Class 7 Biology - BeTOPPERS NEET Foundation Series - 2022 Edition

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NEET FOUNDATION Class VII

BIOLOGY

© USN Edutech Private Limited The moral rights of the author’s have been asserted. This Workbook is for personal and non-commercial use only and must not be sold, lent, hired or given to anyone else.

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Published by

:

USN Eductech Private Limited Hyderabad, India.

PREFACE

Our sincere endeavor in preparing this study material is to enable students to effectively grasp and understand the concepts of IIT foundation. This study material has been compiled by our team of experts who have a decade of experience in various academic fields. These books also proved to be successful in developing of academic skills like concentration power, understanding ability, memory power, retention ability, problem-solving skills, application skills, analytical ability, logical thinking and emotional strengths like interest in learning, self-reliance, confidence, will power, psychological strength, right stir and zeal and physical stamina. The important features of the books are: 1.

Lucidly presented concepts For easy understanding of the concepts, they are presented in simple and easy, comprehensible language. 2. Learning Outcomes Each chapter starts with Learning outcomes which precisely conveys what the students is going to learn in this chapter. 3. Bold-faced key terms The key words, concepts, definitions, formulae, statements, etc., are expressed in bold face, indicating their importance in the content. 4. Tables and charts Numerous strategically placed tables and charts, list out and summarize the important information, making it readily accessible for effective study. 5. Box items Throughout the text, the box items highlight special topics that take the text material to be a more extended level. Students will find them to be a lively and interesting feature as they investigate the subject. 6. Photographs A wide array of visually appealing and informative photographs are used to help the students to understand various phenomena and inculcate interest in the subject. 7. Illustrations Because a picture is worth a thousand words, each chapter has ample number of illustrations that clarify different concepts and enhance learning. 8. Flow diagrams To help students understand the steps in problem-solving, flow diagrams have been included at key locations i.e., at important concepts. These diagrams allow the students to visualize the process of solving a problem. 9. Summary charts At the end of the chapter or important concepts, there is a summary of major concepts covered. Each section is reviewed in a paragraph form. The summary, along with the blueprint, provides a complete overview of the chapter. 10. Concept-wise Formative Worksheet Unlike other books, this book contains concept-wise Formative Worksheet problems. The solutions for these problems shall be discussed by the teacher in the classroom. These questions allow the child to strengthen understanding and application skills.

11. Concept-wise Conceptive worksheet Each Formative Worksheet is followed by a Conceptive worksheet. This contains additional problems of the respective concepts. The problems are expected to be solved by the students for additional practice. This allows the students to get exposed to new style of problems related to the concept. 12. Summative worksheet At the end of each chapter, there is a Summative Worksheet. This worksheet contains problems based on all the concepts of the chapter. Unlike Formative Worksheet and Conceptive Worksheet problems, the problems in this section involve the application of multiple concepts of the given chapter. The worksheet allows the child to strengthen the problem-solving, application and analytical skills. 13. Advanced worksheet Each Summative Worksheet is followed by an HOTS (Higher Order Thinking Skills) worksheet. This worksheet contains problems of advanced type involving Higher Order Thinking Skills. The concepts can be of same chapter or different. The solving of these problems prepares the child to face new patterns of problems that appear in actual IIT and other entrance examinations. Strengthening of all the academic skills of a child is the main objective of this worksheet. 14. IIT JEE worksheet Finally, every chapter ends with a IIT JEE worksheet. This worksheet contains the problems which have appeared in various competitive examinations like IIT, AIEEE, KCET, TCET, JIMPER, BHU, AIIMS, PbCET, CBSE, CET, etc related to the chapter. This part of the worksheets creates awareness and builds confidence as the students get exposed to real problems that appeared in various competitive examinations. 15. Wide variety of problems The problems included in the worksheets cover various models that appear in different competitive examinations. The different models include:

 Non-objective type  Objective type with more than one option correct  Matching type – II (Three columns)  Statement type – II (More than two statements)  Statement and Explanation type  Figurative type  Road Map type

 Objective type with single option correct  Matching type – I (Two columns)  Statement type – I (Two statements)  Assertion and Reason type  True or False type  Comprehensive type  And many more……

We would like to thank all members of the different departments of BeIITIIANS who played a key role in bringing out this student-friendly study material. We sincerely hope that this study material will prove useful to the students undergoing IIT foundation, ensuring their success in various competitive examinations. However, We believe that as there is always scope for improvement, we value constructive criticism of the subject matter, as well as suggestions for improving the book. All suggestions will be duly incorporated in the next edition. Wish you all the best. Academic Team USN Edutech

CONTENTS 1.

Basic Biology

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1 - 20

2.

Organisation in Living Things

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21 - 40

3.

Tissues

..........

41 - 58

4.

Life Under a Microscope

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59 - 80

5.

Nutrition in Plants and Animals

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81 - 108

6.

Digestion

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109 - 124

7

Respiration and Excretion

..........

125 - 140

8.

Movement in Animals and Plants

..........

141 - 158

9.

Key and Answers

..........

159 - 168

Learning Outcomes

Basic Biology Chapter -1

By the end of this chapter, you will understand  About the discovery of the basic unit of life, the cell  The various parts of a cell  The structure and functions of different cell organelles  Slides for examination under the microscope  Differences between plant cells and animal cells  About cell division

1. INTRODUCTION You know that in order to build a house, bricks are arranged in a certain pattern. Similarly, our body is made up of similar structures called cells, which assemble to form our body. Hence, cells are the structural units of our body.Living things are made up of tiny living parts or compartments called cells. Some living things, like the bacteria and Amoeba, have only one cell (unicellular organisms). Large plants and animals contain billions of cells (multicellular organisms). Cells in multicellular organisms are of many different types, each type specially adapted for performing a particular job. Groups of cells of the same type make up the different tissues of the organism, e.g., muscle tissue. Several different types of tissues together form an organ, e.g., stomach. A number of organs together form a system, e.g., digestive system. A cell is the basic unit of living things or life. UNICELLULAR ORGANISMS Living organisms made up of only a single cell are called unicellular organisms (Figure. 1.1). Unicellular organisms can often be observed only with a microscope. Such living organisms are called microscopic, indicating that the organisms are too small to be seen with the naked eye. Examples: Unicellular animals –

Amoeba, Paramecium;

Unicellular plants – Chlamydomonas, bacteria.

Amoeba

Paramecium

Chlamydomnas

Figure 1.1: Unicellular organisms 2. DISCOVERY OF CELL The discovery of cells was first made by Robert Hooke. While examining a section of a cork tree under the microscope, he observed small compartment-like structures and named them cells. But, Hooke observed dead cells under the microscope as cork is made up of dead cells. After the discovery made by Hooke, very little came to be known about cells for a long time. This is because better microscopes were needed to study cells of living organisms. With the discovery of advanced microscopes (like electron microscopes), a study of the structure of cells and various cell organelles was made possible.

7th class biology

2 3. CELL THEORY & ITS PROPERTIES CELL THEORY

The cell theory that all plants and animals are composed of cells and that cell is the basic unit of life was presented by two biologist, Schleiden (1838) and Schwann (1839). The cell theory was further expanded by Rudolf Virchow in 1855. He suggested that all cells arise from pre-existing cells. PRINCIPLES OF CELL THEORY 1. All living organisms are composed of one or more cells. 2. Cells are the basic unit of structure and function in an organism. 3. All cells come only from the reproduction of pre-existing cells. PROPERTIES OF CELL (i)

The cell is the smallest living unit of life.

(ii)

It is so small that it is not visible to the naked eye.

(iii)

The shape of the cell varies in different organisms and within an organism.

(iv)

Size of cells also differs.

(v)

All living cells exhibit certain basic properties like respiration, growth, metabolism etc.

(vi)

Cells originate from a pre-existing cell. A mother cell divides to produce daughter cells. Hence, cells exhibit cell division.

4. CELL ORGANALLE & THEIR FUNCTION All the life functions take place in every cell. A cell itself is made of certain parts. Also, plant and animal cells are not exactly alike. All plant and animal cells have three cell parts - the cell membrane, the cytoplasm and the nucleus (Fig. 1.2 and 1.3). Each cell consists of a mass of living matter called protoplasm.The cytoplasm surrounded by the cell membrane and enclosing the nucleus together constitute the protoplasm (proto = first; plasm = form). Protoplasm, in other words, includes the cell membrane, the cytoplasm and the nucleus.

Figure 1.2: Plant Cell

Figure 1.3: Animal Cell

CELL MEMBRANE Also called the plasma membrane, it is a very thin skin covering the cell. There are very tiny holes in the cell membrane. The plasma membrane performs following functions: (i) It protects the cell, (ii) It provides shape to the cell, (iii) It allows materials to enter and leave the cell through the tiny openings.

Basic Biology

3

CYTOPLASM The cytoplasm is a jelly-like substance occupying most of the inside of the cell. It occupies the space between the cell membrane and the nucleus. All the life functions take place in the cytoplasm. The cytoplasm contains many important tiny structures called the organelles which perform the various life functions. NUCLEUS The nucleus is present inside the cell, surrounded by the cytoplasm. The nucleus is the boss of the cell, just like your school principal. Just as the principal controls everything taking place in the school, the nucleus also controls everything that happens in the cells. Most cells have only one nucleus. Cells like the muscle cells have more than one nucleus. Nucleus is a spherical body consisting of four parts: (i)

Nuclear membrane

(ii)

Nuclear sap or nucleoplasm

(iii)

Nucleolus (plural nucleoli)

(iv)

Chromosomes.

The outermost covering layer of the nucleus is called the nuclear membrane. It separates the nucleus from the cytoplasm. Nuclear membrane, like the cell membrane, has tiny holes in it which allow exchange of substances between the nucleus and the cytoplasm. The jelly-like fluid inside the nucleus is called the nucleoplasm. Chromosomes and nucleoli are present in the nucleoplasm. Chromosomes are thread-like structures which play an important role in the inheritance of characters from one generation to another, that is, from the parents to the children. Functions of the Nucleus (i) Transmission of characters from one generation to another, (ii) Controls all the life functions taking place inside the cell. CELL ORGANELLES & THEIR FUNCTIONS A number of organelles occur in the cytoplasm. These include: MITOCHONDRIA Mitochondrion is a membrane-enclosed organelle found in eukaryotic cells. Mitochondria are responsible for the production of most of the energy (or ATP) in cells. Therefore, mitochondria are also known as the power house of cells. A mitochondrion is composed of two lipid membranes, enclosing the matrix. The inner membrane gets folded to form numerous cristae. Cristae are the main site for ATP production. Mitochondrial matrix contains mitochondrial DNA and ribosomes. Functions of mitochondria (i) They produce energy required for cells in the form of ATP. (ii) They also regulate the free calcium ion concentration in the cytosol. (iii) They participate in apoptosis or programmed cell death. ENDOPLASMIC RETICULUM Endoplasmic reticulum, or ER, is an interconnected network of membranous structures like tubules, vesicles, and cisternae. Cisternae are the flattened disk-like membranous structures. Tubules are tubular in shape, while vesicles are sac-like structures. There are two types of endoplasmic reticulum, namely smooth endoplasmic reticulum (SER) and rough endoplasmic reticulum (RER). When ribosomes get attached to the surface of smooth endoplasmic reticulum, it becomes rough endoplasmic reticulum. The basic functions of endoplasmic reticulum are (i) To provide internal support to the cells (ii) To provide transportation pathway within the cells

7th class biology

4

PLASTIDS Take a peel of the Tradescantia leaf and observe it under the microscope. You will find coloured bodies in the cytoplasm of the leaf cells. Do you know what these are? These are called plastids. The green coloured plastids in the cell are known as chloroplasts. They are responsible for the green colour of the leaves. They carry out the process of photosynthesis and help plants prepare their own food. Plastids are major organelles found in plant cells and algae. There are two major types of plastids, namely Chromoplasts andleucoplasts. Chromoplasts are coloured plastids, while leucoplasts are white or colourless plastids. Chromoplasts contain coloured pigments like carotene (orange), xanthophylls (yellow) etc. These pigments are responsible for the colour of plants. Unlike chromoplasts, leucoplasts lack pigments. Chloroplasts are plastids containing the pigment called chlorophyll. A chloroplast is enclosed by two lipid membranes. They are called the kitchen of the cell. The inner matrix is called the stroma. Thylakoids are the sub-organelles arranged in stacks within the stroma to form grana. The thylakoids are believed to be the main site for photosynthesis. Plastids also contain their own DNA and ribosomes. Functions of plastids (i) They carry out the process of photosynthesis. (ii) They contribute to the colour of leaves, flowers etc.

Figure 1.4: Mitochondria

Figure 1.5: Endoplasmic reticulum

Figure 1.6: Chloroplast

Basic Biology

5

GOLGI COMPLEX Golgi apparatus are the membrane-bound, sac-like structures called cisternae and some small vesicles. They are arranged parallel to each other in stacks. They were discovered by Camillo Golgi in 1898. Golgi body is usually composed of five-eight cisternae in stacks. Some functions of the Golgi apparatus are enlisted below. Functions of Golgi apparatus (i) It involves the transport of lipids in cells. (ii) It involves the formation of lysosomes. (iii) It is involved in the synthesis of cell wall in the plant cell.

Figure1.7: Golgi apparatus

The golgi apparatus present in the plant cell are called dictyosomes. They are small, unconnected and more in number as compared to the animal cell. LYSOSOMES Lysosomes are the membrane-bound vesicles, which contain digestive (hydrolytic) enzymes. They digest a variety of substances including worn out organelles, food particles, viruses, and bacteria. They are also known as ‘suicide-bags’ of cells as they burst out and release hydrolytic enzymes in the cytosol, where cells are heavily injured. Functions of lysosomes (i) They digest macromolecules by phagocytosis. So, they provide protection to the cell against foreign substances. (ii) They also take part in auto-cell lysis. CENTRIOLES AND CENTROSOME (PRESENT ONLY IN ANIMALS) Centrosome is found exclusively in animal cells. It lies very close to the nucleus. It contains two cylindrical structures called centrioles. Both centrioles in a centrosome lie perpendicular to each other. Centrioles have a cartwheel-like organisation. The centriole has a role in cell division. VACUOLE When you observe an onion peel under the microscope, you will observe large empty spaces in the cells. Do you know what these spaces are? These empty spaces are called vacuoles. These vacuoles are larger in plant cells than in animal cells. Vacuoles are membrane-bound structures, which are believed to store substances of cells. In plant cells, vacuoles are large in size, while in animal cells vacuoles are small. The table given below lists some functions of vacuoles. The membrane of vacuoles is called tonoplast. Functions of vacuoles: (i) They help in the removal of unwanted structural debris. (ii) They store all the waste products of cells. (iii) In Amoeba, food vacuoles store food. CELL INCLUSIONS Cell inclusions are the result of various chemical reactions that take place inside the cell, either in the cytoplasm or in the vacuole. Cell inclusions may be the food products like starch or oil globules or the waste materials like gums, resins, tannins, and latex. CELL WALL The cell wall is an extra covering that surrounds the cell membrane of a plant cell. It is made of a stiff, non-living material called cellulose. Cell wall is lacking in animal cells.

7th class biology

6 Functions: (i)

It provides rigidity to the cell.

(ii)

It provides protection to the cell.

Do you Know? Why does a plant cell has a cell wall and chloroplasts? Imagine standing erect without bones or muscles. Also, can your body make its own food? But a green plant stands erect without having any bones and prepares its own food. A plant cell has special parts that make these things possible. It has a cell wall and chloroplasts. The cell wall stiffens the plant. The chloroplasts help it to make food. Table 1.1: Functions of Organelles 1. 2. 3. 4.

5. 6. 7.

Organelles Function(s) Mitochondria(singular mitochondrion) Perform the function of respiration-provide the 'Power house of the cell' cell with energy. Endoplasmic reticulum Being a network of membranes, it provides a large surface area for life functions to take place. Chloroplasts (present only in plant cells) Contain a green pigment called chlorophy help in 'kitchen of the cell' food manufacture (photosynthesis). Golgi complex Collects and distributes the substances made in the cell (for example, proteins); synthesis and secretion of many materials. Lysosomes (suicide bags) Contain enzymes which help in breaking down or destroying the various materials. Centrioles and centrosome (present Concerned with cell division. in animal cells) Ribosomes Site of protein synthesis.

Features shared between Plant and Animal Cells 1.

Plasma membrane present in both.

2.

Nucleus present in both.

3.

Mitochondria present in both.

4.

Endoplasmic reticulum, golgi complex, lysosomes and ribosomes present in both. Table 1.2: Differences between animal and plant cells Animal Cell Plant Cell 1. Cell wall is lacking. 1. A rigid cell wall is present. 2. Chloroplasts are absent. 2. Chloroplasts are present. 3. Centrosome (a cell organelle that 3. Centrosome is absent. 4. Vacuoles are absent; if present, they 4. Vacuoles are larger in size and more

Formative Worksheet 1.

Which type of cells did Robert Hooke observe under the microscope? (A) Cork cells

2.

(B) Leaf cells

(C) Muscle cells

(D) Liver cells

Robert Hooke studied the cork cells during his famous discovery of plant cells. The term ‘cell’ was coined by him. Which cell structure was observed by Robert Hooke when he studied cork cells? (A) Nucleus

(B) Cell wall

(C) Cytoplasm

(D) Cell membrane

Basic Biology 3.

4.

5.

6.

7. 8. 9.

10.

11.

12.

13.

7

Which of the following alternatives describes the appearance of cells viewed by Robert Hooke for the first time? (A) Honey comb-like structures (B) Irregular mobile structures (C) Elongated structures (D) Spherical structures Cells form the basic units of life and are similar in structure in different living organisms. For example, cells present in the human brain, plant leaves, and the intestine of a cow are similar. The given cells are similar in structure due to the presence of (A) Nucleus, cytoplasm, and cell wall (B) Nucleus, cell wall, and cell membrane (C) Nucleus, cell membrane, and cytoplasm (D) Cytoplasm, cell wall, and cell membrane Which of the following corresponds to the properties of a cell? (A) The cell is the smallest living unit of life. (B) It is so small that it is not visible to the naked eye. (C) The shape of the cell varies in different organisms and within an organism. (D) All Which of the following corresponds to the principles of a cell theory? (A) All living organisms are composed of one or more cells. (B) Cells are the basic unit of structure and function in an organism. (C) All cells come only from the reproduction of pre-existing cells. (D) All Which cell organelle controls the movement of particles in and out of the cell? (A) Cell membrane (B) Mitochondria (C) Lysosomes (D) Cytoplasm The flow of molecules in and out of a cell is regulated by (A) Cell membrane (B) Mitochondria (C) Golgi body (D) Nucleus Which of the following statements about cell membrane is correct? (A) It controls all the activities of the cell. (B) It carries out the process of photosynthesis. (C) It stores the waste material produced by the cell. (D) It regulates the movement of substances in and out of the cell. Which of the following functions holds true for plasma membrane? (A) It protects and gives structural support to cells (B) It contains the genetic material (C) It regulates substances moving in and out of cells (D) It maintains the shape of cells Cytoplasm occupies less space in plant cells because of the (A) Presence of cell wall (B) Presence of vacuoles (C) Absence of cell wall (D) Absence of vacuoles Which of the following statements about plasma membrane is incorrect? (A) It is porous in nature. (B) It is present in all cells. (C) It allows the movement of substances in and out of cells. (D) It takes part in the transfer of characters from parents to offspring. Which arrow diagram correctly illustrates the arrangement of cell organelles starting from the outermost layer of plant cells? (A) Plasma membrane → cell wall → cytoplasm → nucleus (B) Cell wall → plasma membrane → cytoplasm → nucleus (C) Cell wall → cytoplasm → plasma membrane → nucleus (D) Plasma membrane → cytoplasm → cell wall → nucleus

7th class biology

8 14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

The nucleus of a cell is a membrane-bound organelle that contains the genetic material i.e., DNA. The cellular material present outside the nucleus is called cytoplasm. Which membrane separates the components of nucleus and cytoplasm? (A) Protoplasm (B) Nucleolus (C) Plasma membrane (D Nuclear envelope Which of the following statements about nucleus is true? (A) It allows the movement of substances both into and out of the cell. (B) It holds information that is transferred from parents to offspring. (C) It carries out the process of photosynthesis. (D) It protects the cell from external injury. Prokaryotes are distinguished from eukaryotes by the (A) Presence of cell wall (B) Absence of nucleus (C) Presence of ribosomes (D) Absence of chloroplasts The thread-like structures present inside the nucleus that are visible only during cell division are known as (A) Genes (B) Plastids (C) Vacuoles (D) Chromosomes A certain cell organelle controls various activities of the cell such as protein synthesis. It also contains the hereditary information of an organism. The described cell organelle is the (A) Nucleus (B) Ribosome (C) Chloroplast (D) Mitochondrion The power house of a cell is (A) Nucleus (B) Cell wall (C) Lysosome (D) Mitochondria The site of production of ATP in mitochondria are (A) Matrix (B) Lipid membranes (C) Cristae (D) Both (A) & (B) Which of the following is the function of mitochondria? (A) They produce energy required for cells in the form of ATP. (B) They also regulate the free calcium ion concentration in the cytosol. (C) They participate in apoptosis or programmed cell death. (D) All the above Which cell organelle performs the following functions? (i) To provide internal support to the cells (ii) To provide transportation pathway within the cells (A) Chloropolast (B) Endoplasmic reticulum (C) Nucleus (D) Ribosomes RER has _____ on its surface. (A) Proteins (B) Lysosomes (C) Ribosomes (D) Chlorophyll

Basic Biology 24.

25.

26.

27. 28.

29. 30.

31. 32.

33.

34.

9

The given diagram illustrates a plant cell.

Which labelled structure helps in the process of photosynthesis? (A) I (B) II (C) III (D) IV Chloroplasts are green-coloured plastids found in the leaves of plants. They perform the function of (A) Controlling the activities of the cell (B) Carrying out photosynthesis (C) Storing cellular waste (D) Protecting the cell Chlorophyll performs the function of (A) Absorbing water in leaves (B) Trapping light energy in leaves (C) Releasing carbon dioxide into atmosphere (D) Releasing manufactured food into atmosphere Which of the following structures is present as “many in number” in a plant cell? (A) Nucleus (B) Vacuole (C) Cytoplasm (D) Chloroplast Which cell organelle produces glucose? (A) Vacuole (B) Lysosome (C) Chloroplast (D) Mitochondrion Who discovered the cell organelle that involves in the transport of lipids within the cell? (A) Robert Brown (B) Rudolf Virchow (C) Camillo Golgi (D) Schwann Identify the cell organelle with the following functions. (i) It involves the transport of lipids in cells. (ii) It involves the formation of lysosomes. (iii) It is involved in the synthesis of cell wall in the plant cell. (A)Mitochondria (B) ER (C) Golgi apparatus (D) Plastids Suicidal bags of a cell are (A) Ribosomes (B) Lysosomes (C) Chloroplasts (D) Vacuoles Vacuole is cell structure present in both plant and animal cells. Which of the following statements about plant and the animal cell vacuoles is true? (A) The plant cell has many small vacuoles, but the animal cell has one large vacuole. (B) The plant cell has one large vacuole, but the animal cell has many small vacuoles. (C) The plant as well as the animal cell has many small vacuoles. (D) The plant as well as the animal cell has one large vacuole.] Which of the following in found only in animals cells? (A) Nucleus (B) Cytoplasm (C) Centrosome (D) Mitochondria Cell wall is present in only in the plant cell. The main function of the cell wall is to (A) Protect the cell (B) Control cellular activities (C) Carry out photosynthesis (D) Perform cellular respiration

7th class biology

10 35.

36.

Which of the following statements about cell wall is correct? (A) It controls all the activities of the cell. (B) It carries out the process of photosynthesis. (C) It protects the plant cell from variations in the temperature of the external environment. (D) It contains thread-like structures called chromosomes, which take part in inheritance. Green plants produce oxygen which is utilized by all animals. The cell organelle that produces oxygen in a plant cell is the (A) Mitochondrion (B) Chloroplast (C) Vacuole (D) Nucleus

Conceptive Worksheet 1.

2. 3.

4. 5. 6.

7.

8.

Who observed cork cells under the microscope for the first time? (A) Robert Hooke (B) Robert Brown (C) J.E. Purkinje (D) J.M. Schleiden Which part of a plant did Robert Hooke use to observe a cell using a microscope? (A) Cork (B) Leaf (C) Root (D) Flower Which of the following facts about Robert Hooke’s experiment leading to discovery of cell is not correct? (A) He observed cells as honey comb-like structures. (B) He took the sample from the stem of a tree. (C) He conducted his experiment in 1665. (D) He observed living cells. Cell theory was proposed by (A) Schleiden (B) Schwann (C) Both (D) None Cell theory was expanded by (A) Schleiden (B) Schwann (C) Rudolf Virchow (D) All The given illustration represents a cell. In the given illustration, the structure labelled X is (A) Cell membrane (B) Cell wall (C) Vacuole (D) Plastid Which of the following statements about cell membrane is incorrect? (A) It regulates the entry and exit of substances in the cell (B) It separates the cell from its surrounding medium (C) It holds together the contents of the cell (D) It controls all the functions of the cell The given figure shows a labeled plant cell. In the given figure, the cytoplasm is labeled as (A) I (B)II (C) III (D) IV

Basic Biology

9.

The given diagram illustrates an animal cell. Which labelled structure in animal cell controls all the cellular activities? (A) I (B)II (C) III (D) IV

10.

The given figure illustrates structure X present in a cell. Which of the following alternatives represents the correct function of structure X? (A) To provide rigidity to cell (B) To provide turgidity to cell (C) To help in energy synthesis (D) To transfer the hereditary information

11.

The given diagram illustrates a cell. If the image illustrated represents a constituent cell of a multi-cellular animal, then the nucleus is labeled as (A) I (B) II (C) III (D) IV

12.

13.

14.

15.

16. 17.

Which of the following statements about prokaryotes is true? (A) All prokaryotes have a cell wall (B) Nucleus is absent in all prokaryotes (C) Prokaryotes are larger than eukaryotes (D) Ribosomes are larger in prokaryotes as compared to eukaryotes Which of the following statements about nucleus is incorrect? (A) It is surrounded by a membrane called nuclear membrane. (B) It contains thread-like structures called chromosomes. (C) It is that part of the cell where food is stored. (D) It takes part in the transfer of characteristics. Nucleus controls all life processes because of the presence of (A) Nuclear membrane (B) Nuclear pores (C) Chromosomes (D) Lysosomes Which of the following is responsible for the production of energy in eukaryotic cells? (A) Nucleus (B) Cell wall (C) Lysosomes (D) Mitochondria Mitochondrial matrix contain (A) DNA (B) Ribosomes (C) Both (D) None Cisternae are the flattened disk-like membranous structures are a part of (A) Chloropolast (B) Endoplasmic reticulum (C) Nucleus (D) Ribosomes

11

7th class biology

12

18.

19. 20.

21.

22. 23.

24.

25. 26.

27.

The given figure represents a plant cell. The labelled structure is present only in plant cells. In the given figure, label X represents (A) Vacuole (B) Nucleus (C) Nucleolus (D) Chloroplast What is the primary function of chloroplast? (A) Photosynthesis (B) Food storage Carbon dioxide + Water → Glucose + Oxygen. The illustrated process occurs in the (A) Mitochondria (B) Chloroplasts

(C) Cell division

(D) Protection

(C) Ribosomes

(D) Lysosomes

Chloroplasts are cell organelles in plants which help to produce food for the plant. Which of the following is a source of energy used by chloroplasts to produce food? (A) Air (B) Sun (C) Soil (D) Water

The Golgi apparatus present in plant cell are called (A) Dictyosomes (B) Chromosomes (C) Plastids (D) Centromeres Which of the following cell organelle digest a variety of substances including worn out organelles, food particles, viruses, and bacteria? (A) Mitochondria (B) Golgi apparatus (C) Lysosomes (D) Chloroplasts In the given figure, the structure labeled X is called (A) Vacuole (B) Nucleus (C) Ribosome (D) Chloroplast In plant cells, nucleus is found at the periphery of cells because of the presence of a central (A) Plastid (B) Lysosome (C) Ribosome (D) Vacuole Jyoti drew a diagram of a plant cell and labelled one of its parts as X.

Which cell component is labelled as X by Jyoti? (A) Cell membrane (B) Cell wall (C) Nucleus Which of the following structures is prominent in plant cells? (A) Vacuole (B) Centriole (C) Ribosome

(D) Plastid (D) Chloroplast

Basic Biology 3.

13

DIVERSITY IN CELLS

So far we have considered the basic features of cells in general. But this does not mean that all cells are identical. Structures like nucleus, mitochondria, cytoplasm are common to virtually all cells, but the shape, size and contents of individual cells show a lot of variation. These features are closely linked to the functions which the cells perform. In a unicellular organism, all the functions of the body, like nutrition, respiration, excretion, growth and reproduction are carried by the single cell. In a multicellular organism, however, these tasks or functions are divided among groups of cells. All the cells do not do all the jobs. This feature of multicellular organisms is known as division of labour. The group of cells show variability in their shape, size and other features depending upon the function being performed by them. CELL NUMBER Unicellular organisms are formed of single cells. Multicellular organisms are formed of many cells, which in turn may be of many types. Even in multicellular organisms, the number of cells may vary a lot. It may be just a few (as in some algae), to a few hundred (as in some algae) to several million (as in most plants and animals). CELL SIZE Some plant and animal cells are visible to the naked eye. Most cells, however, are visible only with a microscope. For example, an ostrich egg is the largest animal cell. It is as big as 170 × 135 mm. Smallest known cell is that of a bacterium, PPLO. This bacterium measures about 0.1 to 0.5 microns (micrometres) in size. In plants, some algae have very big cells. For example, an alga, Acetabularia (a unicellular organism), consists of a single cell which is about ten centimetres in length. In our body, nerve cells are the largest, measuring about 90 micrometres in length. Some nerve cells are longer than a metre. Some blood cells are the smallest. Most other cells (as that of kidney, liver, intestine, etc.) are between 20 to 30 microns (micrometres) in length. CELL SHAPE Cells are of diverse shapes (Figure. 1.8). Some cells like those of Amoeba and white blood cells of our blood continuously change their shapes. Most cells, however, maintain a constant shape all through their existence. The shape of a cell is related to its function. A nerve cell clearly exhibits this relationship. It is long and has thread-like projections, as it has to convey messages to different parts of the body.

Figure. 1.8: Different cell shapes

7th class biology

14 4.

CELL DIVISION

An important characteristic of living beings is the capacity to reproduce. Cells do so. Cells arise only from other cells by a process called cell division. Most cells are capable of growing and splitting into two similar cells. The cells so produced are called the daughter cells. These are identical to the mother cell. During the formation of daughter cells, the nucleus of the mother cell divides into two, so that each daughter cell gets one nucleus each. This is followed by division of the cytoplasm. Finally, two daughter cells are formed. This mode of division is well exhibited by Amoeba, a unicellular organism (Figure. 1.9).

Figure 1.9: Amoeba stops moving and rounds off. 2. The nucleus begins to divide. 3. The nucleus has divided and the cytoplasm starts to constrict. 4 & 5 The constriction continues to divide the cytoplasm. 6. The daughter amoebae separate. In a multicellular organism, however, besides the cell dividing for reproduction, the body cells have to multiply for growth of the organism itself. How does a small seedling grow into a big tree or a young infant grows into an adult? This growth is brought about an increase in the number of cells by cell division. The cells so produced in due course of time undergo a change in size and shape. The whole organism, thus, shows overall growth. While plants grow throughout their life, animals grow upto a certain age and then stop growing. Cell division in most organisms is of two types: (a) Mitosis and (b) Meiosis Mitosis takes place in normal cells (vegetative or non-reproductive cells) of the body. It is responsible for growth of organisms. Meiosis is the type of cell division which occurs only in the reproductive parts of the body. It is a common observation that a child has some features of the mother, and other ones of the father. It is the meiotic division which is responsible for the passing on of characters from the two parents to the child. SNAP SHOT 1.

Living things are made up of one or more cells. In unicellular organisms, like the bacteria and amoeba, all life functions are performed by the single cell. In multicellular organisms, the cells are specialized to perform certain functions (division of labour).

2.

Cells have three parts. The outer covering (cell membrane) encloses a jelly-like cytoplasm. Within the cytoplasm is present the controlling centre of the cell, the nucleus.

Basic Biology

15

3.

In addition to nucleus, cell organelles such as the chloroplast, mitochondria, endoplasmic reticulum, golgi complex, centrosome and vacuoles are present in the cytoplasm.

4.

Plant cells differ from animal cells in some respects. Cell wall and chloroplasts are present in plant cells, and absent from animal cells. On the other hand, centrosome is present in animal cells, and absent from plant cells.

5.

Cells show great variation in their sizes and shapes.

6.

New cells for growth and reproduction are formed by cell division.

Fomative Worksheet 37.

38. 39. 40.

41.

42.

43.

44.

Which of the following statements is/are correct? (A) Unicellular organisms are formed of single cells (B) Multicellular organisms are formed of many cells (C) Millions of cells are present in plants (D) All the above The largest animal cell is (A) Peacock egg (B) Ostrich egg (C) Crocodile egg The smallest animal cell is of (A) PPLO (B) Ostrich egg (C) Virus Which of the following cells change their shape continuously? (A) Amoeba (B) Blood cells (C) Nerve cells (D) Both (A) & (B) Which of the following is true for nerve cells? (A) They change their shape continuously (B) They are long and conveys messages to different parts of the body (C) They help in respiration and photosynthesis (D) All

(D) Hen egg (D) None

Identify the true statements. (I) Mitosis takes place in vegetative ells (II) Meiosis takes place in non reproductive cells (III) Cell division in plants occur throughout their life (A) Only I (B) Both I and II (C) Both II and III (D) Both I & III The cell division responsible for the passing on of characters from the two parents to the child is (A) Mitosis (B) Meiosis (C) Both (D) None The cell division that is responsible for the growth of an animal body is (A) Mitosis (B) Meiosis (C) Both (D) None

Conceptive Worksheet 28. 29. 30.

31.

Division of labour is seen in (A) Amoeba (B) Bacteria The size of ostritch egg is: (A) 170 × 25 mm (B) 150 × 150 mm The size of PPLO is about (A) 0.1 to 0.5 micron (C) 10 to 20 microns Growth and inheritance is the result of (A) Mitosis (B) Meiosis

(C) Frog

(D) None

(C) 170 × 135 mm

(D) 150×15mm

(B) 1 to 5 microns (D) 100 to 200 microns (C) Both

(D) None

7th class biology

16 32.

In which of the following, the cell division takes place throughout life? (A) Frog (B) Man (C) Fish

Summative Worksheet

(D) Neem plant I.

Multiple Choice Questions — Tick mark (  ) the correct choice. 1. 2. 3.

4.

5.

6.

7.

8.

9.

Cell was discovered by (A) Robert Brown (B) C. Linnaeus (C) Robert Hooke (D) C. Darwin Each cell has a (A) Nucleus (B) Cell wall (C) Chloroplast (D) All the above The cell is surrounded by a membrane called (A) Cell wall (B) Cell membrane (C) Cytoplasm (D) Nuclear membrane Organelles are present in (A) Cytoplasm (B) Vacuoles (C) Nucleus (D) All the above A cell organelle commonly called 'suicide bag' (A) Nucleus (B) Lysosome (C) Chloroplast (D) Ribosome Robert Hooke was the first person to observe ____i_____ cells. He observed these cells using a ____ii______. The information in which alternative completes the given statements? (A) i- cork ii- microscope (B) i- cork ii- magnifying glass (C) i- onion peel ii- microscope (D) i- onion peel ii- magnifying glass The given figure depicts a diagram of a eukaryotic animal cell. It shows organelles labeled I and II.

The function of the part of the cell marked as I is to (A) Absorb energy from the sun and prepare food (B) Perform aerobic respiration and synthesize acids (C) Regulate the exit and entry of substances in the cell (D) Control cell metabolism, and form ribosomes, DNA and RNA Cytoplasm is composed of all cell organelles except nucleus. The contents of nucleus are separated from cytoplasm by the nuclear membrane. Nucleus and nuclear membrane together form nucleoplasm. Cytoplasm and nucleoplasm are together referred to as (A) Protoplast (B) Cytonucleus (C) Protoplasm (D) Nucleolus Nucleus is usually spherical in shape and is located at the centre of the cell. Which of the following statements about nucleus is incorrect? (A) It controls all the activities of the cell. (B) It is surrounded by a porous nuclear membrane. (C) It takes part in the transfer of characteristics from parents to offspring. (D) It protects the plant cell from variations in the temperature of the external environment.

Basic Biology 10.

11.

12.

13.

14.

17

Tarun draws the diagram of a cell and labels one of its components as X.

The cell component labelled by Tarun is (A) Nucleolus (B) Nucleus (C) Vacuole (D) Plastid Chloroplasts are cell organelles found mostly in all plant cells. Chloroplasts facilitate the process of (A) Respiration (B) Photosynthesis (C) Lipid production (D) Protein production ____i_____ is a type of plastid that is only present in plant cells. It carries out the process of ____ii_____. The information in which alternative completes the given statements? (A) i- Chloroplast ii- photosynthesis (B) i- Vacuole ii- photosynthesis (C) i- Chloroplast ii- excretion (D) i- Vacuole ii- excretion Which cell organelle produces oxygen? (A) Mitochondrion (B) Chloroplast (C) Lysosome (D) Ribosome The vacuole present in a plant cell differs from that of an animal cell because the former has (A) Many small vacuoles (B) Double membrane vacuole (C) A single membrane vacuole (D) A large centrally placed vacuole

15.

The given illustration represents a cell.

16.

The function of protecting the cell from external injury is performed bythe structure labelled (A) I (B) II (C) III (D) IV Which figure represents a plant cell?

(A) IV

(B) III

(C) II

(D) I

7th class biology

18 17.

18.

19.

20.

The given figure illustrates five organelles of a cell.

Which of the following groups represents the basic components of a cell? (A) I, II and III (B) I, II and IV (C) I, III and IV (D) III, IVand V Cell membrane performs the function of (A) Controlling the movement of materials in and out of the cell (B) Manufacturing energy to carry out various functions (C) Controlling the activities of the cell (D) Storing food, water, and waste Sunaina read in her science book that a jelly-like substance is present inside the cell, which is mostly made up of water. Which cell component did Sunaina read about? (A) Nucleus (B) Cell wall (C) Cytoplasm (D) Cell membrane Sonali took a toothpick and gently scraped the inner side of her cheek with it. She placed the contents of the toothpick on a clean glass slide containing a drop of water and then added a drop of methylene blue stain to it. She gently placed a cover slip over the slide and observed the glass slide under the microscope. The given illustration represents the observation made by Sonali.

The darkly-stained region of cheek cells represents the (A) Nucleus (B) Vacuole (C) Cytoplasm (D) Mitochondria II.

1. 2. 3. 4. 5. 6. 7. 8.

Fill in the blanks, using the words given below. One word can be used twice: Egg, Microscope, Nucleus, Chloroplast, Cytoplasm, Cell membrane, Mitochondria, Robert Hooke, Plant The _____________ is the control centre of the cell. The instrument used to see tiny objects is called a__________. __________ is called the kitchen of a cell. An ________ is a cell that can be seen without a microscope. The _____________, ______________ and _________________ are parts of a cell. Energy is produced in _________________ cells. The term cell was given by _________________. Cell wall is present in _________________.

III. 1. 2. 3. 4. 5. 6.

Define the following: Cell Nucleus Cytoplasm Protoplasm Cell membrane Microscopic organisms

Basic Biology

19

IV. 1. 2. 3. 4. 5. 6. 7. 8.

Which of the following statements are true (T) and which ones are false (F)? Mark T or F. Most cells have only one nucleus. [ ] Only the nucleus of a cell represents the protoplasm. [ ] Most cells are microscopic. [ ] All living organisms are made of cells. [ ] Cells must have a nucleus to live. [ ] Every cell has a cytoplasm. [ ] All cells in a multicellular organism can live independently. [ ] The outermost covering in an animal cell is called cell wall. [ ]

V.

Match the statements in Column A with those in Column B. Column-A Column-B 1. Cell (a) Plants 2. Nucleus (b) Tiny structures inside cells 3. Cell wall (c) Unit of living body 4. Chloroplast (d) Boss of the cell 5. Cytoplasm (e) Contains green pigment 6. Organelles (f) Jelly-like substance between cell membrane and nucleus

VI. 1. 2. 3. 4.

Answer the following questions: Define a cell. Give three examples of unicellular organisms. Mention the functions of the following: (i) Cell membrane (ii) Chromosomes. Why are the following important to a plant cell? (i) Cell wall (ii) Chloroplast (iii) Mitochondria (iv) Nucleus. Which cell organelle is found only in animal cells? Draw an outline diagram of an animal cell. Label its different parts. Mention at least four differences between plant cells and animal cells. What features are possessed by both plant cells and animal cells? Name the cell organelles which are found only in the plant cell. Name the different cell organelles and the functions these organelles perform in the cell. Mention the two types of cell division. How do cells increase in number?

5. 6. 7. 8. 9. 10. 11. 12.

