

is

However ,

water

and be

rain.

nitrogen

(nitric

and

sulfuric

acid)

oxides

wet

deposition

(acid

rain)

dr y

deposition

power

and

stations,

vehicles

into

the

industries

release

gases

trees

atmosphere

rivers

and

affecting

decreasing

the

lakes

water

and

polluted

pH

and

affecting

soils

These

gases

winds

dissolved

both

can

before

of

in

carried

being

the

these

be

21.6.1

over

deposited

rain.

types

The

The

of

term

causes

and

large

as

dry

‘acid

effects

of

distances

particles

rain’

acid

by

to

deposition.

are

acid

rain

falls

on

trees

it

kills

leaves

their

ability

to

resist

disease.

Many

European

forests

have

been

killed

trees

by

sulfur

is

affected

dioxide.

Most

by

high

sensitive

lichens,

Increasing

280

of

sulfur

dioxide

in

aluminum

from

soils

algae

their

Some

grow

can

and

water

species

only

fungi

and

are

where

tolerate

high

living

together.

nutrients

very

the

from

sensitive

air

is

free

of

concentrations.

the

to

sulfur

the

gas

Others

tolerate

useful

intermediate

indicators

the

of

concentrations.

pollution.

By

Lichens

looking

at

the

rain.

of

growing

average

b

concentration

of

c

atmosphere

→

in

an

concentration

which

a

leaches

in

acid

concentrations

are

and

some

species

Vegetation

rain

polluted

life

and

are central

acid

all

atmosphere.

can reduces

absorb

dioxide

the

and

composed

They

and When

polluted

lakes

water

rain.

or

refers

affected

life

rivers

Figure

vegetation

area,

of

you

sulfur

can

deduce

dioxide.

the

acid

because

the

falls

on

and

there

out

of

these

on

is

of

soils

affected

The

•

by

•

ue

station

and

and

chimneys

catalytic

aluminium

water

converters

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little

rain

effect,

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already

it

acidic

causes

soluble

low

waste

or

pH

plant

and

coal

live

and

the

can

in

pH

increase

Trees

these

aluminium

have

been

in

exhaust

These

fumes

solutions

are

of

but

are

and

sulfur

washing

its

from

with

before

being

the

damage

America

China’s

are

cleaning

rapid

stations

means

b

Name

d

Explain

country

time

the

the

with

a

content,

powdered

can

escape,

nitrogen

introduced

has

when

damage

and

use

of

oxides

gradually

Europe

done

coal

problems

Sulfur

Acid

normal

gases

rainfall

which

sources

the

of

effects

aquatic

in catalytic

by

in

with

and

acid

its

carbon

they

convert

acid

also

reduces

monoxide

oxides

of

pollutants

and

by

hydrocarbons;

nitrogen

(NOx)

to

North

rain,

many

converter

oxidising

nitrogen.

palladium

when

The

which

vehicles

catalysts

are

are

are

recovered

platinum

and

or

recycled

scrapped.

power

rain.

is

slightly

dissolve

in

the

acidic.

water

in

clouds

to

form

these

of

acid

gases.

rain

on

coniferous

trees,

soils

animals.

what

dioxide

from

rain

also

Acid

can

be

done

to

reduce

the

effects

of

acid

rain.

from

car

dissolves

causes

rain

the

burning

exhausts

useful

the

are

nutrients

release

damages

of

the

leaves

of

fossil

main

out

of

aluminium

and

kills

fuels

causes

the

soil

ions

trees.

and

of

rain.

making

that

Fish

nitrogen

acid

are

and

it

infertile

toxic

to

sh.

invertebrates A

die

if

lakes

become

ue

gas

power

Measures

taken

to

reduce

acid

rain

include

removing

fuels

and

acidic

gases

from

waste

sulfur

dioxide

plant

station

that

from

which

burns

waste

coal.

gases

The

at

a

product

sulfur

of

from

desulfurisation

acidic. extracts

4

rain.

POINTS

and

3

the

Explain

oxides

2

of

a

acid

rain.

State

KEY

some

At

expansion

the

why

the

c

e

up

rain.

by

QUESTIONS

Explain

and

1

that

a

acid

acid

industrial

SUMMARY

1

from

killed

power

wet

they

it

sulfur

into

stop

Europe

as:

cars.

expensive,

Central

them.

A

the

in

ions

badly

animals

reducing

reduce

5.5.

lowers

no

such

gases

gases

to

pH,

few

the

tted

that

Norway

Crushing

the

be

a

compounds

acidic

below

rivers

sh

rain

removes

can

is

acid.

is

become

and

very

acid

used.

the

the

concentration

and

have

sulfur

treating

neutralising

there

soil

rain.

to

and

with

Scotland

be

the

the

soluble

streams

combat

could

by

become

some

to

dissolves

acid

invertebrates

Canada,

fuels

neutralises

calcium,

lakes,

tolerate

chalk

infertile.

soils

The

or

granite,

the

and

them

in

of

exists

this

as

neutralise

enters

rain

limestone

such

desulfurisation

limestone,

•

in

acid

that

gas

to

water.

cannot

sulfur

solvent

rocks,

leaving

of

technology

low

alkaline

Species

Lakes

on

potassium

that

bodies

toxic.

soils

compounds

considerably.

are

are

hard

as

water

ecosystems

on

nothing

such

Aluminium

Acidied

falls

soils

soils

nutrients,

wash

rain

tnemelppuS

When

this

process

is

gypsum

(calcium

sulfate)

gases. which

is

used

in

the

construction

industry.

281

21.7

Sustainable

A LEARNING

resource

Dene

any

substance,

organism

or

source

of

energy

that

we

OUTCOMES take

•

is

resources

the

term

from

the

environment.

sustainable A

sustainable

resource

is

a

resource

which

is

renewed

by

the

resource activity

•

Explain

the

need

to

organisms

the

environment

State

that

stocks

can

forests

be

that

there

is

always

enough

for

us

to

without

it

running

out.

Examples

of

take

these

resources sustainable

•

so

conserve from

non-renewable

of

and

sh

timber

for

or

renewable

building

and

resources,

sh

that

harvested

can

from

be

maintained,

the

sea

and

are

lakes.

managed Non-renewable

resources

include

energy

sources

such

as

fossil

sustainably tnemelppuS

fuels

•

Explain

how

forests

and

cannot

sh

stocks

are

minerals,

e.g.

copper,

zinc

and

lead

ores.

gone,

they

are

These

resources

and be

replaced:

once

they

are

gone

forever.

managed

sustainably

The •

Dene

the

term

development

that

it

at

and

requires

planning

local,

and

The

explain

management,

is

world’s

supplied

conserve

cooperation

national

international

need

to

conserve

fossil

fuels

sustainable

by

and

by

future

There

•

the

for

sources

various

fossil

fuels

energy

energy

fuels

–

coal,

non-renewable

generations

are

Use

fossil

these

renewable

levels

demand

of

until

we

more

released

so

can

oil

increasing

and

a

time

that

natural

so

by

we

burning

combustion,

have

e.g.

all

fuels

them

most

We

they

supply

fossil

and

gas.

that

that

they

conserve

efciently

on

ever

resources

such

energy

ways

is

be

this

to

used

developed

for

to

need

can

our

combined

of

energy

the

needs.

future:

make

heat

full

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use

of

power

plants.

•

Reduce

houses

wastage

in

cold

conditioning

that

•

use

Reducing

public

•

Heat

and

Power

plants

like

and

or

in

Berlin,

Germany,

distribute

steam

to

heat

houses

surrounding

in

generate

the

and

form

hot

in

water

from

the

fast

to

is

a

As

soon

an

example

to

quotas

282

has

alternatives

more

for

energy

petrol/gasoline,

encouraging

(see

fuels

nuclear

willow

as

production

of

contributed

the

tree

cover

charcoal

to

the

from

for

removal

the

of

country.

so

trees

of

at

be

by

timber

valuable

products.

forests

all

insulation

to

of

conventional

efcient,

such

as

air

those

Topic

car

e.g.

by

providing

better

pools.