______________

 ______________

20

7th class biology

Learning Outcomes

Organisation in the Living Things

By the end of this chapter, you will understand About the various levels of organisation in the living world



The terms used to describe the different levels of organisation



How bodies of plants and animals are organised



About the general characteristics shared by the different levels



About the organisation of the human body in terms of the organ systems present

Chapter-2



1. INTRODUCTION There are millions of different things in this world around us. Some of them are living and some are not. People, cats, mice, insects and trees, are living things, while rocks, water, chair and table are not living and are called nonliving. Living things exist along with non-living objects on this earth. However, living things show certain characteristics that distinguish them from non-living things. These characteristics include cellular organisation, nutrition, respiration, growth, excretion, reproduction, movement and response to stimuli. In addition to the cellular organisation, the living things exhibit a unique organisation which allows them to coordinate the different functions of life. Biosphere

The term organisation denotes the manner in which smaller units or components of any structure are aggregated into higher or bigger units.

Ecosystem

Popula on

Organ System

Organs

Lower Levels

2. LEVELS OF ORGANISATION IN THE LIVING WORLD

(Individual) Number Increases

Organism

The main functions of organisation are to help the living thing to perform different functions, and thus sustain life.

There are two broad levels of organisation - one below the level of the organism (the individual plant or animal) and the other above the level of the organism. These two levels constitute the lower levels and higher levels of organisation respectively (Figure 2.1).

Community

Complexity Increases

Each unit of aggregation represents the level. There can be different levels of organisation. At each level, there are interactions between the units.

Higher Levels

ORGANISATION

Tissues

Living Cells

Organelles

Molecules and Compounds

Atoms

Figure: 2.1: Levels of Organisation in the Living World

Organisation in living things

22

3. LOWER LEVELS OF ORGANISATION Lower levels of organisation are of two types: (A) Molecular level, and (B) Cellular level. MOLECULAR LEVEL (i) All organisms are made up of cells. (ii) The cells are made up of smaller parts called organelles. (iii) The organelles in turn are made up of various molecules. The molecules are made up of atoms of various elements. (iv) Six of these elements (carbon, hydrogen, nitrogen, oxygen, sulphur and phosphorus) make up 95% of living matter. (v) Atoms of these elements are organised to form important molecules like those of water, carbon dioxide, methane, and so on. (vi) These molecules have further given rise to large molecules and compounds like carbohydrates, proteins, fats and nucleic acids (DNA - deoxyribonucleic acid, RNA -ribonucleic acid). (vii) The living substance called protoplasm, which makes up cells, is made up of all these compounds. (viii) DNA is an important compound, responsible for the transfer of characters from parents to children. It is known as the molecule of life. Thus, at the molecular level, following organisation occurs: Atoms  Molecules  Compounds  Organelles  Cells. CELLULAR LEVEL (i) Cells o A cell is the lowest level of cellular organisation. o It is the smallest living unit, and is capable of performing all the functions of life. In unicellular organisms like Amoeba, Paramecium and bacteria, all the functions are carried out by the single cell. o But it is not so in a multicellular organism. In a multicellular organism, although each cell can carry out the important functions of life, it is not capable of existence on its own. o A muscle cell cannot obtain its own food or oxygen. Other specialized cells in the body collect food or carry oxygen. o All the cells do not perform all the jobs. Different tasks or functions like ingestion of food, digestion, respiration, excretion and reproduction are divided among groups of cells. For example, nerve cells are very long and this helps them to conduct messages from one part of the body to another. o Similarly, in plants, xylem elements are long and tubular, and are specialised for movement of water from the roots to the stem and leaves. o It would be clear from the above account that the body of a multicellular organism is highly organised. It shows various levels of organisation, starting from the cells. o Cells that are alike in size and shape team up. They work together to do special jobs. These cell "teams" are called tissues. Thus, cells combine to form tissues. (ii) Tissues o A group of similar cells that work together to do the same job is called a tissue. In other words, a tissue is a group of cells similar in structure and function. o Tissues in plants - Epidermal tissue, vascular tissue and ground tissue. o Each of these tissues is meant for a different function. For example, epidermis (epidermal tissue) which is the outermost layer of tissue provides protection to the plant body. The ground tissue represented by cortex lies inner to epidermis. It performs the function of storage. The vascular bundles (vascular tissue) help in conduction of water Figure 2.2: Cross section of Stem and food materials.

23

7th Biology

All these tissues can be observed by taking a section of the root or stem (Fig. 2.2). Tissues in animals — Epithelial tissue, connective tissue, nervous tissue, and muscular tissue. As in plants, different tissues in animals also perform different functions. For example, nervous tissue helps in the conduction of messages from one part of the body to another. o Epithelial tissue is a protective tissue. Skin is an epithelial tissue. o Connective tissue consisting of cartilages and bones provides support to the body. (iii) Organs An organ is a structure made up of different tissues working together to perform a specific function. o Tissues combine to form organs. o An organ is made of different kinds of tissues. o Our stomach is an organ. It is made up of different tissues like nerve tissue, blood tissue, fat tissue and muscle tissue. o Similarly, mouth, food pipe, and small intestine are all organs. These are organs of digestion (Fig. 2.3). o An organ performs a specific function. Stomach as an organ Stomach is an organ of digestion. It is made up of different tissues like epithelial tissue, nervous tissue, blood tissue and muscular tissue. Different parts of the stomach help in the job of digestion of food. One part causes contractions and expansions, so that the food is thoroughly mixed. Digestive juices are secreted by another part of the stomach. Different tissues take part in each of Figure 2.3: Organisation of cells into organs these activities. o o o

Similarly, your heart is an organ. The heart pumps blood. It is made mostly of muscle tissue, with some blood tissue and fat tissue. These tissues work together to allow the heart to pump blood. "Your lungs and windpipe are organs used for breathing. o Our kidneys are the organs of excretion. o We also possess organs for sensing what is happening around you. The ear is a sense organ. Eyes, tongue, skin and nose are sense organs too. o Largest organ in the body is your skin. It covers and protects your body. It helps you to get rid of three waste materials — salts, water and heat. o Organs may be external or internal. The organs described above like the stomach, heart, kidneys, intestine are internal organs. External organs, for example, include ear, eye, arms, legs, hands and feet. o In plants, roots, stems, leaves and flowers are organs. These organs perform different jobs, and are composed of different tissues like the epidermal tissue, vascular tissue (xylem and phloem), and the ground tissue. (iv) Organ system A group of organs working together is called an organ system. o Our digestive system is an organ system. The organs of this system include: the mouth, the food pipe, the stomach and the intestines. Each organ has a special job to do. Together, they digest your food. Likewise, there are many systems in our human body. o There are some organs that are parts of more than one system. For example: The liver is a part of the digestive system. The liver is also a part of the excretory system, which gets rid of wastes. o The large intestine is a part of the digestive system. But it is also a part of the excretory system.

Organisation in living things o

24

In plants, there are two organ systems –– the root system and the shoot system. Each of these systems has several organs. For example, the shoot system has stem, branches, leaves, flowers and fruits. The root system has roots and root branches.

(v) Organism The organ systems collectively form an organism (Fig. 2.4). The whole organism is a product of all the systems working together in unison with each other. Each organism, thus, possesses a well organised structure consisting of smaller parts. The cell is the smallest unit or level of cellular organisation. Molecular and cellular levels of organisation are, thus, represented as follows: Fig. 2.4: Organisation of the living body ORGANISM  Organ systems  Organ  Organs  Tissues  Cells  Organelles  Molecules and compounds  Atoms

Formative Worksheet 1. 2. 3.

The cells are made of (A) Organelles (B) Molecules (C) Atoms (D) All The molecule of life is (A) Water (B) Oxygen (C) RNA (D) DNA Which of the following is true for molecular level of organisation? (A) Atoms  Molecules  Cells  Compounds  Organelles (B) Cells  Organelles  Compounds  Molecules  Atoms (C) Atoms  Molecules  Compounds  Organelles  Cells (D) Molecules  Atoms  Compounds  Organelles  Cells

25

7th Biology

4.

The the smallest living unit, and is capable of performing all the functions of life is (A) Cell (B) Tissue (C) Organ (D) Organ system Statement - I: In unicellular organisms like Amoeba, Paramecium and bacteria, all the functions are carried out by the single cell. Statement – II: In multicellular organisms, each cell has the ability to perform all the activities. (A) Statement - I is true, Statement - II is false. (B) Statement - I is false, Statement - II is true. (C) Both statements are true. (D) Both statements are false. In a tissue , cells (A) Have same shape (B) Perform similar function (C) Both (D) None Which of the plant tissues is involved in protection? (A) Epidermal tissue (B) Vascular tissue (C) Ground tissue (D) All The function of vascular bundles is (A) Protection (B) Storage (C) Supply of water (D) Supply of food The protective animal tissue is (A) Epithelial tissue (B) Connective tissue (C) Nervous tissue (D) All Largest organ of our body is (A) Stomach (B) Lungs (C) Heart (D) Skin The internal organs of our body are (I) Heart (II) Ear (III) Lungs (IV) Nose (V) Liver (VI) Legs (A) I, II, III (B) II, III, IV (C) I, III, V (D) II, IV, VI Which of the following is an organ system in plants? (A) Root system (B) Shoot system (C) Digestive system (D) Nervous system

5.

6.

7.

8. 9.

11. 12.

13.

Conceptive Worksheet 1. 2.

3. 4. 5.

6. 7. 8. 9.

All organisms are made of (A) Cells (B) Tissues (C) Organs (D) Organ systems The important compound, responsible for the transfer of characters from parents to children (A) Carbohydrates (B) Proteins (C) Fats (D) DNA The lowest level of a cellular organisation is (A) Cell (B) Tissue (C) Organ (D) Organ system The cell teams are called (A) Atoms (B) Molecules (C) Tissues (D) Organs Tissues in plants include (A) Epidermal tissue (B) Vascular tissue (C) Ground tissue (D) Both A and B The function of cortex is (A) Protection (B) Storage (C) Supply of water (D) Supply of food Tissues combine to form (A) Organs (B) Cells (C) Organ system (D) None Which of the following represents the organs of human body? (A) Stomach (B) Lungs (C) Heart (D) All The external organs of our body are (I) Heart (II) Ear (III) Lungs (IV) Nose (V) Liver (VI) Legs (A) I, II, III (B) II, III, IV (C) I, III, V (D) II, IV, VI

Organisation in living things 10.

Digestive system represents (A) A cell (B) A tissue

26

(C) An organ

(D) An organ system

2.4 HIGHER LEVELS OF ORGANISATION Higher levels of organisation beginning from the organism, in the order of increasing complexity, are the following: (i) Population, (ii) Biotic community, (iii) Ecosystem, and (iv) Biosphere. (i) POPULATION An organism or an individual does not exist in isolation. Rather, it lives in association with other individuals of its own kind, i.e., species. All the individuals of a single species existing in a given locality or area constitute a population. A population is, thus, the next higher level of organisation above the individual level. For example, we belong to a human species called Homo sapiens. The different individuals occurring in a particular area represent a population of Homo sapiens. Likewise, there exist populations of different species of plants and animals. Individuals of populations of one species can breed among themselves only. They do not breed with individuals of other species. Thus, a frog breeds with frog only and a cat with another cat. This is true in case of plants also. The members of a population compete with each other for same resources food, space, light and water. (ii) BIOTIC COMMUNITY The populations of different species occurring in a locality constitute the next higher level of organisation called the community or biotic community. For example, in a wheat field, you find, along with wheat plants, other plants called weeds which grow in the wheat field. In addition, different kinds of insects, worms, birds and mammals (like rat) are found in the field. Figure 2.5: Biotic community The populations of all these different species found in the wheat field or any crop field constitute a biotic community. Members of different populations do not have similar requirements of food and shelter, though they live in the same area. Community, thus, is a higher level of organisation above the population (iii) ECOSYSTEM The biotic community in an area interacts with the non-living physical environment, and the two (i.e., the biotic community and the abiotic environment) together constitute the next higher level of organisation, termed the ecosystem. Forests, crop fields, deserts, ponds and rivers are -all examples of ecosystems. There are two main components of an ecosystem — non-living (abiotic) and living (biotic) components. Abiotic components, or non-living components, include (i) physical environment (like soil, water, air and minerals), and (ii) climatic factors (light, temperature, wind and rain).

Figure 2.6: An ecosystem

7th Biology

27

Biotic components, or living components, consist of (i) Autotrophs or producers (green plants) (ii) Heterotrophs or consumers. Different types of heterotrophs are herbivores and carnivores. Decomposers (saprophytes) like bacteria and fungi play an important role in the recycling of minerals. The different living organisms in an ecosystem are interconnected through the food chains starting from the producers to the consumers. (iv) BIOSPHERE The various ecosystems found in all the geographical regions of the world form the next level of organisation is called the biosphere. Biosphere is the highest level of organisation in the living world. Biosphere is that part of universe that supports life in air, soil and water. Thus, all living organisms inhabiting soil, air and water constitute biosphere. Biosphere consists of four components, of which three are non-living (Figure 2.7). These are: 1. Hydrosphere (water bodies) Figure 2.7: Components of Biosphere 2. Lithosphere (land or soil) 3. Atmosphere (air) 4. Living organisms (plants and animals). 5. GENERAL CHARACTERISTICS SHARED BY LEVELS OF ORGANISATION (i) All the levels in the living world, beginning from cell, consume energy to maintain themselves. (ii) Each level of organisation is more complex and has lesser units than the previous level. For example, there are lesser number of tissues than cells. Thus, the number goes on decreasing with increasing complexity, as one moves from a lower level to the next higher level. In other words, the number increases as we move down from the biosphere. Biosphere is only one, but there are many ecosystems functioning in the biosphere. Further, in each ecosystem, there are a number of communities, each of which consists of a large number of populations of different species. Each population, in turn, has a large number of individuals. This process of increase in number goes on, as we keep moving down from one level to another level of organisation. (iii) All constituent units of a particular level interact, cooperate and compete with each other, and ensure the success of that level.

Formative Worksheet 14. 15. 16.

17. 18.

Which of the following is more complex? (A) Population (B) Biotic community (C) Ecosystem (D) Biosphere The next higher level of organisation above the individual level is (A) Population (B) Biotic community (C) Ecosystem (D) Biosphere Statement - I: Individuals of populations of one species can breed among themselves only Statement – II: They do not breed with individuals of other species (A) Statement - I is true, Statement - II is false. (B) Statement - I is false, Statement - II is true. (C) Both statements are true. (D) Both statements are false. The next higher level of organisation above the population level is (A) Population (B) Biotic community (C) Ecosystem (D) Biosphere The biotic community in an area interacts with the non-living physical environment, and the two (i.e., the biotic community and the abiotic environment) together constitute the next higher level of organisation. This is termed as (A) Population (B) Biotic community (C) Ecosystem (D) Biosphere

Organisation in living things 19.

20. 21. 22. 23.

28

Match the following Column-1 (1) Biotic (2) Abiotic

Column-2 (p) soil (q) plants (r) water (s) animals (A) 1-p,r; 2-q,s (B) 1-p, q; 2-r,s (C) 1- q,s; 2-p,r (D) 1- p,s; 2-q,r Which of the following is the component of biosphere? (A) Hydrosphere (B) Lithosphere (C) Atmosphere (D) All Which of the following components of a pond ecosystem is biotic in nature? (A) Detritus (B) Oxygen (C) Algae (D) Water Which of the following factors are biotic components of the ecosystem? (A) Soils (B) Fungi (C) Rocks (D) Minerals i and ii are the abiotic factors of the ecosystem. The information in which row completes the given statement? (A) i- Sunlight ii- Consumers (B) i- Wind ii- Decomposers (C) i- Water ii-Soil (D) i-Producers ii-Scavengers

Conceptive Worksheet 11. 12.

13. 14. 15. 16.

17.

All the individuals of a single species existing in a given locality or area constitute a (A) Population (B) Biotic community (C) Ecosystem (D) Biosphere The populations of different species occurring in a locality constitute the next higher level of organisation called the (A) Population (B) Biotic community (C) Ecosystem (D) Biosphere Community has populations of ____ species. (A) same (B) different (C) both (D) none Which of the following is an example for an ecosystem? (A) Forest (B) Desert (C) Ponds (D) All The highest level of organisation in the living world is (A) Population (B) Biotic community (C) Ecosystem (D) Biosphere Consumers are organisms that are dependent on other organisms for food. Which of the following organisms is not a consumer? (A) Cow (B) Lion (C) Plant (D) Rabbit The following food chain exists in an enclosed forest region. Plants → Rabbit → Fox Which of these is a consequence of the excessive hunting of rabbit population by humans? (A) The plant population remains unaffected (B) The food chain remains unaffected (C) The fox population decreases (D) The fox population increases

2.6 ORGAN SYSTEMS IN HUMAN BODY There are ten different organ systems present in our body. The different organ systems are as follows: 1. Digestive system 2. Respiratory system 3. Circulatory system 4. Nervous system 5. Excretory system 6. Reproductive system 7. Skeletal system 8. Muscular system 9. Integumentary system 10. Endocrine system 1. DIGESTIVE SYSTEM Parts of the Digestive System (Figure 2.8) 1. Mouth: Tongue, teeth, salivary glands 2. Oesophagus (food pipe) 3. Stomach 4. Liver and gall bladder 5. Small intestine 6. Pancreas 7. Large intestine 8. Anus

2. RESPIRATORY SYSTEM Parts of the Respiratory System (Figure 2.9) 1. Nose 2. Trachea (wind pipe) 3. Bronchi (singular bronchus) 4. Lungs Function: To exchange oxygen and carbon dioxide and produce energy.

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29 Function: To convert complex food into simple, soluble form so that it can be easily absorbed by the blood.

Figure 2.8: Digestive System in humans 3. CIRCULATORY SYSTEM Parts of the Circulatory System (Figure 2.10) 1. Heart 2. Blood vessels (arteries, capillaries, veins) 3. Blood (plasma, red and white blood cells, platelets) Function: To transport gases and materials throughout the body.

Fig. 2.10: Circulatory System in humans

Figure 2.9: Respiratory System in humans 4. NERVOUS SYSTEM Parts of the Nervous System (Figure 2.11) 1. Brain 2. Spinal cord 3. Nerves (cranial nerves, spinal nerves) 4. Sense organs (eye, ear, nose, tongue, skin) Function: Controls the working of body and coordinates body parts.

Figure: 2.11: Nervous System in humans

Organisation in living things

30

5. EXCRETORY SYSTEM Organs of Excretion: Lungs, kidneys and skin Organs of Urinary system (Figure 2.12) 1. Kidneys 2. Ureters 3. Urinary bladder 4. Urethra Function: To remove waste products from the body. Figure 2.12: Excretory System in humans 6. REPRODUCTIVE SYSTEM All living beings produce young ones of their own kind. This process of producing young ones of its own kind is called reproduction. It is an important characteristic of all living organisms and it is essential to ensure the continuity of life."You may have seen birds laying eggs. How many animals can you think of that lay eggs? Birds, frogs, fish, turtles and insects-all lay eggs. It takes two birds, a male and a female, to make the eggs. The female makes tiny eggs. The male makes special reproductive cells called sperms. The sperm fuses with the egg. The fused egg then gets bigger. Then, the female lays them, and sits on them to keep the eggs warm. In two or three weeks, the young birds hatch. Mammals like cats, dogs, horses and humans also make eggs and sperms which fuse. In human beings, the male reproductive organs are called testes (singular testis) and female reproductive organs are called ovaries (singular ovary). The males produce special tiny sex cells or reproductive cells called sperms. The females produce sex cells called eggs or ova (singular ovum). One sperm fuses with an egg and this Figure 2.13: Reproductive System in humans process of fusion is called fertilisation. The fused eggs or zygotes stay inside the female's body (in uterus) until they have grown into baby animals (like pups in case of dogs, kittens in case of cats, and human babies in case of human beings). When the babies are born, the mothers make milk specially to feed them. They look after them for quite a long time. 7. SKELETAL SYSTEM In our body, the different organ systems which you have studied so far consist of delicate organs like stomach and heart. To support and protect these organs in their places and to keep the body upright, a rigid supporting system is required. Such a system is called skeletal system. A skeletal system consists of bones and cartilages present in the body from head to toe. Bones are hard and are present in the skull, backbone or spine (as vertebral column consisting of vertebrae), chest (as ribs) and the limbs (Figure 2.11). In all, there are about 208 bones in the human body. The cartilages are comparatively soft and elastic. The points or places where two bones are joined is a joint. There are 22 joints in our body. The joints help us to bend our body. Skeleton is the term used to describe the framework of the body formed by the bones and cartilages. Have you ever seen a X-ray unit in a hospital? Doctors use X-rays to examine the bones in our body, particularly when you suffer from a fracture. Figure 2.14: Skeleton System in humans

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Parts of Skeletal System Bones of the skull, ribs (chest), vertebral column (backbone or spine) and the limbs (hands and legs). Functions of Skeletal System 1. Protection: It protects delicate internal organs from injury. 2. Provides form and shape to the body. 3. Movement: Bones provide a surface to which muscles are attached. Contraction and relaxation of muscles produce movement. o When we are born we have more than 300 bones in our bodies. By the time we have grown up, there are about 208. Many of the infant's bones get joined together or fused. o Giraffe seven bones in its neck, just like us. 8. MUSCULAR SYSTEM Muscular system consisting of muscles (Figure 2.15) helps in locomotion and movement. Locomotion is the result of co-ordinated action of muscles of the limb bones. The contraction and relaxation of muscles move the bones. Many bones of the skeleton act as levers. When muscles pull on these levers, they produce movements, such as the breathing movements of the ribs, the chewing action of the jaws and the flexing of the arms.

Figure 2.15: Muscular System in humans

Formative Worksheet 24.

The given diagram illustrates the human digestive system. Which part represents stomach? (A) I (B) II (C) III (D) IV

25.

The given diagram illustrates the human digestive system. Which part represents small intestine? (A) I (B) II (C) III (D) IV

26.

Oesophagus is the part of (A) Digestive system (C) Excretory system The topmost part of the digestive system is (A) Mouth (C) Oesophagus The food pipe is (A) Stomach (C) Oesophagus

27.

28.

(B) Reproductive system (D) Nervous system (B) Small intestine (D) Anus (B) small intestine (D) Anus

Organisation in living things 29.

31.

32. 33.

34.

35.

32

Which of the following statements about cellular respiration is correct? (A) Oxygen is released during cellular respiration. (B) Cellular respiration leads to the formation of starch. (C) Cellular respiration leads to the formation of glucose. (D) Carbon dioxide is released during cellular respiration. The given diagram illustrates the human respiratory system. Identify A and B. (A) A-Lungs, B- Trachea (B) A-Trachea, B- Lungs (C) A-Trachea, B- Bronchi (D) A-Bronchi, B- Trachea

Circulatory system includes (A) Heart (B) Blood Brain is the part of (A) Digestive system (C) Excretory system Nervous system includes I . Brain II. Spinal cord III. Heart IV. Ear (A) I, III, V (B) II, IV, VI The given diagram illustrates the human Identify spinal cord in the diagram. (A) I (B) II (C) III (D) IV

(C) Blood vessels

(D) All

(B) Circulatory system (D) Nervous system V. Liver VI. Pancreas (C) I, II, IV (D) I, III, IV nervous system.

36.

The given illustration represents the human excretory system. In the given illustration, the structure labelled X represents (A) Kidney (B) Ureter (C) Urinary bladder (D) Urethra

37.

What is the primary excretory product of humans? (A) Ammonia (B) Urea (C) Glucose (D) Starch Which of the following functions is not performed by kidneys? (A) Removal of body toxins (B) Supplying oxygen to body (C) Maintaining body salt balance (D) Filtering of wastes from the blood This process of producing young ones of its own kind is called (A) Digestion (B) Reproduction (C) Excretion (D) Circulation The male reproductive cells are (A) Eggs (B) Ova (C) Sperms (D) All The female reproductive organ is (A) Testis (B) Ovary (C) Both (D) None

38.

39.

40. 41.

33 42.

7th Biology

The skeletal system provides shape and rigidity to the body. It also helps in protecting a number of internal organs. Which of the following internal organs is not protected by the ribcage? (A) Heart (B) Liver (C) Lungs (D) Stomach 43. Which of the following statements about constituents of rib cage is correct? (A) Rib cage consists of chest bones only. (B) Rib cage protects stomach, lungs, and heart. (C) Vertebral column alone comprises rib cage. (D) Twelve ribs and backbone constitute rib cage. 44. The given figure represents the human skeletal system. In the given figure, label X represents the (A) Skull (B) Rib cage (C) Shoulder bones (D) Pelvic bones 46. The given figure represents the human skeletal system. In the given figure, label X represents the (A) Skull (B) Rib cage (C) Shoulder bones (D) Pelvic bones 47. The given diagram illustrates the human skeleton. The structure labelled I in the given diagram illustrates the (A) Ribs (B) Skull (C) Backbone (D) Pelvic bones 48. The given diagram illustrates the human skeleton. Pelvic bones in the given diagram are labelled as (A) I (B) II (C) III (D) IV

50.

Column A Column B i Brain a Rib cage ii Heart b Skull iii Spinal cord c Backbone (A) i → a, ii → b, iii → c (B) i → b, ii → a, iii → c (C) i → b, ii → c, iii → a (D) i → c, ii → a, iii → b 51. The given diagram illustrates the human skeleton. Which labelled structure helps in protecting the brain? (A) I (B) II (C) III (D) IV

Organisation in living things 52.

34

The given figure illustrates two arm muscles X and Y at two positions i and ii. During transition from i to ii, (A) Only the relaxation of muscle Y takes place (B) Only the contraction of muscle X takes place (C) Relaxation of both muscles X and Y takes place (D) Contraction of both muscles X and Y takes place

Conceptive Worksheet 18.

The given diagram illustrates the human digestive system. Which part represents large intestine? (A) I (B) II (C) III (D) IV

19.

The given diagram illustrates the human digestive system. Which part represents caecum? (A) I (B) II (C) III (D) IV

20.

The lowest part of digestive system is (A) Stomach (B) Small intestine (C) Oesophagus (D) Anus Cellular respiration is a process in which food is broken down in a cell and is converted into energy. Respiration is an example of (A) a catabolic process (B) transportation of ions (C) anabolic process (D) excretion of ions

21.

22.

The given diagram illustrates the human respiratory system. Identify bronchi in the diagram. (A) I (B) II (C) III (D) IV

23.

In general, the blood vessel that carry impure blood is (A) artery (B) vein (B) both (D) none Which of the following organ system transports gases and materials throughout the body? (A) Digestive system (B) Circulatory system (C) Excretory system (D) Nervous system Spinal cord is the part of (A) Digestive system (B) Circulatory system (C) Excretory system (D) Nervous system

24.

25.

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35 26.

The given diagram illustrates the human nervous system. Identify I in the diagram. (A) Brain (B) Nerves (C) Spinal cord (D) None

27.

The given illustration represents the human excretory system.

28.

29.

30. 31. 32.

33.

34.

35.

In the given illustration, the structure labelled X represents (A) Kidney (B) Ureter (C) Bladder (D) Urethra Human excretory system is made up of kidneys, ureters, urinary bladder, and urethra. The structure that helps in the storage of urine is (A) Kidney (B) Ureter (C) Bladder (D) Urethra The kidneys are present in most vertebrate animals. The kidneys are important because they (A) Remove body waste (B) Digest food material (C) Pump blood to all body parts (D) Control different body movements The female reproductive cells are (A) Eggs (B) Ova (C) Sperms (D) All The male reproductive organ is (A) Testis (B) Ovary (C) Both (D) None What is the long, hard structure that starts from the neck to the lower back of the body known as? (A) Backbone (B) Cartilage (C) Pelvic bone (D) Shoulder bone The given diagram illustrates a part of the human skeletal system. Which of the following functions is performed by the illustrated image? (A) Breathing (B) Holding (C) Running (D) Sitting The given figure represents the human skeletal system. In the given figure, the shoulder bones are labelled as (A) I (B) II (C) III (D) IV The given figure represents a part of the human skeletal system. The given figure represents the (A) Bones of the hand (B) Bones of the feet (C) Rib cage (D) Back bone

Organisation in living things

36

36. The illustrated structure belongs to the (A) Skeletal system (B) Nervous system (C) Muscular system (D) Circulatory system 37. The given figure represents the human skeletal system. In the given figure, label X represents the (A) Pelvic bones (B) Skull (C) Rib cage (D) Shoulder bones 38.

The rib cage is a part of the skeletal system. It performs the function of protecting the (A) Heart and the lungs (B) Kidney and the lungs (C) Heart and the stomach (D) Kidney and the stomach 39. The given figure represents the human skeletal system. In the given figure, the pelvic bones are labelled as (A) I (B) II (C) III (D) IV 40. The given diagram illustrates the human skeleton. Label I in the given diagram depicts the (A) Ribs (B) Skull (C) Backbone (D) Pelvic bones 41. The given figure represents the human skeletal system. In the given figure, label X represents the (A) Rib cage (B) Skull (C) Shoulder bones (D) Pelvic bones 42.

43.

44.

Which of the following statements about muscles is incorrect? (A) They contract to move a bone in a particular direction. (B) They contract to bring a bone to its original position. (C) They can only push the bone. (D) They can only pull the bone. Muscles are necessary for the movement of bones. Which of the following statements is correct regarding contraction of muscles? (A) Bones can move in the absence of muscles. (B) Muscles become longer and thinner on contraction. (C) Muscles become shorter and thicker on contraction. (D) Bones can move in the presence of only one muscle. Humans perform a variety of activities, like running, walking, playing, lifting weights etc. They are able to do so because of organ system X. The organ system X referred to in the preamble is the (A) Muscular system (B) Digestive system (C) Excretory system (D) Circulatory system

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SNAP SHOT 1. Living organisms exhibit a unique organisation. , 2. There are two broad levels of organisation -- "higher" levels and "lower" levels of organisation. 3. Lower levels of organisation beginning from the basic unit of organisation, the cell, in order of increasing complexity are: Cells  Tissues  Organs  Organ systems  Organism. 4. Below the level of the cell, there exists a molecular level of organisation. Cells are made up of organelles which are made up of compounds and molecules, which in turn are composed of atoms. 5. Higher levels of organisation beginning from the organism (individual) in order of increasing complexity are: Organism  Population  Community  Ecosystem  Biosphere. 6. Different levels of organisation share some basic features — require energy for maintenance, complexity increases and number decreases as we move from lower levels to higher levels. 7. All the constituent units of a level interact, cooperate and compete with each other, and ensure urvival of their level. 8. There are a number of different organs and organ systems in the human body. 9. The digestive system consists of the mouth, oesophagus, stomach, small intestine, large intestine and anus. Liver, gall bladder and pancreas also take part in digestion. The digestive system helps to convert food particles into simple soluble form so that these can be easily incorporated into body cells. 10. The respiratory system consists of the nose, wind pipe (trachea), bronchi and lungs. Muscles of chest and diaphragm help in the breathing process. Respiration is an energy-producing process, in which oxygen is taken in and carbon dioxide is given out. 11. The circulatory system consists of the heart, blood and the blood vessels (arteries, veins and capillaries). It carries oxygen and nutrients to all parts of the body. 12. The nervous system consists of the brain, spinal cord, nerves and the five sense organs ears, eyes, nose, skin and tongue. 13. The excretory system helps to remove the waste products from the body. It consists of kidneys, ureters, urinary bladder and urethra. 14. The reproductive system helps an organism to produce young ones of its own kind. Testis and ovaries are the male and female reproductive organs respectively in humans. 15. The skeletal system consists of bones and cartilages. It performs the functions of protection, movement and providing shape to the body. 16. The skeleton comprises the skull, ribs, backbone (vertebral column) and the limbs (hands and legs).

Summative Worksheet I. 1.

2.

3.

4.

Multiple Choice Questions The lowest level of cellular organisation is a (a) Cell (b) Organism (c) Tissue (d) Organelle A group of similar cells which perform a particular function is called a (a) Organism (b) Tissue (c) Organelle (d) Organs Two organ systems in plants are (a) Roots and stern (b) Root system and shoot system (c) Stem and branches (d) All the above A level of organisation above the population is (a) Organism (b) Ecosystem (c) Community (d) Biosphere

Organisation in living things 5.

6.

7.

8.

II. 1.

38

Biosphere consists of (a) Atmosphere, lithosphere and hydrosphere (b) Atmosphere and hydrosphere (c) Ecosystem only (d) Abiotic and biotic components Biotic community consists of (a) Only animals (b) All organisms (c) Only plants (d) Organisms and the environment Trachea is a part of (a) Digestive system (b) Excretory system (c) Respiratory system (d) Circulatory system Bones and cartilages are a part of (a) Skeletal system (b) Respiratory system (c) Muscular system (d) Excretory system

2. 3. 4. 5. 6.

Fill in the blanks: The higher levels of organisation in a multicellular organism are ________, ________, ________, ________ and ________. A group of cells that are similar in size and shape, and do the same job is called a __________. Different tissues that work together form _____________. An organ used to get rid of the wastes in our body is _____________. In plants, the organ that makes food is the _____________. Individuals of the same kind of organisms form a _____________.

III. 1. 2. 3. 4.

Differentiate between the following: Organism and Population Population and Community Ecosystem and Biosphere Tissues and Organs

IV. 1. 3. 5. 7. 9.

Classify the following as ceils, tissues, organs, organ systems or organisms: Chlamydomonas 2. Leaf Stomach 4. Stem Shoot system 6. Skin Amoeba 8. Blood Flower 10. Bone

V. 1. 2. 3. 4. 5. 6.

Name the main organs of the following systems: Digestive system Respiratory system Circulatory system Nervous system Excretory system Skeletal system

VI. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

Which of the following statements are true (T) and which ones are false (F)? Mark T or F: Plants have organs. [ ] A root is an example of an organ. [ ] Cells are made of tissues. [ ] An organ is made of tissues. [ ] One-celled plants and animals have organs. [ ] The heart is an organ. [ ] The stomach is a tissue. [ ] The heart is an organ of digestion. [ ] Different cells that join up and work together are called organs. [ ] Tissues alone cannot do same jobs in the body. [ ] Tissues, organs and organ systems are made of cells. [ ]

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12. 13. 14.

Different organ systems help each other. [ ] All members of a population compete for similar resources. [ ] Complexity goes on increasing as we move from lower levels to higher levels of organisation.[]

VII. Answer the following questions: 1. What is meant by (i) higher levels of organisation and (ii) lower levels of organisation? 2. Arrange the following in an increasing order of their organisation. Also, complete the missing links in the hierarchy. Cell, Organ, Community, Population, Biosphere 3. Mention the different levels of organisation in a multicellular organism. 4. Explain the relationship between cells, tissues and organs. 5. Give the functions of each of the following systems: (a) Digestive system (b) Respiratory system (c) Circulatory system (d) Nervous system (e) Excretory system (f) Skeletal system 6. Represent each of the above-mentioned systems by means of labelled diagrams. VIII. The organs of various systems are listed in the first column of the chart. Put a tick in any of the other columns if the organ belongs to any of the systems. Note: An organ may belong to more than one system. ORGANS SYSTEM Digestive Respiratory Excretory Reproductive Circulatory Nervous Skeletal 1. Vertebrae 2. Large intestine 3. Bladder 4. Brain 5. Nose 6. Pancreas 7. Liver 8. Kidneys 9. Spinal cord 10. Lungs 11. Heart 12. Ureter 13. Mouth 14. Nerves 15. Wind pipe 16. Food pipe 17. Bone 18. Cartilage

Organisation in living things

40

Learning Outcomes

TISSUES



The functions of different animal and plant tissues



About the distribution of different tissues in animals and plants

Chapter -3

By the end of this chapter, you will understand  The structure of different animal and plant tissues

1. INTRODUCTION Having learnt about the cells and their organisation into higher levels, namely, the tissues, organs, organ systems and the organism, let us now study in greater detail the tissues, which are found in animals and plants. 2. TISSUES IN ANIMALS In higher animals including man, cells are organised into four basic types of tissues. These are : 1. Epithelial tissue 2. Muscular tissue 3. Nervous tissue 4. Connective tissue. EPITHELIAL TISSUE We are familiar with the cheek cells. These cells are nothing but the cells of the epithelial tissue lining the mouth cavity. Epithelial tissue is a protective tissue. It forms a continuous outer layer all over the body as a part of the skin. It also forms a lining of all organs such as the stomach, oesophagus (food pipe), mouth, intestine, and trachea (wind pipe). Cells of the epithelial tissue called epithelial cells lie close to each other. They possess different shapes depending on their location and function. The cells may be flattened (squamous epithelium), cubical (cuboidal epithelium), or columnar (tall forming a column; columnar epithelium) (Figure 3.1).

Epithelial Tissue 3 common types

Squamous epithelium

Squamous

(i)

(ii)

Cuboidal epithelium

Columnar epithelium

Cuboidal Columnar Figure. 3.1 : Different types of epithelial tissues Squamous and stratified squamous epithelium • Present as thin, delicate, flat lining. • Present in the lining of the mouth, oesophagus, and skin. • Skin forms a protective covering on the body surface, it often gets damaged. Therefore, it is present in multiple layers. This is called stratified squamous epithelium. Columnar and ciliated columnar epithelium When you think of the word column, what structure comes to your mind? Is it a pillar? Columnar epithelial cells are pillar-like cells. • They are present in the inner lining of the intestine and respiratory tract. • Their functions include secretion of mucus and absorption of digested food. • Columnar epithelial cells are often marked by the presence of cilia. Cilia are hair-like projections coming out of cells. Cilia can move freely. This helps the mucus to move forward. These cells are called ciliated columnar epithelium.

Tissues

42

(iii)

Cuboidal epithelium Cuboidal epithelium is composed of cube-shaped epithelial cells. • They are present in the lining of kidney tubules and ducts of salivary glands. • Some special cells form the surface of secretory glands and gland cells • Glandular epithelium is often formed by the inward folding of epithelial tissues. Functions of Epithelial tissue (a) It is a protective tissue. It protects the underlying parts of the body from injury, entry of germs, and desiccation. (b) Epithelial cells lining the stomach wall secrete juices. These juices help in digestion. (c) Epithelial cells of the skin help in the removal of waste as sweat. (d) Epithelial cells also help in absorption of digested food as in the case of epithelial cells of the small intestine. MUSCULAR TISSUE The human body performs different types of functions. Since different cells perform different functions, the body must have many cells to perform one or more specific functions. Tissues are broadly classified into four different groups, namely epithelial, connective, muscular, and nervous tissues. Let us explore muscular tissues in detail. Movement is an important function in animals. The system called muscular system performs this function. The muscular system is composed of muscular tissues. Close your fingers to form a fist and then open the same. Repeat the process and observe the movements of your skin. What do you observe? You will observe contractions and relaxations of muscles. Muscle cells are elongated cells that contain special contractile proteins to aid this function. Some movements are controlled, while some other movements cannot be controlled. Therefore, these muscles are categorised into voluntary muscles and involuntary muscles. Types of muscular tissues: Based on structure and function, there are three types of muscle tissues Voluntary muscles [figure 3.2(a)]  Their movements can be controlled.  Cells of muscular tissues are elongated with many nuclei; they can be branched or unbranched.  When observed under the microscope, they appear as alternating dark and light bands. Therefore, they are called striated muscles. Involuntary muscles [figure 3.2(b)]  Their movements cannot be controlled.  Cells are long and pointed. It has a single nucleus.  They can be found in the alimentary canal, uterus, iris, bronchi of the lungs etc.  They are non-striated muscles Cardiac muscles[figure 3.2(c)]  The tissues present in the heart contract and relax in a rhythmic mode, which forms the heart beat. These tissues are called cardiac tissues.

(a) Voluntary muscles

(b) Involuntary muscles Figure. 3.2

(c) Cardiac muscles

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Table 3.1 : Differences between three muscular tissues Skeletal (or striated) Cardiac Smooth (or unstriated) Elongated, cylindrical with Elongated, cylindrical, Elongated, spindleblunt ends, possess branched, fused with shaped with pointed transverse bands (striations) one another ends, no striations Location Attached to skeleton Wall of heart Walls of stomach, intestine, etc. Voluntary muscles, as the name suggests, work at our will. These muscles help in working, writing, running or doing other jobs. Involuntary muscles are not under our control; these work on their own. These muscles take part in breathing movements, digestion and other activities. Cardiac muscles, found only in the heart, expand and contract. These muscles help in pumping the blood to different parts of the body. Function Movement of various body parts. Feature Shape

  

There are about 639 muscles in our body. About two third of the body weight is due to muscular tissues, which we commonly call flesh. When you eat meat, you are in fact eating muscles.

NERVOUS TISSUE Nervous tissue consists of a group of specialised cells called nerve cells or neurons (Figure 3.3). Each nerve cell consists of three parts – (a) The cell body or cyton, (b) The dendrites which are short branching structures arising from the cell body, and (c) The tail or axon which is a long tube like part with fine terminal nerve endings. Nerve cells are found in the brain and the spinal cord. Functions Nerve cells are joined end to end forming long nerve fibres. The nerve fibres conduct messages from one part of the body to the other. Figure 3.3: Nerve cells CONNECTIVE TISSUE Connective tissue is composed of cells which are embedded in a non-living medium or fluid. Unlike the epithelial, muscular and nervous tissues where cells are closely packed together, the cells in the connective tissues are separated from one another. The space between the cells is filled with solid or liquid materials forming matrix. Connective tissues are of three kinds depending upon their structure and function : Connec ve Tissue

Connec ve ssue proper

Tendon

Ligament

Skeletal ssue

Bone

Fluid connec ve ssue

Car lage

Blood

Lymph

Tissues

44

(a)

Connective tissue proper : consisting of tendons and ligaments connects parts of the body, muscles to bones, bones to other bones. (b) Skeletal tissue : consisting cartilage and bones, provides support to the body. (c) Fluid connective tissue : consists of blood and lymph. Connective tissue is present throughout the body and may be solid or fluid. Blood and lymph are fluid connective tissues. Cartilage, bone (Figure 3.4 a, b), tendons and ligaments are all examples of solid connective tissues. Cartilage, though a solid connective tissue, is less harder than the bone. It helps in making the organs or tissues flexible, and is present in the nose and in the external ear.

(a) Cartilage tissue

(b) Bone tissue

(c) Blood Figure 3.4 Bone is a hard connective tissue (harder than cartilage) due to the presence of calcium phosphate in the matrix. The bones perform two functions - support the body and help in the movement of muscles. Blood is a fluid connective tissue, the matrix consists of a fluid or liquid called plasma. The plasma contains three types of blood cells (called blood corpuscles) red blood cell (RBC), white blood cell (WBC) and platelets. Lymph • Lymph is blood lacking the red blood cells. • While blood flows in blood channels, lymph surrounds the body cells. Functions 1. Connective tissues connect different tissues of the body and provide support to the body. 2. Blood, being a liquid connective tissue, connects every part of the body (Figure 3.4 c) and transports substances to all body parts.

Formative Worksheet 1.

2.

3.

Which type of epithelial tissue is found in the cells lining blood vessels? (A) Squamous epithelium (B) Cuboidal epithelium (C) Columnar epithelium (D) Ciliated epithelium The given illustration represents the human respiratory system. In the given illustration, the structure labelled I is lined with which type of epithelial tissue? (A) Columnar epithelium (B) Stratified squamous (C) Cuboidal epithelium (D) Simple squamous Skin is a protective body covering. Which epithelium is present in skin? (A) Stratified squamous epithelium (B) Simple squamous epithelium (C) Columnar epithelium (D) Cuboidal epithelium

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7th Biology

4.

The goblet cells are specialised cells found in the intestine, which secrete mucus. Mucus acts as a lubricant. Which of the following epithelial cells is modified as goblet cells? (A) Cuboidal epithelium (B) Columnar epithelium (C) Simple squamous epithelium (D) Stratified squamous epithelium Ciliated columnar epithelium, which is made of cilia, is found in the lining of the (A) Respiratory tract (B) Kidney tubules (C) Oesophagus (D) Mouth i epithelium is present in the internal lining of kidney tubules. ii present in the lining of the small intestine. The information in which alternative completes the given statements? (A) i-columnar ii-it is also (B) i-cuboidal ii-it is also (C) i-cubiodal ii- columnar epithelium is (D) i-columnar ii-cubiodal epithelium is The linings of i and ii are made of simple squamous epithelial cells. The information in which alternative completes the given statement? (A) i-oesophagus ii-blood vessels (B) i-kidney ii-blood vessels (C) i-kidney tubules ii-intestines (D) i-oesophagus ii-intestines The matrix of i is composed of compounds of phosphorus and calcium. The matrix of composed of ii proteins and sugars. The information in which alternative completes the given statements? (A) i-cartilage ii-bone is (B) i-bone ii-bone is also (C) i-cartilage ii-cartilage is also (D) i-bone ii-cartilage is Blood is a type of connective tissue. Which of the following statements about the functions of blood is correct? (A) It helps in transporting gases and nutrients (B) It helps in connecting bones to muscles (C) It helps in the digestion of food (D) It helps in the storage of fats In human respiratory system, the air enters the nostrils and is transported to the lungs through trachea. A particular connective tissue lines the trachea and prevents it from collapsing. Which connective tissue supports the trachea? (A) Adipose (B) Ligament (C) Tendon (D) Cartilage The given figure illustrates a type of connective tissue. In the given figure, the structure labelled ‘X’ is composed of which types of cells? (A) Adipocytes (B) Osteocytes (C) Monocytes (D) Lymphocytes

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

Polar bears live at the North Pole. They have a number of adaptations to enable them to live in the harsh conditions. For example, they have a thick layer of blubber (fat) up to 11 cm, which helps them in keeping warm while swimming in cold water. Which type of tissues helps the polar bear in the given situation? (A) Areolar tissue (B) Adipose tissue (C) Cartilage tissue (D) Skeletal tissue i muscle fibre helps in the contraction and relaxation of blood vessels. It is spindle in shape and in ii action. The information in which alternative completes the given statements? (A) i-smooth ii-voluntary (B) i-skeletal ii-voluntary (C) i-smooth ii-involuntary (D) i-skeletal ii-involuntary Smooth muscle cells are found in i and ii . The information in which alternative completes the given statement? (A) i-bronchi ii-hands (B) i-bronchi ii-iris (C) i-heart ii-iris (D) i-heart ii-hands The given illustration represents a type of muscle. The type of muscle shown in the given illustration is likely to be found in the (A) Muscles of arms (B) Muscles of legs (C) Stomach (D) Heart

Tissues

16.

17.

46

The oesophagus helps in the passage of food from the mouth to the stomach. The muscle cells present in the oesophagus are i and ii . The information in which alternative completes the given statement? (A) i-multinucleate ii-spindle shaped (B) i-uninucleate ii-cylindrical (C) i-multinucleate ii-cylindrical (D) i-uninucleate ii-spindle shaped The given figure illustrates the types of muscle tissues.

The information in which alternative correctly completes the given flowchart? i ii iii i ii (A) Cardiac Multinucleate Striated (B) Striated Uninucleate muscle muscle muscle i ii iii i ii (C) Cardiac Enucleate Striated (D) Striated Enucleate muscle muscle muscle

iii Cardiac muscle iii Cardiac muscle

18.

The given illustration represents a neuron. In the given illustration, the structure labeled I is the (A) Nerve ending (B) Cell body (C) Dendrite (D) Axon

19.

Which connective tissue helps in storing fats? (A) Tendon (B) Ligament (C) Adipose tissue (D) Areolar tissue Bones and muscles are connected to each other with the help of a connective tissue. Which connective tissue joins muscles to bones? (A) Tendon (B) Ligament (C) Areolar tissue (D) Adipose tissue The given figure illustrates the structure of nerve cell. All the activities of the cell are controlled by the part labelled as (A) I (B) II (C) III (D) IV

20.

21.

22.

The given figure illustrates some animal tissues.

Which of the following statements best describes the relationship between the cells in the given figure? (A) IV transmits messages to III. (B) III transports oxygen to II. (C) I is synthesised by IV. (D) III is composed of I.

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47

Conceptive Worksheet 1.

2.

3.

4.

The primary function of the cells of the nervous tissue is to (A) Protect the internal organs (B) Transmit stimulus (C) Transport oxygen (D) Aid in movement The cells of the tissue that transmit stimulus are known as. The information in which alternative completes the given statement? (A) i-nervous ii-muscle (B) i-muscular ii-muscles (C) i-nervous ii-neurons (D) i-muscular ii-neurons The given illustration represents a neuron. In the given illustration, the cell body of the neuron is labelled as (A) I (B) II (C) III (D) IV The given illustration represents a neuron. In the given illustration, the structure labelled X is the (A) Axon (B) Dendrite (C) Cell body (D) Nerve ending

5.

The given illustration represents a type of muscle fibre. The illustrated muscle fibre is present in the (A) Heart (B) Ureters (C) Iris of the eyes (D) Bronchi of the lungs

6.

Involuntary muscles control the movement of food in the alimentary canal. The cells of involuntary muscles are (A) Cylindrical and uninucleate (B) Cylindrical and multinucleate (C) Spindle-shaped and uninucleate (D) Spindle-shaped and multinucleate The muscles of heart are known as i muscles, whereas the muscles found in the ureters are known as ii muscles. The information in which alternative completes the given statement? (A) i-cardiac ii-striated (B) i-cardiac ii-smooth (C) i-skeletal ii-smooth (D) i-skeletal ii-striated The cells of voluntary muscles are long, cylindrical, i , and ii . The information in which alternative completes the given statement? (A) i-branched ii-uninucleate (B) i-branched ii-multinucleate (C) i-unbranched ii-uninucleate (D) i-unbranched ii-multinucleate Which of the following statements about bone is incorrect? (A) It stores fats (B) It is non-flexible and strong (C) It contains calcium and phosphorus compounds (D) It anchors muscles and protects the delicate organs of the body

7.

8.

9.

Tissues 10.

11.

12.

13. 14.

15.

16.

17.

Which of the following statements about blood is incorrect? (A) It transports gases to various parts of the body (B) It forms the framework of the body (C) It has a fluid matrix (D) It contains proteins The tissue found between the skin and muscles is called i tissue. Fats are stored in the ii tissue. The information in which alternative completes the given statements? (A) i-areolar ii-cartilage (B) i-areolar ii-adipose (C) i-ligament ii-cartilage (D) i-ligament ii-adipose Cartilage has a solid matrix that is composed of i and ii . The information in which alternative completes the given statement? (A) i-calcium ii-phosphorus (B) i-proteins ii-calcium (C) i-sugars ii-phosphorus (D) i-proteins ii-sugars Which connective tissue transports gases, nutrients, and wastes to different body parts? (A) Bone (B) Blood (C) Ligament (D) Cartilage Ligaments that connect two i are a type of ii tissue. The information in which alternative completes the given statement? (A) i-bones ii-muscular (B) i-muscles ii-muscular (C) i-bones ii-connective (D) i-muscles ii-connective What is the primary function of cuboidal epithelium? (A) To prevent wear and tear (B) To provide useful secretions (C) To prevent microbial infection (D) To provide mechanical support The given figure represents a cell present in the inner lining of the gut. Which epithelial tissue is represented in the given figure? (A) Stratified squamous epithelium (B) Simple squamous epithelium (C) Columnar epithelium (D) Cuboidal epithelium Which illustration represents stratified squamous epithelium? (A) (B)

(C)

18.

19.

48

(D)

Which epithelial tissue forms the lining of the mouth? (A) Stratified squamous (B) Simple squamous (C) Columnar (D) Cuboidal The linings of i and the ducts of salivary glands are formed by ii provides mechanical support to these structures. The information in completes the given statement? (A) i-kidney tubules ii-tubules (B) i-lung alveoli (C) i-kidney tubules ii-cuboidal (D) i-lung alveoli

epithelium, which which alternative ii-columnar ii-cuboidal

7th Biology

49 20. 21.

22.

Which type of epithelium is present in the inner lining of the intestine? (A) Stratified squamous (B) Simple squamous (C) Columnar

(D) Cuboidal

Which type of epithelium is illustrated in the given figure? (A) Simple squamous (B) Stratified squamous (C) Cuboidal epithelium (D) Columnar epithelium Simple squamous epithelial cells are extremely i and ii . The information in which alternative completes the given statement? (A) i-thick ii-columnar (B) i-thick ii-flat (C) i-thin ii-columnar (D) i-thin ii-flat

3. TISSUES IN PLANTS Broadly, there are two types of tissues in plants: 1. Meristematic tissues 2. Permanent tissues MERISTEMATIC TISSUES Meristematic tissues are formative tissues which add new cells to the plant body. They, thus, contribute towards growth in length and width of the plant (Figure 3.5 a, b, c).

(a) Sprout of Mustard seed

(b) Root tip (c) Shoot tip Figure 3.5 These tissues are found in the growing regions - the tip of the root and the tip of the stem. The growth in thickness is also due to a meristematic tissue which is present laterally in the plant body. Meristematic cells, composing the meristematic tissue, show the following characteristic features (Figure 3.6). (i)

The cells are small.

(ii)

The cells are thin-walled.

(iii)

The cells are rich in cytoplasm with large prominent nuclei, (iv) The cells lack spaces between them. They divide actively, adding to the growth. Meristematic tissues give rise to permanent tissues.

(v)

Figure 3.6: Meristematic cells

Tissues

50

Types of meristematic tissues: Meristem can be further classified based on the position or locations of meristematic tissues. They are of three types: • Apical meristem: They are present at the tips of stems, roots, and branches. They are responsible for the axial growth in a plant. • Intercalary meristem: They are present at the base of internodes, and are responsible for the growth of internodal region. • Lateral meristem: They are present on the lateral side of stems and roots. Lateral meristem is responsible for the radial growth of plants. Vascular cambium and cork cambium are examples of lateral meristem. Figure 3.7 PERMANENT TISSUES Permanent tissues are derived from meristematic tissues. These tissues form the bulk of the plant body. The cells comprising permanent tissue show following features: (i) Cells may no longer be small and thin-walled. (ii) Cytoplasm is much less. Nucleus is small. (iii) Cells do not divide. Permanent tissues can be classified in two ways: 1. Based on their place or origin, permanent tissues are of three types : (a) Dermal tissue (b) Vascular tissue (c) Ground or fundamental tissue 2. Based on the kinds of cells constituting a permanent tissue, the permanent tissues are of two types : (a) Simple tissues (b) Complex tissues Simple tissues consist of only one type of cells while more than one type of cells is present in a complex tissue. Examples of simple tissue — parenchyma, collenchyma and sclerenchyma. Examples of complex tissue - - xylem and phloem. Simple Permanent Tissues Simple permanent tissues are of three types : (a) Parenchyma (Figure 3.8) (b) Collenchyma (Figure 3.9) (c) Sclerenchyma (Figure 3.10)

Figure 3.8 : Parenchyma Figure 3.9 : Collenchyma Figure 3.10 : Sclerenchyma Parenchyma : Parenchyma is composed of thin-walled cells. It is present in the softer parts of the plant, and performs various functions. It stores food, as in potato. In leaves, these cells contain chloroplasts, and thus help in photosynthesis (manufacture of food). (b) Collenchyma : Collenchyma has cells which possess thickenings at the corners. It is present in growing stems and leaves, providing mechanical support. (c) Sclerenchyma : Sclerenchyma is composed of thick-walled dead cells and is found in hard parts of the plant body. This tissue also provides strength to the plant parts. (a)

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51

COMPLEX PERMANENT TISSUES Simple permanent tissues are of two types : (a) Xylem (Figure 3.11 (a) (b) Phloem (Figure 3.11(b) (a) Xylem : Xylem is made of several kinds of cells. The important ones are the thick-walled, tubular cells, often dead at maturity. These are called vessels. (b) Phloem : Phloem is also made up of several kinds of cells, the most important of which are called the sieve tubes. These are also tubular cells having perforated walls joined end to end. In addition to sieve tubes, certain specialised thin-walled cells closely Figure 3.11 (a) : Xylem vessels associated with sieve tubes are present. These cells are called companion cells.

(a) Xylem vessels

(b) Sieve tubes Figure 3.11 Phloem, unlike the xylem is a living tissue (Figure 3.11 b). Phloem also contains phloem parenchyma and phloem fibres. DERMAL TISSUES Dermal tissue is usually present in the outermost layers of the plant body. Thus, the surface of roots, stem, leaves, flowers and fruits is made up of dermal tissue, commonly referred to as the epidermis. Plant Tissues

Meristema c ssues

Permanent ssues

Simple

Parenchyma

Collenchyma

Dermal tissue performs various functions : (i) It protects the plant body and is, therefore, also known as a protective tissue. (ii) Cells are often thick-walled and develop waterproof coating on their surface. This helps to reduce evaporation of water from leaf surface. (iii) (iv)

Complex

Sclerenchyma

Xylem

Phloem

Figure 3.12 : Stomata In the roots, this tissue helps in the absorption of water and minerals from the soil. In the leaves, the dermal tissue helps in exchange of gases like oxygen and carbon dioxide between the atmosphere and the plant. This exchange takes place through small pores, called stomata (Figure 3.12).

Tissues

52

VASCULAR TISSUE This tissue is also known as the conducting tissue, as it transports or conducts water, minerals and food to different parts of the plant body. Vascular tissue consists of two types of tissues - - xylem and phloem. Vascular tissue may be compared to the blood vessels of man as a tissue meant for transporting materials through the plant body. Movement of water and minerals occurs through xylem, whereas the food manufactured by the leaves is transported to other parts through phloem. Vascular tissues perform two major functions: 1. These act as conducting tissues. Xylem transports water and minerals from the roots to various body parts; phloem transports food from the leaves to all other body parts. 2. They also provide mechanical support to the stems and leaves. Ground Tissue Also known as fundamental tissue, it is basically a supporting tissue. The tissue is present in the root, stem, leaf, as well as in flowers and fruits.

Formative Worksheet 23.

24.

25. 26.

27.

i meristem is responsible for the increase in the length of the stem and roots. ii responsible for the increase in the girth of the stem and roots. The information in which alternative completes the given statements? (A) i-laterl ii-apical meristem is (B) i-apical ii-lateral meristem is (C) i-apical ii-apical meristem is also (D) i- lateral ii-lateral meristem is also The figure illustrates the location of meristematic tissues in plants.The label ‘X’ in the given illustration is i meristem that helps in increasing the ii of stem and root. (A) i-apical ii-thickness (B) i-apical ii-length (C) i-lateral ii-thickness (D) i-lateral ii-length Which of the following organelles is absent in the cells of the meristematic tissue? (A) Nucleus (B) Vacuoles (C) Ribosomes (D) Mitochondria In plants, meristematic tissue is of three types. The i helps in increasing the length of the plant while the intercalary meristem helps in the ii growth of plants and the iii meristem helps in increasing the thickness of plants. The information in which alternative completes the given statement? (A) i-lateral meristem ii-longitudinal iii-apical (B) i-apical meristem ii-equatorial iii-lateral (C) i-lateral meristem ii-equatorial iii-apical (D) i-apical meristem ii-longitudinal iii-lateral The given figure illustrates the section of a stem. In the given figure, which labelled structure helps in increasing the girth of a banyan tree? (A) I (B) II (C) III (D) IV

53

7th Biology

28.

Which type of permanent tissue helps in storing food in plants? (A) Parenchyma (B) Collenchyma (C) Xylem (D) Phloem Simple permanent tissue is made of only one type of cells. Which type of permanent plant tissue provides buoyancy to aquatic plants? (A) Chlorenchyma (B) Sclerenchyma (C) Aerenchyma (D) Collenchyma Permanent plant tissues are of two types: simple and complex. Which type of simple permanent tissue provides flexibility to plants? (A) Parenchyma (B) Aerenchyma (C) Collenchyma (D) Sclerenchyma Stomata are present on the epidermis of the leaf. What is the primary function of stomata? (A) Storage (B) Photosynthesis (C) Providing flexibility (D) Carrying out gaseous exchange The epidermis of some desert plants is covered with a thick, waxy coating of a chemical called i . ii The chemical present in the walls of cork cells. It makes them impervious to water. The information in which alternative completes the given statements? (A) i-cutin ii-suberin is (B) i-suberin ii-cutin is (C) i-cutin ii-cutin is also (D) i-suberin ii- suberin is also Some fruits such as plum and apricot have a hard coving over their seeds. Almond fruit has a hard covering over its seeds because of the presence of (A) Parenchyma (B) Aerenchyma (C) Collenchyma (D) Sclerenchyma The alternatives in the given table can be correctly matched as Column A Column B i Cellulose a Epidermis ii Suberin b Sclerenchyma iii Lignin c Parenchyma iv Chitin d Cork (A) i  d, ii  c, iii  a, iv  b (B) i  c, ii  d, iii  b, iv  a (C) i  b, ii  a, iii  c, iv  d (D) i  c, ii  b, iii  a, iv  d The given list presents some of the simple permanent tissues found in plants. I. Parenchyma II. Collenchyma III. Sclerenchyma IV. Epidermis V. Cork Which of the following pairs of tissues are made up of dead cells? (A) I and III (B) II and IV (C) III and V (D) I and V The given figure illustrates the types of plant tissues.

29.

30.

31.

32.

33.

34.

35.

36.

37.

The information in which alternative correctly completes the given figure? i ii iii iv (A) Sclerenchyma Cork Epidermis Parenchyma i ii iii iv (B) Parenchyma Sclerenchyma Epidermis Cork i ii iii iv (C) Sclerenchyma Cork Parenchyma Epidermis i ii iii iv (D) Parenchyma Epidermis Sclerenchyma Cork i conducts water and minerals from the roots to different parts of the plant. This movement of water and minerals is ii . The information in which alternative completes the given statements? (A) i-xylem ii-unidirectional (B) i-xylem ii-bidirectional (C) i-pholem ii-undirectional (D) i-pholem ii-bidirectional

Tissues

54

Conceptive Worksheet 23.

24.

25.

26. 27.

28.

29.

30.

31. 32.

33.

The xylem is a complex permanent tissue, which is made of four different components. The tracheids and vessels are made up of dead cells and help in the vertical transportation of water and minerals. Which type of cells makes up the tracheids and vessels? (A) Aerenchyma (B) Collenchyma (C) Chlorenchyma (D) Sclerenchyma In an experiment to study parasitism in rice plants, it was found that a species of fungi was able to penetrate the stem of rice plant. The fungi produced chemicals which degraded (A) Cellulose (B) Cuticle (C) Suberin (D) Lignin Piyush cut a branch of a dicot plant and put it in blue ink. After 2 hours, he observed that the leaves as well as the stem had turned blue.

The parts of stem and leaf respectively which have turned blue first are (A) I and III (B) II and III (C) I and IV (D) II and I Which tissue constitutes the husk of a coconut? (A) Aerenchyma (B) Collenchyma (C) Sclerenchyma (D) Chlorenchyma Collenchyma consists of i cells that have ii intercellular spaces between them. The information in which alternative completes the given statement? (A) i-dead ii-no (B) i-dead ii-small (C) i-living ii-no (D) i-living ii-small ____i_____ is a type of complex permanent tissue that helps in the bi-directional transportation of ____ii_____ in plants. The information in which alternative completes the given statement? (A) i-pholem ii-food (B) i-pholem ii-water (C) i-xylem ii-food (D) i-xylem ii-water In plants, water and minerals are primarily transported through (A) Tracheids and vessels (B) Tracheids and sieve tubes (C) Vessels and companion cells (D) Sieve tubes and companion cells Phloem is a type of complex permanent tissue that helps in the translocation of food. Which component of phloem consists of dead cells? (A) Sieve tube (B) Phloem fibre (C) Companion cell (D) Phloem parenchyma Sieve tubes and companion cells are components of (A) Xylem (B) Phloem (C) Collenchyma (D) Parenchyma In xylem, i helps in the sideways conduction of water and ii play a supportive role. The information in which alternative completes the given statement? (A) i-vessel ii-tracheids (B) i-tracheids ii-parenchyma (C) i-parenchyma ii-fibres (D) i-fibres ii-vessels The structural components that conduct water and nutrients vertically in xylem are i and ii . The information in which alternative completes the given statement? (A) i-companion cells ii-tracheids (B) i-companion cells ii-sieve tubes (C) i-vessles ii-sieve tubes (D) i-vessels ii-tracheids

55 34.

35.

7th Biology The given figure represents the different types of complex permanent tissue in plants.

The information in which alternative correctly completes the given flowchart? i ii iii iv i ii iii iv (A) Tracheids Living Sieve Dead (B) Sieve Dead Tracheids Dead tube tube i ii iii iv (D) i ii iii iv Sieve Living Sieve Living Tracheids Living (C) Tracheids Dead tube tube The flow of food material in phloem is i and the cells of ii aid in this transport. The information in which alternative completes the given statement? i ii (B) i ii (A) Bidirectional sieve tubes Unidirectional phloem fibres (C) i ii (D) i ii Bidirectional phloem fibres Unidirectional sieve tubes

SNAP SHOT 1. In animals, there are four basic types of tissues — epithelial, muscular, connective and nervous tissues. 2. Epithelial tissue forms a lining of various organs all over the body and protects them. 3. Muscular tissue is responsible for movement of body parts, and is of three types — skeletal, cardiac and smooth muscles. 4. Nervous tissues consist of nerve cells called neurons. A neuron consists of a cell body, dendrites and a long axon. This tissue conducts messages from one part of the body to the other. 5. Connective tissue connects or binds different tissues of the body and provides support to the body. Bones, cartilage, tendons and ligaments are all solid connective tissues. Blood and lymph are liquid connective tissues. 6. In plants, broadly, there are two types of tissues — meristematic and permanent tissues. 7. Meristematic tissues are capable of division and contribute towards growth in length and width of the plant. They are present at the tips of the roots and stems. 8. Permanent tissues are of three types — dermal, vascular and ground tissues. Based on the kinds of cells present in a permanent tissue, there are two types of permanent tissues — simple (of one type of cells) and complex (having more than one type of cells). 9. Dermal tissue is a protective tissue forming a protective covering on the outer surface of plant organs. 10. Vascular tissue is responsible for conduction of water, minerals and food to different parts of the plant body. Xylem and phloem constitute vascular tissues. Xylem transports water and minerals from the roots upwards to different parts whereas phloem transports food manfactured by the leaves to other parts of the plant body. Xylem and phloem are complex tisues. 11. Ground tissue, basically a supporting tissue, consists of parenchyma, collenchyma and sclerenchyma. All these three tissues are simple tissues.

Tissues

56

Summative Worksheet I.

II.

Multiple Choice Questions 1. Which of the following is a protective tissue? (a) Muscular tissue (b) Connective tissue (c) Epithelial tissue (d) Nervous tissue 2. The tissue which forms the internal lining of organs is (a) Nervous tissue (b) Epithelial tissue (c) Connective tissue (d) A muscle 3. Nervous tissue consists of (a) Nerve cells (b) Tendons (c) Cyton (d) Lymph 4. Short branching structures arising from the cell body of a neuron are called (a) Axons (b) Cyton (c) Dendrites (d) Lymph 5. The muscles which take part in breathing movements are (a) Involuntary muscles (b) Cardiac muscles (c) Voluntary muscles (d) All the above 6. Muscles found in heart are (a) Voluntary muscles (b) Cardiac muscles (c) Involuntary muscles (d) All the above 7. Tissues found in growing regions are (a) Meristematic tissues (b) Complex tissues (c) Simple tissues (d) Permanent tissues 8. Meristematic tissues have (a) Small, thin-walled cells rich in cytoplasm (b) Small, thick-walled cells (c) Dead cells (d) Cells which can divide for a short period 9. Sclerenchyma is a (a) Thick-walled tissue consisting of dead cells (b) Thick-walled tissue consisting of living cells (c) Thin-walled, living cells (d) None of the above 10. Vascular tissues in a plant are (a) Xylem and phloem (b) Xylem, phloem and epidermis (c) Only xylem (d) Only phloem Fill in the blanks : 1. About two-third of the body weight is made up of ____________ tissue. 2. Bone is a type of ____________ tissue. 3. Nerve cells are also called ____________ 4. Nerve cells are found in ____________ and ____________. 5. ____________ muscles are found in the walls of stomach and intestine. 6. Cells are living, elongated and thickened at the corners in ____________ tissue. 7. Xylem and phloem constitute ____________ tissue in a plant body. 8. Water moves upward inside the plant body through ____________ tissue. 9. Movement of food material in the plant body takes place through ____________ tissue. 10. Permanent tissues arise from ____________ tissues. 11. Cells of ____________ tissue bring about increase in plant length.

7th Biology

57 III.

Answer the following questions: 1. Name the different types of animal tissues. 2. Describe the structure and functions of different types of animal tissues. 3. How is connective tissue different from other tissues? 4. Mention the main characteristics of meristematic tissues. 5. Where do we find the meristematic tissue in plants? 6. What is the function of meristematic tissues? 7. Name the different types of plant tissues. 8. Where are stomata present in a plant cell? 9. What is the function of stomata? 10. Name the tissue which takes part in the movement of water and minerals in the body.

IV.

Differentiate between: 1. Parenchyma and Collenchyma 2. Collenchyma and Sclerenchyma 3. Skeletal muscle tissue and Cardiac muscle tissue. 4. Squamous epithelium and Columnar epithelium 5. Meristematic tissue and Permanent tissue 6. Simple and Complex tissues.

V.

Name the tissue found in the following: 1. At the tips of root and stem 2. On the surface of roots 3. Lining of stomach 4. Wall of heart 5. Blood 6. Brain 7. Mango peel Find the odd one out, giving reasons: 1. Cyton, dendrite, plasma, axon 2. Bone, cartilage, tendon, blood 3. Bone, epithelium, tendon, cartilage 4. Xylem, collenchyma, parenchyma, sclerenchyma 5. Vessels, companion cells, sieve tubes, collenchyma.

VI.

VII. Which of the following statements are true (T) and which ones are false (F)? Mark F.: 1. Meristematic cells are small and thin-walled. [ 2. Cells of the permanent tissues lack the property of division. [ 3. Permanent tissue is an immature tissue. [ 4. Stomata are present in the ground tissue of the leaf. [ 5. Xylem tissue is made of sieve tubes. [ 6. Epithelial tissue is a protective tissue. [ 7. Muscular tissues show the property of contraction and expansion. [ 8. Cyton and axon are the parts of a nerve cell. [ 9. The fluid part of the blood is called plasma. [ 10. Sclerenchyma consists of thick-walled dead cells. [ 11. Phloem is a complex tissue. [

T or ] ] ] ] ] ] ] ] ] ] ]

Tissues

58

VIll. See the figures shown below. Identify these figures giving reasons.

(a)

(b)

(c)

(d)

By the end of this chapter, you will be able to  Define micro-organisms  Know the different kinds of micro-organisms  Describe the three basic shapes of bacterial cells  Mention the places of occurrence and important features of bacteria  Describe the different kinds of fungi, their structure, nutrition and common method of reproduction  Describe the different types of algae.  Know about the protozoa and viruses  Describe the useful and harmful micro-organisms, their roles in environment, agriculture and industry  Learn the conditions required for the growth of micro-organisms  List the diseases caused by different micro-organisms  Mention the preventive measures to be adopted to avoid infection  Learn the methods for the prevention of spoilage of food

Life Under A Microscope (Microorganisms)

Chapter -4

Learning Outcomes

1. INTRODUCTION You have studied about the flowering plants in earlier classes. These plants have root, stem, leaves, flowers, fruits and seeds. They are green in colour and make food for all animals. You might have seen mushrooms during the rainy season in the gardens. These are also plants, although they are not green in colour. These are examples in which plants are quite big and can be seen with the naked eye. Is it true for all living things? Are there any other type of living things? Let us find answers to the above questions in this chapter. MICRO–ORGANISMS The water, air and soil around us are all full of living organisms. These organisms are very small and are not visible to the naked eye. Some cause diseases and are sometimes called germs. However, most are harmless. Today scientists call these small living things microbes or microorganisms. Most micro-organisms are too small to be seen without the aid of a magnifying glass or a microscope. Micro–organisms are minute living organisms which cannot be seen with the naked eye. A magnifying glass or a microscope is needed to see them. The scientists who study micro-organisms are called microbiologists. The field of study is called microbiology ("micro" means small). A feature shared by all these micro-organisms is that they are very hardy. Under unfavourable environmental conditions, they form a hard outer covering called the cyst. Consequently, they can survive under extreme temperature conditions, and dryness. 2. KINDS OF MICRO-ORGANISMS Major kinds of micro-organisms include: (i) bacteria, (ii) fungi, (iii) algae, (iv) protozoans, and (v) viruses. Viruses are the smallest of all micro-organisms. They, strictly speaking, cannot be grouped along with living things. They lie on the borderline separating the living things from the non-living things. Viruses lack a cellular structure (a non-living feature) but can grow only on other living cells (a living feature). Microbiology is subdivided into a number of diverse fields, based on the kind of organisms under study. Bacteriology is the study of bacteria, Virology is the study of viruses, Protozoology is the study of protozoans, Phycology is the study of algae, and Mycology is the study of fungi. These micro-organisms, in structure, may be unicellular (consisting of only one cell) or multicellular (many celled). UNICELLULAR MICRO-ORGANISMS A. Plant (i) Algae : Chlamydomonas, Chlorella, desmids and diatoms, (ii) Fungi : Yeast (iii) Bacteria

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B.

Animals (i) Protozoa — Amoeba, Euglena, Paramecium (also written as Paramoecium) MULTICELLULAR MICRO-ORGANISMS (i) Algae - Volvox, Spirogyra, Nostoc (ii) Fungi - Bread mould, Aspergillus, Penicillium 3. HABITAT OF MICRO-ORGANISMS i. ii. iii. iv.

v.

Micro-organisms are found all around us in all types of places - in air, in water, in soil, on plants, inside our bodies and bodies of all other animals. They can survive in extremely harsh environmental conditions like hot springs, desert soil, saline water, ice-cold water and marsh lands. They are also found at the bottom of sea. Micro-organisms are also present in dead and decaying organic matter. These organisms help in the release of minerals to the soil after the death of living organisms by decomposing them. Some micro-organisms live as parasites either outside or inside the body of other organisms. The nose, throat, mouth and intestine of many animals, and even human beings are inhabited by a number of micro-organisms. Some micro-organisms, however, cause diseases. For example, malaria is caused by a protozoan, Plasmodium, which lives as a parasite in the blood of human beings.

4. BACTERIA Man's relationship with bacteria is a very interesting one. We all know that, many bacteria are harmful. Diseases such as typhoid, cholera, diphtheria, pneumonia and all infections that occur in open wounds are each caused by a particular kind of bacteria. Yet, without the action of other types of bacteria, life would be impossible on earth. In fact, man actually cultivates certain bacteria because he needs and uses them. Bacteria are probably the most common forms of life on earth. They are also among the simplest and smallest living things. SIZE A bacterium generally consists of only one cell. Sometimes, they may exist as a chain or a group of cells. They vary in size from 0.2 to 100 microns. A single drop of sour milk may contain 100,000,000 bacteria. Bacteria are much smaller than protozoa, algae or fungi. 1 micron = 1/1000 of a millimetre (mm) SHAPE Bacteria have three basic shapes (Figure. 4.1), which take their names from Latin words. These are: (i) Rod-shaped called bacilli (singular bacillus) meaning "little rod"; examples - Bacillus, Lactobacillus and Pseudomonas. (ii) Ball-shaped called cocci (singular coccus) meaning "berry"; examples – Micrococcus, Streptococcus and Sarcina. (iii) Spiral or corkscrew-shaped called spirilla (singular spirillum) meaning "spiral"; examples – Vibrio, Triponema and Camphilovector. Some of these bacteria show movement by means of filaments called flagella which protrude from them.

Figure 4.1: Shapes of bacteria (a) Rod shaped (b) Ball-shaped (c) Spiral-shaped

HABITAT Bacteria are found everywhere. Some live in the mouths, noses, and intestines of animals and people. Some live on fallen leaves or animal wastes. Still others live in water, milk, dust and soil.

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STRUCTURE (i) Bacteria are unicellular micro-organisms, Plasma membrane (ii) They have a primitive cell structure, (iii) They lack a well organised nucleus. The Nuclear nuclear material is present in the cytoplasm material without a nuclear membrane (Figure. 4.2). (iv) Membrane bound cell organelles are lacking. Plasma Capsule (v) Cell wall is present. membrane Cell wall (vi) Cytoplasm is granular, viscous and colloidal in nature containing 70% - 85% water. (vii) In some bacteria, a slime layer or capsule is present on their cell surface. These are secreted by the bacterial cells. When the Flagellum secreted material is diffused (not compact), Figure. 4.2: Structure of a bacterial cell it is called a slime layer. But when the material is compact, it is called a capsule. Disease-producing bacteria are often capsulated. NUTRITION On the basis of nutrition, bacteria are of two types (i) Autotrophs which can synthesize their own food, and (ii) Heterotrophs which depend on food synthesized by other organisms. Autotroph bacteria may be (i) phototrophs which utilize energy from sunlight, and (ii) chemotrophs which utilize energy of inorganic compounds of hydrogen, ammonia and iron. Heterotroph bacteria may be saprophytic or parasitic. Are bacteria plants or animals? Bacteria have features of both plants and animals. Scientists have never entirely agreed on how to classify bacteria. Bacteria lack chlorophyll, the green colouring matter that most plants need to make their own food. In their use of outside sources of food, bacteria seem like animals. But in their sizes, shapes, and general living habits most bacteria resemble lower plants such as fungi and algae. Many scientists classify bacteria and other micro-organisms that have characteristics of both plants and animals as protists meaning first things. OXYGEN USE i.

Like all living things bacteria need oxygen to burn up food materials for energy. Bacteria requiring oxygen for their growth are called aerobes. ii. Most bacteria take oxygen from the air, but some get oxygen by breaking down chemical compounds in their food. For example, bacteria that Parent cell ferment milk (cause it to turn sour) get oxygen from milk sugar. iii. Some kinds actually cannot live in the presence of oxygen. These bacteria are called anaerobes, meaning "without air". REPRODUCTION Parent cell i. Bacteria generally reproduce by binary fission, that is, a bacterium divides into two, and so on (Figure. 4.3). Cell elongation ii. Rate of reproduction is very high under favourable conditions of nutrition, temperature, moisture; division may take place every 10 to 40 Invagination of cell wall & distribution of minutes. This means that within a few hours, nuclear material there could be millions and millions of bacteria. Formation of transverse cell wall & organised iii. But, there is not enough food or moisture in any distribution of cellular one place to support such numbers. Competition material into two cells for food and exposure to harmful conditions Separation into two keeps the bacteria in check. new cells Each cell repeats process

Figure. 4.3: Bacterial – Binary fission

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HARMFUL BACTERIA (a)

(b)

Certain bacteria cause diseases in people and animals. Some of the common human diseases caused by bacteria are cholera, diphtheria, pneumonia, tetanus, and tuberculosis. Other bacteria produce diseases in plants. Black rot in cabbage and fire blight in pears are caused by bacteria. Food is spoiled by still other bacteria, such as those that cause meat to rot. Some bacteria damage food in unseen ways. For example, botulism, a dangerous disease, is caused by a poison-producing anaerobe in improperly canned foods. Another bacterium, Salmonella, found in contaminated meat and eggs, causes a severe digestive disease. Bacteria also spoil milk if it is not boiled. During summer, it becomes necessary to warm the milk several times or store it at low temperature.

USEFUL BACTERIA Most bacteria are useful. Some are even necessary to life. Others have been put to work for a specific purpose. (a) Bacteria in the Cycle of Life: Bacteria cause the decay of dead plants and animals, both on land and in water. Without such bacteria the earth would soon be covered with material from dead organisms. There would have been a shortage of carbon and nitrogen compounds which are so essential for the living organisms. As they take in food, bacteria break down plant and animal tissues into simple chemical substances. These substances are then restored to the soil, water and air in forms that can be used for nourishment and growth by living plants and animals. Bacteria also play an important part in the digestive processes of animals. There are many bacteria in the human intestine. As the bacteria eat, they break down foods. At the same time they make certain vitamins, which the body then uses. The bacteria inside the stomach of grass-eating animals can break down cellulose, the stiff wall of green plant cells. By enabling cows to digest grasses, bacteria play a part in the production of milk. (b) Bacteria in Agriculture: All living tissues of plants as well as animals need nitrogen, the gas that makes up almost 80 per cent of Root Nodules the air. Some bacteria, called nitrogen- (contains Rhizobium) fixing bacteria, are the only organisms that can take nitrogen from the air. These bacteria live in the soil. They change nitrogen into substances that plants can use. They live in symbiotic partnership with roots of plants such as peas and beans and form root nodules (Figure. 4.4). Note: The bacterium Rhizobium is found in Figure 4.4: Root of a leguminous plant, with root nodules the root nodules of plants belonging to the pea family. (c) Bacteria in Industry: The ability of bacteria to break down organic compounds into simpler product finds several commercial applications. 1. Retting of Fibres: Fibres from certain plants are obtained by submerging the stems in water for variable periods. The fibres are acted upon by the bacteria growing in water, and the fibres are set free from the stem. 2. Curing of Cheese, Tobacco and Tea: The flavour of cheese, tea and tobacco depends upon the type and degree of fermentation and putrefaction that it has undergone. The process is known as curing and is brought about by different species of bacteria. 3. Production of Vinegar: Ethyl alcohol is converted into acetic acid (vinegar) by the action of aerobic bacteria, like Acetobacter. 4. Formation of Curd (dahi): Making of curd is a process in which the lactose (milk sugar) of the milk is converted into lactic acid by the action of certain bacteria (mainly Lactobacillus).

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How curd is made? Add a small amount of curd to warm milk to make fresh curd, and keeps the milk-containing vessel in a warm place. (ii) The curd, in fact, contains some bacteria, of which Lactobacillus is the one which promotes the formation of curd. (iii) When warm milk is mixed with the curd, Lactobacillus starts growing and converts milk sugar (lactose) of the milk into lactic acid. This in turn begins to make the milk thicker. (iv) Finally, curd is made. Once the curd is made, it: is transferred to a cooler place. This is done in order to reduce further growth of bacteria. Otherwise, the bacteria would make it sour by excessive productions of lactic acid. (i)

5.

6.

Production of Fuel: We can produce methane from the manure (solid wastes) of cattle with the help of anaerobic bacteria. Methane is an inflammable gas and a valuable fuel. It is used for heating homes and factories and for other energy needs. When methane gas is produced, protein and minerals in the manure are removed and can be used as fertilisers in fields. Treatment of Sewage: Sewage is the waste water from kitchens, toilets and industries. Treatment of sewage consists of three steps: (i) Primary treatment (ii) Secondary treatment (iii) Tertiary treatment Primary treatment is a mechanical process by which large suspended and floating materials are removed. Secondary treatment is a biological process and involves the use of bacteria and other microbes.