21.8).

as

sources

power,

of

and

energy

burning

are

wind,

rubbish

solar,

and

wood

trees.

area.

tend

almost

and

fossil

and

growing

harvested

cooking

using

are

the

cooling.

materials

hydroelectric

many

the

improving

this

Timber

Haiti,

and

that

demand

Sustainable

In

e.g.

electricity

of

industry

for

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Alternatives one

countries

systems

transport

Recycling

energy,

resource

Some

are

felled,

same

softwood,

issuing

they

trees

restocking

the

as

can

they

so

rate

it

not

that

many

in

a

replanted.

the

resource

becoming

trees.

logging

more

in

grown

are

without

to

take

used

be

coniferous

permits

do

production

Some

industries

The

can

than

continue

They

are

regrow.

is

to

These

governments

can

make

way.

replanting

depleted.

companies.

trees

to

sustainable

be

trees

manage

given

tnemelppuS

Combined

ice

of

tnemelppuS

Sustainable

Populations

now

For

example,

Some

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of

are

steps

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need

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to

•

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too

•

can

•

them

of

of

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a

other

cod

sea

Many

that

To

of

they

collapsed

creatures

sustainably.

sea

to

are

This

the

‘no

in

in

these

are

the

such

continue

declared

ensures

stock

take’

to

off

that

each

zone

shing

sustainable.

1990s.

as

to

populations

not

crustaceans

do

this

and

various

limits

a

year.

help

for

suitable

The

shing

Cayman

conserve

during

number

a

of

young

Islands

sh

in

known

the

as

to

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captivity

in

be

a

red

so

that

boats

cannot

take

be

restocked

them

where

sea

minimum

size

so

that

small

sh

breed.

raise

Japan

including

certain

to

can

and

authorities

season.

survive

of

are

by

each

have

and

stocks

sh

stocks.

taken:

issued

nets

in

sh

overshing

Atlantic

and

season.

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Examples

the

as

by

grouper.

escape

Some

sh

has

are

many

Fishing

of

recruited

Nassau

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depleted

hunted

be

areas

Caribbean

the

of

be

breeding

are

are

stocks

can

Certain

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severely

species

molluscs

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in

if

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it

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and

are

to

as

breed

hatcheries.

several

released

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forestry:

ready

felled

as

to

and

into

the

released

into

Sustainable

Sustainable

increasing

Many

Sturgeon

Caspian

Sea

aims

population

signed

up

development

Janeiro,

impact

the

year.

development

countries

de

each

by

to

provide

facilities

in

caviar

are

Brazil.

assessments

to

Agenda

that

arose

Agenda

that

to

provide

without

21

assess

21,

from

a

risk

of

needs

the

global

the

promotes

the

the

harming

action

1992

the

of

trees

have

use

Earth

of

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20

years

to

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grow.

for

Summit

in

environmental

developments

to

the

This

is

one

way

in

which

cooperation

exists

at

national

and

local

factory

ships

like

this

one

have

taken

the many

sh

from

the

oceans

that

stocks

are

levels. sustainable

to

and

some

species

are

being

extinction.

POINTS SUMMARY

A

another

an

driven

1

are

trade.

environment.

not

KEY

trees

timber

Iran.

so

international,

mature

the

reared

Large

environment.

for

development

human

sustainable

Rio

sea

be

young young

stages

the

species

sustainable

resource

is

one

which

can

be

removed

from

the 1

environment

without

it

running

QUESTIONS

Dene

the

term

sustainable

out. resource

There

is

a

need

to

conserve

non-renewable

resources,

such

as 2

fossil

fuels,

for

future

Explain

tnemelppuS

stocks

3

Forests

and

sh

stocks

can

quotas

and

restocking.

be

sustained

using

education,

legal

but

3

4

Sustainable

increasing

development

human

provides

for

the

needs

of

an

Cooperation

between

organisations

is

List

may

forests

fossil

ve

fuels

be

and

sh

fuels

ways

can

be

sustainable,

are

in

not.

which

fossil

conserved.

population. 4

5

why

generations.

international,

essential

for

national

sustainable

and

local

development.

Discuss

in

the

role

conserving

of

education

forests

and

sh

stocks.

283

tnemelppuS

2

21.8

Sewage

treatment

and

recycling

Sewage LEARNING

Raw •

Outline

how

sewage

is

make

the

water

sewage

that

faeces

safe

environment

to

or

return

for

made

and

up

urine,

of

but

a

number

industrial

of

unpleasant

waste

and

materials,

run-off

from

not

roads

and

it paths.

contains

is

treated just

to

treatment

OUTCOMES

to

Not

only

is

it

unpleasant,

but

it

is

also

a

major

health

hazard.

the

human

use

sewage

aeration settlement tank

•

State

and

that

metal

paper,

can

glass,

be

plastic

reused

tank

outlet

or

recycled

river

air

pump

pump screening

for

and

grit

disposal generator

anaerobic sludge

tank

processed

Figure

There

•

21.8.1

are

solids

•

Activated

sludge

three

Primary

twigs,

Components

main

means

are

of

allowed

Secondary

a

stages

treatment

by

of

sewage

in

the

involves

lters

to

or

settle

treatment

treatment

removing

out

in

involves

of

large

Then

large

out

plant.

treatment

screens.

sludge

sewage:

solids,

the

grit

like

and

paper

and

organic

tanks.

microbes,

mainly

bacteria,

treatment.

decomposing

material

suspended

in

water.

This

may

happen

in

two

ways.

•

The

activated

sewage

respire

with

in

proteins

Trickle

lters

the

large

rotating

•

T ertiary

the

any

may

population

which

provide

dumped

Trickle

put

is

a

passes

into

break

The

sea

down

methane

or

for

is

waste

spread

on

the

the

down

microbes.

these

beds

through

settling.

tanks.

out

may

to

go

matter

burned

operating

of

large

it

the

which

carbohydrates,

broken

with

over

secondary

or

is

through

protists

to

the

The

liquid

from

gravel,

the

matter.

settle

the

and

ions.

trickles

period

into

material

back

covered

sprayed

pumped

down

Urea

nitrate

liquid

is

fungi

break

organic

microorganisms

energy

at

the

the

air

as

a

form

anaerobic

an

increase

methane

in

the

soil

from

in

the

stage

water

make

it

to

all

kill

return

leaving

safe.

to

For

the

plant

example

it

microorganisms.

the

environment

will

be

may

Water

or

for

treated

be

in

treated

a

works

may

also

be

conditioner.

variety

with

leaving

the

human

use.

of

chlorine

process

is

in

anaerobic

sewage

Sludge

and

This

to

to

a

sludge.

to

fuel

as

liquid

microbes

stage

machinery.

land

The

Here

lters.

The

284

of

bacteria

conditions.

to

organic

be

to

gravel

involves

process

remaining

sludge

As

down

treatment

secondary

and

dioxide.

treatment

arms.

break

of

which

bacteria,

converted

beds

primary

microbes

carbon

then

are

from

to

in

of

conditions

fats

and

process

community

aerobic

and

ammonia

•

sludge

a

ways

or

now

to

ozone

safe

to

Recycling

Another

of

more

of,

it

and

sites

This

to

than

a

them.

saves

be

to

same

such

the

savings

mass

of

in

which

in

of

metals,

paper

aluminium

tips

animals

and

the

you

raw

extracted

of

useful

less

carefully

can

For

plants

managed

habitats.

all

be

materials

ore,

disposed

materials

recycled

its

production

and

animals,

energy

materials.

from

the

their

plastics

compare

to

and

recyclable

and

is

handled

harm

conserving

from

if

cause

rubbish

quantities,

material

energy

population

properly

and

because

large

is

can

plants

problem

materials

in

make

the

increasing

waste

waste

deprives

Glass,

raw

made

95%

Dumping

to

an

this

pollution

also

solution

of

Unless

cause

ourselves.

recycle

waste

consequence

waste.

may

landll

The

our

is

is

to

recycled.

do

not

used

to

example,

have

recycle

there

aluminium

to

is

the

bauxite.

This

recycling

bin

says

it

all?

What

do

you

recycle?

Paper

is

a

However,

paper

These

Waste

paper

pulp

pulped,

toilet

resource

the

is

are

be

are

and

up

and

it

is

made

recycled.

The

waste

the

converted

paper

and

as

and

required.

removed

other

bundled

supply

collected

is

dried

and

SUMMARY

limited

trees

dyes

paper

paper

can

from

sheets

in

pulp

into

from

This

paper

is

then

wood.

means

is

rolled

newsprint,

that

less

collected,

into

paper

sheets.

towels,

products.

shredded.

This

saves

it

being

otherwise

thrown

into

landll

sites,

like

the

KEY

QUESTIONS

1 1

Outline

what

happens

one

to

raw

sewage

as

it

passes

through

above

right.

POINTS

Sewage

treatment

screening sewage

treatment

to

remove

a

Make

a

list

of

materials

that

can

be

material,

recycled. decomposition

b

Describe

on

the

the

effects

that

recycling

of

these

materials

have

and

following:

i

the

raw

ii

the

energy

iii

landll

materials

used

needed

sites

settling

suspended

in

making

and

in

making

rubbish

to

Make

a

list

of

the

different

these

goods

Decomposition

populations

that

dumps

types

of

digest

packaging

that

of

by

protein,

In

and

fats,

cellulose

in

wastes.

shops.

3 b

requires

bacteria

are human

used

microbes

material.

carbohydrates

a

by

remove

goods 2

3

non-

plant.

biodegradable

2

involves

a

what

ways

does

this

packaging

cause

problems

Recycling

materials,

such

for as

paper,

saves

money,

raw

society? materials,

c

Explain

how

the

recycling

of

paper

helps

the

energy

and

reduces

environment. pollution

by

waste.

285

21.9

Endangered

A LEARNING

species

becomes

Explain

why

become

and

organisms

endangered

or

extinct

tnemelppuS

Explain

the

risks

to

a

they

time.

far •

the

size

of

decreases

its

so

in

the

are

we

reducing

variation

in

the

of

becoming

numbers

We

have

already

hunting

(T asmanian

wolf)

died

and

difcult

becomes

been

to

extinct,

Reserve

there

in

know

but

periglenes,

seen

predation

past

the

last

was

Costa

since

the

when

as

Golden

restricted

Rica

and

the

to

the

has

the

wild.

Extinction

that

past.

are

This

is

captivity

occurs

occurring

as

a

result

all

the

now

are

of

all

the

decrease

most

and

of

are

to

is

to

the

causes

habitat

Others

kill

such

described

a

level

as

of

that

it

is

at

endangered

species

destruction,

becoming

climate

are:

animals

that

are

a

threat

to

livestock

that

humans

have

moved

from

one

part

or

alien

species.

the

ancient

the

ago.

habitats,

here

trees

that

Jurassic

They

but

in

are

occurring

in

cooled

most

ice

is

as

of

sheets.

the

As

warming

heated

North

the

land

result

Climate

and

Europe,

species

a

atmosphere.

world

will

with

equator.

tropical

Plants

outcompete

lower

Brazil

Florida.

over

threatened

grow

have

little

period

are

can

is

of

even

changes

at

was

more,

to

was

different

America

world

that

of

change

and

warmed,

a

the

feature

times.

much

the

ice

of

During

of

Asia

melted

and

exposed.

regions

better

other

able

are

and

plants

to

species.

extending

and

survive

Examples

in

their

animals

ranges

changing

of

this

are

away

from

environments

evident

on

1989.

safe

in

100

Plants

in

adapted

altitudes

there

will

and

be

destruction

have

the

largely

is

not

habitats

been

drained

and

lion

as

cold

in

of

cause

provide

migrating

to

provide

for

down.

tamarin

they

towards

left

covered

cut

only

leisure

conditions

retreating

was

the

for

to

nowhere

been

golden

grounds

development

their

peaks.

If

this

go.

21.2.

The

robbed

Atlantic

many

forests

species,

habitats.

habitat

Many

for

to

has

ecological

birds.

land

Topic

disappearing

mountain

them

This

of

are

loss.

Wetlands

services

wetlands

farming,

for

us

across

housing,

are

and

the

very

also

world

industrial

facilities.

their

botanic

Pollution

reefs

Sea

oil

are

is

occurring

endangered

otters,

like

pollution.

they

286

the

species

survival

the

world

associated

feeding

as

alive

in

another

colonised

important

gardens,

in

overshing.

species

the

of

Deforestation

years

the

extinctions

These

introduced

age

covered

including

natural

left

only

a

of

million

to

by

to

ice

Habitat

since

and

change

continues

are

extinct.

with

world

the

from

changed

considered

sport

mountains.

Cycads

in

alive

Unit.

the

or

•

Now

not

individuals

kept

1936.

sometimes

Monteverde

of

been

species

food,

organisms

Incilius

no

are

in

was

Toad,

a

crops

competition

the

of

for

composition

species

extinct

this

life,

•

Climate

is

in

extinct

pollution

Threats

It

have

describe

risk

of

thylacine

as

number

they

When

human

Zoo

are

species

population

•

Hobart

there

Some

species

change,

last

the

than

endangered

The

world.

described

However,

higher

activities if

if

OUTCOMES anywhere

•

extinct

species

ingest

many

Oil

toxic

on

a

global

ecosystems

marine

sticks

to

a

animals,

their

chemicals

scale.

as

fur

that

are

and

cause

As

we

result

at

stops

organ

of

have

seen,

coastal

risk

of

coral

pollution.

extinction

providing

damage

thanks

insulation

(see

T opic

to

and

21.2).

Many

sea

Exxon

otters

Valdez

Introduced

Sometimes

sport

•

or

half

in

small

1872

by

crop.

They

parts

of

have

done

Alaska

been

this

small

to

become

foxes

Indian

to

of

the

release

in

of

oil

from

the

tanker

1989.

moved

around

deliberately

by

the

globe

introducing

by

humans.

animals

for

pests:

the

have

predation

The

Bay

have

control

Australia

•

the

following

species

we

to

Almost

in

died

medium-sized

extinct

introduced

mongoose

control

rats

proved

due

so

by

was

that

native

eating

to

in

rabbits

Jamaica

much

they

with

and

colonists.

introduced

that

marsupials

competition

European

were

successful

to

of

were

the

from

sugar

introduced

India

cane

to

other A

the

Caribbean.

However,

as

with

many

such

project

tamarin

the

to

•

mongoose

fed

on

other

prey

as

well

as

the

one

it

was

intended

to

Plant

species

can

become

introduced

species

damage

many

hunted

to

has

for

remove

involved

natural

the

golden

captive

habitat

breeding

in

in

lion

Brazil

many

has

zoos.

food,

and

populations

the

for

sport,

ago

of

15 000

years

moved

southwards

People

have

because

goats,

extinction

for

animals

harvested

many

extinct

especially

of

which

overgrazing

have

done

by

untold

islands.

caused

dangerous

animals

or

plants

these

people

they

of

trade

and

pests.

from

some

migrated

a

the

wild

have

for

Asia

many

of

policy

been

to

hunted

With

increasing

unsustainable.

into

the

have

always

food.

became

from

They

deliberate

Humans

populations

destroyed

as

species.

the

large

About

Americas.

mammal

As

they

species.