Figure 4.5 Set up of a sewage plant — basic plan Tertiary treatment consists of advanced biological, chemical and physical processes. It aims at further purifying waste water and also in its recycling. Chlorination, to kill germs, is done during tertiary treatment. Let us discuss the secondary treatment of sewage in more details. (i) As mentioned above, secondary treatment involves microbial activity. Aerobic bacteria are used for this activity. (ii) The bacteria are put in large sewer tanks through which oxygen (air) is also pumped. The bacteria, in the presence of oxygen, bring about rapid decomposition. (iii) Undigested sewer is then transferred to another anaerobic digestion tank. (iv) Aerobic bacteria are left behind. In the second tank, anaerobic bacteria cause digestion and produce a mixture of gases. The main gas produced is methane. (v) The mixture of gases so produced is called biogas which is used as a fuel. (vi) The sludge left after digestion of sewer by aerobic and anaerobic bacteria is rich in nitrogen. After drying, it is used as manure. (d) Other Uses of Bacteria: Valuable medical, agricultural and industrial products can be prepared from bacteria. This involves changing certain characteristics, or traits, that are inherited. Units of heredity, called genes, pass on traits from generation to generation. Genes are made up of long, twisted chains of a chemical called deoxyribo-nucleic acid (DNA). To change particular traits of an organism, scientists make changes in its genes, using genetic engineering. This method is also called recombinant DNA and gene splicing.

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For example, gene splicing is used to change bacteria so that they produce human insulin. This substance is extremely important in regulating the body's use of sugar and other nutrients. The insulin made by bacteria is used to help diabetics - people whose bodies produce little or no insulin. To change the genes of bacteria, scientists remove a small section of DNA. They replace it with a section of DNA taken from human cells. This human DNA controls the making of insulin. The bacteria follow the "instructions" of the transferred human DNA and produce human insulin. When a changed bacterium divides, each of the newly formed bacteria is able to make human insulin.

Formative Worksheet 1.

2. 3. 4. 5.

6. 7. 8.

9. 10.

11.

12.

13.

14.

15.

Robert Hooke was the first scientist who coined the term ‘cell’. Which cell did he observe under the microscope? (A) Fiber (B) Cork (C) Root (D) Leaf The range of size of bacteria is (A) 0.2 to 100 microns (B) 0.2 to 100 mm (C) 0.2 to 100 cm (D) 0.2 to 100 m Which of the following bacteria is rod shaped? (A) Micrococcus (B) Streptococcus (C) Sarcina (D) Lactobacillus Which of the following bacteria is ball shaped? (A) Micrococcus (B) Streptococcus (C) Sarcina (D) Lactobacillus Which of the following is absent in a bacterial cell? (A) Nuclear material (B) Membrane bound cell organalles (C) Cell wall (D) All The nutrition in bacterial (A) Autotrophic (B) Heterotrophic (C) Chemotrophic (D) All Bacteria are (A) Aerobes (B) Anaerobes (C) Both (D) None Bacteria reproduce by (A) Fragmentation (B) Spore formation (C) Binary fission (D) Multiple fission Which of the following diseases are caused by bacteria? (A) Cholera (B) Tuberculosis (C) AIDS (D) Tetanus Which of the following examples represents a symbiotic relationship between two organisms? (A) Fungi growing on leather (B) Lice present on human head (C) Cuscuta intertwined on a tree (D) Rhizobium present in the root of gram Decomposers decompose matter present in dead plants and animals to ammonia. This ammonia is converted into nitrates which are absorbed by plant roots. This process is called nitrification. Ammonia is converted into nitrates with the help of (A) Bacteria (B) Fungus (C) Protists (D) Viruses ____i____which are present in the root nodules of a pea plant follow ____ii____mode of nutrition. The information in which alternative completes the given statement? (A) i – Cuscuta; ii – saprotrophic (B) i – Rhizobium; ii – saprotrophic (C) i – Rhizobium; ii – symbiotic (D) i – Cuscuta; ii – symbiotic Which of the following microorganisms is capable of fixing atmospheric nitrogen and converting it into some usable nitrogenous compounds? (A) Fungi (B) Virus (C) Bacteria (D) Protozoa Lactobacillus is a _____i____ that promotes the formation of ____ii____. The information in which alternative completes the given statement? (A) i – bacterium; ii – curd (B) i – bacterium; ii – alcohol (C) i – fungus; ii – curd (D) i – fungus; ii – alcohol Rhizobium bacteria are present in the root nodules of leguminous plants such as gram pea. The Rhizobium bacteria present in leguminous plants help in the fixation of (A) Carbon (B) Oxygen (C) Phosphorus (D) Nitrogen

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Conceptive Worksheet 1.

2. 3. 4. 5. 6.

7.

8.

9.

10.

11.

12.

Robert Hooke coined the term cell. Which part of a plant did Robert Hooke use to observe a cell using a microscope? (A) Cork (B) Leaf (C) Root (D) Flower Which of the following bacteria is spiral shaped? (A) Vibrio (B) Triponema (C) Camphilovector (D) All Which of the following is present in disease producing bacteria? (A) Nuclear material (B) Capsule (C) Cell wall (D) All Bacteria can be included in (A) Plants (B) Animals (C) Both (D) None Severe digestive diseases are caused due to (A) Acetobacter (B) Salmonella (C) Lactobacillus (D) All Which of the following nutrients will not be enriched in a soil lacking the presence of bacteria and fungi? (A) Oxygen (B) Nitrogen (C) Carbon dioxide (D) Sulphur dioxide Microorganisms are used in the manufacture of many food products and beverages. Which of the following processes occur during the manufacture of wine by microorganism? (A) Respiration (B) Photosynthesis (C) Fermentation (D) Digestion Plants are incapable of taking up nitrogen directly from the atmosphere. Which of the following organisms converts atmospheric nitrogen and makes it available to plants into the soluble form? (A) Protozoa (B) Bacteria (C) Fungi (D) Virus Lactobacillus, which is a friendly microorganism, is used in the preparation of which of the following substances? (A) Curd (B) Wine (C) Bread (D) Alcohol Nitrogen cycle helps in the movement of nitrogen within biosphere. In nitrogen cycle, soil nitrifying bacteria help in the (A) Formation of nitrates (B) Formation of nitrogen (C) Absorption of nitrates by plants (D) Absorption of nitrates by animals Amit took a bit of a substance X, mounted it on a slide, and viewed it under the microscope. He observed the given organism. Which of the following substances did Amit observe? (A) Milk (B) Vinegar (C) Fruit juice (D) Buttermilk Which of the following statements about nitrogen cycle is incorrect? (A) Plants can directly absorb nitrogen from the atmosphere. (B) Nitrogen enters the animal world when they feed on plants. (C) Nitrogen returns to the atmosphere by the action of certain bacteria. (D) Animal waste is converted into nitrogenous compounds by certain bacteria.

5. FUNGI All of you would have seen a mushroom. A mushroom is a familiar kind of fungus. It belongs to a kingdom of non-green living things called fungi. Observations: • Blue-green patches on the surface of a rotting orange. • Greyish-white patches on stale bread, old pickles and jams. •

Figure 4.6 Hyphae of a fungus Greenish patches during the rainy season on old shoes and damp shoes. These patches are all made of different types of fungi (Figures. 4.6 and 4.7)

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Figure. 4.7: Different types of Fungi: (a) Yeast (b) Mushroom (c) Penicillium (d) Aspergillus STRUCTURE Fungi are both unicellular and multicellular. Multicellular forms consist of long threads called hyphae'(Figure. 4.6), that grow close together. Hyphae collectively form a highly inter-woven compact mass called mycelium. The three common types of fungi (Figure. 4.7) are – (i) yeasts, which are unicellular, (ii) moulds, which are multicellular, for example, common bread mould, and (iii) mushrooms which are also multicellular. Yeasts and moulds are microscopic organisms, while mushrooms are quite big and macroscopic. Fungi — Plants or Animals Fungi are often classified as plants. But fungi differ from plants in many ways. One difference is that fungi are non-green (lack chloroplasts and chlorophyll) and so cannot make their own food. Like the plants, however, they possess cell walls. FEEDING The absence of chlorophyll means that fungi cannot synthesize food. Fungi are either saprophytic or parasitic. The parasitic ones live on or in the tissues of another living organism, the host, absorbing nourishment from its body. Some of the most devastating diseases of crops are due to parasitic fungi, e.g., potato blight and wheat rust. The saprophytes derive their food from dead and decaying materials. Examples are the moulds which develop on stale, damp food and the many fungi which live in the soil and feed on the humus there. REPRODUCTION Reproduction takes place both by sexual and asexual means. Asexual reproduction may be through binary fission, budding, regeneration of fragments, or through spore formation. Spore formation is a very common method. Fungi produce in a great number tiny dust-like cells called spores. These spores are released into the air. If they land in a suitable place, they grow into new hyphae. Yeast commonly reproduces by budding (Figure. 4.8), whereas common bread mould, by spore formation (Figure. 4.9).

Figure. 4.8: Budding in Yeast

Figure. 4.9: Spore formation in common bread mould

7th Biology

67 Yeast belongs to genus Saccharomyces. It is a unicellular, saprophytic fungus. It may be spherical, elliptical or cylindrical in shape. It has a cell wall, cell membrane, a distinct nucleus, a large vacuole, numerous granules and fat globules. Yeast cells can be stored in dry form upto 4 years. It however, gets destroyed at a temperature of 60°C. The common mode of reproduction is asexual — budding. Sexual reproduction is also reported. Common species of yeast – Saccharomyces cerevisiae. Saccharomyces grows rapidly in sugary medium, like sugarcane juice, grapes and nectar of flowers. Due to fermentation, ethyl alcohol and CO2 are produced. Fermentation of fruits and fruit juices by yeasts makes their taste unpleasant and thus spoils the foods and food products.

Figure. 4.10: Structure of Yeast

HARMFUL FUNGI Some fungi damage food products, paper, leather, paint and textiles. Some fungi cause diseases in crops (for example Puccinia and Ustilago), in human beings (fungi like Microsporium, Arthroderma) and in animals (Dactylella and Arthrobotrys). One beautiful mushroom, Amanita, contains a poison deadly to humans. USEFUL FUNGI (a) 1. Some fungi, such as mushrooms are eaten raw or cooked. 2. Yeasts being rich in amino acids and proteins are an important source of food for humans and farm animals. (b) 1. Some fungi produce antibiotics that are used to treat infections and diseases. For example, antibiotic penicillin is obtained from a fungus, Pencillium. 2. Another fungus Aspergillus is used for producing large quantities of citric acid, used in soft drink industry. (c) In bread-making, yeast is added to the uncooked dough to make the dough "rise". The dough rises due to the production of carbon dioxide (because of respiration of yeast) in the dough. The bread can now be baked. Heat of baking drives off the carbon dioxide, making the bread porous and light. (d) 1. Yeast is also used in the preparation of products like wines and beers from fruit juices or barley. Yeast brings about fermentation of sugars into alcohol and carbon dioxide. 2. In day-to-day household food items like idli and dosa too, yeast finds its use. For making idli and dosa, the mixture of ground rice and dal is first allowed to stand for a few hours. This mixture rises and becomes sour, due to the growth of yeast cells. (e) Saphrophytic fungi break down dead material for their own food, and return to the soil chemicals or nutrients for plant growth. Fungi, thus, help in recycling of nutrients. (f) Some fungi (Aspergillus and Pencillium) are added to cheese to give a special flavour. ANTIBIOTICS Antibiotics are chemicals that kill or stop the growth of certain kinds of microbes. They help our body to fight disease. The name antibiotics comes from two Greek words meaning against life. Antibiotics work only against certain forms of life. The development of antibiotics began with the discovery of penicillin by Sir Alexander Fleming in 1928. Fleming noticed that an agar plate inoculated with the bacterium Staphylococcus aureus had become Alexander Fleming – the discoverer of contaminated with a mould. He further noticed the presence of a clear zone Pencillin in the agar plate in which breakdown of the bacterial cells had occurred. Detailed studies led to the isolation of an inhibitory substance from the mould. As the mould was identified as Pencillium, Fleming called the antibiotic penicillin. Soon other antibiotics were isolated. Some well-known antibiotics are streptomycin, gramicidin and tetracycline. The antibiotics have been obtained from either bacteria or fungi.

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Formative Worksheet 16. 17. 18. 19. 20.

21. 22. 23.

24.

25. 26. 27.

28.

29. 30.

31.

32.

Which of the following is a fungus? (A) Acetobacter (B) Salmonella (C) Lactobacillus (D) Aspergillus Fungi are (A) Unicellular (B) Multicellular (C) Both (D) None Mushroom is a type of fungi. Which mode of nutrition is exhibited by mushroom? (A) Autotrophic (B) Insectivorous (C) Aprotrophic (D) Parasitic Which of the following organisms exhibits saprotrophic mode of nutrition? (A) Mushroom (B) Rhizobium (C) Algae (D) Wheat Organisms that obtain their food from dead and decaying matter are called saprotrophs. Which of the following organisms has a saprotrophic mode of nutrition? (A) Mushroom (B) Rhizobium (C) Cuscuta (D) Rose Potato blight is caused by (A) Bacteria (B) Fungi (C) Virus (D) Protozoa Asexual reproduction in fungi takes place through (A) Binary fission (B) Budding (C) Fragmentation (D) All Yeast reproduces by (A) Binary fission (B) Budding (C) Fragmentation (D) Spore formation Bread mould reproduces by (A) Binary fission (B) Budding (C) Fragmentation (D) Spore formation Which of the following cause diseases in crops? (A) Puccinia (B) Microsporium (C) Arthroderma (D) Dactylella Which of the following contains a poison that is deadly to human beings? (A) Puccinia (B) Amanita (C) Arthrobotrys (D) Dactylella Yeast is commercially used for the preparation of alcohol and ____i____ by the process of _____ii______. The information in which alternative completes the given statement? (A) i – wine; ii – fermentation (B) i – antibiotics; ii – fermentation (C) i – wine; ii – aerobic respiration (D) i – antibiotics; ii – aerobic respiration The addition of yeast is responsible for the presence of small holes in bread after it is baked. These holes appear because of the evolution of _____I_____ during _____II_____. Which alternative completes the given statement? (A) i – Carbon dioxide; ii – Fermentation (B) i – Oxygen; ii – Fermentation (C) i – Carbon dioxide; ii – Photosynthesis (D) i – Oxygen; ii – Photosynthesis Vaccines are not available for which of the following diseases? (A) Tuberculosis (B) Hepatitis (C) Cholera (D) Malaria Penicillin is an antibiotic which inhibits the growth of bacteria by inhibiting the synthesis of cell wall in them. Penicillin does not have any effect on humans. Which of the following statements is incorrect regarding the given observation? (A) Penicillin is effective only against bacteria. (B) Antibiotics target specific biochemical pathways. (C) Large doses of penicillin will have an effect on humans also. (D) Humans lack the biochemical pathway in which penicillin acts. _____i_____ are weakened or dead microorganisms which, when injected into the body of a healthy person, protect the person from disease-causing microorganisms by initiating the production of ____ii______. The information in which alternative completes the given statement? (A) i – Vaccines; ii – antibodies (B) i – Vaccines; ii – antigens (C) i – Antibiotics; ii – antibodies (D) i – Antibiotics; ii – antigens _____i_____ and ____ii____ are examples of antibiotics that are derived from bacteria and fungi. The information in which alternative completes the given statement? (A) i – Glucose; ii – alcohol (B) i – Alcohol; ii – streptomycin (C) i – Streptomycin; ii – tetracycline (D) i – Tetracycline; ii – glucose

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Conceptive Worksheet 13. 14. 15.

16.

17.

18. 19. 20.

21. 22. 23.

24.

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Mushroom is a (A) Bacteria (B) Fungus (C) Protozoa (D) Virus Bread moulds consist of thread like structures called (A) Pseudopodia (B) Tentacles (C) Hyphae (D) Clitellum Mushroom is a type of fungi. Which of the following statements about fungi is incorrect? (A) They grow in nutrient-deficient soil. (B) They consume food in the solution form. (C) They obtain food from dead and decaying matter. (D) They secrete digestive juices on dead and decaying matter. While having a walk in a garden, Sonia observed numerous mushrooms growing on a piece of wood lying on the ground. Mushrooms obtain nutrition by (A) Manufacturing their own food (B) Trapping and feeding on insects (C) Growing as a parasite on the body of plant (D) Feeding on dead and decaying organic matter The nitrogenous wastes produced by the dead remains of plants and animals are reconverted into nitrogen compounds, which can again be used by plants. Which two organisms convert nitrogenous wastes into nitrogen compounds? (A) Bacteria and fungi (B) Fungi and algae (C) Algae and virus (D) Virus and bacteria Fungi are (A) Autotrophic (B) Saprophytic (C) Parasitic (D) All Wheat rust is caused by (A) Bacteria (B) Fungi (C) Virus (D) Protozoa The common method of reproduction in fungi is (A) Binary fission (B) Budding (C) Fragmentation (D) Spore formation Microsporium causes disease in (A) Crops (B) Humans (C) Animals (D) None Yeast is not used in the preparation of which of the following substances? (A) Curd (B) Wine (C) Bread (D) Alchohol Yeast is used to manufacture alcoholic beverages like wine and beer. It is used in the production of breads. It is also used as a nutrient supplement for human beings.Which of the following processes uses yeast to make wines and breads? (A) Photosynthesis (B) Fermentation (C) Decomposition (D) Chemosynthesis Microorganisms are used for producing medicines called antibiotics, which reduce the growth or kill other microorganisms. Which two microorganisms are used in the preparation of antibiotics? (A) Bacteria and fungi (B) Fungi and protozoa (C) Protozoa and viruses (D) Viruses and bacteria Yeast is used in the commercial production of _____i_____ and _____ii_____. The information in which alternative completes the given statement? (A) i – vinegar; ii – alcohol (B) i – alcohol; ii – oil (C) i – oil; ii – glucose (D) i – glucose; ii – vinegar ___i___ are substances produced by certain microbes, which inhibit the growth of other microbes while ___ii___ are substances which are produced by our body to fight against a disease. The information in which alternative completes the given statement? (A) i – antibodies; ii – antibiotics (B) i – toxins; ii – antibodies (C) i – antibiotics; ii – toxins (D) i – antibiotics; ii – antibodies

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6. ALGAE The commonly used terms like pond scum or sea weeds in fact refer to organisms, collectively termed as algae. It is found floating on the surface of a pond or a lake. It also tends to develop on the sides of tanks which have not been cleaned for some time. These are all algae. The term algae refers to many types of aquatic, photosynthetic organisms. Often scientists classify these organisms along with plants, as they possess chlorophyll and distinct cell walls. OCCURRENCE Algae are aquatic organisms, found in ponds, lakes, ditches, sea shores, moist soil, bark of trees. Some are even found in snow and hot water springs. They also occur symbiotically within the bodies of other living organisms, as in lichens. In structure, algae exhibit a wide variety (Figure. 4.11).

Figure. 4.11: Types of algae — (a) Chlamydomonas (b) Volvox (c) Spirogyra (d) Nostoc (e) Oscillatoria (f) Fucus. They may range from tiny unicellular microscopic forms like Chlamydomonas, Chlorella, barely 1.0 micron in size, to multicellular giant seaweeds or kelps, several metres in length. Unicellular algae may be of various shapes - spherical, oval, rod-shaped or spindle-shaped. Diversity in structure is much more in multicellular forms. These forms may exist in colonies (for example, Volvox) or form filaments (Spirogyra), or even plant-like bodies (Fucus). Algae are often named after their colour as green algae, blue-green algae, red algae, brown algae, yellow-green algae and so on. The difference in their colour is due to the presence of certain other pigments in addition to chlorophyll. Examples: Green algae – Chlamydomonas, Spirogyra, Chlorella, Volvox. Blue-green algae – Nostoc, Osdllatoria, Anabaena. Brown algae – Fucus, Laminaria Red algae – Polysiphonia Golden-brown algae – Diatoms BLUE-GREEN ALGAE These are single celled or multicellular algae (like Nostoc, Osdllatoria), blue-green in colour (figure 4.11). Some cells in multicellular forms are modified to perform a special function of nitrogen fixation. The modified cell is called the heterocyst. Blue-green algae resemble bacteria in many respects. For this reason, these algae are also called as cyanobacteria. Both have a primitive cell structure, lacking membrane-bound cell organelles and a well-defined nucleus. Reproduction in blue-green algae is commonly by binary fission or by fragmentation (asexual reproduction).

7th Biology

71 DIATOMS Diatoms (figure 4.12) are golden-brown microscopic algae, rich in marine places. These algae have variously designed bodies impregnated with glass-like silica. They may be unicellular, colonial or filamentous. The cell wall consists of two overlapping halves, hence named as diatom. Diatoms after their death leave large amounts of silica deposits called diatomaceous earth. This being rough, it is used for polishing and in making filters. Examples — Navicula, Pinnularia, Cyclotella. Note: Diatoms are known as the.'jewels of the plant world.

Figure. 4.12: Some forms of diatoms

HARMFUL ASPECTS OF ALGAE Algae are generally considered to be a great nuisance by many people. They cause problems by fouling beaches and drinking water. Excess growth of algae also blocks the movement of water in channels. Some algae also produce poisons which prove deadly to fish, many smaller organisms and even man. USEFUL ALGAE 1. Cell walls of diatoms are a rich source of silica. Large deposits of diatom shells (diatomaceous earth) are mined and used in industry for making glass, toothpaste, filters and for polishing. 2. The blue-green algae can fix atmospheric nitrogen. These algae are used to increase the soilfertility and thus function as biofertilisers. 3. Being producers, algae form the first link in the food chain in all water-bodies. 4. Certain algae like Chlorella and Porphyra are used as food. Sea weeds are used as food in China and Japan. 5. Kelp, a brown alga, is a rich source of iodine. 6. An important product agar is obtained from a red alga. This product is used in laboratory experiments for growing organisms. It is also used in the preparation of medicines, food and cosmetics. 7. Sea weeds are even used as fertilisers. It is estimated that in paddy fields about 625 kg of nitrogen can be fixed in a year by these algae in one kilometre square area. The addition of blue-green algae to barren fields increases the nitrogen and humus content of the soil. Because of increase in humus content, the water holding capacity of soil is improved. The net result is that there is better growth of crops. 7. PROTOZOA The name 'protozoan' is derived from the Greek words meaning "first animal." Protozoa are onecelled living things. They live nearly everywhere on earth, in water and moist soil. In size, they range from 2 to 200 microns. Examples: Amoeba, Paramecium, Euglena, Plasmodium, Trypanosoma.

(a)

(b)

(c) (d) Figure. 4.13. Protozoa — (a) Amoeba (b) Paramecium (c) Euglena (d) Trypanosoma

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72

Amoeba Amoeba is the simplest and most common of all protozoa. Protozoa are often included in the animal kingdom as they do not possess a cell wall, and lack chlorophyll. They obtain their food from other living things. The parasitic forms absorb digested food from the host. (iii) Some forms are oval, spherical or elongated, while others, like the Amoeba, lack any definite shape (Figure. 4.13 a). (iv) A typical protozoan cell contains a definite nucleus and membrane-bound cell organelles. (v) All the functions of life like nutrition, respiration, excretion, locomotion and reproduction are carried out by the single-celled body. (vi) Locomotion takes place by pseudopodia, cilia or flagella. (vii) Sexual and asexual reproduction in this group of organisms is complex and varied. In Amoeba, asexual reproduction is quite common. A parent amoeba cell divides into two. Paramecium, however, reproduces sexually as well as asexually. Two paramecia produce offspring together. HARMFUL PROTOZOA Several protozoa cause diseases in man and other animals. One such kind is Entamoeba histolytica which causes amoebic dysentery (Figure. 4.14) in man. Another dangerous protozoan is Plasmodium which causes malaria in man. Plasmodium is a parasite and is transmitted by the bite of the female anopheles mosquito. The mosquito merely acts as the carrier of the parasite. Trypanosoma causes an infectious disease called sleeping Figure.4.14 Active and encysted forms sickness in man, cattle, pigs and horses. This disease is of the agent of amoebic dysentery common in some African countries. USEFUL PROTOZOA 1. Protozoa form an important link in aquatic food chains. They feed on algae and are food for other protists and small animals, which in turn become food for others. 2. Protozoa decompose organic matter and thereby help in converting organic wastes into simpler useful soil nutrients. 3. Protozoa also exist in symbiotic association with other organisms. This association is mutually beneficial to both the organisms. (i) (ii)

8. VIRUSES — NON-CELLULAR MICROBES When we suffer from common cold, the physician tells us that this is due to virus-infection. What are these viruses? Viruses are peculiar - their structure is unlike all the other microbes mentioned so far. These are not considered to be organisms at all since they do not possess a cellular organisation. They have no life until they enter another living cell. They are unable to carry out any of the typical life functions until they are inside a host cell. Outside a host cell, viruses are like any non-living substance. They can be crystallized and stored. Viruses are, thus, obligate parasites. The relationship between the host and the virus is known as parasitism as the virus (parasite) benefits and the host is harmed. Figure. 4.15 Different types of viruses

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In size, viruses are smaller than bacteria, and cannot be seen with simple microscopes. They vary from 15 m to 275 m, and can be viewed only under an electron microscope. They exhibit a wide variety of shapes (Figure. 4.15). In a virus, a small amount of genetic material (in the form of DNA or RNA) is enclosed inside a protein coat (Figure.4.16). Viruses are generally named on the basis of (i) the host, or (ii) the disease that they produce. For example, tobacco mosaic virus (TMV) is so named as its host is a tobacco plant, and the virus Figure. 4.16: Internal structure in different viruses produces mosaic pattern on the leaves. Similarly, the measles virus causes measles in man. The virus which attacks bacteria is called bacteriophage (meaning bacterium-eater). In humans, viruses cause measles, mumps, flu, smallpox and the common cold. As viruses lack their own metabolism, antibiotics have no effect on them. 9. CONDITIONS FOR GROWTH OF MICRO-ORGANISMS Of all the micro-organisms, bacteria are the most abundant. They grow and multiply very fast. The most common bacteria used in biological research are E. coli. This bacterium is found in human intestine. It takes about 20 minutes to double itself. Some bacteria, like Pseudomonas, reproduce about every 10 minutes. Some of the important factors affecting their growth are 1. Temperature, 2. Moisture, and 3. Availability of food. A moist and warm environment is good for bacterial growth. Growth is less when environment is dry or the temperature is too high or too low. Also, some bacteria require oxygen for their growth and others grow without oxygen. Oxygenrequiring bacteria are called aerobic bacteria, whereas those that grow without oxygen are called anaerobic bacteria. 10. MICRO-ORGANISMS AND DISEASES For thousands of years, man lived in ignorance of what caused disease. People had explanation and beliefs about what caused disease, the most common of which was that sickness was caused by evil spirits inside the body of the victim. Malaria was thought to be due to inhalation of "bad air". The chickenpox, smallpox, cholera were thought to be inflicted as a curse of some angry goddess. It was not until 1865 that science was able to prove that microbes (or germs) were the cause of diseases. It was Louis Pasteur who first stated the "germ theory of disease". Through a series of elegant experiments Pasteur proved that the microbes were present in the air. Table 4.1: Some Common Diseases Caused by Micro-organisms in Humans Micro-organism Disease Virus Common cold, chickenpox, smallpox, measles, polio, rabies Bacteria Cholera, typhoid, tuberculosis, diphtheria, plague Protozoa Malaria, dysentery, sleeping sickness Fungi Ringworm (skin disease) Table 4.2: Some Common Diseases Caused by Micro-organisms in Animals Micro-organism Disease Virus Foot and mouth disease (in cattle) Protozoa Anthrax (in cattle), sleeping sickness (in cattle, pigs and horses)

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74

Table 4.3: Some Common Diseases Caused by Micro-organisms in Plants Micro-organism Disease Virus Tobacco mosaic Bacteria Mosaic bacterial wilt Fungi Rusts 11. PREVENTIVE MEASURES TO AVOID INFECTION Certain measures need to be taken to promote good health and prevent the body from catching infection and falling sick. Such measures include: (i) Eating a proper balanced diet so that the body remains healthy to fight infections. (ii) Drinking clean and safe water. (iii) Eating freshly prepared food, stored properly and kept away from flies and mosquitoes, (iv) Keeping the food in clean utensils and properly covered to avoid contact with flies and insects. (v) Storing unused cooked food at a low temperature in a refrigerator to avoid spoilage. (vi) Using a handkerchief while sneezing or coughing, so that others do not get infection. (vii) Putting garbage in properly covered bins. It should not be thrown in the open. (viii) Regular physical exercise helps in resisting infections and building up health. (ix) Maintaining personal cleanliness by taking following precautions. (a) Taking bath regularly with clean water. (b) Keeping nails short and clean. (c) Cleaning teeth after each meal and before going to bed. Otherwise tooth decay may take place. (d) Washing hands with soap before taking meals. (e) Walking barefooted must be avoided. Injuries due to bacteria like tetanus, insects and hookworms may be caused if barefoot walk is undertaken. (f) Comb and towel of other persons should not be used. (x) Maintaining cleanliness of the surroundings by following measures like(a) Open drains, if any, should be covered. (b) Drinking water should not be contaminated by bathing or by washing clothes. (c) Water should not be allowed to stagnate, as mosquito-breeding takes place in stagnant water. Kerosene oil can be sprayed on the surface of stagnant water. (d) Pollution-free environment should be maintained. (xi) Timely vaccination and health education are necessary to keep the body away from infections. 12. PREVENTION OF SPOILAGE OF FOOD What for do you use a refrigerator at home? Not only for cooling water, but also to store food items. These food items, if kept at room temperature, start producing foul smell. In other words, the foods get spoilt and become unfit for consumption. This is true for both cooked and raw foods. Spoilage of cooked food takes place because of the action of microorganisms like bacteria and fungi. Uncooked or raw food is contaminated or spoilt by insects, rats, fungi and bacteria. Enormous quantities of potentially useful food are thus wasted. In addition to spoilage of food, quality of food and its nutritive value too are affected. FOOD PRESERVATION Food preservation is the answer to this problem. There are many advantages of preserving food. Some of these are: 1. Reduces food wastage by avoiding spoilage. 2. Increases the storage period of foodstuff. 3. Nutritive value is retained for a longer period. 4. Ensures food availability in distant places and during off-season. METHODS OF FOOD PRESERVATION 1. By Sun drying : Drying in the sun reduces the moisture content of food materials. Removal of water from food materials like vegetables (spinach, cauliflower and methi) and fruits is called dehydration. Micro-organisms cannot grow in dry condition. Sun drying is generally used in case of vegetables like spinach, cauliflowers and methi leaves.

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2. 3.

By Heating : Heating kills germs. Milk, at home, is prevented from spoilage by boiling. By Smoking : Smoking is used for dehydrating food items like meat, fish and their products. In this method, small pieces of fish or meat are dried with heat and smoke of the fire lit below. By Salting and Sugar : Fruits and vegetables are commonly preserved by using salt or sugar. The food items are made into jams, jellies and pickles. In jams, sugar is used. In pickles, salt is used. Sugar and salt remove water from the cells, thereby preventing growth of microorganisms. Besides salt and sugar, oil and spices are also used as preservatives. These preservatives do not allow the growth of micro-organisms and thus help in preserving the food items. By Refrigeration and Freezing : Cooling by refrigeration and freezing stops micro-organisms from growing and multiplying but it does not kill them. A refrigerator keeps food at about 5°C. This keeps the food fresh for a few days. A freezer preserves food at below -18°C. This stops all microbial activity and food can be preserved for many months. Frozen foods should be thoroughly cooked and should not be left in the open for too long, otherwise the microbes become active again. By Pasteurization : Milk is preserved by this method. First the milk is heated to kill bacteria. Next it is cooled very fast to prevent bacteria from growing. It is finally stored at low temperature. This method of preservation is called pasteurization. Pasteurization kills the bacteria in milk and does not affect its flavour.

4.

5.

6.

Food Poisoning If food is not preserved properly, it can lead to poisoning. Microorganisms like bacteria and fungi are responsible for food poisoning. Bacteria causing food poisoning: Salmonella and Clostridium. Fungi causing food poisoning: Moulds like Aspergillus and Penicillium. Food hygiene is essential for preventing food poisoning. Note: The French scientist, Louis Pasteur, gave the method of preservation, named after him as pasteurisation.

Formative Worksheet 33.

34. 35.

36.

37.

38.

_____i_____ prepare their own food by the process of photosynthesis. Therefore, they are known as _____ii_____. The information in which alternative completes the given statements? (A) i – Fungi; ii – autotrophs (B) i – Fungi; ii – saprotrophs (C) i – Algae; ii – autotrophs (D) i – Algae; ii – saprotrophs Which of the following organisms exhibits symbiotic relationship? (A) Mushroom (B) Lichen (C) Pitcher plant (D) Soyabean Lichens exhibit symbiotic relationship between _____i_____ and _____ii_____. The information in which alternative completes the given statement? (A) i – fungus; ii – alga (B) i – alga; ii – Rhizobium (C) i – Rhizobium; ii – soyabean (D) i – soyabean; ii – fungus Which of the following statements regarding the symbiotic relationship between algae and fungi is correct? (A) Fungi contain chlorophyll. (B) Algae manufacture food. (C) Fungi provide food. (D) Algae provide water. Blue-green algae increase the fertility of soil. Which plant nutrient is added to soil by bluegreen algae? (A) Phosphorus (B) Potassium (C) Nitrogen (D) Calcium Biological nitrogen fixation is the process of fixation of atmospheric nitrogen into the soil by the action of microorganisms. Examples of biological nitrogen fixers include _____i_____ and _____ii_____. The information in which alternative completes the given statement? (A) i – viruses; ii – fungi (B) i – fungi; ii – blue-green algae (C) i – blue-green algae; ii – bacteria (D) i – bacteria; ii – viruses

Life Under a Microscope (Microorganisms) 39.

40. 41. 42. 43.

76

Which of the following statements about a symbiotic relationship is correct? (A) It involves a relationship where one organism grows as a parasite on the body of another organism. (B) It involves a relationship where the two organisms live together and share nutrients. (C) It is a mode of nutrition where an organism feeds on dead and decaying matter. (D) It is a mode of nutrition where an organism traps and feeds on insects. The golden-brown microscopic algae, rich in marine places are (A) Chlamydomonas (B) Osdllatoria (C) Laminaria (D) Diatoms The ‘jewels of the plant world’ are (A) Yeasts (B) Bacteria (C) Fungi (D) Diatoms Which of the following are generally considered to be a great nuisance by many people? (A) Yeasts (B) Bacteria (C) Fungi (D) Algae Which of the following are algae are generally used in making glass, toothpaste, filters and for polishing?

44.

(A) Diatoms (B) Red algae (C) Brown algae (D) Blue green algae Which of the following are algae is rich in iodine?

45.

(A) Diatoms (C) Brown algae Protozoa are included in

46. 47.

48.

49.

50. 51. 52. 53. 54.

(B) Red algae (D) Blue green algae

(A) Plant kingdom (B) Animal kingdom (C) Both Locomotion in protozoans is by (A) Pseudopodia (B) Cilia (C) Flagella Which of the following are harmful? (A) Amoeba (B) Paramecium (C) Entamoeba histolytica (D) All Sleeping sickness is caused by (A) Trypanosoma (B) Paramecium (C) Entamoeba histolytica (D) Plasmodium Choose the correct statement. (A) Protozoa form an important link in aquatic food chains. (B) Protozoa decompose organic matter and thereby help in converting simpler useful soil nutrients. (C) Protozoa also exist in symbiotic association with other organisms. (D) All Which of the following is almost closer to a non living being? (A) Protozoa (B) Bacteria (C) Virus Which of the following is a bacterial disease? (A) Chickenpox (B) Small pox (C) Typhoid Ring worm is caused by (A) Bacteria (B) Fungi (C) Virus Which of the following is caused by protozoans? (A) Malaria (B) Dysentry (C) Sleeping sickness Anthrax disease in cattle is caused by (A) Bacteria (B) Fungi (C) Virus

(D) None (D) Akk

organic wastes into

(D) Fungi (D) Rabies (D) Protozoa (D) All (D) Protozoa

7th Biology

77

Conceptive Worksheet 27.

28.

29.

30.

31.

32. 33.

34. 35. 36.

37. 38. 39. 40. 41. 42.

Lichens are organisms which are formed as a result of a symbiotic relationship between two organisms. Which two organisms form a symbiotic relationship in lichens? (A) Algae and bacteria (B) Bacteria and plants (C) Plants and fungi (D) Fungi and algae Which of the following statements about a symbiotic relationship is correct? (A) It involves a relationship where one organism grows as a parasite on the body of another organism. (B) It involves a relationship where the two organisms live together and share nutrients. (C) It is a mode of nutrition where an organism feeds on dead and decaying matter. (D) It is a mode of nutrition where an organism traps and feeds on insects. Heterotrophs are organisms which are dependent on plants and other animals for food. Which of the following organism is not a heterotroph? (A) Algae (B) Cuscuta (C) Mushroom (D) Earthworm Which of the following statements about nitrogen cycle is correct? (A) Animals obtain nitrogen directly from the soil. (B) Plants take nitrogen from the atmosphere through stomata. (C) Rhizobium converts nitrogen compounds into free nitrogen. (D) Blue-green algae help in the fixation of free atmospheric nitrogen. Organisms ‘X’ and ‘Y’ live in close association with each other. ‘X’ depends on ‘Y’ for support and ‘Y’ depends on ‘X’ for its food. Which of the following pairs represents organisms ‘X’ and ‘Y’? (A) Cuscuta and Peepal tree (B) Pitcher plant and insect (C) Fungi and bacteria (D) Fungi and algae Diatoms are (A) Unicellular (B) Colonial (C) Filamentous (D) All Which of the following can fix atmospheric nitrogen into the soil? (A) Diatoms (B) Red algae (C) Brown algae (D) Blue green algae Which of the following are algae are used as food? (A) Chlorella (B) Porphyra (C) Blue green algae (D) All Plasmodium lacks (A) Cell wall (B) Chlorophyll (C) Mitrochondria (D) Ribosomes Which of the following protozoan causes malaria (A) Amoeba (B) Paramecium (C) Entamoeba histolytica (D) Plasmodium Which of the following conditions are favourable for bacterial growth? (A) Moist (B) Warm (C) Dry (D) Hot Measles is caused by (A) Bacteria (B) Fungi (C) Virus (D) Protozoa Malaria is caused by (A) Bacteria (B) Fungi (C) Virus (D) Protozoa Foot and mouth disease in cattle is caused by (A) Bacteria (B) Fungi (C) Virus (D) Protozoa Tobacco mosaic in tobacco is caused by (A) Bacteria (B) Fungi (C) Virus (D) Protozoa Rusts in plants is caused by (A) Bacteria (B) Fungi (C) Virus (D) Protozoa

Life Under a Microscope (Microorganisms)

78

SNAP SHOT 1. Micro-organisms or microbes are tiny living organisms invisible to the naked human eye and can be seen with the help of a microscope. They are present all around us and even inside our bodies. 2. Microbes are of five major kinds — bacteria, fungi, algae, protozoa and viruses. 3. Bacteria are generally single-celled organisms reproducing by binary fission. They are one of the simplest organisms. In shape, they may be rod - shaped (bacilli), ball-shaped (cocci) or spiral-shaped (spirillum). 4. Bacteria are both harmful as well as useful to man. 'Harmful bacteria cause diseases in humans, animals and plants. They also spoil food. Useful bacteria are important in several ways: (i) decomposition of dead organisms and recycling of nutrients, (ii) increasing soil fertility by nitrogen fixation, (iii) in industry (flavouring of cheese, tea, tobacco, production of acetic acid, formation of curd) (iv) in sewage disposal plants, and (v) in medicines. 5. Fungi are non-green (lacking chlorophyll) plants, which may be unicellular or multicellular. 6. Yeasts, moulds and mushrooms are the three common types of fungi. While yeasts are unicellular, moulds and mushrooms are multicellular. 7. In multicellular fungi, the body consists of long threads called hyphae. 8. Some fungi spoil food and cause diseases. 9. Fungi are useful in several ways: (i) production of antibiotics, (ii) source of food, (iii) in breadmaking, (iv) preparation of wine and beers, and (v) nutrient-cycling. 10. Algae are aquatic, green (contain chlorophyll) photosynthetic organisms, Both unicellular and multicellular forms occur. 11. Excess growth of algae kills other organisms and makes water unfit for drinking. 12. Blue-green algae, also called cyanobacteria, are helpful in fixing atmospheric nitrogen and increasing soil fertility. 13. Diatoms are unicellular algae, having cell walls rich in silica. 14. Protozoa are minute unicellular organisms which lack cell wall and chlorophyll; hence, included in the animal kingdom. 15. Viruses are very small (rather smallest) sub-microscopic entities. They are not considered to be organisms as they lack a cellular organisation.The viruses, however, can grow and multiply inside a host organism. 16. Viruses cause several deadly diseases in man, plants and animals. 17. Spoilage of food takes place because of the action of micro-organisms like bacteria and fungi. 18. Preservation of food can be done by drying, heating, salting or by adding sugar, chemicals or by freezing and pasteurisation.

Summative Worksheet I. 1.

2.

3.

4.

5.

Multiple Choice Questions Bacilli bacteria are (a) Rod-shaped (c) Ball-shaped Bacteria, on the basis of nutrition, may be (a) Autotrophic (c) Heterotrophic Fungi, on the basis of nutrition are (a) Saprophytic (c) Autotrophic Algae are found (a) In water (c) On land Heterocyst is found in (a) Algae (c) Blue-green algae

(b) Spiral in shape (d) Variable in shape (b) Both autotrophic and heterotrophic (d) Symbiotic (b) Parasitic (d) Saprophytic and parasitic (b) On tree branches (d) On mountains (b) Brown algae (d) Diatoms

7th Biology

79 6.