Coral

collected

been

hunted

beautiful

trapped

materials

and

became

deliberate

policy

T asmania,

some

and

shot

animals,

interesting

for

their

available.

as

is

people

the

In

case

hunted

such

plants

fur

in

some

with

the

as

‘big

for

the

show.

days

places,

or

for

before

that

sport

Animals

animals

elephants

thylacine,

cats’

and

by

reef

tnemelppuS

There

is

very

and

With

little

in

no

it

genetic

individuals

are

evolving

because

endangered

few

species

partly

at

alive,

left.

to

believed

variation

species

left

longer

response

was

This

in

to

small

particular

many

of

reduces

changes

in

the

the

are

threatened

change

and

overexploitation.

have

shot

invade

as

a

farmland.

wolf,

to

POINTS

sheep.

populations,

risk

the

climate

man-made

are

T asmanian

kill

communities

pollution,

KEY extinction

rare

reintroduce

its

control.

Hunting

In

to

introductions,

of

so

becoming

alleles

of

chances

the

of

environment

makes

1

in

left

that

are

18.4).

become

there

alive

in

captivity.

population

Topic

Organisms

when

extinct.

genes

the

(see

this

are

the

no

extinct

individuals

wild

or

Endangered

those

that

are

at

in

species

risk

of

extinction.

SUMMARY

2

QUESTIONS

An

at

1

Dene

the

following

terms:

a

extinction,

b

endangered

endangered

risk

because

species.

small 2

Explain

a

d

how

these

hunting

habitat

b

threaten

the

overshing

destruction

e

survival

c

of

Use

examples

to

explain

the

of

species

may

climate

population

very

When

a

population

population

survival

of

decreases

decreases.

a

species

What

when

in

are

this

little

is

genetic

species: variation

that

adapt

changing

to

effects

that

is

needed

to

conditions.

Causes

on

food

webs

of

extinction

size,

the

variation

and

change,

habitat

ecosystems.

within

implications

happens?

are

the

destruction,

4

is

extinct

change

possible

have

its

with

climate introduction

species

becoming

hunting

3 3

of

for

the

the

pollution

by

hunting,

and

introduced

competition

predation

species

with

or

them.

287

21.10

Conservation

Endangered LEARNING

by

•

Describe

species

how

can

area

endangered

be

putting

tnemelppuS

Explain

why

important

conserved

species

a

alone.

changes •

should

to

to

in

No

can

for

National

be

•

and

the

legs

information

of

birds

about

has

how

•

live

and

how

migrate

far

over

they

travel.

thousands

Some

of

in

parks

•

like

this

should

Lanka.

bred

of

rare

plants

be

and

in

for

the

enjoyment

of

conserved

animals,

future

it

had

zoos

and

reintroduced

being

on

in

planet

closely

and

East

them.

East

a

the

so

it

monitor

counting

Africa

Other

duty

which

land

Africa

areas

set

to

this

aside

which

of

Island

animals

to

the

Pacic

are

such

the

as

sea

Marine

and

wild.

use

is

the

ocks

of

aeroplanes

techniques

conserve

is

have

to

ecosystems

done:

for

wildlife

patrolled

Masai

from

by

Mara

damage

Reserve

breeding

Many

islands

ready

was

become

them

but

which

wardens,

in

Kenya

and

in

New

them

in

by

shing

Zealand.

species

of

captivity

Partula

and

snails

during

the

20th

century.

Some

are

which

in

bred

to

in

nearly

released

and

back

into

their

reintroduced

to

habitats.

Oman

extinct.

plants

the

be

zoos

in

botanical

gardens

and

re-

wild.

destruction,

e.g.

deforestation

issuing

and

licences

protecting

for

logging

wetlands

to

in

prevent

drained.

establishing

Preventing

may

of

dry

take

ecosystems

forest

up

in

to

where

land

Guanacaste

300

years

to

has

become

National

Park

degraded,

in

Costa

achieve!

trade

in

Trade

endangered

in

species.

Endangered

CITES,

Species,

the

Convention

imposed

a

of

worldwide

generations.

on

the

ivory

has

into

in

Encouraging

Seed

for

in

1989.

like

sustainable

forests

natural

are

cold

seeds

wild.

Their

from

or

produce

may

to

of

an

increase

in

elephant

conserve

in

the

case

for

products

by

planting

Trees

or

allowing

seeds.

around

useful

ecosystems.

replaced

from

species

be

valuable

be

that

banks

many

genes

led

management

stores

Seed

This

Kenya.

should

replacement

species.

store

to

trade

countries

from

banks

they

crop

such

seeds

world

as

of

endangered

hope

become

to

extinct

improvement

medicinal

collect

in

in

the

drugs.

or

and

the

future

Seeds

been

the

collected

from

plants

in

the

wild

and

are

put

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EXPERIMENTAL

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Suggest

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SKILLS

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EXPERIMENTAL

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EXPERIMENTAL

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295

EXPERIMENTAL

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QUESTION

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EXPERIMENTAL

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the

linkage

a

sex

the

location

chromosome,

an

of

of

the

sensitive

reproduction

to

hole

allows

and

out.

by

The

guard

size

of

cells.

muscular

that

sac

at

mixes

the

food

end

of

with

The

begins

chemical

in

the

digestion

of

stomach.

the

X

Suspensory

ligaments

hold

in

the

lens

the

eye

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in

that

place

the

alter

its

shape

when

the

ciliary

process

fusion

of

haploid

contract

and

relax.

nuclei

cut form

a

diploid

eye

zygote

and

of

genetically

the

dissimilar

Sustainable

development

development

that

cell

is

able

to

so

that

they

conserve

that natural

resources

are

cells. Sexually

small

structure

transmitted

infection

in

the

future.

a

where disease

that

is

transmitted

through

Sustainable

resource

a

resource,

made. body

sensory

that

a

juice.

available

are

small

genes

usually

offspring.

Ribosome

a

that

places.

part

light

)

leaves

enzyme

production

eye

a

stimulus.

to

the

in

oesophagus

gastric

male.

involving

the

in

by

an

engineering

specic

of

controlled

Stomach

a

is

muscles

a

change

food.

particular

genetic

stomata

epidermis

hole

and

Rod

a

detected

to

Sexual Restriction

proteins

is

of

chromosome.

contains

stimuli)

that

cells,

molecules

on

Retina

(plural:

of

Sex energy

at

for

organ.

protein

DNA

specialised

organism.

and break

in

become

make

person’s

used

can

environment

sense

responses.

chromosomes Respiration

release

that

daughter

functions.

Stimulus

detect

environment

the

that

cells

produce

fail.

Sex of

to

chemicals

the Reproduction

more

unspecialised

mitosis

machine

waste

transmits when

Stem

neurones.

Sensory to

that

stimulus

system

and Renal

organ

sensory

changes to

touch,

and

Sensitivity that

receptor

particular

a temperature

neurone

a

a

action.

or Relay

organ

of

cell

in

the

responds

to

retina

light

e.g.

of

of

uids

during

sexual

e.g.

activity,

as

HIV .

timber

rapidly

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cell

anaemia

an

sh,

is

so

which

is

removed

that

it

produced

from

does

the

not

run

out.

inherited

intensity. disease

Root

the

organ

into

the

ground

and

mineral

that

and

anchors

absorbs

plants

water

alters

and

that

hairs

a

of

large

cells

surface

water

and

in

a

system

area

mineral

alimentary

for

endoplasmic

of

red

which

blood

cells

membranes

ribosomes

digestion

the

are

reticulum

inside

canal

and

the

region

that

are

in

the

to

heat

lose

neurones

absorbs

digested

food.

a

by

found

which

secrete

evaporation.

a

substance

that

dissolves

a

gap

between

in

is

which

released

the

second

a

two

chemical

to

stimulate

an

neurone.

in

a

liquid

that

T

dissolves

and T est

cross

a

genetic

cross

used

to

made.

with

are

Sclerotic

the

of

which

tough,

Secretion

the

substances

by

white

keeps

release

it

in

of

outer

layer

shape.

useful

a

group

similar

Sperm

of

the

which

interbreeding

fertile

and

sex

cell

or

T estis

sex

offspring.

male

an

insoluble

the

genotype

(plural:

organs

gamete.

carbohydrate

testes,

from

glucose

breeding

see

articial

store

in

plant

molecules.

cells

An

of

the

an

organism.

and

an

human

the

sperm

male

cells

and

produced.

the

that

hormone,

stimulates

produced

the

of

secondary

sexual

males

the

energy

in

and

important

development component

of

made

development

cells.

are

T estosterone

the

testes)

where

testosterone

by Starch

out

organisms

characteristics

capable

producing

of

characteristics

selection.

glands

skin

solvent.

cells

attached

S

Selective

the

across

transmitter

nd

eye

coiled

of

impulse

Species

the

glands

dermis

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of

completes

substances.

proteins

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sweat

anaemia.

salts.

Solvent

where

the

severe

intestine

root

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Rough

in

haemoglobin,

of

salts.

specialised

provide

absorption

shape

results

Small

Root

affecting

the

of

sperm

cells.

diet.

305

Glossary

Tissue

a

together

Tissue

cells

group

to

uid

when

blood

of

similar

perform

the

uid

plasma

cells

pass

the

that

and

out

cells

same

the

act

bathes

some

of

that

function.

the

white

Urinary

lters

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the

capillaries.

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an

a

poisonous

substance.

organ

produces

excretory

kidneys

contains

excess T oxin

system

blood,

and

uid

stored

excess

system

and

urine.

produced

in

water,

surface

that

stores

the

in

bladder.

urea,

Virus

be

toxins

as

waste

nucleic

bring

disease,

about

e.g.

high

the

Uterus

the

womb;

a

symptoms

of

a

fever .

the

and

amino

movement

acids

in

than

acid

a

disease

which

chamber

with

the

develops.

fetus

a

soft

lining

in

a

one

pathogen

host

to

can

phloem.

disease

be

passed

or

dead

a

Vitamin

preparation

pathogenic

stimulate

and the

water

surfaces

consist

of

surrounded

coat.

They

can

reproduce

cells.

small

a

micronutrient,

amounts

in

the

needed

diet.

is

provided

evaporation

in

the

If

diet

not

a

V

Vaccine

another.

Transpiration

cannot

which

containing

disease

give

the

microorganisms

production

of

can

result.

mild

action

an

action

that

we

to

decide from

for

microscope.

they

DNA)

living

Voluntary in

that

light

bacteria,

intestine

food.

of

the

a

the

(e.g.

protein

inside

deciency Transmissible

small

microorganism

under

enough sucrose

the

digested

muscular

in T ranslocation

of

of

Bacteria

products

only which

a

seen

Smaller

and

salts.

by release

area

absorption

to

make.

antibodies

immunity .

of

W

cells

from

in

water

the

leaves

followed

vapour

through

of

by

mesophyll

diffusion

stomata

of

Vaccination

provide

a

vaccine

to

Water

immunity.

water

into Vacuole

the

giving

uid-lled

sac

Water

Trophic

level

the

position

of

sap

present

in

a

food

chain,

food

of

numbers,

biomass

For

example,

herbivores

consumers

and

form

a

to

tube

the

trophic

diffuses

potential

leading

outside.

from

It

water

potential.

during

birth

sexual

a

plant

to

a

stimulus,

by

e.g.

of

of

higher

lower

blood

of

the

body’s

Lymphocytes differences

in

cells

they

form

intercourse

the

defence

features

release

system.

antibodies

and

between

that

may

to

combat

pathogens.

show ingest

and

kill

pathogens.

part continuous

of

area

area

canal.

antitoxins

response

an

an

the

level.

growth

to

the

receives

Phagocytes a

from

water

part the

individuals

Tropism

for

diffusion.

cells.

White penis

is

Variation second

plant

are and

primary

most

or erect

energy.

by

web, uterus

pyramids

tendency

move

an Vagina

organism

in

the

to

containing

atmosphere. cell

potential

molecules

light

variation

or

discontinuous

or

Wilting

loss

leaves

droop

of

turgor

causes

plant

variation.

gravity. Vasoconstriction

Thrombosis

a

blood

clot

that

a

vein

or

an

Withdrawal in

arterioles

to

reduce

that through

a

swollen

stem

of

a

potato

storage

and

asexual

plant

the

cell

pressure

onto

its

exerted

cell

wall.

by

arterioles

are

rm

because

through

this

can

they

support

relaxation

that

of

increases

addictive

side

they

effects

give

up

drug.

ow

are

Xerophyte

full

a

plant

blood

vessel

through

a

plant

adapted

to

dry

which

of

conditions. travels

towards

the

heart.

organs Xylem

as

when

capillaries.

Ventricle such

feels

muscles

blood

T urgid

blood

water;

symptoms

person

X

a

Vein

cells

a

reproduction. in

Turgor

lacking.

for Vasodilation

food

is

capillaries.

an T uber

water

blood

artery. ow

if

of

occurs muscles

in

contraction

to

the

lower,

more

the

plant

tissue

that

transports

muscular

stems. water chamber

of

the

heart.

In

and

right

the

lungs

ventricle

salts

from

roots

to

mammals,

leaves, the

mineral

pumps

blood

owers

and

fruits.

to

U

Umbilical

the

cord

placenta

to

the

the

cord

connecting

fetus.

It

blood

to

and

the

umbilical

arteries

and

rest

left

of

ventricle

the

pumps

body.

Y

contains Vertebrate

two

the

a

an

animal

with

a

backbone.

Urea

a

waste

product

formed

amino

acids

in

the

liver.

ltered

out

of

the

blood

and

in

small

and

passed

out

in

the

a

tube

through

which

from

the

kidney

to

by

membrane

the

made

that

by

cells,

Yield

crop

the

or

as

enzymes

or

the

bladder

306

tube

to

that

the

passes

outside

quantity

from

a

of

product

fermentation

(plural:

villi)

tiny,

nger-like

Z

bladder.

urine

at

dioxide.

neurotransmitters.

from

the

wall

of

the Zygote

a

that

ethanol

structures

substances

projection

Urethra

fungus

produce

urine Villus

passes

carbon

to

urine. such

Ureter

cell

sugar

from

a

the contain

kidneys

single-celled

It surrounded

is

a

ferments

from Vesicles

excess

Yeast

vein.

from

intervals.

small

intestine.

Villi

increase

the

a

fertilised

egg.

process.