7.

8.

9.

10.

11.

12.

Sleeping sickness is caused by a (a) Protozoan (b) Fungus (c) Alga (d) Bacterium Non-cellular microbes are (a) Bacteria (b) Fungi (c) Viruses (d) Diatoms Yeast helps in the production of (a) Sugar (b) Alcohol (c) Oxygen (d) Agar Pasteurisation of milk destroys its (a) Vitamins (b) Fat content (c) Bacteria (d) None of the above The bread or dosa dough rises because of the action of (a) Heat (b) Growth of yeast cells (c) Kneading or grinding (d) All the above Salting the food helps to preserve it by (a) Extracting water from the cells (b) Lowering its temperature (c) Increasing its acidity (d) None of the above Algae are an important part of the aquatic food chain because they are (a) Decomposers (b) Producers (c) Consumers (d) None -of the above

II. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

Fill in the blanks: Micro-organisms can be seen with the help of a _______________. The largest fungi are the _______________. Algae can prepare their own food because they possess _______________. Iodine is obtained from _______________. Agar is obtained from _______________. The plant body in multicellular fungi is made up of _____________________ Viruses are _______________ in size than bacteria. The fungus that grows on bread is known as _______________ Bacteria generally reproduce by _______________ The virus which attacks bacteria is called _______________ Cell walls of diatoms are a rich source of _______________ The disease causing micro-organisms are called _______________

III. 1. 2. 3. 4. 5. 6. 7. 8. 9. 11. 12. 13. 14.

Name the following: A bacterium that helps in the curdling of milk. A fungus used in the preparation of antibiotics. A fungus used in bread industry. The specialised cell found in blue-green algae. A micro-organism used in the production of alcohol. Two diseases caused by bacteria, fungi, protozoa and viruses. Two diseases each caused by mycoplasma. The scientist who discovered pencillin. Two food items prepared using yeast. 1-0. A nitrogen-fixing bacterium. Malaria causing micro-organism. Five protozoans. Two bacteria causing food poisoning. Two fungi causing food poisoning.

IV. 1. 2. 3.

Find the odd one out. Give reasons in support of your answer. Algae, fungi, protozoa, flowering plants Chlorella, Chlamydomonas, yeast, bread mould Chlorella, Spirogyra, diatoms, mushroom

Life Under a Microscope (Microorganisms)

80

V.

Match the statements in Column A with those in Column B. Column A Column B 1. Phycology (a) An alga 2. Spirilla (b) A disease 3. Chlorella (c) Study of algae 4. Measles (d) Curd making 5. Bacteria (e) A kind of bacterium

VI.

Make diagrams of the following: 1. Mushroom 2. Yeast

3. Amoeba

4. Bacteriophage.

VII. 1. 2. 3. 4. 5. 6. 7. 8.

Which of the following statements are true (T) and which ones are false (F)? Mark T or F: Malaria is caused by a virus. [ ] Germ theory of disease was given by Leeuwenhoek. [ ] Study of fungi is called mycology. [ ] Plague is caused by the bite of infected fleas. [ ] Agar is obtained from blue-green algae. [ ] Study of algae is called psychology. [ ] Moulds are a type of fungi. [ ] Milk is preserved by pasteurization. [ ]

VIII. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

Answer the following questions: What are micro-organisms? Mention the different kinds of micro-organisms. How do microbes survive adverse environmental conditions? Mention the different habitats in which micro-organisms are found. How are bacteria classified on' the basis of their shapes? Describe nutrition in bacteria. Mention some beneficial effects of bacteria. Describe reproduction in bacteria. What are the three groups of organisms in fungi? Mention two important uses of fungi. Why does the milk spoil quickly during summer? What beneficial role do micro-organisms play in the life of human beings? State two ways in which the following microorganisms are harmful to mankind: bacteria, protozoa, viruses. How are viruses different from other microbes? Why do farmers cultivate plants of pea family? Draw a diagrammatic sketch of root nodules as found in leguminous plants. Mention the role of nitrogen-fixing bacteria in soil. Name the causal organisms of the following diseases: (a) Amoebic dysentery (b) Sleeping sickness (c) Measles (d) Common cold Mention the contributions of the following: (a) Louis Pasteur (b) Leeuwenhoek Describe the role of blue-green algae in the fertility of soil. Mention some advantages of food preservation. Define pasteurization. Describe the different methods used to prevent the spoilage of food.

13. 14. 15. 16. 17.

18. 19. 20. 21. 22.

_______________



_______________

By the end of this chapter, you will be able to  Define the terms like food, nutrition and nutrients  Answer why we need food  Know about the modes of nutrition -- autotrophic and heterotrophic  Understand that heterotrophic nutrition exists in some plants as well  Know about the seven nutrients present in the food you eat  Find the sources of carbohydrates, proteins, fats, vitamins, minerals and roughage  Know the functions of the different nutrients  Identify the nutrients in the foods eaten by you  Perform experiments to test the presence of different nutrients  Calculate the energy values of different food items  Plan a balanced diet. + learn about food fads  Learn about the autotrophic nutrition - - photosynthesis in plants  Know the role of stomata, carbon dioxide, light and chlorophyll in photosynthesis  Perform experiments for showing the various requirements and the end products in photosynthesis  Identify the diseases in plants due to the deficiency of nutrients

NUTRITION IN PLANTS AND ANIMALS

Chapter -5

Learning Outcomes

1. INTRODUCTION In our previous classes, we have learnt about living and non living things. Though there are many differences, a living organism shows seven basic characteristics that differentiate it from a non-living one. These characteristics are called life characteristics, because together they ensure that an organism continues to live.

In this chapter, we will learn about nutrition, more specifically nutrition in plants. But, what does the term nutrition mean? Before, knowing about it, let’s know what food is. Any substance that can be broken down through chemical processes in the body of an organism to give energy is called food Food gives energy to perform many activities like studying, playing, talking, drawing, etc 2. NUTRITION The entire process of taking in food and drink by living organisms and using it for the purpose of growth and daily activities is called Nutrition. There are two major modes of nutrition: (a) Autotrophic nutrition (b) Heterotrophic nutrition AUTOTROPHIC NUTRITION We have seen animals and humans eating food. We get energy from the food we eat. How about plants? Neither they can cook food nor they can to different places like animals in search of food. How then are they preparing food?

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Photosynthesis Green plants actually make their own food through a process called photosynthesis (photo, light; synthesis, to put together). The mode of nutrition whereby a living organism makes its own food is called autotrophic nutrition. Organisms that are able to synthesize their own food are termed autotrophs (auto, self; trophe, nutrition). The term photosynthesis was coined by Charles Reid Barnes in 1883. It is a process in which carbon dioxide from the atmosphere is taken in by the leaves. Water absorbed by the roots reacts with carbon dioxide in presence of sunlight to produce starch and oxygen. The starch is stored in various parts of the plant and oxygen is released into the atmosphere. The reaction that takes place can be written as: Carbon dioxide + Water

sunlight and chlorophyll

Starch + Oxygen

Thus, photosynthesis can be defined as: Figure 5.1 The process of using the energy in sunlight to convert water and carbon dioxide into carbohydrates (starch) and oxygen is called Photosynthesis. PHOTOSYNTHESIS – NECESSARY CONDITIONS

i)

ii)

iii)

iv)

Figure 5.2 Chlorophyll It is a green pigment present in the structures called chloroplasts of leaves in a plant. Note: A naturally occurring substance that gives a particular colour to a plant or an animal part is called a pigment. On an average there are about 500,000 chloroplasts per square millimeter of a leaf. Sunlight It is the source of light energy required for photosynthesis. Chlorophyll traps the light energy to make energy-carrying particles. Carbon dioxide It is obtained from the atmosphere through small openings called stomata (singular: stoma) in the underside of the leaves. Water This is another important requirement for photosynthesis. The root system of plants enables them to obtain water from the soil.

Figure 5.3

Figure 5.4

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FACTORS AFFECTING PHOTOSYNTHESIS Following factors affect the rate of photosynthesis: 1. Light intensity: Photosynthesis increases with increase in light intensity, upto a certain point. 2. Availability of carbon dioxide: Photosynthesis increases with increase in carbon dioxide concentration. 3. Temperature: Upto a certain temperature value, rate increases with increase in temperature. This value ranges generally between 20° to 35°C. 4. Availability of water: Less availability of water reduces photosynthesis through closure of stomata. 5. Inorganic mineral ions: A dehydrated green plant (a plant from which all water has been removed) consists of four elements - carbon, hydrogen, oxygen and nitrogen. These elements consist of about 96% of total plant's dry weight combined together in the form of organic compounds (proteins, carbohydrates, fats etc.). The remaining 4% of the green plant dry weight consists of the following chemical elements in the form of inorganic compounds - sulphur, phosphorus, calcium, iron, magnesium, potassium, chlorine, aluminium, boron, manganese, copper, zinc and chlorine. These elements are obtained from soil water, taken up through the root system as ions. Each of the inorganic ions has different functions in the process of photosynthesis. Some of the elements are required in higher quantities (called macronutrients) while others are required in lower quantities (called micronutrients or trace nutrients). Macronutrients: Carbon, hydrogen, oxygen, nitrogen, phosphorus, sulphur, potassium, calcium, iron and magnesium. Micronutrients: Copper, zinc, boron, manganese, and molybdenum.

1. 2. 3. 4. 5.

Table 5.1: Deficiency diseases of some nutrients Nutrient Deficiency disease Nitrogen Chlorosis — yellowing of leaves Calcium Abnormal leaf shape, stunted plants Iron Chlorosis of young leaves Magnesium Chlorosis of older leaves Phosphorus Poor plant growth

3. TRANSPORT OF MATERIALS There are two aspects of transport in plants: (i) Movement of water and minerals from the roots upwards to other plant parts, and (ii) Movement of food material synthesized in the leaves to other plant parts. Upward movement of water and minerals occurs through channels, called xylem elements, present in roots, stem and leaves of plants. The prepared food material in a soluble form is carried through another channel, called phloem, from the leaves to all other parts of the body. DEMONSTRATION OF UPWARD MOVEMENT OF WATER Take a cut shoot of balsum plant and dip it in a dilute red coloured dye, eosin or safranin. Leave it for some time. Then, take sections from different parts of the stem starting from the tip region. You will observe red colour dye in the region of xylem (Figure. 5.5).

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Figure. 5.5 DEMONSTRATION OF THE TRANSPORT OF FOOD MATERIAL This is easily demonsttated by an experiment commonly known as 'girdling experiment'. Girdling of stem removes phloem tissue (Figure. 5.6). If a stem is girdled, the downward and upward movement of food material gets blocked. So, the trunk portion shows swelling in the area due to accumulation of food material.

Figure. 5.6: Girdling experiment

Formative Worksheet 1.

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Statement - I : Excretion and reproduction are seen in plants. Statement– II : Respiration and movement are see in earthworm. (A) Statement - I is true, Statement - II is false (B) Statement - I is false, Statement - II is true (C) Both statements are true (D) Both statements are false Statement - I : Any substance that can be broken down through chemical processes in the body of an organism to give energy is called food. Statement– II : The entire process of taking in food and drink by living organisms and using it for the purpose of growth and daily activities is called Nutrition. (A) Statement - I is true, Statement - II is false (B) Statement - I is false, Statement - II is true (C) Both statements are true (D) Both statements are false Which of the following is the type of nutrition? (A) Autotrophic (B) Heterotrophic (C) Aerobic (D) Both a and b Spot the error/s in the following statements and rewrite correcting them. A) Plants show heterotrophic nutrition. B) Animals show autotrophic nutrition. Pick the odd one out (A) Amoeba (B) Flatworm (C) Wood (D) Starfish

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Assertion (A): Green plants are autotrophs. Reason (R): They prepare their own food material by the process of photosynthesis. (A) A is correct and R is the correct explanation of A. (B) A is correct and R is not the correct explanation of A. (C) A is correct and R is wrong. (D) A is wrong and R is correct. Which of the following are the raw materials for photosynthesis? (A) Sunlight, oxygen, CO2 (B) Soil, water, CO2 (C) Light, water, CO2 (D) All Assertion (A): The process by which plants prepare their own food material is called Photosynthesis. Reason (R): This is called so because the food is prepared in the presence of sunlight. (A) A is correct and R is the correct explanation of A. (B) A is correct and R is not the correct explanation of A. (C) A is correct and R is wrong. (D) A is wrong and R is correct. Spot the error/s in the following statements and rewrite correcting them. A) The mode of nutrition whereby a living organism makes its own food is called heterotrophic nutrition. B) The process of using the energy in sunlight to convert water and carbon dioxide into carbohydrates (starch) and oxygen is called Photosynthesis. During photosynthesis, A is taken by leaves from atmosphere, B is absorbed by the roots. A and B reacts in the presence of C to produce D and E. If D is stored in different parts of the plant and E is released into atmosphere, then identify A B C D E. Identify the sources of the following requirements of photosynthesis.

7.

8.

9.

10.

11.

Chlorophyll  12.

12. 13.

14.

Light Energy 

Carbon Dioxide 

Water 

Assertion (A): More water absorbed through root hairs. Reason (R): Root hairs increase the surface area of roots. (A) A is correct and R is the correct explanation of A. (B) A is correct and R is not the correct explanation of A. (C) A is correct and R is wrong. (D) A is wrong and R is correct. CO2 enter the leave through (A) Epidermis (B) Endodermis (C) Stoma (D) Grana Statement - I : Water and soluble nutrients enter the root hair, pass through the secondary roots, and travel through the main root into the stems and reaches the leaves through structures called xylem. Statement– II: This starch is carried to various parts of the plants through structures called phloem. (A) Statement - I is true, Statement - II is false. (B) Statement - I is false, Statement - II is true. (C) Both statements are true. (D) Both statements are false. Statement - I: All plants contain chlorophyll. Statement– II: All plants can prepare their own food material by the process of photosynthesis. (A) Statement - I is true, Statement - II is false. (B) Statement - I is false, Statement - II is true. (C) Both statements are true. (D) Both statements are false.

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17.

Statement - I: A naturally occurring substance that gives a particular colour to a plant or an animal part is called a pigment. Statement– II: The green leaves are green due to the presence of chlorophyll. (A) Statement - I is true, Statement - II is false. (B) Statement - I is false, Statement - II is true. (C) Both statements are true. (D) Both statements are false. On an average there are about 500,000 chloroplasts per square millimeter of a leaf. If the area of a leaf of a bean plant is 10 cm2, then find the total number of chloroplast cells present in this leaf. Choose right order of transport of water and soluble nutrients in plants. (A) Leaves  stem  Main root  Secondary roots  Root hair (B) Root hair  Secondary roots  Main root  Stem Leaves (C) Root hair  Main root  Secondary root  Leaves Stem (D) Main root  Secondary root  Root hair  Stem Leaves Say True or False (A) Nutrition is not the basic life characteristics of living organisms. (B) Plants make their own food through a process called photosynthesis. (C) Most plants are autotrophic in nature. Label the parts in the following figure.

18.

Label the parts in the following figure.

14.

15.

16.

A

B

C

D

E

Conceptive Worksheet 1. 2. 3. 4. 5. 6.

Any substance that can be broken down through chemical processes in the body of an organism to give energy is called ________. The entire process of taking in food and drink by living organisms and using it for the purpose of growth and daily activities is called ________. There are two major modes of nutrition are _________ and __________. Green plants actually make their own food through a process called ___________. The mode of nutrition whereby a living organism makes its own food is called_________. Organisms that are able to synthesize their own food are termed _________.

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7. 8. 9.

The term photosynthesis was coined by _____________in 1883. The photosynthesis reaction is ___________. In photosynthesis process, ___________ is absorbed from the atmosphere is taken in by the leaves. In photosynthesis process, ___________ absorbed by the roots reacts with carbon dioxide in presence of sunlight to produce starch and oxygen. The end products of photosynthesis are __________ and __________. _________ is the process of using the energy in sunlight to convert water and carbon dioxide into carbohydrates (starch) and oxygen. _________is a green pigment present in the structures called chloroplasts of leaves in a plant. _________ is a naturally occurring substance that gives a particular colour to a plant or an animal part. CO2 is obtained from the atmosphere through small openings called _________in the underside of the leaves. Water and soluble nutrients enter the root hair, pass through the secondary roots, and travel through the main root into the stems and reaches the leaves through structures called ________. The starch is carried to various parts of the plants through structures called _______. Say true or false. a) Chlorophyll is present in the stroma of a chloroplast. b) Stomata are small openings present in the underside of the leaves.

10. 11. 12. 13. 14. 15. 16. 17. 18.

4. HETEROTROPHIC NUTRITION Most of plants on the Earth are in green. But there are certain plants which do not contain chlorophyll, neither in their leaves nor in any other part. Such plants, called non-green plants, are unable to prepare their own food. Such plants depend on green plants or on other living bodies for their nutrition. The mode of nutrition in which organisms cannot manufacture food and have to depend upon other plants and animals to obtain energy is called heterotrophic nutrition. Organisms which have heterotrophic mode of nutrition are called heterotrophs [heteron, (an)other; trophe, nutrition]. According to the mode of nutrition, heterotrophic plants are of the following types:

I. PARASITIC PLANTS Parasitic plants are those which absorb food from another growing green plant, called the host. Usually, parasitic plants develop special roots which penetrate into the tissues of the host plant. The prepared food is generally absorbed from the root or the stem of the host plant. Mistletoe has leathery, green leaves, and so they can make their own foo(D) But they depend on the host for minerals and water.

Cuscuta (Dodder)

Figure 5.7

Mistletoe

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Cuscuta (Dodder) has a short root and a long, thread-like stem. It twines around the host stem and sends branches around neighbouring stems giving the appearance of a mass of noodles or spaghetti. An Interesting Fact A parasitic plant, Rafflesia, bears the world’s largest flower. The flowers have five petals and may have a diameter of up to 106 cm, and weigh up to 10 kg. In a parasitic relationship, only the parasitic plant benefits.

Figure5.8 Does a parasitic do any harm to the host plant? Parasitic plants harm the host plant. Dodder and mistletoe are serious problems for plants. Dodder can cover woody plants and cause heavy damage to certain economically important crops. Mistletoe can become so abundant on a tree that most of the foliage is of the parasite and not of the host. Does this mean that the host plant is slowly killed off by the parasite? Scientists believe that parasitic plants rarely, perhaps never, kill the host plant, so that the parasite can continue to live off the host. II. SAPROPHYTIC PLANTS Saprophytic plants are usually whitish, but can have brightly coloured flowers. These plants have no green leaves; often they even have no leaves at all. So, how do saprophytic plants manage their nutrition? Saprophytic plants are plants that live off rotting material (sapros, rotting; phyton, plant). They grow in places with lots of rotting dead leaves, often in deep shade in tropical forests. Some examples are Indian Pipe and coral root. Indian Pipe is found commonly in Asia and throughout North America. Coral roots are found in forest environments around the world.

Figure 5.9 The roots of saprophytes contain living organisms called fungi. Fungi are capable of digesting dead and decaying matter. The fungi produce digestive juices which converts the dead and decaying matter into sugar which can be then used as food by these plants. Fungi are also called saprotrophs. Interesting Point According to the latest system of classification of organisms, fungi is no longer considered in plant kingdom. It is placed in a separate kingdom — Kingdom Fungi.

Figure 5.10 Mushrooms and toadstools are the most common examples of fungi.

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III. INSECTIVOROUS PLANTS These plants are usually green so they can make their own food. However, the soil in which they grow is sometimes deficient in certain nutrients, especially nitrogen. Hence, these plants need to obtain these nutrients from outside sources. Insectivorous plants are plants that derive some or most of their nutrients by trapping and consuming animals, mainly insects.

Pitcher plant

Drosera

Bladderwort

Venus flytrap

Figure 5.11 Examples i) In the pitcher plant, the leaf is modified to form a tubular pitcher like structure. The inside of the pitcher is lined with downward pointing hairs. These hairs do not allow any insect to climb back up and escape. The fluid at the bottom of the pitcher contains digestive juices that digest the insect. ii) The slender leaves of bladderworts bear a large number of very small, pear-shaped bladders. This opens a trapdoor and the prey is sucked in within one-thousandth of a second iii) The leaves of sundew (Drosera) have tentacles with drops of a sticky substance called mucilage at the ends; insects get stuck in this substance and become entangled. The helpless insect then gets digested. iv) The trap of the Venus flytrap is a highly modified leaf. On the inner surface (reddish here to attract insects) there are short, stiff hairs. When anything touches these hairs, the two lobes of the leaves snap shut in less than a second, IV. SYMBIOTIC PLANTS There are certain plants which live in association with other species and share their food resources. Both the types mutually gain from each other. Such plants are called symbiotic plants and the relationship is called symbiosis. A good example is lichens. • Lichens are an association between a fungus and a microscopic plant — green algae. The fungus obtains nutrients from the algae, and the fungus in turn provides shelter to the algae, so that it can grow in harsh conditions like rock surfaces where it would otherwise not survive.

Figure 5.12 Roots of certain plants such as peas contain bacteria called Rhizobium. It converts atmospheric nitrogen into plant-usable forms, e.g., ammonia. The plant in turn provides nutrient for the bacteria’s growth. Replenishment of Nutrients in the Soil Plants utilize the mineral nutrients, especially nitrogen present in the soil, for their growth. As a result there is a depletion of nitrogen in the soil over a period of time. Manure contains a lot of nitrogen apart from potassium and phosphorus. This is needed by the plant for healthy growth. •

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Formative Worksheet 19.

20.

21.

22.

23.

24.

25.

26.

27.

Statement - I : The mode of nutrition in which organisms cannot manufacture food and have to depend upon other plants and animals to obtain energy is called heterotrophic nutrition. Statement– II : Organisms which have heterotrophic mode of nutrition are called heterotrophs (A) Statement - I is true, Statement - II is false. (B) Statement - I is false, Statement - II is true. (C) Both statements are true. (D) Both statements are false. Spot the errors in the given statements and correct them. (A) Saprophytic plants are those which absorb food from another growing green plant, called the host. (B) Usually, parasitic plants develop special roots which penetrate into the tissues of the host plant. Statement - I: Cuscuta is a saprophyte. Statement– II: Mistletoe is a parasite. (A) Statement - I is true, Statement - II is false.(B) Statement - I is false, Statement - II is true. (C) Both statements are true. (D) Both statements are false. Match the following: Column-1 Column-2 a) Mistletoe p) Symbiotic b) Indian pipe q) Insectivorous c) Drosera r) Saprophytic d) Lichens s) Parasitic Assertion (A): Dodder can cover woody plants and cause heavy damage to certain economically important crops. Reason (R): Parasitic plants harm the host plant. (A) A is correct and R is the correct explanation of A. (B) A is correct and R is not the correct explanation of A. (C) A is correct and R is wrong. (D) A is wrong and R is correct. Assertion (A): Saprophytes cannot prepare their own food material by the process of photosynthesis. Reason (R): They do not have green leaves and hence cannot prepare their own food. (A) A is correct and R is the correct explanation of A. (B) A is correct and R is not the correct explanation of A. (C) A is correct and R is wrong. (D) A is wrong and R is correct. Assertion (A) : Though saprophytes do not perform photosynthesis, yet they can manage their nutrition. Reason (R): The fungi in the roots of saprophytes produce digestive juices which converts the dead and decaying matter into sugar which can be then used as food by these plants. (A) A is correct and R is the correct explanation of A. (B) A is correct and R is not the correct explanation of A. (C) A is correct and R is wrong. (D) A is wrong and R is correct. Spot the errors in the given statements and correct them. A) Saprophytic plants are usually blackish in colour. B) The roots of saprophytes contain living organisms called fungi. Fungi are capable of digesting dead and decaying matter. Give two examples for the following: A) Autotrophic plants ________________ ________________ B) Parasitic plants ________________ ________________ C) Saprophytic plants ________________ ________________ D) Insectivorous plants ________________ ________________ E) Symbiotic plants ________________ ________________

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Statement – I: Insectivorous plants are usually green but they canot make their own food. Statement– II: The soil in which the insectivorous plants grow are deficient in certain nutrients, especially nitrogen. (A) Statement - I is true, Statement - II is false. (B) Statement - I is false, Statement - II is true. (C) Both statements are true. (D) Both statements are false. Statement - I: Insectivorous plants are plants that derive some or most of their nutrients by trapping and consuming animals, mainly insects. Statement– II: In the pitcher plant, the leaf is modified to form a tubular pitcher like structure. The inside of the pitcher is lined with downward pointing hairs. (A) Statement - I is true, Statement - II is false. (B) Statement - I is false, Statement - II is true. (C) Both statements are true. (D) Both statements are false. Identify the following insectivorous plants. A) The leaf in this plant is modified to form a tubular pitcher like structure. B) The leaves of these plants bear a large number of very small, pear-shaped bladders. C) The leaves of this plant have tentacles with drops of a sticky substance called mucilage at the ends. D) The leaf of this plant is modified into a big trap. Statement - I: The relation in which both the plants are benefited is called symbiosis. Statement– II: The relation in which a one plant absorbs food from another growing green plant is called parasitism. (A) Statement - I is true, Statement - II is false. (B) Statement - I is false, Statement - II is true. (C) Both statements are true. (D) Both statements are false. Spot the errors in the given statements and correct them. a) Parasitism benefits both the plants in the relation. b) Symbiosis harms both the plants in the relation. Assertion (A): The relation between fungus and green algae is parasitic in nature. Reason (R): The relation between fungus and green algae is symbiotic in nature. (A) A is correct and R is the correct explanation of A. (B) A is correct and R is not the correct explanation of A. (C) A is correct and R is wrong. (D) A is wrong and R is correct.

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Conceptive Worksheet 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29.

The mode of nutrition in which organisms cannot manufacture food and have to depend upon other plants and animals to obtain energy is called ____________nutrition. Organisms which have heterotrophic mode of nutrition are called __________. Heterotrophic plants are classified in to ____________, ____________, ____________ and ____________. Parasitic plants are those which absorb food from another growing green plant, called the _______. ________ and _________ are examples of parasitic plants. A parasitic plant, ___________, bears the world’s largest flower. Saprophytic plants are usually ____________, but can have brightly coloured flowers. Indian Pipe and coral root are the examples for __________ plants. Indian Pipe is found commonly in __________and ___________. The roots of saprophytes contain living organisms called __________. ______________are plants that derive some or most of their nutrients by trapping and consuming animals, mainly insects.

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In the ____________, the leaf is modified to form a tubular pitcher like structure. The leaves of ____________have tentacles with drops of a sticky substance called mucilage at the ends. Roots of certain plants such as peas contain bacteria called __________. Parasitic plants derive food from the host by modified _________ ( roots /leaf) __________ (Mushrooms / Lichens) are an association between a fungus and an algae. Peas have a symbiotic relationship with a/an _____________. (fungus / algae / bacteria/virus)

5 COMPONENTS OF FOOD — NUTRIENTS IN FOOD There are seven essential components or substances called nutrients in our food. These are: 1. Carbohydrates 2. Fats 3. Proteins 4. Mineral salts 5. Vitamins 6. Water 7. Roughage (Fibre) Of these carbohydrates, proteins and fats are the three main components. CARBOHYDRATES These are the common energy-giving compounds. Foods rich in carbohydrates are potato, sweet potato, bread, rice, wheat, honey, common sugar, jaggery (gur) and milk. Most processed foods like pizza, burger, jams, jellies, and noodles are rich in carbohydrates. Macronutrients Nutrients that are required by our body in large amounts and form the main bulk of our diet are called macronutrients. Carbohydrates, fats and proteins are macronutrients FATS These are also energy-giving foods, producing more energy than carbohydrates. Fat-rich foods are (i) milk products such as butter and cheese, (ii) vegetable oils such as coconut oil, groundnut oil, (iii) nuts, (iv) milk and (v) animal fat from meat. Fats provide more than double the energy provided by carbohydrates or proteins. PROTEINS These are body-building foods. Proteins help the body in its growth and repair of body cells and tissues, protect and help the body to fight against infections and regulate body functions. Protein sources of plant origin include pulses (soyabean, peas) and to a lesser extent cereals. Meat, eggs, cheese, milk and fish provide proteins of animal origin. Table 5.2: Food nutrients — functions, sources and daily needs Nutrient in food Roles/Functions Sources Daily needs 1. Carbohydrates Main source of energy Wheat, Rice, Maize, Adult person doing light (Energy-providing, Potato, Bread, Honey, work needs 600 g. foods) Common sugar, Milk, Banana 2. Proteins (i) For body building Pulses (peas, Adults require 1 g for (Body-building (ii) For digestion soyabean), Egg, Meat, every 1 kg of body weight; foods) (iii) Growth Paneer, Cheese, children, require 1.46 g for (iv) Energy Groundnut, Milk, Fish every 1 kg of body weight; (v) Body protection women during pregnancy from infections and lactation period also require more proteins. 3. Fats (i) Energy source Butter, Cheese Adults require 70 - 80 g (Energy-providing (ii) Taste and flavour Vegetable oil (coconut foods) (iii) Reserve food source oil, Groundnut oil, Sunflower oil), Nuts, Milk, Animal fat from meat

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5. Roughage

(i) Medium for body reactions (ii) Transport of substances (iii) Digestion (iv) Waste removal (v) Maintenance of constant body temp (i) Being rich in fibre, Spinach, cabbage, it absorbs water and beans, peas, cereals, helps in food wheat, lady's-finger movement inside the intestine (ii) Helps in bowel movement by preventing constipation

MINERAL SALTS Mineral salts are important for various body functions. They are required in small quantities and are obtained from the food we take in. Minerals have no energy value. Rich sources are milk, cheese, green leafy vegetables (like spinach), pulses, meat and eggs. Salts of calcium and phosphorus are required for making bones and teeth hard and for promoting blood clotting. Iron is essential for forming haemoglobin, a component of our blood, the deficiency of which causes anaemia. Green leafy vegetables, eggs, groundnuts, and liver are good sources of iron.Iodine, another mineral, controls the functioning of an important gland, thyroid. Deficiency of iodine leads to goitre. Iodised salt, fish and seafood are the sources of this mineral. Table 5.3: Minerals — sources, functions, deficiency effects and daily needs Chemical Deficiency effect / Sources Functions Daily adult needs element disease Bread, flour, cheese, Bone and teeth Brittle bones, 500 mg (more in milk, green leafy formation, Blood Excessive bleeding, growing children 1. Calcium vegetables, pulses, clotting, Muscle Bad muscle and pregnant eggs, meat activity movement women) Bone and teeth Fish, eggs, meat, formation, Nucleic Bad bones and teeth 2. Phosphorus milk, cheese, 1.4 g acid formation, Body weakness .potatoes, bread Energy transfer, ATP Osmocontrol-blood Beef, eggs, milk, 3. Potassium and tissue fluid, Nerve 2.0 g cheese, potatoes impulse conduction Osmocontrol-blood and tissue fluid, Nerve Salt, cheese, bread, Dehydration, 4. Sodium impulse conduction, 4.0 g butter extreme weakness Gastric juice, HCI acid Cheese and green Activity of muscles Energy transfer, Bone 5. Magnesium vegetables, and and nerves, 200-300 mg and teeth formation most foods weakness

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6. Iron

Bread, flour, meat, liver, eggs, green leafy vegetables

94 Blood haemoglobin formation, Muscle myoglobin formation Enzyme activity

Anaemia

20-30 mg

7. Iodine

Thyroid gland Sea fish, iodised salt function

Goitre (enlarged thyroid), Abnormal metabolism

0.5 mg

8. Fluorine

Sea fish, tea, and Bone and teeth some drinking water formation

Dental cavities

1.0 mg

VITAMINS Vitamins are neither body-building nor energy-giving foods, but are very important for proper functioning of our bodies. They are required by the body in very small quantities. Green leafy vegetables, fruits, milk, eggs and cheese are rich in vitamins. Micronutrients Nutrients that are required by our body in small quantities are called micronutrients. Vitamins and minerals are the micronutrients in our food.

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Table 5.4: Vitamins — sources, functions, deficiency disease and daily needs Essential Deficiency Vitamin Sources Daily adult needs for disease Milk, butter, cheese, Night-blindness Good Vitamin A tomatoes, carrots, cod (poor night 600 micrograms eyesight liver oil, yellow fruits vision) Thiamine - 0.5 mg/1000 kcal Vitamin B of energy intake Beri-beri Milk, eggs, cheese, Riboflavin - 0.6 mg/1000 kcal complex Digestion, (nervousness, (mixture of meat, liver, husk of of energy intake growth loss of appetite, several cereals and pulses Niacin - 6.6 mg/1000 kcal of paralysis) vitamins) energy intake B6 - 2 mg / day Scurvy Vitamin C Citrus fruits (orange, (bleeding of Muscles and (ascorbic lemon, Jime), green gums and 40-60 mg teeth acid) vegetables, tomatoes swelling of joints) Rickets Vitamin D Milk, yellow of egg, (decaying teeth, Strong (produced liver, fish liver oil, weak bones) in bones and 2.5 micrograms by sun in especially sunlight, cod children and teeth skin) liver oil. osteomalacia in adults Vitamin K (made by Leafy green vegetables Blood Haemorrhage bacteria in 0.03 mg/kg body weight (spinach, cabbage) clotting (bleeding) large intestine)

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WATER Water is indispensable. About 70 per cent of our body weight is that of water. It helps the body in various functions. It is a means of transporting substances in the organism. It helps to maintain a constant body temperature. Water helps in the absorption of food and excretion of waste products from the body. Our body needs 2-3 litres of water every day. Many invertebrates, some birds and desert animals do not need to drink water as they produce enough 'metabolic' water for their use from the breakdown of food they consume. ROUGHAGE (FIBRE) Fibre is found in vegetables, fruits, beans and cereals. It has no nutritive value, but prevents constipation and is necessary for proper functioning of the digestive system. 6. TYPES OF FOOD BASED ON THEIR ROLE Foods, on the basis of their role in the body, are classified into three major food groups: (i) energy-giving foods (like carbohydrates and fats) (ii) body-building or growth-promoting foods (like proteins), and (iii) protective foods (vitamins and minerals). No single food can supply all the components required for proper nutrition. Food items included under these three food groups are given in Table 5.4 and shown in Figure. 5.13.

Figure. 5.13: Types of foods Table 5.5: Food items included in three major food groups. FOOD GROUPS Energy-giving foods Body-building foods Protective foods Cereals (wheat, rice, maize) Milk Fruits Sugar Pulses (Peas, soyabean) Green leafy vegetables Jaggery (gur) Cheese (spinach, cabbage, Potato Eggs cauliflower) Sweet potato Fish Other vegetables Honey Meat (carrot, tomato) Oils and fats Milk Eggs

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COMPOSITION OF SOME FOOD ITEMS Table 5.6 gives the per cent composition of nutrients per 100 g of different food items. Table 5.6: Composition of nutrients in different food items Carbohydrates S.No. Food item Proteins (%) Fats (%) (%) 1. Rice, wheat (cereals) 10 70 Traces 2. Milk/curd 3 3 3 3. Curd 3 3 3 4. Pulses 20 60 Traces 5. Apple 0.5 15 Traces 6. Orange 1 11 Traces 7, Ghee / Butter/Oil Traces Traces 95-100 8. Sugar –– 100 –– 9. Eggs 13 Traces 13 10. Meat / Fish 20 Traces Traces 11. Nuts 20 20 50

8. FOODS AND THEIR ENERGY VALUES When food is eaten, it is broken down into simpler compounds, and in this process energy is produced. The energy producing life function in living organisms is known as respiration. For instance, when sugar, a simple form of carbohydrate, is burned in air, it produces heat and light as energy. Carbon dioxide and water are also produced as by-products. Sugar + Oxygen   Carbon dioxide + Water + Energy C12H22O11 + 12O2   12CO2 + 11H2O + Energy Similar reaction takes place, if glucose is burnt in place of sugar. C6H12O6 + 6O2   6CO2 + 6H2O + Energy Glucose This process occurs inside our body too, during the process of respiration, but with following modifications: 1. Inside the body, the breakdown of glucose or sugar does not take place in one step as in burning. Instead, it occurs in several steps. 2. Secondly, the energy is also released in small packets, without raising body temperature. 3. Thirdly, inside the body, certain protein molecules, called enzymes, take part in the process of breaking down of food molecules. This does not happen in burning. Thus, one of the major functions of food is to produce energy. Different foods produce different quantities of energy. The energy jn foods is measured by a unit called Calorie. Note: 1 kilocalorie (kcal) = 1000 calories 1 calorie =4.18 joule 1000 joules = 1 kilojoule (kJ) The energy value of foods Fats : 9 kcal/gram or 37 kilojoules Carbohydrates : 4 kcal/gram or 17 kilojoules Proteins : 4 kcal/gram or 17 kilojoules Water is the only nutrient that supplies no energy. Calorific values of some individual food items are given in Table 5.6. Table 5.7 gives the energy used up in different activities.

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Table 5.7: Calorific value of some foods Table 5.8: Energy consumption in different activities Food Amount Calories Energy used Egg (boiled) One 75 Activity (kilojoules/min) Bread (enriched) One slice 70 Walking to school 10 Rice (cooked) 100 grams 500-600 Fast walking 20 Chapatti One 150 Slow cycling 20 Milk (toned) 182 ml. (one cup) 125 Jogging 25 Milk (full cream) 182 ml. (one cup) 240 Swimming 35 Butter One tablespoon 100 Fast cycling over 40 Sugar One tablespoon 50 Disco dancing over 40 Apple Medium-sized 80 Sitting idle 4-5 Orange Medium-sized 70 Eating 5-6 Banana One large 100 Driving 12 Mango 100 grams 50 Grapes 100 grams 70 Meat 50 grams 100 WHO NEEDS MORE FOOD? • A person doing hard physical work requires more energy. So, a greater carbohydrate content is required. • Pregnant women need more nutrients. The child growing inside, needs (i) proteins for growth, (ii) calcium for the bones, (iii) iron for the blood. • For breast-feeding the baby, the nursing mothers need more of (i) calcium, (ii) protein-rich milk, (iii) vitamins. • Growing children need more food in proportion to their body weight.' See Table 5.8 to know how much energy is spent in different activities which children generally perform. Table 5.9 shows the average daily requirements of energy by people of different age groups. Different people need different amounts of food energy. Their calorie needs are different. Some people need more calories than others. Table 5.9: Recommended Average Energy Requirements Energy Required per day Group (calories) Children 1-3 years 1240 4-6 years 1690 7-9 years 1950 Adolescents 10-12 years (males) 2190 (females) 1970 13-15 years (males) 2450 (females) 2060 16-18 years (males) 2640 (females) 2060 Adults Males (light work) 2425 (moderate work) 2875 (heavy work) 3800 Females (light work) 1875 (moderate work) 2275 (heavy work) 2975 Lactation

Pregnancy (first 6 months) (6-10 months)

+300 +550 +400

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The number of calories a person needs depends on many things. Here are a few: (i) Age: Young people need extra energy because they are very active. Extra calories are also needed for their growth. (ii) Weight and Size: Tall people need more calories than the small ones. (iii) Activity: An active adult needs more calories than an inactive adult. For example, a labourer needs more calories than a clerk. Adults who play sports need extra calories. (iv) Temperature: The body uses energy to maintain a normal temperature. In cold climates, extra calories are required to maintain this temperature. 9. BALANCED DIET Our body requires balanced quantities of proteins, carbohydrates, fats, vitamins and minerals for its proper growth and maintenance. Deficiency of one or the other nutrient in the food leads to poor health, and makes it prone to disease. Deficiency of food in terms of quantity, or undernutrition as it is called, may lead to starvation. Inadequate diet results in the loss of weight, and the person's digestive system gets affected. Often a person suffers from diseases due to improper intake of food. The food taken in may be deficient in essential nutrients due to wrong food habits. This is known as malnutrition.

Figure. 5.14: Balanced diet ensures health Some eat only rice while others prefer chapaties or bread. Illiteracy adds to the problem. A mixed diet containing all the essential nutrients in the right proportion is necessary for body's proper growth. Such a diet is known as a balanced diet. A balanced diet, thus, provides the body with (a) all the essential nutrients, (b) all the materials necessary for proper growth and repair of body, (c) energy required by the body to carry out its life activities, and (d) extra nutrients to withstand short period of fasting. Over-eating may also lead to diseases. Obesity is one such disease. This often leads to other problems like heart diseases and high blood pressure. Also, a balanced diet is related to one's age, health and occupation. For example, a labourer needs more carbohydrates and fats in his diet which would provide him more energy. A young child should take more proteins, as they help in body building.