Index

aorta

A

abiotic

environment

absorption

78,

accommodation

acid

rain

desert

pond

plants

asexual

the

temperature

respiration

effect

on

of

the

rate

by

using

respiring

energy

uptake

seeds

of

disadvantages

reproduction

brain

219

in

of

plants

seeds

78,

atherosclerosis

cleaning

control

plant

hormones

(BMI)

106–7

75

261

201

132

breathing

170

synthetic

to

82

depth

oxygen

adapted

107

function

index

breast-feeding

144

are

107

and

breadmaking

108

112–13

154

breathing

assimilation

of

germinating

auxin

the

184,

185

of

139

investigating

and

asexual

138

3,

vessels

vessels

mass

bolus

240–1

reproduction

advantages

164–5

respiration

investigating

selection

body

208

110–11

110,

functions

structure

(AI)

22,

cells

106

blood

shunt

107

insemination

articial

236

93

adrenaline

aerobic

articial

237

blood

their

11

113

cells

vessels

how

11

100

arterioles

236

adaptations

adhesion

arteries

34–5

features

blood

12–13

spinnerets

192

transport

adaptive

buds

110,

blood

white

96

arachnids

280–1

acrosome

active

apical

163

red

96

stylets

84–5

platelets

103

aphids

254

and

the

of

of

exercise

air

134–5

133

breathing

breathing

135

135

171

expiration

139

(breathing

inspiration

138

out)

(breathing

in)

133

132

B

afterbirth

vital

201 babies

agriculture

bronchi breast-feeding

agricultural

chemicals

(Acquired

6,

can

C cycle

253

calcium

HIV/AIDS

be

in

bacterial

growth

prevented?

capillaries basal

metabolic

rate

(BMR)

pairing

carbohydrates batch

culture

Benedict’s

solution

beta-blockers

alcohol

effects

social

problems

carbon

dioxide

effect

128,

amino

acids

223

chemical

uid

amniotic

sac

tests

for

the

steroids

anaemia

77

angina

breadmaking

environment

cells

membrane

cell

organelles

differences

birth

200–1

birth

control

diffusion

methods

methods

implications

size methods

of

cells

cellulases

119,

218–19

specimens

cells

21

22–3

262

146

201

cellulose blood

mitosis

41

239

112–13,

of

and

207

specialised solution

bladder

39,

18

309

240–1 surgical

39,

cells

signicance

biuret

resistance

30–1

30–1

206–7

175

antibodies

and

207

9 social

antitoxins

methods

plant natural

antibiotics

plant

18–19

28–9

cell

osmosis

(warm-blooded)

breeding

between

cells

206

18–19 chemical

selective

30

206

model

animals

6,

20–1

8–9

animal

homeothermic

34–5

18

254

141

barrier

antigens

transport

cell

4

cells

281

262–3

140

6

animal

converters

261

108

animals

36

46

260

and

234–5

birds

35

34,

18

active

biotic

anatomy

32,

262

cells

enzymes

140,

180

108

proteins

animal

acid

release

247

biofuels

anaemia

dioxide

washing

179

respiration

rate

262

262

biotechnology

lactic

arrest

catalytic

84,

the

biological

8

anabolic

cell

of

non-biological

powder

sickle

monoxide

cardiac

catalysts

biomass

anaerobic

powders

action

159

82,

carbon

carbon

catalase

and

79,

on

61

41

carrier washing

comparing

amylase

C

198 biological

amphibians

dioxide

40–1

vitamin

198

amphetamines

carbon

photosynthesis

38–9

58 testing

amniotic

and

130

121 molecules

131

39,

air

261

biological

alveoli

of

measuring biofuels

alleles

144

267

226–7

recessive

63,

inspired

261

of

and

57,

in

184

179

biodiversity

dominant

56,

dioxide

expired ssion

222–3

codominance

200

250–1

84

179

biodiesel

anus

cycle

carbon

binary

alleles

carbon

159

178 bile

long-term

114–15

72,

40

178

of

38,

264–5

145

biology

capillaries

42–3

234

addiction

100

70

lymph base

alcohol

200

255

211

albinism

128

250

210 phases

how

135

bronchioles

201

Immunodeciency nitrogen

Syndrome)

and

275 bacteria

AIDS

capacity

200

270–1

110,

23,

38,

58

119

120

centipedes blood

circulation

blood

clotting

120

central

nervous

system

(CNS)

154

113

86

cervix oxygenated

10

100–1

blood

100,

194

110–11

307

Index

chlorophyll

12,

chloroplasts

cholera

on

the

symptomless

meiosis

87

86

108

disease

180–1

circulatory

single

22

system

circulation

circulation

binomial

101

system

4–5

286

diploid

93

disease

169

colon

activity

blindness

competition

228–9

244–5,

liquid

a

238–9,

DNA

6,

71,

109

role

digestion

number

118,

214,

3,

of

eye

diseases

against

disease

diseases

118–21

276

144

liver

144

145

and

exercise

134–5

10

286

160–1

of

focusing

124–5

lactose-free

40

control

122–3

making

105

extracts

255

in

products

the

extinctions

78

46

144

exoskeletons

220

47

129

breathing

78–9

protein

263

41

exercise

29

of

juice

263

excretory

28–9

50–1

work

lactase

excretion

29

solvent

transmissible

255

us?

262

47

48–9

eutrophication

70–1

for

diffusion

digestion

defences

254

of

milk

78

control

communities

bad

effect

autoimmune

86

colour

as

fruit

assimilation

mechanical

226–7

use

206

14–15

pH

powders

complex

made

enzymes

epiglottis

be

that

digestion

226

alleles

control)

28

versus

water

278–9,

and

are

temperature

13

fat

47

washing

enzymes

how

123

keys

and

chemical

codominance

cohesion

can

factors

194

multiple

sex

why

gas

change

1)

74

216

enzymes

ethanol

diffusion

4

DNA

70

age,

site

extracting

(birth

100

see

176

diaphragm

100

100

acid

128

100

circulation

78,

biological

blood

(Type

7,

244

output

enzyme-substrate

diaphragm

diet

active

252

48

dicotyledons

classication

climate

273

dichotomous

cells

double

244,

deforestation

diabetes

pulmonary

133

blood

decomposers

depressants

transfer

and

enzymes

145

deoxyribonucleic

214

intake

218

deoxygenated

73,

83

22,

cells

denaturation

220–1

ciliated

cold

daughter

86

therapy

obstructive

(COPD)

clitoris

64

86

71,

chromosomes

cilia

body

carriers

transmission

cholesterol

chyme

54,

deamination

rehydration

chronic

energy

D

23,

86

effects

oral

56

12,

rods

the

pupil

reex

162

162

and

cones

162–3

118

214 F

concentration

gradients

28,

30,

130

base

pairing

42–3 faeces

conservation

288–9

genetic

code

86

216–17 farming

reasons

for

conservation

289

sequence

of

bases

fats constipation

75

structure

270–1

216 39,

71,

testing consumers

244

double

helix

206–7

drugs

145,

for

acids

implications

309

41

39

174 feedback

social

fats

42 fatty

contraception

72

42

addiction

174,

166

176 fermenters

coordinators

155

excitatory

and

misuse

drugs

inhibitory

drugs

159 batch

cornea

160

coronary

arteries

angioplasty

108

of

recreational

109

duodenum

in

drugs

83,

sport

culture

264–5

179 industrial

fermentation

industrial

production

265

174 of

penicillin

84 264

coronary

artery

bypass

operation ferns

12

108 E coronary

heart

disease

(CHD)

fertilisation

ecosystems risk

factors

for

CHD

108–9,

154,

78,

nerves

157

86,

implantation

145

cells

23,

seed

185,

192,

194

197,

formation

fertilisers

195

fertility

190

203

191

66,

270,

276

treatments

208–9

266 electrocardiograms

advantages

and

disadvantages

crops

monocultures

185

208

implications

bre,

dietary

brin

and

73,

309

75

270 84

brinogen

113

10 endocrine

system

164

sh

8

10 comparing

cephalothorax

the

compound

endocrine

and

shing

283

10 nervous

eyes

systems

165

accidity

33

10 endorphins

gills

drugs

social

181

emulsication

antennae

104

267 emphysema

crustaceans

(ECGs)

of embryos

genetically-modied

176

owers

12–13,

186

10 energy

cytoplasm

36,

70

insect-pollinated

owers

186

6 communities

308

188,

196

154 ejaculation

crops

186,

fertilisation

13 egg

cranial

human

109 egestion

cotyledons

254

181 effectors

treatment

185,

108

244–5

energy

losses

energy

pyramids

248–9

248

wind-pollinated

ue

gas

owers

desulfurisation

focusing

162

187

281

Index

accommodation

follicles

gravitropism

163

203

follicle

stimulating

hormone

(FSH)

food

chains

food

preparation

food

production

social,

245,

food

fruit

food

webs

fruits

cells

passive

278

218,

economic

in

65

vitro

197,

habitat

destruction

272,

human

on

food

119

2,

78

214,

and

webs

and

alleles

need

to

7,

conserve

102,

coronary

heart

disease

linkage

(CHD)

fuels

(ECGs)

cell

11,

heart

action

11

103

7,

heart

and

heart

sounds

exercise

11

105

insulin

184

166–7

104

industrial

184

septum

muscles

intestines 102,

bladder

84–5,

heat

84

hepatic

184–5

portal

vein

and

female

gametes

192–3

herbicides

266,

exchange

heroin

29

159,

out

carbon

dioxide

social

130

problems

77,

200

(intra-uterine

exchange

at

gas

exchange

surfaces

plants

the

alveolus

131

heterozygous

HIV

130–1

structure

of

the

gas

exchange

how

genes

juices

42,

gene

what

genetic

109,

and

is

a

gene?

222–3

215

engineering

266,

vitamins

in

plants

advantages

and

disadvantages

genetically-modied

herbicide

resistance

insect

genetics

in

crops

crop

medicines

resistance

code

variation

genotypes

in

of

crop

insulin

plants

267

period

glucagon

glycerol

of

blood

38,

166–7

growth

human

256–7

population

257

destruction

167

272–3

287

lactic

85

acid

241

larynx

236

253,

a

56,

64–5

65

57,

lightning

lipase

immunity

leaf

63,

95

photosynthesis

84

response

276

64

stomata

light

124

141

86

128

inside

83

140,

intestine

leaves

hydrophytes

active

6–7

76

263

leaching

vigour

immune

36

4,

200

lacteals

large

95

acid

ileum

148

149

L

labour

I

glucose

2,

kwashiorkor

60,

58

39

glycogen

water

202–5

hydrochloric

hygiene

63

the

167

38,

control

198

production

in

164

population

hunting

hybrid

glasshouse

kingdoms

166

147

147,

151

energy

lactase

habitat

191

transplants

kinetic

223

7

humidity

232

4

gestation

organs

controlling

216–17

tubules

reabsorption

166

hormones

148

kidneys

277

growth

223

germination

164–5,

148

the

kidney

166–7

166

organisms

hormones

human

266

glucose

feedback

supply

sex

214

genetic

glucose

conditions

hosts

266

production

genetic

genus

controlling

267

plants

150–1

glomerulus

211

inside

blood

contraceptive

of

146

dialysis

135

controlling

target

184,

kidneys

prevented?

transmitted?

homozygous

266

industrial

be

ltration

HIV

hormones

266

human

is

negative

270

crop

IUS

virus)

211

HIV/AIDS

homeostasis

234

alleles

additional

tracing

can

how

216

mutations

genes

immunodeciency

211

83

and

206

223

K

contact

system

128–9

gastric

(human

organisms

210

67

device)

system)

177

(intra-uterine gas

155

176–7

IUD breathing

actions

40

270

iron gas

86

10–11

85

iodine male

267

169

involuntary 3,

insulin

103

invertebrates

gametes

of

128

102

ventricles

G

production

102

intercostal valves

234–5

266

104

cuticle

282

228–9

anaemia

108–9

insects electrocardiograms

fossil

233

224–5

103

spiracles

7,

mycelium

(atrium)

sickle

281

environment

inheritance

102–3

sex atria

250

hyphae

gall

versus

220

monohybrid

261

222–3

77

inheritance

261

226–7

272–3

22,

number

100,

222

chains

genes

fuels

208–9

273

inuences

haemoglobin

haploid

sulfur

(IVF)

124

codominance

heart

low

201

241

inheritance

271

fuel

122,

286

ingestion deforestation

272–3

neutral

system

203

fertilisation

barriers

271

fuels

carbon

immune

H

and

263

biofuels

the

immunity

implantation

219

infections

270–1

supply

245,

70,

inbreeding

191

fungi

gases

3,

of

122–3

278–9

124

environmental

juice

greenhouse

guard

272–3

implications

world

effect

growth

204

malfunction

170

greenhouse

120–1

121

liver

84,

84,

and

light

intensity

62

253

262

145

cirrhosis

179

309

Index

lungs

103,

lung

128–9

cancer

luteinising

lymphatic

lymph

nodes

lymph

vessels

lymphocytes

HIV

and

lysozyme

natural

hormone

system

ovules

N

181

(LH)

204

competition

114–15

115

119

lymphocytes

selection

241

variation

cells

medicine

meiosis

between

meiosis

219

70

rate

(BMR)

70

73

138,

between

meiosis

of

mitosis

and

157

bacteria

production

pepsin

resources

282

limbs

nervous

cycle

244,

cycle

2,

variation

phloem

2,

needs

nutrients

74–5

72–3

limiting

oxygen

stem

cells

of

monocultures

monohybrid

of

ratio)

parental

test

cross

mucus

causes

gene

sickle

swallowing

82

respiration

140–1

2–3,

mutations

cell

234

anaemia

156

10

234

234–5

plant

204

rate

6–7,

systems

orgasm

24

rate

58

54–5

62

and

light

intensity

and

temperature

organs

25

65,

animal

cells

33

osmosis

in

potato

cells

32

plants

in

outbreeding

(ovum)

effects

gas

194

of

199,

203

201

and

monocotyledons

nutrients

of

on

owering

growth

plants

12

exchange

inheritance

mineral

194

4

202

12

hydrophytes

241

192,

gland

198,

67

13

ferns

77

194,

6,

60–1

170–1

(phyla)

pituitary

features

33

32

osteomalacia

ovulation

respiration

dicotyledons

31

in

ovaries

56–7

plants

92

58–9

photosynthesis

requirements

placenta

30–1,

osmosis

ova

62

products

of

phylum

24

and

195

turgidity

mutations

the

59

phototropism

plasmolysis

234

202,

261

tissues

osmosis

163

of

myriapods

194,

osmometers

162,

on

61

62

61,

24

organ

2

anaerobic

dioxide

photosynthesis

photosynthesis

109

82

58

organs

4

and

75,

rape

organisms

224

24

mutations

seed

oils

82

muscles

oil

plant

movement

310

(3:1

82

chewing

myelin

oestrogen

224

generation

225

morphology

eye

F1

74,

oesophagus

224

cross

mouth

obesity

13

inheritance

96

54

photosynthesis

factors

58,

60,

O

270

the

38,

218–19

219

monocotyledons

crossing

mitosis

transport

23,

carbon

photosynthesis signicance

119

232

photosynthesis

investigating

energy

112,

90–1

and

of

119

31,

223

importance

251

154

30

112,

12,

of

252–3

70–1

of

28,

phenotypic

effect

250–1

cycle

(PNS)