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10. FOOD ADDITIVES When some foods are manufactured, chemicals are put in them. These chemicals are called food additives. Food additives have no nutritional value. They are added for a number of reasons. 1. As colourings: These make the food look more attractive. Tinned peas arid strawberries, for example, owe their colour to these chemicals. 2. As preservatives: These slow down the rate at which foods go bad and keep the food fresh. Thus, the foods can be carried to long distances. 3. As flavourings: These restore the flavour of the food that is often lost when it is processed. Most additives are harmless. Some additives may cause headache, asthma, mage to organs such as the liver and kidneys and even cancer. 11. FOOD FADS Food forms an essential part of our daily life. A considerable part of our time and money is spent in selecting and purchasing foods. We are exposed to a variety of information and views about the foods and their nutritional value through newspapers, magazines, books, advertisements id through conversation. Our views are influenced by what we hear and see. Very often, expensive foods are considered more nutritious and good for health than less expensive foods. Similarly foods which are difficult to obtain are considered better than easily available ones. Such wrong notions prevail in our society. Misinformation or wrong and unscientific information about food is termed food fads. Some of the food fads have arisen in due to certain customs, traditions and wrong beliefs. Expensive vs. inexpensive food - grapes vs. spinach Let us take the example of two food items -- the expensive grapes and the inexpensive leafy green vegetable spinach (palak). The nutrients present in 100 grams of grapes and spinach are listed in given table. Spinach contains much more proteins, fats, minerals and vitamins than grapes. It clearly proves that spinach is more nutritious than the costlier grapes. Similarly, cheaper fruits like bananas and guavas have a greater nutritive value than more expensive fruits like grapes and pomegranates. Table 5.10: Nutrients in Grapes and Spinach Nutrients in Grapes and Spinach Nutrient Grapes Spinach Protein 0.5 g 2.0 g Fat 0.3 g 0.7 g Carbohydrate Nil 2.9 g Minerals 0.6 g 1.7 g Vitamin A Nil 3.0 mg Vitamin C 1.0 mg 30.00 mg Fibre (roughage) 2.9 g 0.6 g Energy 17.0 26.0 (calories perl 00 g) FOOD FADS ABOUT CEREALS AND CEREAL PRODUCTS 1. There is a wrong notion that starchy foods, such as rice and bread, are rich in calories. In an attempt to reduce weight, many persons reduce or cut down their intake of cereals from their diet. What is to be remembered is that cereal foods such as chapatti or bread are not a very high source of energy. The calories come from the foods added to them such as ghee, butter, cheese, jam, sugar and chutney etc. It is these high-calorie foods that need to be avoided.

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Another wrong notion is that weight reduction is possible by eating bread or chapatti instead of rice. It is well known that both rice and wheat contain about the same number of calories, and so eating one and leaving the other one will not make any difference. It is the total calorie intake that needs to be reduced for effective weight reduction.

FOOD FADS ABOUT OILS AND FATS Some manufactures claim and suggest that people should use a particular brand of vegetable oil, as it has a high content of poly-unsaturated fatty acids (PUFA) and contains no cholesterol, and is thus beneficial for heart patients. The fact is that all vegetable oils (except olive and coconut oils) contain a high amount of PUFA and also do not contain any cholesterol. By stating that a particular brand of vegetable oil contains no cholesterol is intended to misguide the layman to think that other brands of vegetable oils contain cholesterol. These claims make a person feel that he can safely consume as much oil as he wants without any problem. FOOD FADS ABOUT WHITE EGGS AND BHLNDL 1. White eggs are better than brown ones. There is no truth in it. Both types of eggs have the same amount of nutrients. 2. Eating bhindi (lady's-fmger) makes a student good in mathematics. There is no truth in this belief. 12. GOOD FOOD HABITS For maintaining good health, we need to develop and maintain good food habits. These include: 1. Eat balanced diet, keeping in mind your age, health and occupation. 2. Eat clean food, kept protected from dust, house flies and mosquitoes. 3. Eat properly cooked fresh food. 4. Avoid fried foods as far as possible. 5. Use clean utensils. 6. Take adequate amounts of green salad, green vegetables and fruits in your diet. 7. Consume simple digestible food. 8. Drink large quantities of clean filtered water. 9. Chew food well.

Formative Worksheet 34.

35.

36.

37.

Carbohydrates and fats are important nutrients required by the body. What is their primary function? (A) Keeping the bones healthy (B) Providing energy to the body (C) Keeping the eyes and skin healthy (D) Protecting the body against diseases Plants use carbon dioxide and energy from sunlight to form complex molecules. Plants prepare food in the form of (A) Amino acids (B) Carbohydrates (C) Sulfates (D) Fats Athletes are advised to eat banana and drink fruit juice as these are rich sources of i and provide ii . The information in which alternative completes the given statement? (A) i- carbohydrates ii-energy (B) i-proteins ii-protection (C) i- carbohydrates ii-protection (D) i-proteins ii-energy Which of the following pairs of food items is rich in fats? (A) Gram and fish (B) Rice and mango (C) Pulses and potatoes (D) Ground nut and butter

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Foods rich in i and ii are known as energy-giving foods. These nutrients provide energy to the body. The information in which alternative completes the given statement? (A) i-fats ii-proteins (B) i-proteins ii-vitamins (C) i-vitamins ii-carbohydrates (D) i-carbohydrates ii-fats Which nutrient helps in the growth and repair of the body? (A) Fats (B) Carbohydrates (C) Proteins (D) Roughage Proteins are important nutrients required by the body. The primary function of proteins is to (A) Provide energy to the body (B) Help the body remove undigested food (C) Protect the body against various diseases (D) Help in the growth and repair of the body i and ii are the major nutrients present in food. The information in which alternative completes the given statement? (A) i- Carbohydrates ii- proteins (B) i- Proteins ii-water (C) i- Carbohydrates ii- water (D) i-Roughage ii-carbohydrates Mineral salts are required by the body for (A) Providing energy (B) Growth and repair (C) Healthy teeth and strong bones (D) Proper functioning of intestines Minerals are required by the body in small amounts. The primary function of minerals is to help the body (A) Fight diseases (B) Get rid of undigested food (C) Use calcium for bones and teeth (D) Grow and remain healthy Which nutrient helps the body fight diseases? (A) Proteins (B) Vitamin A (C) Vitamin C (D) Fats _____i______helps the body fight against various diseases, while _____ii______helps the body uptake calcium for bones and teeth. The information in which alternative completes the given statement? (A) i- Vitamin B ii- Vitamin A (B) i- Vitamin A ii- Vitamin C (C) i- Vitamin C ii- Vitamin D (D) i- Vitamin D ii- Vitamin B Which of the following fruits is a good source of vitamin C? (A) Pear (B) Peach (C) Prune (D) Papaya What is the primary function of Vitamin D? (A) Providing energy to the body (B) Keeping the eyes and skin healthy (C) Helping the body get rid of undigested food (D) Helping the body use calcium for bones and teeth What is the main function of vitamin A in the body? (A) To add bulk to food (B) To keep skin and eyes healthy (C) To provide energy to the body (D) To help in calcium uptake by bones The given equation represents the process of photosynthesis.

39. 40.

41.

42.

43.

44. 45.

46. 47.

48.

49.

Sunlight Carbondioxide + i   ii + Oxygen Chlorophyll

50.

51.

The information in which alternative completes the given equation? (A) i- Water ii- Carbohydrate (B) i- Carbohydrate ii-urea (C) i-Urea ii-Fats (D) i-Fats ii-Water Which of the following nutrients is not digested by the digestive system but required for the correct function of the intestines? (A) Carbohydrates (B) Vitamins (C) Fibers (D) Fats Plants are the sources of roughage. The primary function of roughage is to (A) Keep the skin healthy (B) Provide energy to the body (C) Help the body fight diseases (D) Help the body get rid of undigested food

Nutrition In Plants and Animals 52.

53.

54.

55.

56. 57.

58.

59. 60.

102

Food contains _____i______and _____ii______along with the major nutrients. Apart from the nutrients, these components are also required by the body. The information in which alternative completes the given statement? (A) i-water ii-fats (B) i-fats ii-vitamins (C) i-vitamins ii-roughage (D) i-roughage ii-water Dietary fibre or roughage is a very important part of a balanced diet. The main function of roughage is to (A) Relieve constipation (B) Provide energy during stress (C) Form the structural framework of the body (D) Form the structural components of genetic materials Plants use carbon dioxide and energy from sunlight to form complex molecules. Plants prepare food in the form of (A) Amino acids (B) Carbohydrates (C) Sulfates (D) Fats i and ii are nutrients that provide the maximum amount of energy to the body. The information in which alternative completes the given statement? (A) i-fats ii-proteins (B) i-proteins ii-vitamins (C) i-vitamins ii-carbohydrates (D) i-carbohydrates ii-fats Some food substances are known as body building foods. These food substances are rich in (A) Fats (B) Proteins (C) Vitamins (D) Carbohydrates Athletes are advised to eat banana and drink fruit juice as these are rich sources of i and provide ii . The information in which alternative completes the given statement? (A) i- carbohydrates ii- energy (B) i-proteins ii-protection (C) i- carbohydrates ii-protection (D) i-proteins ii-energy _____i______ are required for _____ii_____ and for maintaining its good health. The information in which alternative completes the given statement? (A) i- Minerals ii- the proper growth of the body (B) i- Roughage ii- the proper growth of the body (C) i- Minerals ii- providing energy to the body (D) i- Roughage ii- providing energy to the body Which nutrient helps the body to use calcium for bones and teeth? (A) Carbohydrates (B) Vitamin A (C) Fats (D) Vitamin D The primary function of vitamin A is to (A) Provide energy to the body (B) Keep the eyes and skin healthy (C) Help the body fight diseases (D) Help in the growth and repair of the body

Conceptive Worksheet 36.

37.

Michael is told by his teacher that food is broken down into smaller pieces in the human body. Nutrients from food are absorbed during this process. The process referred to in the preamble is performed by the (A) Respiratory system (B) Excretory system (C) Digestive system (D) Nervous system A biology class was divided into four groups and each group was asked to grow a plant. Group I watered their plant with water collected from the school laboratory tap. Group II watered their plant with water containing dissolved nutrients. Group III watered their plant with water collected from a polluted lake.

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38. 39.

40. 41. 42.

43.

44.

45. 46.

47.

Group IV watered their plant with water containing dissolved salt. The group whose plant will grow the best, is (A) I (B) II (C) III (D) IV Which nutrient helps in the growth and repair of the body? (A) Fats (B) Carbohydrates (C) Proteins (D) Roughage Foods rich in i and ii are known as energy-giving foods. These nutrients provide energy to the body. The information in which alternative completes the given statement? (A) i- fats ii- proteins (B) i- proteins ii- vitamins (C) i- vitamins ii- carbohydrates (D) i- carbohydrates ii- Fats Which mineral is required to keep the bones healthy? (A) Iron (B) Iodine (C) Sodium (D) Calcium Which nutrient keeps the skin and eyes healthy? (A) Vitamin A (B) Vitamin C (C) Fats (D) Proteins What is the primary function of vitamin C? (A) Providing energy to the body (B) Keeping the skin and eyes healthy (C) Helping the body fight diseases (D) Helping the body get rid of undigested food Wrestlers and body builders need to eat food items rich in _____i______, which help them in keeping their bodies strong while food items rich in _____ii______provide protection against diseases. The information in which alternative completes the given statement? (A) i- carbohydrates ii- proteins (B) i- proteins ii- vitamins and minerals (C) i- carbohydrates ii- vitamins and minerals (D) i- proteins ii- fats Roughage is mainly provided by plant-derived products in food. What is the main function of roughage in our body? (A) To provide energy to the body (B) To keep eyes and skin healthy (C) To help the body fight various diseases (D) To help the body get rid of undigested food Which component of food helps the body get rid of undigested food? (A) Water (B) Roughage (C) Minerals (D) Fats The alternatives in the given table can be correctly matched as Column A Column B i Carbohydrates a Protection ii Proteins b Digestion iii Roughage c Strength iv Vitamins d Energy (A) i → d, ii → b, iii → c, iv → a (B) i → a, ii → b, iii → c, iv → d (C) i → d, ii → c, iii → b, iv → a (D) i → b, ii → a, iii → d, iv → c The given flowchart represents some nutrients which are essential for our body.

The information in which alternative completes the given flowchart? (A) i-water ii-roughage (B) i-roughage ii-sprouts (C) i-sprouts ii-water (D) i-water ii-sweets

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SNAP SHOT 1.

Food is required by the body (i) for producing energy required for various life activities, (ii)for growth, (iii) for repair of damaged or injured body parts, and (iv) for protection from diseases and infection,

2.

There are six essential dietary constituents called nutrients in food -- carbohydrates, proteins, fats, mineral salts, vitamins and water. Roughage is another important constituent.

3.

Foods, on the basis of function, are classified into three types - - energy-providing foods (carbohydrates and fats), growth-promoting or body-building foods (proteins), and protective foods (proteins, minerals and vitamins).

4.

Carbohydrates are energy-providing foods and include sugars and starches.

5.

Fats are also energy-providing foods.

6.

Proteins are body-building foods required for growth and repair of body cells. Body functions too are regulated by proteins.

7.

Minerals are chemical elements required by the body in small quantities for proper growth and body functions.

8.

Vitamins are neither body-building nor energy-providing foods, but are very important for proper functioning of our bodies. Deficiency of vitamins leads to diseases.

9.

Water makes up about 70 per cent of our body weight. It helps in transport of substances within the body, absorption of food and excretion of waste products from the body.

10.

Roughage is essential for proper functioning of the digestive system.

11.

Food is used by organisms to produce energy, which is needed for performing life activities.

12.

The energy in foods is measured in units called calories.

13.

Fats release more energy than carbohydrates or proteins.

14.

A balanced diet (a mixed diet containing all the essential nutrients in their correct proportions) is necessary for body's proper growth and functioning.

15.

Chemicals called additives are put in foods during their manufacture.

16.

Many food fads are prevalent about various food items amongst people.

17.

Food provides energy and materials for growth and maintenance of living organisms.

18.

Green plants are autotrophs. Non-green plants and animals are heterotrophs.

19.

(a)

The process by which green plants prepare their own food is called photosynthesis.

(b)

Photosynthesis can be summarised as follows: Light Carbon dioxide + Water   Carbohydrates + Oxygen Chlorophyll (food)

(c) Photosynthesis takes place mostly in green leaves which contain green pigment, chlorophyll inside chloroplasts (d)

Gaseous exchange in the leaves takes place through tiny pores called stomata

20.

Macronutrients required by plants are carbon, hydrogen, oxygen, nitrogen, phosphorus, sulphur, potassium, calcium, iron and magnesium.

21.

Micronutrients are copper, zinc, boron, manganese and molybdenum.

22.

In plants, transport occurs through xylem and phloem. Movement of water and mineral occurs through

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Summative Worksheet I. 1.

2.

3.

4.

5.

II. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23.

III. 1. 2. 3. 4. 5. 6. 7.

Multiple Choice Questions - Tick mark (/) the correct choice. Which one is an insectivorous plant? (a) Lichens (b) Venus fly-trap (c) Mushrooms (d) Yeast Two different organisms living together and both benefiting from each other, are known as (a) Saprophytic (b) Symbiotic (c) Parasitic (d) Heterotrophs The process, by which green plants prepare their own food is known as (a) Photosynthesis (b) Respiration (c) Symbiosis (d) None of these The green colour pigment in the leaves is (a) Chlorophyll (b) Anthocyanin (c) Protoplast (d) Chloroplast Tiny pores on the lower surface of leaf are (a) Lamina (b) Stomata (c) Chlorophyll (d) Leaf stalk Fill in the blanks: The body-building function of food is related to the presence of ___________. Energy-giving foods are carbohydrates and ___________ Nutrient balance can only be achieved by supplying all nutrients in the correct ___________ and ___________ proportions. ___________ and ___________ are the major sources of carbohydrates in our diets. Water makes up approximately ___________ percent of the total weight of an adult. Pulses are rich in ___________. Minerals present in bones and teeth are ___________ and ___________. The main function of carbohydrates is to provide ___________ to the body. The vitamin necessary for blood clotting is ___________. The vitamin synthesized by the skin in sunlight is ___________. Deficiency of iodine leads to ___________ in man. Food energy is measured in units called ___________. We get most of our calories from and ___________. Citrus fruits are rich in vitamin ___________. Deficiency of vitamin C causes a disease called ___________. To stay healthy, we should consume ___________ Two foods that have a lot of starch are ___________ and ___________. Green plants use ___________ and ___________ to prepare food. During photosynthesis, the gas released is ___________. The presence of starch can be tested by using ___________. On testing with iodine, starch turns ___________ in colour. The pigment ___________ is present inside certain structures called ___________ in a leaf. The small pores present on the leaves through which carbon dioxide enters the leaf are called ___________. Which of the following statements are true (T) and which ones are false (F)? Mark Tor F.: You use more calories when you swim than when you walk. [ ] Proteins supply the maximum calories to our bodies. [ ] A diet that supplies enough calories is a balanced diet. [ ] We can live without proteins. [ ] Iron is an important part of blood. [ ] Potato is rich in carbohydrates. [ ] Iodine solution is used to test the presence of fats in the food. [ ]

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8. 9. 10. 11.

The chlorophyll pigment enables the plant to use sunlight. If there were no plants, the amount of oxygen in the air would go on decreasing. Green plants prepare their food by using oxygen and water. Photosynthesis occurs only in chlorophyll containing parts of the plant.

IV. 1. 3. 5. 7. 9. 11.

Define the following: Food Nutrient Carnivores Herbivores Symbiotic nutrition Heterotrophic nutrition

V. 1. 2. 3. 4. 5.

8. 9. 10.

Name the following: Energy-providing foods Growth-promoting foods Protective foods Some food items that is rich in calcium. Three sources of each of the following nutrients: (a) Carbohydrates (b) Fats (c) Proteins Diseases caused by the deficiency of (a) Vitamin A (b) Iron (c) Vitamin C (d) Iodine Mineral supplied by the following foods (a) Seafood (b) Milk (c) Table salt The pigment which gives green colour to leaves. Gas used in photosynthesis. One plant which can eat insects.

VI. 1. 2. 3. 4. 5. 6. 7. 8.

How do you test for — Proteins in food Carbohydrates in food Water in food Fats in food Starch in a green leaf after photosynthesis Starch in food items The role of chlorophyll in photosynthesis The role of light in photosynthesis

VII. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Answer the following: List three functions of food. Name the various components of food. What is roughage? How is it important for the body? Why is water essential for our bodies? What is a balanced diet? What is obesity? Give a brief account of three food fads. Mention five good food habits. Mention the roles of different components of food. What are the average daily requirements of proteins in case of children and adults? Why do children need more proteins than adults? Why should we include vitamins in our diet? Mention the sources of different vitamins.

6.

7.

11.

2. 4. 6. 8. 10. 12.

[ [ [ [

] ] ] ]

Nutrition Autotrophic nutrition Omnivores Insectivorous plants Saprophytic nutrition Parasitic nutrition

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13. 14. 15. 16. 17. 18. 19. 20. 21. 22.

Which one offers you more energy? (a) one large banana or 100 grams of grapes (b) one egg or one teaspoon of butter. Which substances eaten by man have little or no nutrient value? Why do living organisms need food? Describe the role of chlorophyll in photosynthesis. Define nutrition. What are the various types of nutrition? Which part of the plant body takes in water? Where from does carbon dioxide enter a plant? What is produced during photosynthesis? Mention the different factors affecting the rate of photosynthesis. Describe the role of stomata in photosynthesis. How is food material transported from the leaves to other plant parts?

VIII. Match the statements in column A with those in column B. Column-A Column-B 1. Tiny pores in leaves (a) Leaf 2. Needed by plants to make food (b) Stomata 3. A plant's food factory (c) Water, sunlight 4. Living on another organisms and derive (d) Symbiosis food from them 5. Two different organisms live together (e) Parasitic and both are mutually beneficial IX.

Complete the following table S.No. 1. 2. 3. 4.

X.

Food Product

Source (Name of animals providing the food product)

Milk Egg Meat Honey

Look at the figure. The girl in the picture has a number of food items before her. How can you solve her problem?

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Learning Outcomes

DIGESTION



Know about the four types of teeth and their functions in human beings



Know about the organs involved in the digestion of food in humans (digestive system)



Learn about the process of digestion and the role of enzymes



Know about the teeth in different animals



Know how to take care of your teeth

Chapter -6

By the end of this chapter, you will be able to  Know the various steps in the process of nutrition

1. STEPS IN DIGESTION In the last chapter, you have learnt that the food consumed by us consists of a number of nutrients. What happens to the food as well as the nutrients which we eat? Whatever may be the food and the nutrients present in the food, it undergoes following five steps: These five steps are the steps in the process of digestion. (i) Ingestion: The process by which food is taken in by the organisms is called ingestion. (ii) Digestion: It is the process of breaking down of complex food into simpler absorbable molecules. This is brought about with the help of special molecules called digestive juices or enzymes. (iii) Absorption: It is the process by which digested food is taken up (or absorbed) by the body. (iv) Assimilation: The absorbed food is incorporated into living cells and is used by the body for its growth and other purposes. (v) Egestion: This is the process by which undigested food is removed from the body. Nutrition: The process by which organisms obtain and use food is known as nutrition. Enzymes: Enzymes are proteins in nature. These act as catalysts. 2. DIGESTIVE SYSTEM IN HUMANS The body cells cannot use the food in the form it is eaten by us. It is converted into a simpler form by the process of digestion. The process of digestion starts in the mouth. From the mouth, the food passes through a food canal (called alimentary canal). Alimentary canal is a long, muscular and coiled tube. It starts from the mouth and ends at anus. Why do we need a Digestive System? All animals need food to survive, grow and function properly. Often the food eaten is solid. Solid food cannot be absorbed by the body cells as it is. Our digestive system has two basic jobs to do with the food we take in. The first job is to break down large food particles so that they can be carried through the body. The second job of the digestive system is to transform the molecules of food into simple molecules. We take in foods of all kinds—milk, meat, tea, potato, fish, and so on. These molecules must be broken down into simpler molecules, so that they can finally be built into human protoplasm. Digestive system ensures that the digested material is absorbed into the blood vessels. In this way nourishment reaches all the body cells.

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The different organs of the alimentary canal are as follows: 1. Mouth and mouth cavity 2. Oesophagus (gullet) 3. Stomach 4. Small Intestine 5. Large Intestine 6. Anus Associated with the alimentary canal are some glands. These are: 1. Salivary glands 2. Liver 3. Pancreas. The alimentary canal along with the associated glands is called the digestive system (Figure. 6.1).

Figure 6.1: Digestive System 1. MOUTH The mouth contains the tongue, teeth and salivary glands. Process of digestion starts in the mouth itself. Food is bitten off and chewed (masticated) by the teeth. The chewed food gets mixed with the saliva secreted by the salivary glands. The tongue helps in mixing the food with saliva and its swallowing down the digestive system. Teeth: There are four main kinds of teeth in man - incisors, canines, premolars and molars (Figure. 6.2 and Table 6.1). The front four teeth in each jaw are the incisors. They are flat and help in biting the food. On either side of the incisors are the canines. These are sharp and two in number in each jaw. They are meant for tearing the food.

Table 6.1: Types of Teeth in Humans Type of Number in Function teeth each jaw Incisors 4 Biting food Canines 2 Tearing food Premolars 4 Grinding and crushing food Molars 6 Grinding and crushing food Figure. 6.2: Different types of teeth

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The premolars and molars are meant for grinding and crushing the food. Premolars are behind the canines, two in number on either side in each jaw. Molars are behind the premolars. In an adult, they are six in number in each jaw, three each on either side of the premolars. In young people, there are 8 molars in all. The second set of 4 molars appears at the age of eighteen or even later. These are called the wisdom teeth. Each jaw in an adult has 16 teeth, or 32 teeth in all. Man has two sets of teeth - - milk teeth and permanent teeth. The first set of teeth in a baby are called milk teeth. These are replaced by permanent teeth when one is a child.  At birth, a human infant has no teeth. After six months or so, the first teeth appear in the centre of the lower jaw.  Milk teeth are twenty in number. Tongue: Tongue is-: also important for eating. It helps in Bitter mixing the chewed food with saliva and swallowing the food. Further, the tongue tastes, as it has sense organs called the taste buds. These buds distinguish four basic tastes - salty, sour, sweet and bitter (Figure. 6.3). In addition, tongue helps us to speak. Salivary glands: There are three pairs of salivary glands in our mouth. A watery material called saliva is secreted by these glands. Saliva helps in the digestion of food. Saliva contains an enzyme called amylase (also called ptyalin). Amylase acts on starch and changes it into a sugar (called maltose). This sugar is sweet and soluble in water. Note: Liver is the largest gland in the body.

Figure. 6.3: Location of taste buds on the tongue

2. OESOPHAGUS (GULLET) Oesophagus connects the mouth cavity with the stomach, and is also called the food pipe. No digestion takes place here. It only helps in pushing the food into stomach. 3. STOMACH The stomach is a muscular bag lying in the upper abdomen. Here the food is churned and converted into a semi-solid paste. The stomach secretes a juice called gastric juice and an acid. Proteins present in the food are digested by the gastric juice partly. The partly digested food from here goes to the small intestine. 4. SMALL INTESTINE Small intestine is a long coiled tube. It also secretes a juice and digestion of all types of food is carried out here. As a result of digestion, food is converted into simple form, and glucose, amino acids and fatty acids, etc., are formed. These end products are ready for absorption. The inner surface of the small intestine has a number of finger-like projections called villi (Figure. 6.4). These villi increase the area for absorption of digested food. Saliva contains an enzyme called amylase {also called ptyalin). Amylase acts on starch and changes it into a sugar (called maltose). This sugar is sweet and soluble in water. Small intestine also absorbs the digested food and passes it on to the blood system. Thus, the nutrients are carried to all parts of the body. Note: Small intestine is larger in length (about 6 metres) than the large intestine (about 1.5 metres). It is the main organ for the absorption of digested food. Figure. 6.4: Villi in the small intestine

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5. LARGE INTESTINE Large intestine has no digestive function to carry out. It helps in absorbing water and in removing the undigested solid wastes through the anus. Liver and Pancreas: These are special organs connected with the digestive system. The liver secretes juices which help in digestion and are stored in a small bag called the gall bladder (Figure. 6.5). The pancreas secretes a substance called insulin and also a juice. Insulin is important for regulating sugar level in the body.

Figure. 6.5: Associated glands - liver and pancreas - with the alimentary canal 3. DIGESTION IN HUMANS We have already studied the digestive system of humans. The process of digestion is brought about with the help of digestive juices called enzymes. An outline of the different enzymes produced in humans along with the food acted upon and the products formed is given in Table 6.2. Table 6.2: Summary of Digestion Part of the Digestive Enzymes/Juices Food acted upon Products formed System Mouth Saliva (amylase) Starch Sugars Stomach Gastric juice (pepsin) Proteins Amino acids Pancreas Pancreatic juice Proteins, starch, fats Amino acid, maltose, (several enzymes like fatty acids, glucose trypsin, lipase and sucrase) Small intestine Intestinal juice Partially digested Glucose and other (several enzymes) proteins and simple sugars carbohydrates (by juices from stomach and pancreas)

Formative Worksheet 1.

2.

3.

4.

The sequential steps of digestion are (A) Ingestion, digestion, assimilation, excretion (B) Digestion, ingestion, assimilation, excretion (C) Ingestion, digestion, excretion, assimilation (D) Excretion, assimilation, digestion, ingestion The main role of the digestive system is to facilitate the (A) Filtration of cellular wastes, toxins and excess water (B) Exchange of gases between the blood and the organs (C) Relay of chemical signals through the body and brain (D) Breakdown and absorption of nutrients essential for growth The mouth, Oesophagus and stomach are organs of the (A) Respiratory system (B) Digestive system (C) Endocrine system (D) Excretory system Digestive system begins with the (A) Oesophagus (B) Intestine (C) Stomach

(D) Mouth

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113 5. 6.

7. 8. 9. 10. 11. 12.

13.

14.

15.

16.

17. 18.

What is the role of pre-molars? (A) Grinding (B) Cutting (C) Biting Teeth, that are a part of the buccal cavity, help in the mechanical breakdown of food. The given illustration depicts the type of teeth present in the mouth. The teeth that perform the function of piercing and tearing are labelled as (A) I (B) II (C) III (D) IV

(D) Slicing

The teeth that help in the biting of food are known as (A) Incisors (B) Canines (C) Premolars (D) Molars The respective number of incisors, canines, and pre-molars in a human adult are (A) 12, 4, 4 (B) 8, 4, 8 (C) 8, 8, 4 (D) 4, 4, 12 In humans, the total number of piercing and tearing teeth is (A) 4 (B) 8 (C) 12 (D) 16 What is the role of molars? (A) Grinding (B) Cutting (C) Tearing (D) Biting What is the role of tongue during the digestion of food? (A) Grinding (B) Mixing (C) Cutting (D) Chewing The given illustration represents different regions of taste on the tongue. Suppose Radha eats a salty food item Which labelled region on the tongue will detect the salty taste of the food? (A) I (B) II (C) III (D) IV

Salivary glands are present in the buccal cavity and secrete saliva that helps in the digestion of food. Which complex food nutrient is broken down by the saliva into simple compounds? (A) Fats (B) Starch (C) Proteins (D) Vitamins The major organs of the human digestive system are located in the abdominal cavity. Which of the following organs is not a part of the digestive system? (A) Oesophagus (B) Stomach (C) Intestine (D) Trachea What is the function of oesophagus? (A) Churning food (B) Absorbing the digested food (C) Removing the undigested food from the body (D) Transporting food from the mouth to the stomach Oesophagus transports food from the _____i_____ to the _____ii______. The information in which alternative completes the given statement? (A) i- buccal cavity ii- stomach (B) i- stomach ii- small intestine (C) i- small intestine ii- anus (D) i- anus ii- buccal cavity Which secretion checks the growth of pathogenic bacteria in the stomach? (A) Pancreatic juice (B) Gastric juice (C) Saliva (D) Bile Which organ secretes hydrochloric acid to kill the bacteria present in the food? (A) Small intestine (B) Stomach (C) Large intestine (D) Oesophagus

Digestion 19.

20.

21.

22.

23.

24.

25.

26. 27. 28.

29.

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The gastrointestinal tract between the oesophagus and the large intestine includes the i and the ii . The given statement is correctly completed by alternative (A) i- stomach ii- small intestine (B) i- small intestine ii- pancreas (C) i- pancreas ii- liver (D) i-liver ii-stomach If stomach were not a part of the digestive system, then (A) It would not have been possible to consume large quantities of food (B) The organs of the excretory system would become highly inefficient (C) One would continuously feel hungry (D) It would not be necessary to chew food at all Digestion of ____i_____ begins in the stomach and is completed in the small intestine where it is broken down into ____ii_____. The information in which alternative completes the given statement? (A) i- carbohydrates ii- glucose (B) i-proteins ii-glucose (C) i- carbohydrates ii- amino acids (D) i-proteins ii-amino acids ______i_____ is the part of the alimentary canal that transfers food from the mouth to the _____ii_____. The information in which alternative completes the given statement? (A) i- oesophagus ii-stomach (B) i-oesophagus ii-small intestine (C) i-liver ii-stomach (D) i-liver ii-small intestine What is the function of stomach? (A) Storing bile juice (B) Absorbing the digested food (C) Receiving secretions from the liver and pancreas (D) Secreting mucous, hydrochloric acid, and digestive juices The inner lining of the stomach secretes ____i____ that protects the lining of the stomach from the action of ____ii___. The information in which alternative completes the given statement? (A) i- mucous ii- hydrochloric acid (B) i- hydrochloric acid ii- bile juice (C) i- bile juice ii- digestive juices (D) i- digestive juices ii-mucous The given figure represents the passage of food through the alimentary canal. At point B, the food is passing through (A) Mouth (B) Stomach (C) Small intestine (D) Large intestine

The process of absorption of nutrients takes place in (A) Stomach (B) Oesophagus (C) Large intestine (D) Small intestine Which is the longest part of the digestive tract with respect to length? (A) Oesophagus (B) Small intestine (C) Large intestine (D) Colon Which of the following statements is correct for villi? (A) It helps in swallowing of food. (B) It protects the inner lining of stomach. (C) It breaks down proteins into peptides. (D) It increases the surface area for food absorption. The information in which alternative completes the given table? The given table illustrates the parts of digestive system and their functions. Part of the digestive system Function i Absorption of food Stomach Ii (A) i- Large intestine ii- Killing of bacteria (B) i- Large intestine ii- Absorption of water (C) i- Small intestine ii- Killing of bacteria (D) i- Small intestine ii- Absorption of water

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During the process of _____i_____, the digested food in the small intestine enters the ____ii______. The information in which alternative completes the given statement? (A) i- absorption ii- blood vessels (B) i- absorption ii- food pipe (C) i- assimilation ii-blood vessels (D) i-assimilation ii-food pipe Which part of the alimentary canal has finger-like projections called villi for the absorption of food? (A) Large intestine (B) Small intestine (C) Stomach (D) Oesophagus The breakdown of food is completed in the (A) large intestine (B) small intestine (C) stomach (D) rectum The inner lining of the small intestine has numerous finger-like projections called ______i______ that take part in the ____ii______ of food. The information in which alternative completes the given statement? (A) i- pseudopodia ii- absorption (B) i-pseudopodia ii-digestion (C) i-villi ii-absorption (D) i-villi ii-digestion The given diagram illustrates the human digestive system. Which part of the human digestive system helps in the absorption of water from undigested food? (A) I (B) II (C) III (D) IV

31.

32. 33.

34.

36.

37.

38.

39.

40.

41.

Which of the following events takes place in the large intestine? (A) Absorption of nutrients (B) Absorption of water (C) Digestion of starch (D) Digestion of fats Liver is an important gland of the digestive system. The primary function of liver is to (A) Produce mucous (B) Produce hydrochloric acid (C) Help in the digestion of fats (D) Help in the digestion of proteins The given figure illustrates the human digestive system. Buccal cavity is marked as I, stomach as II, gall bladder as III, and liver as IV. Which part of human digestive system produces bile? (A) I (B) II (C) III (D) IV Jaundice is a disease that affects the liver. A person suffering from jaundice will face maximum difficulty in (A) Digesting carbohydrates (B) Absorbing proteins (C) Absorbing water (D) Digesting fats Many secretory glands are present in the digestive glands. These glands release digestive juices for the digestion of food. Which organ of the digestive system secretes bile? (A) Liver (B) Pancreas (C) Small intestine (D) Large intestine The given figure illustrates some labelled parts in human digestive system. The structures that secrete digestive juices are labelled as (A) I, II, and III (B) II, IV, and VI (C) I, III, and VI (D) IV, V, and VI

Digestion 42.

43.

44. 45.

46. 47. 48.

49. 50.

116

The liver produces bile which helps in fat digestion, which occurs in the duodenum. The bile is secreted into the duodenum and excess bile is stored in the organ present between the liver and the duodenum. Which organ stores excess bile secreted by the liver? (A) Stomach (B) Gall bladder (C) Small intestine (D) Urinary bladder Liver is the largest gland present in the human body. The bile juice secreted by the liver is stored in the (A) Salivary glands (B) Small intestine (C) Large intestine (D) Gall bladder Which of the following organs help in digesting sugar? (A) Liver (B) Rectum (C) Stomach (D) Pancreas The liver secretes bile juice that takes part in the digestion of fats. Digestion of fats results in the formation of which substance? (A) Glucose (B) Glycerol (C) Amino acids (D) Hydrochloric acid Salivary glands are present in the (A) Mouth (B) Throat (C) Tongue (D) Oesophagus During the process of digestion, starch is broken down into (A) Glucose (B) Sucrose (C) Amino acids (D) Fatty acids A person suffers from a disorder in which his stomach is unable to produce gastric acid. What is the result of the given condition? (A) Improper digestion of fat (B) Improper digestion of lipids (C) Improper digestion of glucose (D) Improper digestion of proteins The saliva produced in the mouth is responsible for the digestion of (A) Carbohydrates (B) Vitamins (C) Proteins (D) Fats Shruti took a teaspoonful of boiled rice in a test tube I and a teaspoonful of chewed rice in a test tube II. She then added 3- 4 mL of water to both the test tubes and then added 2-3 drops of iodine solution to each of the test tubes. The result in terms of changes in colour was observed. Which of the following statements regarding the observation made by Shruti is correct? (A) The contents of test tube I will show no change in colour while the contents of test tube II will show a colour change. (B) The contents of test tube II will show no change in colour while the contents of test tube I will show a colour change. (C) The contents of both test tubes I and II will not show any colour change. (D) The contents of both test tubes I and II will show changes in colour.

Conceptive Worksheet 1. 2.

3.

4. 5. 6.

Which step occurs after ingestion? (A) Assimilation (B) Absorption (C) Digestion (D) Egestion Which of the following organs is not a part of the digestive system? (A) Kidney (B) Stomach (C) Large intestine (D) Small intestine Which of the following events does not occur inside the mouth? (A) Wetting of the ingested food with the help of saliva (B) Crushing of the ingested food with the help of teeth (C) Breakdown of proteins into simpler compounds (D) Breakdown of starch into simple sugar The teeth used to bite an apple are the (A) Molars (B) Canines (C) Incisors (D) Premolars How many teeth does a human adult have? (A) 26 (B) 28 (C) 30 (D) 32 Teeth are classified according to their shape and function. Incisors are chisel-shaped front teeth. Incisors are specialized for (A) Cutting (B) Tearing (C) Piercing (D) Grinding

7th Biology

117 7.

Teeth are structures present in the jaws of human beings and animals. In human beings, teeth help in biting, tearing, and chewing of food. Which of the following functions is performed by incisors? (A) Biting (B) Tearing (C) Chewing (D) Grinding

8.

What is the role of canines? (A) Cutting (B) Biting (C) Tearing The given illustration represents different regions of taste on the tongue. The region on the tongue that detects a sweet taste is labelled as (A) I (B) II (C) III (D) IV

9.

(D) Grinding

10.

The labelled parts in the given figure illustrate the location of different taste buds on tongue. The location on tongue that possess the taste buds to identify bitter taste is labelled as (A) I (B) II (C) III (D) IV

11.

Oesophagus connects the (A) Mouth to the small intestine (B) Small intestine to the colon (C) Mouth to the stomach (D) Stomach to the large intestine Which part of the alimentary tract is not involved in digestion? (A) Stomach (B) Mouth (C) Oesophagus (D) Small intestine Which of the following organs does not secrete digestive enzymes? (A) Mouth (B) Liver (C) Oesophagus (D) Stomach The stomach does not perform the function of (A) Storing food (B) Absorbing nutrients (C) Mixing food with gastric juices (D) Mashing food into smaller pieces The food from the stomach enters the (A) Rectum (B) Oesophagus (C) Small intestine (D)Large intestine Digestion of food occurs with the help of (A) Intestines and kidneys (B) Heart and intestines (C) Stomach and mouth (D) Kidneys and mouth Which of the following organs aids in the digestion of food? (A) Stomach (B) Kidneys (C) Lungs (D) Skin Which of the following functions is not performed by the stomach? (A) Storing food for some time (B) Absorbing certain chemicals (C) Breaking food into smaller particles (D) Releasing bile for the digestion of fat Where does the digestion of proteins start in the human body? (A) Mouth (B) Stomach (C) Liver (D) Small intestine

12.

13. 14.

15. 16.

17. 18.

19.

Digestion 20.

21.

22. 23. 24. 25. 26.

27.

28. 29. 30.

31. 32.

33.

118

Which of the following functions is not performed by stomach? (A) Storage of food (B) Adsorption of water (C) Digestion of protein (D) Secretion of bile The process in which the digested food in the small intestine enters the blood vessels is known as (A) Ingestion (B) Assimilation (C) Digestion (D) Absorption From the stomach, food passes into the (A) Small intestine (B) Large intestine (C) Oesophagus (D) Rectum Food is absorbed into the blood in the (A) Stomach (B) Oesophagus (C) Small intestine (D)Large intestine Maximum absorption of nutrients from the digested food takes place in the (A) Stomach (B) Oesophagus (C) Small intestine (D)Large intestine The absorption of nutrients from digested food occurs in the (A) Rectum (B) Oesophagus (C) Large intestine (C)Small intestine What is the function of small intestine? (A) Releasing bile juice (B) Transferring food to the stomach (C) Absorbing water from the undigested food (D) Absorbing nutrients from the digested food The given figure shows the digestive system. In the given figure, the part that is labeled A is the (A) Rectum (B) Oesophagus (C) Large intestine (D) Small intestine The absorption of water from undigested food takes place in the (A) Small intestine (B) Large intestine (C) Stomach Which organ performs the function of absorption of water and minerals? (A) Large intestine (B) Small intestine (C) Stomach The liver is the largest gland in the human body. What is the main function of the liver? (A) Secretion of bile (B) Digestion of proteins (C) Absorption of nutrients (D) Transportation of oxygen The liver helps in the digestion of (A) Fats (B) Sugar (C) Protein The human digestive system is represented in the given figure. In the given figure, the organ that secretes bile is labelled (A) V (B) IV (C) III (D) I Liver is situated on the right hand side of the human body. It plays a major role in digestion by secreting enzymes. Liver secretes (A) Bile juice (B) Pancreatic juice (C) Insulin (D) Glycogen

(D) Liver (D) Rectum

(D) Minerals

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119 34.

The liver is a very important part of the body and its main function is the secretion of bile. Bile is a digestive fluid. Apart from bile, other secretions control a host of activities. Which of the following statements about the liver is false? (A) It aids digestion of lipids (B) It aids digestion of fats (C) It secretes insulin (D) It secretes bile

35.

Which arrow diagram correctly represents the sequence of digestion? (A) Mouth →oesophagus→ large intestine → small intestine → stomach → rectum (B) Mouth → stomach →small intestine → large intestine → oesophagus → rectum (C) Mouth → oesophagus → stomach → small intestine → large intestine → rectum (D) Mouth→ oesophagus →rectum → large intestine → stomach → small intestine The process of enzymatic breakdown of food is known as (A) Absorption (B) Digestion (C) Excretion (D) Assimilation At the end of digestion, the carbohydrates are broken down into (A) Glucose (B) Glycerol (C) Fatty acids (D) Amino acids The inner lining of the stomach secretes various substances like mucous, hydrochloric acid and digestive juices. The digestive juices secreted by the stomach take part in the digestion of which of the following substances? (A) Starch (B) Proteins (C) Glucose (D) Vitamins During the process of digestion, fats are broken down into ____i_____ and ____ii______. The information in which alternative completes the given statement? (A) i- fatty acids ii- glycerol (B) i- glycerol ii- amino acids (C) i- amino acids ii-glucose (D) i- glucose ii-fatty acids Bile juice is secreted by liver and is stored in the gall bladder. Bile juice is chiefly involved in the digestion of (A) Proteins (B) Carbohydrates (C) Fats (D) Glucose

36. 37. 38.

39.

40.

4. TEETH IN HERBIVORES, CARNIVORES AND OMNIVORES Dentition: The arrangement of teeth in the jaws is called dentition. Teeth in herbivores (like rabbit), carnivores (like dog) and omnivores (like human beings) are related to the diet the animals take. As mentioned earlier, there are four different kinds of teeth (i) incisors (for cutting) (ii) canines (for tearing) (iii) premolars, (iv) molars (for grinding) DENTITION IN HERBIVORES (EXAMPLE RABBIT) They have incisors which are sharp and used for cutting. Canines are absent and a gap occurs between the incisors and premolars. This gap is called diastema. The premolars and molars are used for chewing. The premolars and molars are almost similar in shape and size, as they have the same function. The gap between the incisors and the premolars (diasteina) allows the tongue to manipulate the food. Figure. 6.6: Dentition in a rabbit

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DENTITION IN CARNIVORES(EXAMPLE DOG) In carnivores the teeth in different regions of the mouth are specialised to perform a particular function. They have all four kinds of teeth. The incisors in the front of the mouth grip the food and strip off small pieces of flesh. The canines are long, sharp and pointed and adapted for flesh eating. The molars have somewhat flat surface for grinding and crushing the Figure. 6.7: Dentition in a dog bones. Dentition in omnivores (example human beings) In omnivores, all the four kinds of teeth are well-adapted to cope up with a wide range of foods the vegetables and variety of meat. The teeth are not as specialised as in carnivores and herbivores. The four kinds of teeth in human beings have been already described. 5. STRUCTURE OF A TOOTH You have learnt that teeth, present in the mouth cavity, play an important role in biting and chewing the food. In an adult human being, there are four types of teeth - - incisors, canines, premolars and molars. Fixed to the gums, each tooth has following three parts (Figure. 6.8): (i) Root, the part embedded in the jaw, (ii) Crown, the top part projecting above the gums, and (iii) Neck, the part between the root and the Figure. 6.8: A tooth in section crown. Internally, there are three parts of a tooth - enamel, dentine and the pulp cavity. Enamel is the white part of the tooth, and is the hardest substance in our body. Below the enamel, dentine is present. Inner to dentine is the soft pulp cavity which contains blood vessels and nerves (Figure. 6.8). 6. CARE OF THE TEETH Teeth are commonly seen to become yellow and suffer from cavity formation. When food is eaten, small amounts are left in between the teeth. Saliva and bacteria (present in the mouth) stick to the teeth and form a sticky film. This sticky film is called dental plaque. The enzymes produced by the bacteria act on the food particles, particularly sugars and acids are produced. The acids dissolve away the tooth enamel causing tooth decay. Ultimately a hole or cavity is formed in the tooth. Plaque affects the gums too, causing gum disease. The gums swell and may bleed on brushing. The plaque builds up in the region where the teeth meet the gums, and forms a space. Bacteria growing in this space cause the teeth to fall. Plaque formation and other diseases can be avoided by (i) not eating foods like sweets, chocolates and ice-creams, (ii) consuming foods which contain sufficient calcium, phosphorous and vitamin D such as milk, fish, raw vegetables, carrots, spinach (palak), radish, cabbage and fresh fruits (the teeth and gums get good exercise when fibrous foods are eaten), (iii) cleaning teeth after eating sweet, sticky food,

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(iv)

brushing teeth thoroughly and regularly everyday in the morning and again before going to bed, and using fluoride toothpaste.

(v)

Figure. 6.9: Tooth decay – stages

Formative Worksheet 51. 52. 53. 54. 55. 56. 57. 58. 59. 60.

61.

62.

The incisors in rabbit are used for (A) Cutting (B) Biting (C) Tearing (D) Grinding The gap between incisors and premolars in rabbit is called (A) Diasteina (B) Diastema (C) Triastema (D) None Which of the following allows the tongue to manipulate the food? (A) Diasteina (B) Diastema (C) Triastema (D) None Which of the following is absent in carnivores? (A) Incisors (B) Canines (C) Premolars (D) None In dogs, which of the following helps in grinding and crushing the bones? (A) Incisors (B) Canines (C) Premolars (D) Molars Which of the following part of tooth is embedded in the jaw? (A) Root (B) Crown (C) Neck (D) None The hardest substance in our body is (A) Enamel (B) Dentine (C) Pulp cavity (D) None Which of the following contain blood vessels and nerves? (A) Enamel (B) Dentine (C) Pulp cavity (D) None Teeth problems include (A) Plaque (B) Cavities (C) Decay (D) All Which of the following should be consumed to prevent plaque formation? (A) Foods which contain sufficient calcium (B) Foods which contain sufficient phosphorus (C) Foods which contain sufficient vitamin D (D) All the above Plaque formation can be avoided by (A) Not eating foods like sweets, chocolates and ice-creams (B) Cleaning teeth after eating sweet, sticky food (C) Using fluoride toothpaste (D) All the above Dental hygiene is very important. It involves keeping the mouth clean and protecting it from dental caries. What causes dental caries? (A) Poor nutrition (B) Bacteria (C) Virus (D) Excess nutrition

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Conceptive Worksheet 41. 42. 43. 44. 45. 46. 47. 48.

Which of the following is absent in herbivores? (A) Incisors (B) Canines (C) Premolars (D) Molars The molars and premolars in herbivores help in (A) Cutting (B) Biting (C) Chewing (D) Frinding Which of the following in carnivores, helps to grip the food and strip off small pieces of flesh? (A) Incisors (B) Canines (C) Premolars (D) Molars In humans, each tooth has (A) Root (B) Crown (C) Neck (D) All Internally, a tooth has (A) Enamel (B) Dentine (C) Pulp cavity (D) All Which of the following should be taken to prevent plaque formation? (A) Sweets (B) Chocolates (C) Ice-creams (D) None Which of the following are adopted for eating flesh, in a dog? (A) Incisors (B) Canines (C) Premolars (D) Molars Which of the following part of tooth is projects above the jaw? (A) Root (B) Crown (C) Neck (D) None

SNAP SHOT 1. 2. 3. 4. 5. 6.

The process of converting complex food substances into simpler, absorbable form is called digestion. The canal through which food passes is called a food canal or alimentary canal. The alimentary canal consists of following organs: mouth and mouth cavity, oesophagus, stomach, small intestine, large intestine and anus. The alimentary canal along with the associated glands is called the digestive system. The three glands are the salivary glands, liver and pancreas. Digestive juices called enzymes help in the process of digestion. Teeth in herbivores, carnivores and omnivores are adapted to the diet the animals take.

Summative Worksheet I. 1.

2.

3.

4.

Multiple Choice Questions Which of the following help in the digestion of food? (a) Nutrients (b) Hormones (c) Enzymes (d) Saliva Saliva contains an enzyme called (a) Amylase (b) Trypsin (c) Pepsin (d) None of the above The teeth adapted for flash eating are (a) Incisors (b) Premolars (c) Canines (d) Molars Finger-like projections called villi are present in (a) Stomach (b) Large intestine (c) Small intestine (d) Liver

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123 5.

6.

7.

8.

II. 1. 2. 3. 4. 5. 6. 7.

Most of digestion takes place in (a) Stomach (C) Large intestine Absorption of food takes place in (a) Small intestine (c) Large intestine A tooth consists of following parts: (a) Gum and crown (c) Enamel and dentine Absorption of water takes place in (a) Small intestine (c) Rectum

(b) Small intestine (d) Rectum (b) Pancreas (d) Liver (b) Root, crown and neck (d) Only crown (b) Large intestine (d) Large intestine and rectum

8. 9. 10.

Fill in the blanks: Saliva is secreted by the ____________ in the mouth cavity. Number of molar teeth present in a human adult is ________________. The teeth which help in biting the food in humans are the ________________. Food is digested by chemicals called ________________ Changing food to a usable form is called ________________ The liver and ________________ are found near the stomach. The five steps in the process of nutrition are ________________, ________________, ________________, ________________ and ________________. The white part of the tooth is called the ________________ The part of the tooth embedded in the jaw is called the ________________ In teeth of a rabbit, ________________ are absent.

III. 1. 3. 5. 7.

Define the following terms: Ingestion Digestion Alimentary canal Enzymes

IV. 1. 2. 3.

4. 5. 6. 7. 8.

Answer the following: How is digestive system different from an alimentary canal? Give the functions of different types of teeth in an adult human. Describe the functions of the following: (a) Saliva (b) Oesophagus (c) Tongue (d) Liver Represent the digestive system by means of a labelled diagram. Describe the structure of a tooth. How are teeth different in herbivores and carnivores? Write briefly about 'care of the teeth'. Mention various steps in the process of digestion.

V. 1. 2. 3.

Name the following: Different organs of the digestive system. Different types of teeth in an adult human being. The digestive juices secreted by mouth, pancreas, stomach, small intestine.

2. 4. 6. 8.

Absorption Assimilation Digestive system Plaque

Digestion VI. 1. 2.

124

Complete the following by giving the name of digestive juice/enzyme and the product formed in each case. Protein: ________________________________________________________________ Starch: _________________________________________________________________

VII. Which of the following statements are true (T) and which ones are false (F)? Mark T or F. Statements T/F 1. Canines are meant for tearing flesh. ____________ 2. Molar teeth are present in a human baby. ____________ 3. Mouth cavity is also known as the food pipe. ____________ 4. Gastric juice is secreted by the small intestine. ____________ 5. Food is mostly digested in stomach. ____________ 6. In humans, there are 14 teeth in each jaw. ____________ VII. Complete the following table: Part of the digestive Enzyme/ digestive system juice Mouth gastric juice Pancreas

Food acted upon

Product formed

By the end of this chapter, you will be able to  Understand the characteristics of respiration  Differentiate between aerobic and anaerobic respiration  Differentiate between breathing (external) and cellular (internal)  Understand how exchange of gases takes place in different organisms  Know about the breathing process in humans  Know how the loss of water vapour takes place in plants  Learn about excretion in plants  Understand the excretory organs in human beings

Respiration and Excretion Chapter -7

Learning Outcomes

1. INTRODUCTION Energy is needed by living as well as non-living things to do work. Without energy, they stop doing work. Our body needs energy to carry on its activities. Where from do we get this energy? We have earlier studied that we all eat food. The food we eat is broken down into simpler forms during digestion. The digested food is then absorbed by the walls of the intestine and carried by blood to different parts of the body. How is the energy stored in the food (as chemical energy) used? This can be done by oxidation of the food materials. During oxidation, oxygen combines with the food we eat, liberating energy and carbon dioxide (a waste product). This process of energy production takes place all through the day. Respiration can, thus, be represented as follows: Digested food + Oxygen Energy Waste products   The released energy is stored in some special molecules. CHARACTERISTICS OF RESPIRATION Respiration is characterised by following acts: 1. Food is used up. 2. Energy is produced. 3. Exchange of gases occurs. Oxygen is used up and carbon dioxide is given out. All the three acts take place in living cells. Respiration is a process common to all plants and animals. It is a process whereby living organisms produce energy from the food they eat. This energy is necessary for various life activities. Oxygen is required for this process and carbon dioxide is formed as a waste. How do we know that an organism respires? In respiration, oxygen is consumed and energy, carbon dioxide and water are liberated. Therefore, if we can show that an organism consumes oxygen and gives off carbon dioxide and heat (any one parameter), we can say that it respires. 2. TYPES OF RESPIRATION Respiration is of two types based on whether oxygen is used up in this process or not. AEROBIC RESPIRATION Most organisms require oxygen for respiration; such a respiration is known as aerobic respiration. Carbon More Food + Oxygen + Water +  dioxide energy ANAEROBIC RESPIRATION There are, however, some organisms like yeast and some bacteria which do not require oxygen. They can live without oxygen. Respiratory process in the absence of oxygen is called anaerobic respiration. Ethyl Carbon Food + + Less energy  alcohol dioxide

Respiration and Excretion

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3.

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Table 7.1: Differences between Aerobic and Anaerobic respiration Anaerobic respiration Aerobic respiration It takes place in the absence of oxygen. 1. It takes place in the presence of oxygen. Food molecules (sugars) are completely 2. Food molecules (sugars) are partially broken down into carbon dioxide and broken down into ethyl alcohol, water, releasing energy. carbon dioxide and energy. Energy released is more. 3. Energy released is much less.

3. PROCESS OF RESPIRATION The process of respiration consists of two main stages: (i) Breathing or external respiration: A physical process in which an organism takes in (inhales) oxygen and gives out (exhales) carbon dioxide. This process involves exchange of gases only. The exhaled air has more carbon dioxide than the inhaled air. (ii) Cellular respiration or internal respiration: A chemical process in which food molecules are broken down into simpler molecules within cells and energy is produced. A number of chemical reactions catalysed by enzymes occur during this process. Table 7.2: Differences between Breathing and Cellular respiration Breathing Cellular respiration 1. It is a physical process in which 1. It is a chemical (or biochemical process as it exchange of gases (O2 and CO2) takes occurs in living cells) process in which food place. molecules are oxidised to carbon dioxide and water. 2. It occurs outside the cells. 2. It occurs inside the cells. 3. Enzymes are not involved. 3. Enzymes take part. 4. No energy is released. 4. Energy is released in a gradual and stepwise manner. 4. COMBUSTION AND RESPIRATION Is the process of respiration similar to burning or combustion (of petrol or diesel in vehicle)? When we burn petrol or wood, oxygen is used up and carbon dioxide is given off. The energy is produced in the form of heat and light (flame). Something similar happens in our body. Yes, the two processes differ in many respects. The table given below lists the differences. Table 7.3: Differences between Combustion and Respiration Combustion Respiration 1. It is a fast process. 1. It is a slow stepwise process. 2. It occurs at high temperature. 2. It occurs at normal room temperature. 3. Energy is produced in the form of heat 3. Energy is released in steps, and stored in a and light. special chemical molecule. No heat or light is produced. 4. Conversion to carbon dioxide and 4. Many steps are involved in the conversion of water is in one step. No enzyme is carbohydrates to carbon dioxide and water. involved. These steps or reactions are catalysed by enzymes. 5. RESPIRATION IN PLANTS The process of respiration is similar in all organisms, whether plants or animals - carbon dioxide is given out and oxygen is used up, and a lot of energy is produced. In plants, specific organs for breathing are absent. The exchange of gases, however, occurs by the process of diffusion. Diffusion of gases (oxygen and carbon dioxide) occurs through three sources. (1) Through stomata (singular stoma), the minute openings on the surface of leaves. (2) Through lenticels, openings present in old stems, and (3) Through general surface of the roots. In aquatic plants, gases diffuse through the body surface.

7th Biology

127 STOMATA The opening is surrounded by two kidneyshaped cells called guard cells (Figure 7.1). The guard cells contain chloroplasts and carry out photosynthesis. Guard cells are surrounded by subsidiary cells. The whole structure consisting of the opening, guard cells and the subsidiary cells is called stomatal apparatus. Cellular respiration in plants is similar to that found in animals. It occurs inside mitochondria.

Figure 7.1: Structure of Stomata

ANAEROBIC RESPIRATION IN PLANTS Respiration also takes place in the absence of oxygen. This type of respiration is called anaerobic respiration. This happens in case of certain organisms like the yeast and. some bacteria. Even germinating seeds can respire in the absence of oxygen for some time. In this respiration, the food molecules (sugars) are incompletely broken into ethyl alcohol and carbon dioxide. The energy released is much less in comparison to that produced in case of aerobic respiration. 6. RESPIRATION IN ANIMALS EXCHANGE OF GASES – BREATHING Different organisms have different methods of breathing: (i) In Amoeba, for example, breathing occurs by simple diffusion (Figure 7.2). Hydra also breathes through the body surface. (ii) In insects, movement of skeleton draws air in and out of the openings called spiracles (Figure 7.3). These openings are present on the body surface. LOW Oxygen concentration (Oxygen used as soon as it enters)

Concentration gradient

Inward diffusion of dissolved oxygen along concentration Spiracles Gradient all over larger surface Figure 7.3: Spiracles in an insect HIGH concentration of oxygen dissolved in surrounding water Figure 7.2: Diffusion in Amoeba (iii) Fishes and many other aquatic animals have special structures called gills. Through these gills (Figure 7.4), dissolved oxygen is used from the water entering these organs. (iv) Frogs when in water also breathe through their moist skin. Frogs, on land, breathe through their lungs. (Figure 7.5)

Gills (present under a bony cover which has been cut open)

Figure 7.4: Respiratory organs in fish

Figure 7.5: Lungs of a frog

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Earth worms absorb the atmospheric oxygen through their moist skin.

CO2 O2

Figure 7.6: Exchange of gases in earthworm We breathe through our lungs. Movements of the ribs and diaphragm help to draw air in and out of our lungs through nose. 7. RESPIRATORY SYSTEM IN HUMANS Respiratory system in humans (Figure 7.7) consists of following organs meant for breathing: 1. Nose 2. Trachea or windpipe Nose 3. Bronchi 4. Lungs Mouth When a person breathes in, air passes into the body through the Bronchus Windpipe respiratory tract starting with the nose. The hair inside the nose traps and stops the harmful particles from entering inside. The nose also warms the air. From the nose, the air goes down the wind-pipe or trachea. From here, the air goes through two smaller tubes called bronchi (singular bronchus), one of which enters each lung. The Lungs lungs are large, soft organs. Figure 7.7: Respiratory system (vi)

In the lungs, each bronchus divides and redivides into finer tubes called the bronchioles. Windpipe each bronchiole ends in a number of air sacs, called alveoli (singular alveolus). Alveoli have very thin walls and are supplied with blood capillaries (Figure 7.8). It is here that air is received from the bronchi, the proper gases are used, and unwanted gases are forced out. Thus, exchange of gases takes place in the alveoli. How diaphragm helps in breathing process has been demonstrated in activity number 7.6. How does air move in and out of lungs? Figure 7.8: Inhalation and Exhalation Take in a deep breath. Now breathe out. Lungs are present in the chest cavity. The ribs surround this cavity on the sides. A large flat muscle called diaphragm forms the floor of the chest cavity. During inhalation (breathing in), two things happen – (i) The ribs move out (ii) The diaphragm moves down. This makes the chest cavity larger. Air then rushes into the lungs. The lungs inflate. During exhalation (breathing out) (i) The ribs move downwards and inwards, (ii) The diaphragm moves up. Thus, the chest cavity is reduced. Air rushes out of the lungs. The lungs become smaller (Figure 7.8). Tidal volume It is the volume of air that moves in or goes out in a single stroke, and is about 500 ml.

7th Biology

129 Table 7.4: Composition of Inspired and Expired Air Inspired air Expired air Oxygen 21% 16.4% Carbon dioxide 0.03% 4.0% Nitrogen 78.0% 78.0% Water vapour variable saturated Note: The blood of insects, like the cockroach, is colourless.

ROLE OF BLOOD IN RESPIRATION Blood is red because of the presence of a certain type of cells in it. These are the red blood cells. The red blood cells contain a pigment called haemoglobin. This pigment gives its red colour to blood. Haemoglobin carries oxygen molecules as oxyhaemo-globin. This substance acts as a respiratory carrier in the body. Oxygen diffuses to the cells as blood passes through tissues. At the same time, the blood collects carbon dioxide from the tissues and carries it to the lungs for breathing out. nasal cavity throat bronchi

right lung

diaphragm

air in air out capillaries

alveoli left lung carbon dioxide out

capillary

oxygen in

blood cells

Figure 7.9: Gaseous exchange in the alveoli 8. TRANSPIRATION Transpiration is the process of loss of water in vapour form from the leaves in plants. It occurs through stomata present in the leaves by the process of diffusion. Water absorbed through the roots is moved upwards within the plant body. A part of it is used in the process of photosynthesis, and to stop the plant from wilting (drooping). The rest is lost as water vapour into the atmosphere from the leaves. FACTORS AFFECTING TRANSPIRATION 1. Day/Night: More transpiration takes place during the day than at night. This is because the stomata are open during the day and close at night. 2. Wind: Wind increases the rate of transpiration. 3. Humidity: Rate of transpiration is decreased if the air is humid. The air already contains a lot of water. 4. Temperature: Rate of transpiration is more on a hot day than a cold day. 5. Light: Light causes the stomata to open. This increases the rate of transpiration. IMPORTANCE OF TRANSPIRATION 1. It results in the transport of water and minerals from the soil to the leaves. In the leaves, water forms the raw material for photosynthesis. 2. It produces a cooling effect which helps in preventing hot sunlight from damaging delicate cells.

Formative Worksheet 1.

Cellular respiration is a process in which food is broken down in a cell and is converted into energy. Respiration is an example of (A) A catabolic process (B) Transportation of ions (C) Anabolic process (D) Excretion of ions

Respiration and Excretion 2.

3.

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Which of the following statements about cellular respiration is correct? (A) Oxygen is released during cellular respiration. (B) Cellular respiration leads to the formation of starch. (C) Cellular respiration leads to the formation of glucose. (D) Carbon dioxide is released during cellular respiration. The given equation represents respiration. Sugar + O2 → CO2 + X + Energy In the given equation, X represents (A) Water (B) Lipids (C) Proteins (D) Vitamins During respiration, _____i_____ and _____ii_____ are utilized to produce energy, CO2, and H2O. Which alternative completes the given statement? (A) i- glucose ii- oxygen (B) i- oxygen ii- carbon monoxide (C) i- carbon monoxide ii- sulfur dioxide (D) i- sulfur dioxide ii-glucose Aerobic respiration is a type of cellular respiration which takes place in the presence of oxygen. Which of the following substances is not produced during aerobic respiration? (A) Water (B) Energy (C) Carbon dioxide (D) Lactic acid Which of the following statements regarding the process of anaerobic respiration is correct? (A) It involves breakdown of alcohol. (B) It occurs in presence of oxygen. (C) It involves production of water. (D) It releases carbon dioxide. Yeast is commercially used for the preparation of alcohol and ____i____ by the process of _____ii______. The information in which alternative completes the given statement? (A) i-wine ii- fermentation (B) i-antibiotics ii-fermentation (C) i-wine ii-aerobic respiration (D) i-antibiotics ii-aerobic respiration The given equation illustrates the breakdown of glucose in a yeast cell. i ii Glucose     + Carbon dioxide + Energy The information in which alternative completes the given equation? (A) i- Absence of oxygen ii- Alcohol (B) i- Absence of oxygen ii-Water (C) i- Presence of oxygen ii-Alcohol (D) i- Presence of oxygen ii-Water The alternatives in the given table can be correctly matched as Column A Column B i Normal respiration in humans a CO2 + Ethanol ii Muscle cramps b CO2 + H2O iii Fermentation c Lactic acid (A) i → b, ii → c, iii → a (B) i → c, ii → b, iii → a (C) i → a, ii → b, iii → c (D) i → a, ii → c, iii → b Which of the following statements is correct regarding respiration in plants? (A) Respiration stops when photosynthesis occurs. (B) Roots are underground, hence do not respire. (C) Respiration in plants occurs by diffusion. (D) Germinating seeds do not respire. The ____i____ present on the ___ ii___ of plants help in the exchange of gases. The information in which alternative completes the given statement? (A) i-stomata ii-leaves (B) i-stomata ii-roots (C) i-xylem ii-leaves (D) i-xylem ii-roots Breathing is the process of intake of oxygen-rich air and giving out carbon dioxide-rich air. The process of taking-in oxygen-rich air is known as (A) Exhalation (B) Inhalation (C) Ingestion (D) Egestion The process of releasing carbon dioxide-rich air from the body is known as (A) Exhalation (B) Inhalation (C) Ingestion (D) Egestion During a process X, the ribs of a person are moving out and its diaphragm is moving down towards the abdomen. According to the given information, process X (A) Can only be inhalation (B) Can only be exhalation (C) Signifies holding of breath (D) Signifies breathing on a whole

131

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16.

During the process of exhalation, ribs move ____i_____, while the diaphragm moves ____ii_____. The information in which alternative completes the given statement? (A) i-outward ii-downward (B) i-downward ii-upward (C) i-upward ii-inward (D) i-inward ii-outward The given table illustrates the speed of running of a person at different times. Minute Speed of running (m/s) 1st 1.5 2nd 2.9 3rd 5.0 4th 6.1 th 5 4.9 6th 3.8 7th 1.5 At 4th minute, (A) Only the rate of inhalation increases (B) Only the rate of inhalation decreases (C) The rates of both inhalation and exhalation increase (D) The rates of both inhalation and exhalation decrease

17.

Conceptive Worksheet 1.

2.

3.

4.

5.

6.

7.

8.

Cellular respiration is the process wherein (A) Food is synthesized in the cell to provide energy (B) Food is broken down in the cell to release energy (C) Carbon dioxide is exhaled (D) Oxygen is inhaled Cellular respiration is the process by which cells generates energy molecules. What is not produced during cellular respiration? (A) Carbon dioxide (B) Water molecules (C) Glucose molecules (D) ATP molecules The given equation represents cellular respiration. Sugar + X → CO2 + Water+ Energy In the given equation, X represents (A) Oxygen (B) Sunlight (C) Nitrous oxide (D) Sulfur dioxide Cellular respiration takes place inside the cells of all living organisms. Which of the following events does not occur during cellular respiration? (A) Formation of carbon dioxide (B) Breakdown of glucose (C) Release of energy (D) Release of oxygen Cellular respiration is of two types- aerobic and anaerobic. Which of the following statements regarding aerobic respiration is incorrect? (A) It involves the breakdown of glucose. (B) It does not involve the production of alcohol. (C) It does not require oxygen to carry out the reaction. (D) It releases carbon dioxide as a by-product of the reaction. Anaerobes are organisms which respire through anaerobic respiration. Which of the following organisms is an anaerobe? (A) Fish (B) Yeast (C) Cockroach (D) Earthworm Yeast is used in the commercial production of i and ii . The information in which alternative completes the given statement? (A) i- vinegar ii-alcohol (B) i-alcohol ii-oil (C) i-oil ii-glucose (D) i-glucose ii-vinegar During strenuous exercises, lactic acid is produced in our muscles because (A) O2 supply < O2 demand (B) O2 supply > O2 demand (C) O2 supply is in accordance with O2 demand (D) O2 supply is completely restricted in muscles

Respiration and Excretion 9.

9. 10. 11.

12.

13.

Ayush set up the given experiment to study production of alcohol by yeast. He added some yeast to a test tube (tube A) containing fruit juice. He covered the tube with a piece of cork and connected the test tube to another test tube (tube B) containing some lime water with a delivery tube. The whole set up was maintained air tight. After some time, he noticed that the lime water in tube B had turned milky.

Which of the following gases was produced by yeast which is responsible for the given observation? (A) Oxygen (B) Nitrogen (C) Carbon dioxide (D) Carbon monoxide Which process uses carbon dioxide and produces oxygen as a waste product? (A) Transpiration (B) Respiration (C) Photosynthesis (D) Osmosis In plants, gaseous exchange occurs through (A) Xylem (B) phloem (C) stomata (D) chloroplast Which of the following activities is a significant function of the nasal cavity? (A) Cleaning the inhaled air (B) Cleaning the exhaled air (C) Initiating the process of inhalation (D) Initiating the process of exhalation Which of the following events does not take place during inhalation? (A) Upward and outward movement of ribs (B) Downward movement of diaphragm (C) Decrease in the size of chest cavity (D) Movement of air into the lungs Which illustration represents the process of inhalation? (A) (B)

(C)

14.

132

(D)

Shalini took some freshly prepared lime water in a test tube and with the help of a plastic straw, blew some air into the test tube. Which statement correctly states the observation made in the given experiment? (A) The lime water will turn milky indicating the presence of carbon dioxide in exhaled air. (B) The lime water will turn milky indicating the presence of oxygen in exhaled air. (C) The lime water will remain unchanged indicating the presence of carbon dioxide in exhaled air. (D) The lime water will remain unchanged indicating the presence of oxygen in exhaled air.

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9. EXCRETION Living organisms perform a number of activities. During these activities, a variety of waste products are produced. For example, some of the food we eat is not used by our bodies. The undigested food is a waste product. During respiration, water, carbon dioxide and heat are produced as wastes. Urea is another waste. It comes from used-up protein. Some of the waste products like urea are very harmful and toxic. These must not be accumulated within the body. Otherwise, accumulation of waste produces health problems. Fortunately, each organism has a mechanism of its own to remove the waste products. The process of removal of the waste products is called excretion. EXCRETION IN LOWER PLANTS AND ANIMALS In organisms like Amoeba, Paramecium. Hydra, most of the metabolic wastes are removed through the general surface of the body by the simple process of diffusion. Specialised organs of excretion are lacking (Figure 7.10).

High concentration of waste (owing to production of waste by living protoplasm)

Concentration gradient

Outward diffusion of dissolved carbon dioxide and waste nitrogen compounds all over the large surface.

Figure 7.10 : Excretion in Amoeba EXCRETION IN FLOWERING PLANTS Excretion of waste products is very simple and much less in plants as compared to animals. The waste products of one process are often used as raw materials in another process. This is very clear if you study photosynthesis and respiration. Excess food material in many cases is stored in roots, stems, leaves and seeds. These plant organs are often eaten by man. The various methods of excretion are given below: 1. Waste products of photosynthesis and respiration - - oxygen, carbon dioxide, water and heat - are released into .the atmosphere through stomata in the leaves and lenticels in stems. The waste products of one process are, however, usable as raw products in another process. 2. Ammonia is formed as a breakdown product of proteins. Plants use this ammonia to synthesise useful compounds. 3. Some of the waste products of photosynthesis collect in the leaves and bark of trees. Plants shed their leaves and bark to get rid of these wastes. 4. Some waste materials keep accumulating within cells. Calcium oxalate crystals, called raphides, are such wastes. Yam (zimikand) is rich in raphides. Several of the plant wastes are useful to us. Latex, gums, resins, tannins, saiidalwood oil and eucalyptus oil are such substances. Latex, a white milky fluid, oozes out from any cut on the stem is case of some plants. Latex from rubber plant is used for making rubber. Resins are used for preparing varnish. EXCRETION IN HUMANS Human body has various organs to get rid of wastes. 1. Lungs — for excretion of carbon dioxide and water vapour produced during respiration. 2. Skin — for excretion of urea, salt and excess water by means of sweat glands present in the skin. 3. Large Intestine — for excretion of some wastes alongwith faeces through anus. 4. Kidneys — for excretion products like urea and nitrogen in urine. 5. Liver — for removal of wastes from the blood.

Respiration and Excretion

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10. EXCRETORY SYSTEM IN HUMANS Excretory system consists of the following organs (Figure 7.11): 1. A pair of kidneys 2. Ureters 3. Urinary bladder 4. Urethra. (i) Kidneys are bean-shaped structures, about 10 centimetres long. (ii) They are located just above the waist on either side of the backbone. (iii) Each kidney consists of a large number of coiled tubes called nephrons. (iv) Nephrons act as filters. They filter waste products from the blood. (v) The waste materials collected in the kidney form the liquid urine. Urine contains 95 per cent water, 2.5 per cent urea and 2.5% waste products. (vi) A narrow tube called the ureter runs from the inner side of each kidney. Figure 7.11: Excretory system in (vii) The ureters, in turn, are connected to a large sac humans called the urinary bladder. (viii) Urine passes from the kidney through two ureters into the-urinary Nephrons bladder. (ix) Urine is collected and stored here. Nephrons, the coiled (x) Leading from the bladder is another tube called the urethra. Urethra works as the outlet passage tor urine.

Formative Worksheet 18.

19. 20.

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The given illustration represents the human excretory system.

In the given illustration, the structure labelled X represents (A) Kidney (B) Ureter (C) Urinary bladder (D) Urethra What is the primary excretory product of humans? (A) Ammonia (B) Urea (C) Glucose (D) Starch What is the primary function of ureter? (A) Storing urine (B) Producing urine (C) Passing urine out of the body (D) Transporting urine from kidneys to urinary bladder Kidneys filter waste material from blood and remove them from the body. Blood is supplied to the kidneys by the circulatory system. Blood is supplied to the kidneys by the (A) Renal vein (B) Renal artery (C) Pulmonary vein (D) Pulmonary artery Urea, uric acid, and ammonia are the chief excretory products of a large number of animals. Which of following animals excretes wastes in the form of urea? (A) Sparrow (B) Humans (C) Lizard (D) Snake

7th Biology

135 23.

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The given diagram represents the structure of the human excretory system

Which of following functions is not performed by the kidneys? (A) Formation of urine (B) Oxygenation of blood (C) Reabsorption of water (D) Maintenance of salt balance On an average, a person excretes about 1.2 L of urine in 24 hours. What would be the approximate amount of urea excreted by the person in same time? (A) 10 gm (B) 30 gm (C) 60 gm (D) 80 gm Dialysis is the artificial process of regulation of fluids and mineral concentration in the human body. Which organ is replaced through dialysis? (A) Lung (B) Heart (C) Kidney (D) Liver The alternatives in the given table can be correctly matched as Column A Column B i Kidney a Stores urine ii Ureter b Urinary opening iii Urinary bladder c Filters blood iv Urethra d Carries urine for storage (A) i → a, ii → b, iii → c, iv → d (B) i → a, ii → b, iii → d, iv → c (C) i → c, ii → d, iii → a, iv → b (D) i → c, ii → b, iii → d, iv → a Excretory system performs the functions of formation, storage, and removal of urine. What is the primary function of urethra? (A) Storing urine (B) Producing urine (C) Passing urine out of the body (D) Transporting urine from kidneys to urinary bladder The basic functional unit of kidney regulates the concentration of water and soluble substances in the body. It functions by filtering blood under pressure. It then reabsorbs the necessary fluids and excretes the waste products. The above function is performed by (A) Renal artery (B) Nephron (C) Aorta (D) Renal vein Which of the following functions is not performed by kidneys? (A) Removal of body toxins (B) Supplying oxygen to body (C) Maintaining body salt balance (D) Filtering of wastes from the blood Which of the following functions is not performed by kidneys? (A) Removal of body toxins (B) Supplying oxygen to body (C) Maintaining body salt balance (D) Filtering of wastes from the blood Urine is stored in the urinary bladder before it is excreted. The urinary bladder can expand and contract depending upon the amount of urine present it. Which system allows the expansion and contraction of the urinary bladder? (A) Vascular system (B) Excretory system (C) Nervous system (D) Muscular system Urine is a waste product formed inside the kidneys after the filtration of blood. Which of the following substances is not reabsorbed in the nephron from the urine formed inside it? (A) Salts (B) Glucose (C) Uric acid (D) Amino acids _____i_____ and _____ii_____ are examples of animals that excrete nitrogenous wastes in the form of uric acid. The information in which alternative completes the given statement? (A) i- Birds ii- lizards (B) i- Lizards ii-fishes (C) i-fishes ii-humans (D) i-humans ii-birds

Respiration and Excretion 34.

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The alternatives in the given table can be correctly matched as Column A Column B i Sparrow a Uricotelic ii Prawn b Ureotelic iii Dog c Ammonotelic (A) i → a, ii → b, iii → c (B) i → a, ii → c, iii → b (C) i → b, ii → a, iii → c (D) i → b, ii → c, iii → a Animals inhabit many environments. Aquatic animals have specialized excretory organs well adapted to help them survive in water. Which of the following characteristics is true for fish? (A) Excretion of concentrated urine (B) Excretion of dilute urine (C) Absence of excretory organs (D) Absence of respiratory organs

Conceptive Worksheet 15.

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The given illustration represents the human excretory system.

In the given illustration, the structure labelled X represents (A) Kidney (B) Ureter (C) Bladder (D) Urethra Body cells produce a large number of waste products that enter the blood. These waste products need to be removed from the body for the proper functioning of cells. The organ that filters waste from blood is the (A) Brain (B) Heart (C) Kidney (D) Stomach Which of the following functions is not performed by kidneys? (A) Removal of body toxins (B) Supplying oxygen to body (C) Maintaining body salt balance (D) Filtering of wastes from the blood Human excretory system is made up of kidneys, ureters, urinary bladder, and urethra. The structure that helps in the storage of urine is (A) Kidney (B) Ureter (C) Bladder (D) Urethra The kidneys are present in most vertebrate animals. The kidneys are important because they (A) Remove body waste (B) Digest food material (C) Pump blood to all body parts (D) Control different body movements Dialysis is the artificial process of regulation of fluids and mineral concentration in the human body. Which organ is replaced through dialysis? (A) Lung (B) Heart (C) Kidney (D) Liver The lungs end in alveoli, which are sac-like structures. The alveoli surface allows the exchange of respiratory gases between the blood cells and air. This helps in the purification of blood. Kidneys also play a role in this process. The basic unit of kidney, where blood gets filtered, is called (A) Ureter (B) Neuron (C) Urethra (D) Nephron Excretory organs help the body in getting rid of waste products. Which of the following organs is not an excretory organ? (A) Urethra (B) Kidneys (C) Lungs (D) Heart Human excretory system is made up of kidneys, ureters, urinary bladder, and urethra. The structure that helps in the formation of urine is (A) Urinary bladder (B) Urethra (C) Ureter (D) Kidney The kidneys filter waste products present in the blood and excrete them. This waste is produced due to the chemical reactions occurring in body. The basic unit of kidney is known as the (A) Ureter (B) Urethra (C) Neuron (D) Nephron

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Which of the following organs is not part of the excretory system? (A) Kidneys (B) Ovaries (C) Bladder (D) Ureter Kidneys produce (A) Urea (B) Urine (C) Carbon dioxide (D) Nitrogen dioxide The kidneys are the part of the excretory system. They are present in the abdominal cavity. The kidneys perform the function of (A) Removing metabolic waste from blood (B) Removing carbon dioxide from blood (C) Controlling body movement (D) Aiding body movement Different animals excrete different types of nitrogenous wastes. Which of the following animals excretes ammonia? (A) Fish (B) Snake (C) Lizard (D) Cow

26.

27.

28.

SNAP SHOT 1. Respiration is the process by which living organisms produce energy from the digested food using oxygen. It can be summarised as follows:   Digested food + Oxygen Energy + Carbon dioxide + Water 2. In some organisms, respiration may take place in the absence of oxygen. This is called anaerobic respiration. It can be summarised as follows:   Digested food Energy + Ethyl alcohol + Carbon dioxide 3. Aerobic respiration (respiration in the presence of oxygen) consists of two steps - breathing (external respiration) and cellular respiration (internal respiration). 4. Different organisms have different methods of breathing - simple diffusion, spiracles, gills, moist skin, and lungs. 5. In plants, gaseous exchange takes place through stomata (leaves) and lenticels (stems). 6. In humans, exchange of gases takes place in the alveoli (in lungs). Alveoli are surrounded by a large number of fine blood capillaries. 7. Respiratory system in humans consists of nose, windpipe, (trachea), bronchi and lungs. 8. (A) Transpiration is the process of loss of water in vapour form from the leaves in plants. (B) It takes place through stomata in the leaves. 9. The process of removal of waste products produced in the body is known as excretion. 10. In unicellular organisms, excretion takes place" through the general body surface by the process of diffusion. 11. In plants, waste products of photosynthesis and respiration are excreted through the stomata and lenticels. Other waste materials are discharged through the shedding of leaves and bark. 12. Excretion in humans occurs from lungs (carbon dioxide and water vapour), skin (sweat), kidneys (urine), and liver (wastes from blood). Major excretory organ, however, is the kidney. 13. Excretory system in humans consists of a pair of kidneys, ureters (2), urinary bladder and urethra. A number of filtering tubes called nephrons are present in each kidney.

Summative Worksheet I. 1.

2.

3.

Multiple Choice Questions The process in which food is oxidized and energy is released is called (A) Excretion (B) Respiration (C) Digestion (D) Transpiration The end products of respiration are (A) Only carbon dioxide (B) Carbon dioxide and water (C) Carbon dioxide, water and energy (D) Energy and carbon dioxide The process in which only exchanges of gases takes place is called (A) Respiration (B) Breathing (C) Combustion (D) Internal respiration

Respiration and Excretion 4.

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In earthworm, exchange of gases takes place through (A) Water (B) Gills (C) Moist skin (D) Spiracles Alveoli are structures present in (A) Lungs (B) Bronchi (C) Gills (D) All the above The pigment haemoglobin is present in (A) White blood cells (B) Red blood cells (C) Platelets (D) Lymph Transpiration in plants occurs through (A) Stomata (B) Leaf tips (C) Shoot apex (D) Roots The process of removal of waste products from the body is called (A) Transpiration (B) Evaporation (C) Excretion (D) Respiration The structures, present in kidney, which act as filters are (A) Alveoli (B) Nephrons (C) Villi (D) None of the above The urinary bladder opens into (A) Urethra (B) Nephron (C) Ureter (D) Neuron

2. 3. 6. 4. 5. 7. 8. 9. 10. 11. 12. 13. 14.