270

photosynthesis

250

system

82

phenotypes

aphids

42

4–5

50–1

phloem

42

264–5

83

phagocytosis

253

201

28

118

phagocytes

253

122,

263

pentadactyl

pH

253

25

192

pesticides

252

cycling

sources

movement

peripheral

xing-bacteria

balancing

218

156,

157

158

bacteria

nutrition

221

mitosis

156,

nitrifying

water

218

immunity

penis

23,

84

passive

permeability

nitrogen

193

neurones

253

carbon

65

20,

duct

passive

penicillin

158

158

cells

166

7

pectinases

157

neurones

lightning

nutrient

84,

peristalsis

acids

photosynthesis

111

mesophyll

pathogens

156,

neurones

nucleotides

10

nutrients

process

actions

66

nucleic

in

P

parasites

voluntary

neurones

cycle

141

oxyhaemoglobin

pancreatic

and

165

156

non-renewable

149

differences

154,

nitrogen

260–1

190

mitochondria

mitosis

and

denitrifying

38,

metabolic

minerals

238

180

nitrogen

microorganisms

millipedes

nitrates

203–5

25

3,

89,

endocrine

(connector)

nicotine

202

cycle

23,

microvilli

238

pancreas

systems

neurotransmitters

77,

mesophyll

metabolism

populations

neurones

sensory

203

meristems

micropyles

the

presynaptic

121

menstruation

menstrual

offspring

154

postsynaptic

and

relay

cells

menopause

plant

mitosis

221

234

memory

basal

motor

220–1

differences

melanin

neurones

produced

59

155

266

debt

oxygen

palisade

system

involuntary

109,

58

oxygen

239

within

nervous

76

218,

of

and

22

comparing

66

9

238–9

natural

nerve

M

marasmus

resources

185

oxygen

239

articial

reproduction

210

238,

between

nervous

mammals

for

over-population

115,

160

magnesium

189,

differences

115

112,

selection

223,

salts

nitrogen

in

plants

67

236

224–5

65

cycle

252–3

66

12–13

Index

pyramids

of

biomass

67

pyramids

of

energy

18–19

pyramids

of

numbers

photosynthesis

plants

plant

cells

plant

products

plant

tissues

selective

systems

plasma

rectum

reexes

90–1

roots

plastics

6,

artery

renal

vein

pollen

tubes

pollination

insect

pollen

tubes

female

190

male

190

13,

186,

pollination

self-pollination

186,

and

189

wind

pollination

pollution

land

274,

pollutants

pollution

size

products

care

200

photosynthesis

prokaryotes

protein

39,

enzymes

testing

puberty

58,

72,

(PEM)

76

stem

seeds

eye

202

in

boys

girls

reticulum

(ER)

20

tubers

stimulants

artery

investigating

103

the

effect

105

160

161,

sphincter

162

83

sulfur

of

exercise

for

germination

3,

valves

100

determination

sex

hormones

sex

inheritance

linkage

sex

organs

124–5,

276,

284

228

and

characteristics

195

closing

202

65

238

47

58

for

reducing

dioxide

to

sugars

40

280–1

resources

conserve

282

fossil

fuels

development

282

283

sustainable

shing

283

sustainable

timber

production

effect

156,

transmitter

of

drugs

of

on

the

substance

159

synapse

synaptic

transmission

bulbs

156

synaptic

gap

158

158

158–9

158

postsynaptic

presynaptic

282

158

synaptic

synaptic

sexual

intercourse

91

65

structure

228

stem

157

transmission

228

202–5

184

secondary

and

180

chemical

3

treatment

76–7

83

synapses

160–1

55

58

need

160

structure

sex

root

sustainable

organs

40,

207

154,

sustainable

191

270

192

sex

sexual

240–1,

56

starch

184

the

testing

77

breeding

184

12

sugars

192

286–7

193

needs

stem

sucrose

109

species

219

substrates

71,

of

193

76

cells

struggle

82

191

sewage

105

glands

survival

185,

154

for

opening

262

279

287

58

sterilisation

7

fats

76,

sensitivity

202

202

56,

salivary

semi-lunar

41

sense

in

41,

and

semen

216–17

protein

reex

38,

inside

92

253

180–1

29

154

stem

stems

91

180

184

stimuli

conditions

200

7

pulmonary

nerves

stomata

selective

puberty

pupil

216

275

40,

scurvy

malnutrition

puberty

pyloric

22,

and

endoplasmic

scrotum

192

262

47

for

rate

hairs

nodules

saprotrophs

204

synthesis

protocists

root

root

saturated

gland

protein

the

root

saliva

58–9

194,

energy

proteins

(mRNA)

13

safety

6

51,

spinal

starvation

S

progesterone

duct

testing

RNA

the

23,

cord

stomach

58

to

species

species

de-starching

207

20

smoke

smoking

232

sporangia

157

by

solutions

spinal

spores

138–41

169

96–7

4,

cells

starch

6,

and

sperm

184–5

244

47

protease

154,

tobacco

caused

nutrient

rubbish

208–9

3,

77

rough

206–7

treatments

by-products

prostate

3,

of

endangered

sperm

195

282–3

67,

method

inside

198–9

200–1

producers

2–3,

species

temperature

84

84–5

introduced

9

roots

255

fertility

238–9,

messenger

contraception

pupil

RNA

254–5

192–3

160

rickets

95

ante-natal

pulse

256–7

194–5

8

ribosomes

growth

solvents

threats

reproduction

rhythm

276–7

system

198–9

sexual

retina

254

population

pregnancy

185,

239

intercourse

respiration

275

population

potometers

selection

responses

water

predation

184,

system

sexual

resources

274

plastics

populations

reproductive

reptiles

188–9

275

waste

birth

187,

286–7

pollution

human

3,

sources

reproductive

pregnancy

188

cross-pollination

body

109

diseases

reproduction

natural

188

of

intestine

biology

184

234–5

168

smoking

219

185

anaemia

absorption

157

146

146

asexual

(STIs)

96–7

control

3,

184–5

infections

12–13

cell

small

arcs

renal

275

growing

skin

285

reproduction

260

sinks

157

155

reex

92–3

237

154,

3,

transmitted

210–11

246

86

recycling

110

plasmids

pollen

by

reproduction

sexually

sickle

receptors

240–1

94–5

uptake

sexual

247

248

R

25

96–7

transpiration

xerophytes

in

shoots

organs

breeding

transport

respiration

58–9

and

translocation

water

and

membrane

membrane

158

158

311

Index

trypsin

T

tar

teeth

80

healthy

tooth

teeth

decay

temperature

control

effect

of

on

and

body

169

and

48,

temperature

193,

tissues

uid

and

organs

translocation

96–7

146,

water

194

system

transpiration

transpiration

95

translocation

transpiration

pull

93

transpiration

stream

systems

90

100–1

124

and

63,

non-

materials

275

72

146

121,

96–7

23

3,

185,

types

of

contraceptive

veins

170

170–1

versus

within

environment

populations

hormones

potential

water

uptake

weight

loss

wilting

32,

and

seas

in

30,

92–3,

171

74

94

233

X

238

xerophytes

12,

237

22,

90–1

169

yellow

veins

103,

20

villi

89

8–9

203

115

115

Z

zidovudine

107

column

body

10

zygotes

(AZT)

185,

276–7

92

plants

Y

vesicles

35,

rivers

251

water

xylem

207

subclavian

vertebral

233

230

64

cava

232–3

variation

100

leaves

vertebrates

170

variation

of

cycle

weedkillers

189

variation

vasectomy

venules

244

of

vasodilation

93

water

125

194

discontinuous

vena

90

90–1

phototropism

56,

pollution

variation

95

and

gravitropism

29,

effects

inheritance

94

levels

155

biodegradable

continuous

and

affecting

ow

disposal

biodegradable

145

194

vagina

transpiration

312

waste

71

146

vacuoles

25

96

measuring

tropisms

144,

variation

transpiration

actions

194

W

198

fats

V

282

114

transpiration

76

77

277

128

translocation

trophic

cord

vaccination

animals

voluntary

32

108

production

plants

urea

uterus

24

mass

pressure

266

41,

U

urinary

202

tissues

transport

D

urethra

timber

factors

vitamin

ureter

62

thrombosis

trachea

32

unsaturated

61

128

tissue

turgidity

umbilical

48–9

temperature

testosterone

plant

C

vulva

193

thorax

vitamin

139

temperature

175

73,

181

turgor

95,

photosynthesis

testes

80–1

7,

vitamins

184

tumours

81

63,

enzymes

optimum

61,

gums

viruses

84

tubers

180

211

186,

193,

197

95

Essential

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Biology

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