Fill in the blanks: During respiration, when energy is released, ______________ and ______________ are also produced. The substance in red blood cells that joins with oxygen is called ______________. Anaerobic respiration is carried out by ______________ Skin helps in the excretion of water and ______________ Excretion of wastes in unicellular organisms takes place by ______________ Getting rid of waste materials in living beings is called ______________ In humans, carbon dioxide is excreted through ______________ Kidneys are made up of a number of filters called ______________ Kidneys are connected to the urinary bladder by long tubes called ______________ In insects, breathing occurs through openings called ______________ Fish respire through structures called ______________ Air sacs present in lungs are called ______________ The waste product of respiration is The process by which energy is produced for use in various functions of the body is called

III. 1. 2. 3. 4. 5. 6.

Define the following terms: Respiration Breathing Internal respiration Aerobic respiration Anaerobic respiration Transpiration

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139 IV. 1. 2. 3. 4.

Differentiate between the following: Breathing and Respiration Combustion and Respiration Aerobic respiration and Anaerobic respiration Transpiration and .excretion

V. 1. 2. 3.

Give one word for the following: The process in which breaking down of food into small molecules occurs. Coiled tubes acting as filters and present in kidneys. Large flat muscle found in the chest cavity.

VI. 1. 2. 3. 4.

Write True or False in front of the statements given below: In respiration, oxygen is required and carbon dioxide is given out. Diffusion of gases takes place through a small part of root surface. In anaerobic respiration, complete breakdown of food takes place. Earthworms absorb oxygen through moist skin.

VII. Give labelled diagrams of the following: 1. Respiratory system of humans 2. Excretory system of humans VIII. 1. 2. 3. 4. 5. 6. 7. 8. 9.

10. 11. 12. 13.

Answer the following questions: Mention the end products of respiration. Mention the different organs/methods of breathing in animals. How does respiration occur in plants? Write a note on it. Write in short about the mechanism of respiration. Name the organs of the respiratory system in human beings. Define transpiration. Mention the factors affecting the rate of transpiration. Write a brief note on excretion in flowering plants. What waste products are removed by the following parts? (A) Skin (B) Kidneys (C) Lungs (D) Large intestine Describe the importance of respiration in organisms. Why do body cells require oxygen? How does excretion occur in lower plants and animals? Name the various organs of excretion in humans.

[ [ [ [

] ] ] ]

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By the end of this chapter, you will be able to  Know the difference between movement and locomotion.  Learn about the different methods of locomotion in animals 

Understand the movement in humans and the role of muscles, joints, tendons, ligaments and cartilage



Learn about the different kinds of joints in the human body



Learn about the movement in plants

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Perform experiments to show the role of light, gravity, water in plant movement.

Movement in Animals and Plants Chapter -8

Learning Outcomes

1. MOVEMENT AND LOCOMOTION All living organisms show some type of movement. Animals, however, move more freely. It is obvious when you call your pet dog, it comes running. The same is not true of a tree. This ability to move has been used as a criterion to differentiate plants and animals. Though movement is quite common in plants, it is not always apparent. Animals possess definite organs of locomotion. The act of moving from place to place is known as locomotion. It involves the movement of the whole body, as in walking, running, swimming or flying. Movement is the change in position of only a part of the body, as movement of stem towards light in plants. NEED FOR LOCOMOTION IN ANIMALS • To search for food. • To escape from enemies and predators. • To move to favourable environment. • To come together for reproduction. WHY ANIMALS NEED LOCOMOTION? Locomotion helps the animals in many ways. • Animals have to move from place to place in search of food, since they are heterotrophic. • Locomotion helps the animals to move in search of food. • Locomotion enables animals to move from an unfavourable place or environment to a favourable place or environment. • It helps them to escape from their enemies and predators. • It helps animals to find their partners for reproduction, and to move to favourable areas for egg laying or rearing of the young ones. 2. LOCOMOTION IN ANIMALS IN UNICELLULAR ANIMALS (i)

(ii) (iii)

Amoeba moves about by putting forth its false feet called pseudopodia (Figure. 8.1). The pseudopodia move their position every now and then, and bring about locomotion. This type of locomotion is known as amoeboid. Paramecium has hundreds of small fine hairs called cilia (Figure 8.2). The cilia move together just like the oars of a boat (Figure 8.3). In Euglena a single long hair called flagellum is found. Movement takes place by the whiplike action of the flagellum (Figure 8.4). Both cilia and flagella are locomotory organs and help in locomotion. Locomotion by cilia is called ciliary.

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Figure. 8.1 : Amoeba showing pseudopodia

Figure. 8.2 : Paramecium showing cilia

Figure. 8.3 : Locomotion in Paramecium

Figure. 8.4 : Euglena

IN MULTICELLULAR ANIMALS (1) Figure 8.5 shows movement in a simple multicellular animal, Hydra. At its free end is the mouth. Mouth is surrounded by a number of tubular structures, called tentacles. Hydra uses its tentacles for "walking" as shown in the figure. Movement is caused by contraction and relaxation of body cells, while locomotion is caused by looping and somersault.

Figure 8.5(a): Looping movement in Hydra

(2)

Figure 8.5(b): Somersault movement in Hydra

In looping movement (Figure 8.5a), the following steps take place: (i) Hydra bends its body and fixes its tentacles to the surface. (ii) Then the foot releases or frees itself and is placed close to the tentacles. (iii) Now the tentacles release their hold from the surface and the body becomes straight. Somersault movement (Figure 8.5b) occurs as follows: (i) The body bends till the tentacles touch the surface. (ii) The foot releases itself from the surface and the body becomes straight. Hydra, in this situation, stands on its tentacles. (iii) The process is repeated and the animal moves forward. (i) Earthworm has a long cylindrical body without a skeleton. (ii) Sense organs are not present. (iii) Circular and longitudinal muscle fibres are present on the body wall. (iv) When the circular muscles contract, the body gets longer and narrower. (v) When the longitudinal muscles contract, the body becomes thicker and shorter. (vi) The movement of these muscles pushes the blood in the direction of body movement. (vii) When it moves, the front (anterior) end becomes long and thin while its hind (posterior) end becomes short and thick (Figure 8.6). This is due to the contraction and expansion (relaxation) of body muscles. Thus, locomotion in earthworm is brought about by contraction and relaxation of body muscles.

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Locomotion in leeches is also brought about in the same manner as earthworm (Figure 8.7).

Figure 8.7: Locomotion in earthworm (3)

(4) (5)

In insects, two pairs of wings are usually present. Three pairs of walking appendages are also present. Both these structures help in locomotion. In vertebrate animals (fish, frogs, lizards, birds and mammals), a hard skeleton called endoskeleton is present inside the body. Endoskeleton consists of bones and cartilages. In addition, muscles are present, and these are attached to the bones. Muscles pull the bones and make them move. Note: Some insects like the housefly and mosquito have one pair of wings. Fishes have fins and tails on their body. These help in locomotion inside water (Figure 8.8). In frog, hind limbs with webbed feet help in locomotion (Figure 8.9).

Figure 8.8: Successive strokes for forward movement in fish (6) (7) (8)

Figure 8.7: Locomotion in Leech

Figure 8.9: Webbed feet of frog

In snakes, crawling movement takes place. Their bodies are covered with scales which help them to crawl. The birds use their strong breast muscles to push or pull their wings. The wings help in flying. In water birds, webbed feet are present, which help them to swim. Mammals, like tiger and elephant, use their hind limbs as well as the forelimbs for locomotion. Humans, however, use only hind-limbs for locomotion. We use our forelimbs for various other activities.

3. MOVEMENT IN HUMANS Locomotory movements in humans and rather all vertebrates are brought about by: 1. Bones, comprising the skeletal system (Figure 8.10A), and 2. Muscles (muscular system) (Figure 8.10B). FUNCTIONS OF SKELETAL SYSTEM (i) It supports the body and gives it a definite shape. (ii) It protects the delicate internal organs from mechanical injury. For example, the cranium (skull) protects the brain, the vertebral column protects the spinal cord and the ribs and sternum protect the heart and lungs.

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Figure 8.10: (A) Skeletal and (B) Muscular Systems (iii) (iv)

It provides attachment to the muscles and helps in movement. It produces blood cells in the bone marrow of long bones and ribs. Muscular system helps in movement and locomotion. Locomotion is the result of co-ordinated action of muscles on the limb bones. The contraction and relaxation of muscles move the bones. Many bones of the skeleton act as levers. When muscles pull on these levers, they produce movements, such as the breathing movements of the ribs, the chewing action of the jaws and the flexing of the arms.

JOINTS The places where two or more bones meet are termed joints. In vertebrates, there are three kinds of joints: (a) Immovable or fixed joints or fibrous joints. (b) Slightly movable or cartilaginous joints. (c) Freely movable or perfect joints or synovial joints. Ligaments: The bones are held together at a joint by tough structures called ligaments. (a) Immovable joints: These joints allow no movement. For example, the bones of skull are interlocked with each other by their serrated margins called sutures (Figure 8.11). Joints in tooth sockets are also of this type. (b) Slightly movable joints: In these joints, a pad of flexible cartilage is present between the bones which makes slight movements possible. Such joints are present between adjacent vertebrae in the backbone (Figure 8.12). (c) Freely movable joints: These joints allow free movement of bones in various directions. Such joints are formed by the contact of the articular surfaces of the adjoining bones which are covered with a thin layer of cartilage. A small space is left in between the two bones. The cavity is called the joint cavity or the synovial cavity (Fig 8.13). Synovial cavity is lined with a thin synovial membrane.

Figure 8.11: Immovable joints in Human skull Freely movable joints are of three types: (i) Ball and socket joint, (ii) Hinge joint, (iii) Pivot joint All movable joints have a similar structure.

Figure 8.12: Slightly immovable joint in between vertebrae

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Ball and socket joint: In this joint, the rounded head of one bone fits into a cup-shaped cavity formed by the other bone (Figure 8.13). This allows movement in all directions. Hinge joint: The hinge joints allow the movements only in one direction like those of a door or the lid of a box. Elbow joint (joints between the upper and the lower arm), knee-joint (between thigh and lower leg) and wrist joint (between the fore arm and the wrist) are examples of this type of joint (Figure 8.14)

Figure 8.13: Section of a typical freely movable joint (Ball and socket joint-hip)

Figure 8.14: Hinge joint (elbow)

Table 8.1: Types of joints Joint Where found in body Type of movement Fixed skull and pelvis no movement Slightly movable back bone slight movement Movable (i) Ball-and-socket hip and shoulder in all directions (ii) Hinge elbow, knee, finger in only one plane - like the hinge on a door (iii) Pivot neck nodding or turning Pivot joint: Such joints allow rotation only. It is because of this joint that the head is able to turn from side to side. Pivot joint occurs between the first and second vertebrae in the neck.

Fomative Worksheet 1. 2. 3. 4. 5.

6.

Which of the following is an act of locomotion? (A) Crawling (B) Running (C) Flying (D) Swimming The locomotory organs in amoeba is (A) Cilia (B) Wings (C) Pseudopodia (D) Tentacles The locomotion due to pseudopodia in amoeba is termed as (A) Ciliary (B) Flying (C) Amoeboid (D) Crawling Cilia are the locomotory organs in (A) Amoeba (B) Paramecium (C) Earthworm (D) Hydra Which of the following statements about the body movements of earthworms is incorrect? (A) They move by extending the front portion of their bodies, while keeping the rear portion fixed to the ground. (B) They move by extending the rear portion of their bodies, while keeping the front portion fixed to the ground. (C) Their bodies secrete a slimy substance that helps them in movement. (D) Their body muscles help them in movement. An earthworm takes five seconds each for extending front part of its body, releasing the rear portion of its body, and for pulling the rear forward by shortening its body. It covers a distance of 25 cm on completion of each round of these three steps. In what time will the earthworm cover 1 m distance if it moves with uniform speed? (A) 0.5 minute (B) 1 minute (C) 1.5 minutes (D) 2 minutes

Movement in Plants and Animals 7.

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Which of the following statements about snails is incorrect? (A) They move at a very slow pace. (B) They move with the help of a thick muscular foot. (C) The outer shell of snails plays an important role in movement. (D) The head and foot of snails are out of the shell during locomotion. Which of the following statements about cockroaches is incorrect? (A) They fly with the help of breast muscles attached to their wings. (B) They walk with the help of the muscles attached to their legs. (C) They have two pairs of wings. (D) They have four pairs of legs. Cockroaches have the ability to fly. Also, they can walk on ground. Which of the following statements regarding movement in cockroaches is correct? (A) They fly in air with the help of feathers. (B) They fly in air with the help of wings. (C) They move with the help of a thick muscular foot. (D) They move by extending the front part of their body. Which of the following statements about the body movement of fishes is correct? (A) Fins help fishes maintain the balance of body while swimming. (B) Gills help fishes maintain the balance of body while swimming. (C) The streamlined body of fishes helps them change directions while swimming. (D) The strong muscles attached to the skeleton of fishes help them change directions while swimming. Fishes are aquatic animals. Which of the following adaptations present in a fish does not help in swimming? (A) Presence of a streamlined body (B) Presence of a pair of gills (C) Presence of a tail (D) Presence of fins Fishes are aquatic organisms. Which feature in the body of fishes helps them change directions while swimming? (A) Gills (B) Streamlined body (C) Fins (D) Strong muscles Snakes are terrestrial organisms. Which of the following statements about the body movement of snakes is correct? (A) They move with the help of a thick muscular foot. (B) They move by continuously extending and shortening their body. (C) They move by folding their body into many loops, which gives a forward push to the body. (D) They move by moving the front portion of their body to one side, while swinging their tail to the other side. Column A Column B i Cockroach a Movement with muscular foot ii Birds b Forelimbs modified to wings iii Snake c Wings attached to breast muscles iv Snail d Movement in loop The alternatives in the given table can be correctly matched as (A) i → b, ii → c, iii → a, iv → d (B) i → b, ii → c, iii → d, iv → a (C) i → c, ii → b, iii → a, iv → d (D) i → c, ii → b, iii → d, iv → a What is the long, hard structure that starts from the neck to the lower back of the body known as? (A) Backbone (B) Cartilage (C) Pelvic bone (D) Shoulder bone The skeletal system provides shape and rigidity to the body. It also helps in protecting a number of internal organs. Which of the following internal organs is not protected by the ribcage? (A) Heart (B) Liver (C) Lungs (D) Stomach

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147 17.

The given diagram illustrates a part of the human skeletal system. Which of the following functions is performed by the illustrated image? (A) Breathing (B) Holding (C) Running (D) Sitting 18. Which of the following statements about constituents of rib cage is correct? (A) Rib cage consists of chest bones only. (B) Rib cage protects stomach, lungs, and heart. (C) Vertebral column alone comprises rib cage. (D) Twelve ribs and backbone constitute rib cage. 19. The given figure represents the human skeletal system. In the given figure, label X represents the (A) Skull (B) Rib cage (C) Shoulder bones (D) Pelvic bones

20. The given figure represents the human skeletal system. In the given figure, the shoulder bones are labelled as (A) I (B) II (C) III (D) IV

21. The given figure represents the human skeletal system. In the given figure, label X represents the (A) Skull (B) Rib cage (C) Shoulder bones (D) Pelvic bones

22. The given diagram illustrates the human skeleton. The structure labelled I in the given diagram illustrates the (A) Ribs (B) Skull (C) Backbone (D) Pelvic bones

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23. The given diagram illustrates the human skeleton. Pelvic bones in the given diagram are labelled as (A) I (B) II (C) III (D) IV

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Column A Column B Brain a Rib cage i Heart b Skull ii iii Spinal cord c Backbone (A) i → a, ii → b, iii → c (B) i → b, ii → a, iii → c (C) i → b, ii → c, iii → a (D) i → c, ii → a, iii → b Which joint is present between the upper jaw and rest of the head? (A) Fixed joint (B) Hinge joint (C) Pivotal joint (D) Ball and socket joint Which type of a joint is present in the bones of the head region and upper jaw? (A) Ball and socket joint (B) Pivotal joint (C) Hinge joint (D) Fixed joint Joints are present between bones in the human body. There are different types of joints such as ball and socket joint, hinge joint, pivot joint, and gliding joint. The ball and socket joint is capable of movements in infinite directions. The ball and socket joint is present in the (A) Shoulder (B) Elbow (C) Neck (D) Skull Joints are the meeting points of two or more bones. Which joint allows movements in all directions? (A) Pivotal joint (B) Ball and socket joint (C) Hinge joint (D) Fixed joint ___i_____is a movable joint that allows the bone to move in all the directions. An example of such a joint is___ii_____. The information in which alternative completes the given statement? (A) i – Hinge, ii – elbow (B) i – Ball and socket, ii – elbow (C) i – Hinge, ii – shoulder (D) i – Ball and socket, ii – shoulder Joints are the meeting points of two or more bones. Which joint allows the back and forth movement of the elbow? (A) Ball and socket joint (B) Pivotal joint (C) Fixed joint (D) Hinge joint The given diagram illustrates the knee region in the human skeletalsystem. Which type of a joint is present in the knee region? (A) Ball and socket joint (B) Pivotal joint (C) Hinge joint (D) Fixed joint The ____i___ joint allows no movement of bones, while the ____ii___ joint allows back and forth movement of bones. The information in which alternative completes the given statement? (A) i – hinge, ii – fixed (B) i – fixed, ii – hinge (C) i – fixed, ii – ball and socket (D) i – hinge, ii – ball and socket

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149 33.

The elbow joint is an example of a hinge joint. What kind of movement is possible by a hinge joint? (A) One-dimensional (B) Two-dimensional (C) Three-dimensional (D) Four-dimensional

34.

A student, while studying about different types of joints, wrote the following description about a particular joint X. “The joint allows movement only in four directions (up, down, back, and forth) similar to a rod rotating in a ring”. Joint X represents (A) Ball and socket joint (B) Pivotal joint (C) Fixed joint (D) Hinge joint Which of the following statements about pivotal joint is correct? (A) It is present in the elbow region. (B) It is present is the bones of the skull. (C) It allows movements in all directions. (D) It allows the forward and backward movements of the head. Column A Column B Ball and socket joint a Neck i Pivot joint b Elbow ii Hinge joint c Shoulder iii Fixed joint d Skull iv The alternatives in the given table can be correctly matched as (A) i → a, ii → c, iii → b, iv → d (B) i → b, ii → a, iii → d, iv → c (C) i → c, ii → a, iii → b, iv → d (D) i → d, ii → c, iii → d, iv → c Knee and ___i___ joints are __ ii___ joints, whereas __iii____ joint is a __ iv___ joint. The above statement is completed by the information provided in which row? (A) i – elbow, ii – hinge, iii – hip, iv – ball and socket (B) i – hip, ii – hinge, iii – elbow, iv – ball and socket (C) i – elbow, ii – pivot, iii – hip, iv – hinge (D) i – hip, ii – hinge, iii – elbow, iv – pivot The given graph signifies the number of directions in which joints P, Q, R, and S can move. Which of the following statements regarding the four joints is not correct? (A) Movement allowed by S is unidirectional. (B) Bone rotates in a ring in joint Q. (C) Joint P is present in skull. (D) R represents a hinge joint.

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Conceptive Worksheet 1. 2.

3. 4.

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The act of moving from one place to another is called (A) Locomotion (B) Transpiration (C) Diffusion (D) Effusion Animals need locomotion (A) To search for food (B) To escape from enemies and predators. (C) To move to favourable environment. (D) All the above Tentacles are the locomotory organs in (A) Amoeba (B) Paramecium (C) Earthworm (D) Hydra Locomotion in Hydra is caused by (A) Looping movement (B) Somersault movement (C) Both (D) None Which of the following statements regarding movement in earthworms is correct? (A) It moves with the help of a thick muscular foot. (B) It moves with the help of distinct muscles attached to the legs. (C) It moves by fixing its rear portion to the soil and extending its front part. (D) It moves by curving its body into many loops which pushes the body forward.

Movement in Plants and Animals 5.

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Earthworm lacks legs and bones. Therefore, it moves with the help of muscles that helps in extending and shortening the body. It moves by extending the front portion of the body, while keeping the rear portion fixed to the ground. Then, it releases the rear portion and fixes the front portion on the ground. Which of the following statements about earthworms is correct? (A) They move with the help of a muscular foot. (B) They move with the help of muscles attached to their bones. (C) They move with the help of muscles that help to extend and shorten their bodies. (D) They move with the help of muscles that help in folding their bodies into several loops. Which of the following statements about the body movements of snails is correct? (A) They move with the help of a thick foot that has strong muscles. (B) They move with the help of muscles that extend and shorten their bodies. (C) They move by folding their bodies into several loops, which gives them a push to move forward. (D) They move by moving their bodies to one side, while swinging their tails to the other side. Which of the following statements about the body movements of cockroaches is correct? (A) They move with the help of a thick muscular foot. (B) They have streamlined bodies, which helps them swim. (C) They have hollow and light bones, which helps them fly. (D) They walk with the help of the muscles attached to their legs. Which of the following features does not help a duck in flying? (A) Presence of wings (B) Presence of webbed feet (C) Presence of hollow and light bones (D) Presence of strong shoulder bones Fishes are aquatic animals that live under water. Which of the following features is absent from fishes? (A) Fins (B) Tail (C) Muscular foot (D) Streamlined body Fishes are aquatic animals, well adapted to live under water. Which feature of a fish’s body helps it to keep balance and change direction while swimming? (A) Presence of strong muscles (B) Presence of slippery scales (C) Presence of gills (D) Presence of fins ___i____move with the help of a thick muscular foot. ___ii____ move by curving their body into many loops where each loop gives a forward push to the body. The information inwhich alternative completes the given statements? (A) i – Snakes; ii – Cockroaches (B) i – Cockroaches; ii – Fishes (C) i – Fishes; ii – Snails (D) i – Snails; ii – Snakes The given figure represents a part of the human skeletal system. Which structure is shown in the given figure? (A) Rib cage (B) Skull (C) Backbone (D) Pelvic bone The given figure represents a part of the human skeletal system. The given figure represents the (A) Bones of the hand (B) Bones of the feet (C) Rib cage (D) Back bone

15. The illustrated structure belongs to the (A) Skeletal system (B) Nervous system (C) Muscular system (D) Circulatory system

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151 16. The given figure represents the human skeletal system. In the given figure, label X represents the (A) Pelvic bones (B) Skull (C) Rib cage (D) Shoulder bones

17.

The rib cage is a part of the skeletal system. It performs the function of protecting the (A) Heart and the lungs (B) Kidney and the lungs (C) Heart and the stomach (D) Kidney and the stomach

18. The given figure represents the human skeletal system. In the given figure, the pelvic bones are labelled as (A) I (B) II (C) III (D) IV

19. The given diagram illustrates the human skeleton. Which labelled structure helps in protecting the brain? (A) I (B) II (C) III (D) IV

20. The given diagram illustrates the human skeleton. Label I in the given diagram depicts the (A) Ribs (B) Skull (C) Backbone (D) Pelvic bones

Movement in Plants and Animals

152

21. The given figure represents the human skeletal system. In the given figure, label X represents the (A) Rib cage (B) Skull (C) Shoulder bones (D) Pelvic bones

22.

23.

24.

25.

26. 27.

Which of the following statements about fixed joint is correct? (A) It is present in the elbow region. (B) It is present in the bones of the skull. (C) It allows the movement of arms in all directions. (D) It allows the back and forth movement of the head. Which joint does not allow the movement of bones? (A) Fixed joint (B) Hinge joint (C) Ball and socket joint (D) Pivotal joint A joint is a place in the body where two or more bones meet. From the following, which joint allows free movement in all directions? (A) Ball and socket joint (B) Pivotal joint (C) Hinge joint (D) Fixed joint Joints are the meeting points of two or more bones. Which of the following statements about ball and socket joint is correct? (A) It is present in the bones of the elbow region. (B) It allows movements in all directions. (C) It is present in the bones of the skull. (D) It allows restricted movement. Ball and socket joint is present in (A) backbone (B) shoulder (C) ribs (D) skull The given figure illustrates parts I, II, III, and IV of skeletal system in humans. Which of the following labels represents a hinge joint? (A) I (B) II (C) III (D) IV

28.

29.

30.

The joints of the knee allow movement only in a back and forth direction. The type of joint present in the knee region is known as (A) Ball and socket joint (B) Pivotal joint (C) Hinge joint (D) Fixed joint Joints are the meeting points of two or more bones. Which of the following statements about hinge joint is correct? (A) It is present in the elbow region. (B) It is present in the bones of the skull. (C) It allows the movement of arms in all directions. (D) It allows the back and forth movement of the head. Which of the following statements is correct for hinge joint? (A) It is a type of fixed joint. (B) It can move in all directions. (C) It allows movement in right or left only. (D) It allows only back and forth movement.

153

7th Biology

31.

The pivotal joint is present between the (A) Head and neck region (B) Shoulder and upper arm (C) Bones of the elbow region (D) Bones of the head and upper jaw Which joint allows the movement of head in the forward and backward directions? (A) Ball and socket joint (B) Pivotal joint (C) Hinge joint (D) Fixed joint Sally likes to play tennis. She can move easily while playing tennis because the joints present in human body give her the flexibility to move. Which joint is present in the wrist? (A) Pivot joint (B) Hinge joint (C) Gliding joint (D) Ball and socket joint The locomotory organs in Euglena are (A) Flagella (B) Wings (C) Pseudopodia (D) Tentacles

32.

33.

34.

MUSCLES (i) The muscles possess the property of contraction and relaxation. It is the property of muscles which is responsible for the movement of bones and joints. (ii) A resting muscle is long and thin. When it contracts, it becomes short and fat. (iii) There are three types of muscles — voluntary, involuntary and cardiac. (iv) The movement in higher animals and humans is brought about by the voluntary muscles which are attached to the bones by means of tendons. (v) These muscles pull on our bones when we want to move. This makes our joints bend. (vi) The places where two or more bones meet are called joints. (vii) Tendons are the fibres by which muscles are attached to bones. A muscle has atleast one tendon at each end.  There are more than 350 muscles in our body.  Muscles constitute about 40 to 50 per cent of total body weight.  Tendons attach muscles to the bones. Muscles and movement: Muscles act in pairs; when one contract, the other relaxes. Bones provide leverage for rapid contraction and relaxation of the muscles. HOW DO OUR ARMS MOVE? To understand the movement, let us perform the following acts: 1. Place one of the hands on the underside of a table with the palm facing upwards (Figure 8.15). Now try to lift the table. What happens to the muscles of the arm? Observe carefully. You will find that when a muscle contracts, it gets shorter and fatter. When a muscle is not contracting, it returns to its normal size. In other words, it relaxes. 2. Now push down with the back of your hand against the table top (Figure 8.16). Observe what happens to the muscles which contract and relax.

Figure 8.15

Figure 8.15

As mentioned above, muscles work in pairs. Figure 8.17 and Figure 8.18 explain how it happens.

Movement in Plants and Animals

154

Figure 8.18 (a) Muscles when bending of arm take place; Figure 8.17: Muscles in human arm (b) Muscles when the arm is straightened On both sides of the upper arm bone, there is a pair of voluntary muscles. When one of these muscles contracts, it pulls the bones of the arm. This act bends or straightens the elbow joint. The muscles at the joint work in pairs -one makes the joint bend while the other makes it straight. The biceps muscle contracts when bending of arm takes place. When it contracts, it pulls the two bones of the forearm, bringing them close together. This makes the arm bend at the hinge joint at the elbow. When the arm is straightened, the biceps muscle relaxes. The triceps muscle, however, contracts and helps in straightening. The working together of the biceps and triceps muscles allows the arm to move in both the direction. 4. MOVEMENT IN PLANTS Plants are firmly rooted in the soil, and have no need for locomotory organs. Movement, however, is seen in some cases. (1) Algal forms like Chlamydomonas and Volvox show movement by means of flagella (Figure 8.20). (2) In mosses and ferns mobility is confined to male reproductive cells. They are ciliated (movement by cilia) and move about in water. (3) Movement of plant parts is observed in higher plants in response to an external stimulus. These movements are slow and are not visible. The movements of plant parts which take place towards or away from the stimulus are tropisms or Figure 8.20: Chlamydomonas tropic movements (Figure 8.21). When the movement is towards a stimulus, it is called a positive response; and when it is away from the stimulus, it is called negative response. Tropic movements may be in response to light (phototropism), gravity (geotropism), water (hydrotropism) and touch (thigmotropism). PHOTOTROPISM The movement of plants towards light is called phototropism (Photo = light; tropism = movement). Shoots generally grow towards light (positively phototrophic), while roots away from light (negative phototrophic). GEOTROPISM The movement in response to gravity is called geotropism (Geo = gravity; tropism = movement). Roots generally grow towards soil or gravity and are called positively geotropic. Shoots grow away Figure 8.21: Tropic movements: Response of the stem to from gravity (negative geotrophic). light and of root to gravity and water.

7th Biology

155 HYDROTROPISM

The movement of plant parts in response to water is termed hydrotropism (Hydro = water; tropism = movement). Roots are usually positively hydrotropic. THIGMOTROPISM The movement of plant in response to the stimulus of touch is called thigmotropism. It is seen in touch-me-not (Mimosa pudica) plant. The leaflets of this plant droop on being touched, and recover to normal position after some time. TROPIC AND NASTIC MOVEMENTS Movements in plants may or may not be related to the direction of the stimulus. The movements in which direction of movement is always related to the direction of the stimulus are called tropic movements. For example, bending of stem towards a light source. Nastic movements, on the other hand, are non-directional as compared to tropic movements. The stimulus is generally diffuse, unlike tropic movements where the stimulus is localized. Opening and closing of flowers in response to light is an example of nastic movement (photonasty in this case).

Fomative Worksheet 39.

40.

41.

42.

43.

44.

Humans perform a variety of activities, like running, walking, playing, lifting weights etc. They are able to do so because of organ system X. The organ system X referred to in the preamble is the (A) Muscular system (B) Digestive system (C) Excretory system (D) Circulatory system Which of the following statements about muscles is incorrect? (A) They contract to move a bone in a particular direction. (B) They contract to bring a bone to its original position. (C) They can only push the bone. (D) They can only pull the bone. The given figure illustrates two arm muscles X and Y at two positions i and ii. During transition from i to ii, (A) Only the relaxation of muscle Y takes place (B) Only the contraction of muscle X takes place (C) Relaxation of both muscles X and Y takes place (D) Contraction of both muscles X and Y takes place Muscles are necessary for the movement of bones. Which of the following statements is correct regarding contraction of muscles? (A) Bones can move in the absence of muscles. (B) Muscles become longer and thinner on contraction. (C) Muscles become shorter and thicker on contraction. (D) Bones can move in the presence of only one muscle. A student is provided with the information regarding the number of joints and type of joints present in two organs X and Y. Which of the following questions would the student not be able to answer with the help of the given information? (A) What is the function of X and Y? (B) Which organ has greater flexibility? (C) Which organ has greater contractibility? (D) What is the direction of movement allowed in X and Y? In animals, movements occur because of the changes occurring in the proteins present in the muscle cells. In plants, movements occur because of the (A) Changes in the shape of the cell (B) Changes in the organelles of the cell (C) Re-arrangement of the proteins present in the cell (D) Re-arrangement of the carbohydrates present in the cell

Movement in Plants and Animals 45.

46. 47.

48.

49.

50

51.

52.

156

During the process of seed germination, it is observed that seedlings grow towards the source of light. The phenomenon exhibited by seedlings is known as (A) Gravitropism (B) Phototropism (C) Chemotropism (DThermotropism Which of the following plants show movements with flagella? (A) Chlamydomonas (B) Volvox (C) Spirogyra (D) Mosses Statement - I: Shoots show positive phototropism. Statement – II: Roots show negative phototropism. (A) Statement - I is true, Statement - II is false. (B) Statement - I is false, Statement - II is true. (C) Both statements are true. (D) Both statements are false. The movement in response to gravity is called (A) Phototrophism (B) Geotropism (C) Hydrotropism (D) Thigmotropism The movement of plant parts in response to water is termed as (A) Phototrophism (B) Geotropism (C) Hydrotropism (D) Thigmotropism The Mimosa pudica or the touch-me-not plant is a sensitive plant which when touched responds by folding up its leaves. This is an example of growth independent movement. Which event leads to the folding up of leaves in the plant? (A) Movement of water into the cell (B) Movement of water out of the cell (C) Movement of chemicals into the cell (D) Movement of chemicals out of the cell When Swati touched the leaves of the plant called chhui-mui (touch-me-not), she noticed that the leaves started to fold up and droop. The given phenomenon is observed because of the (A) Response of the plant's nervous system to touch (B) Response of the plant's nervous system to touch (C) Changes in the shape of the plant cells because of the movement of water (D) Changes in the structural proteins produced by the plant’s specialized cells The movement shown by the leaves of touch-me-not on being touched is known as ___i_____. _____ii_____ involves the bending of shoots towards a source of light. The information in which alternative completes the given statements? (A) i – growth-independent movement; ii – Growth-dependent movement (B) i – growth-dependent movement; ii – Growth-independent movement (C) i – growth-independent movement; ii – Growth-independent movement also (D) i – growth-dependent movement; ii – Growth-dependent movement also

Conceptive Worksheet 35.

36.

37.

38. 39.

Bones give shape and structure to the body and help in the different body movements. The bones perform this function with the help of the (A) Muscles (B) Kidney (C) Lungs (D) Heart The muscular system helps the body in movement. In conducting the movements of the body, the muscular system is supported by the (A) Skeletal system (B) Digestive system (C) Excretory system (D) Circulatory system Muscles help in the movement of bones. Which of the following statements about muscles is correct? (A) They contract to become short and thick to push the bone. (B) They relax to become long and thin to push the bone. (C) They work independently to move a bone. (D) They work in pairs to move a bone. In which of the following plants, movement by cilia is observed? (A) Moss (B) Fern (C) Chlamydomonas (D) Volvox The movement of plants towards light is called (A) Phototrophism (B) Geotropism (C) Hydrotropism (D) Thigmotropism

7th Biology

157 40.

41.

42.

Statement - I: Roots are positively geotropic. Statement – II: Show are negatively geotropic. (A) Statement - I is true, Statement - II is false. (B) Statement - I is false, Statement - II is true. (C) Both statements are true. (D) Both statements are false. Roots are usually (A) Positively geotropic (B) Negative phototropic (C) Positively hydrotropic (D) All Which of the following statements is correct about growth independent movements? (A) This type of movement is apparent. (B) This type of movement is dependent on phytohormones. (C) This type of movement is shown by tendrils of the pea plant. (D) This type of movement is independent of the direction of stimulus.

SNAP SHOT 1. Movement is the change in position of only a part of the body. 2. The act of moving bodily from one place to another is known as locomotion. 3. Pseudopodia, cilia, flagella, wings, fins and tails, webbed feet and breast muscles help in locomotion in different animals. 4. In humans, skeletal system and muscular system bring about locomotion. 5. A joint occurs where two bones meet. Different types of joints allow different amounts of movement. 6. Muscles work by contraction and relaxation. Muscles work in pairs - one contracts and the other relaxes. 7. Plants, being rooted to the soil, lack locomotory organs. 8. Movement in lower plants takes place by flagella or cilia. 9. In higher plants, movements may be tropic or nastic. 10. Tropic movements may be in response to light (phototropism), gravity (geotropism), water (hydrotropism), or touch (thigmotropism).

Summative Worksheet I. 1.

2.

3.

4.

5.

6.

Multiple Choice Questions — Tick mark (  ) the correct choice. Cilia are used for locomotion in case of (a) Amoeba (b) Euglena (c) Paramecium (d) Hydra Earthworm moves by means of (a) Flagella (b) Circular and longitudinal muscles (c) Fins (d) Hind limbs Muscles are attached to the bones by (a) Tendons (b) Cartilages (c) Ligaments (d) None of the above Synovial cavity is found in (a) Immovable joints (b) Freely movable joints (c) Slightly movable joints (d) Muscles The joint which allows movement in one direction only is a (a) Hinge joint (b) Pivot joint (c) Ball and socket joint (d) Slightly movable joint In tropic movement, plant parts move (a) Away from the stimulus (b) Towards the stimulus (c) Either towards or away from the stimulus (d) Only towards soil

Movement in Plants and Animals

158

II. 1. 2. 3. 4. 5. 6.

Fill in the blanks: A joint occurs where two _____________ meet. When a muscle _____________ thickens. When a muscle _____________ original shape. Joints in the bones of the skull are of _____________ type. In a positive response, the movement is _____________ the stimulus. Movement in response to touch is called _____________.

III.

Name the structures associated with locomotion in the following organisms: 1. Amoeba 2. Paramecium 3. Euglena 4. Hydra 5. Fish 6. Reptiles 7. Birds 8. Frog

IV.

Define the following: 1. Joints 3. Tropism 5. Thigmotropism

2. Tendons 4. Phototropism

V.

Name the joints found in / between 1. Teeth and gum 2. Finger 3. Skull 4. Knee 5. Shoulder

VI. 1. 2. 3.

Differentiate between the following: Tendons and ligaments. Hydrotropism and thigmotropism Hinge joint and ball and socket joint

VII. 1. 2. 3. 4. 5.

Answer the following: Why do animals need locomotion? How is locomotion brought about in humans? Give a brief account of the various methods of locomotion in animals. How is locomotion different from movement? In which animals, do you find the following structures: (a) Webbed feet (b) Pseudopodia (c) Tentacles How does locomotion take place in an earthworm? What is tropism? What is meant by positive and negative responses. How are tropic movements different from nastic movements? Write in brief, about the different types of tropic movements. Name the stimulus which causes the following movements in plants: geotropism, opening and closing of flowers, phototropism, thigmotropism, hydrotropism

6. 7. 8. 9. 10. 11.

_______________



_______________

7th Biology

159

1.BASIC BIOLOGY FORMATIVE WORKSHEET Q.No Key Q.No Key Q.No Key Q.No Key Q.No Key

1 A 11 B 21 D 31 B 41 B

2 B 12 D 22 B 32 B 42 D

3 A 13 B 23 C 33 C 43 B

4 C 14 D 24 D 34 A 44 A

5 D 15 B 25 B 35 C

6 D 16 B 26 B 36 B

7 A 17 D 27 D 37 D

8 A 18 A 28 C 38 B

9 D 19 D 29 C 39 A

10 C 20 C 30 D 40 D

7 D 17 B 27 A D

8 A 18 D 28

9 C 19 A 29

10 D 20 B 30

7 C 17 C

8 C 18 A

9 D 19 C

10 A 20 A

CONCEPTIVE WORKSHEET Q.No Key Q.No Key Q.No Key Q.No Key

1 A 11 A 21 B 31

2 A 12 B 22 A 32

3 D 13 C 23 C D

4 C 14 C 24 A C

5 C 15 A 25 D A

6 A 16 D 26 B C

SUMMATIVE WORKSHEET Multiple Choice Questions Q.No Key Q.No Key

1 C 11 B

2 A 12 A

3 B 13 B

4 A 14 D

5 B 15 C

6 A 16 B

Fill in the blanks, using the words given below. One word can be used twice: 1.

Nucleus

2.

Microscope

3.

Chloroplast

4.

Egg

5.

Nucleus, Cytoplasm, Cell membrane, Mitochondria

6.

Mitochondria

7.

Robert Hooke

8.

Plant

Which of the following statements are true (T) and which ones are false (F)? 1. 4. 7.

T T F

2. 5. 8.

F F F

3. 6.

T T

Match the statements in Column A with those in Column B. 1.

1-c, 2-d, 3-a, 4-e, 5-f, 6-b

______________________________________________________________________________________________________________________________

Key

160

2.ORGANISATION IN LIVING THINGS FORMATIVE WORKSHEET Q.No Key Q.No Key Q.No Key Q.No Key Q.No Key Q.No Key

1 D 11 C 21 C 31 B 41 B 51 A

2 D 12 ABCD 22 B 32 D 42 D 52 A

3 C 13 AB 23 C 33 D 43 D

4 A 14 D 24 A 34 C 44 D

5 A 15 A 25 B 35 C 45 *

6 B 16 C 26 A 36 C 46 A

7 A 17 B 27 A 37 B 47 B

8 CD 18 C 28 C 38 D 48 D

9 A 19 C 29 D 39 B 49 *

10 D 20 D 30 * 40 C 50 B

10 D 20 D 30 AB 40 A

CONCEPTIVE WORKSHEET Q.No Key Q.No Key Q.No Key Q.No Key Q.No Key

1 A 11 A 21 A 31 A 41 A

2 D 12 B 22 D 32 A 42 C

Multiple Choice Questions Q.No 1 Key A

3 A 13 B 23 B 33 B 43 C

4 C 14 D 24 B 34 D 44 A

5 ABC 15 D 25 B 35 A

6 B 16 C 26 A 36 A

7 A 17 C 27 B 37 D

8 D 18 C 28 C 38 A

9 D 19 D 29 A 39 B

2 B

3 B

4 C

5 D

6 D

7 C

8 A

Fill in the blanks: 1. (i) Population, Biotic community, Ecosystem, and Biosphere. 2. Tissues 3. Organs 4. Kidney 5. Leaf 6.

Species

Classify the following as cells, tissues, organs, organ systems or organisms: 1. organism 2. Organ 3. organ 4. organ 5. organ system 6. tissue 7. organism 8. Tissue 9. organ 10. tissue Name the main organs of the following systems: 1. Stomach 2. Lungs 3. Heart 4. Brain 5. Kidneys 6. Skull Which of the following statements are true (T) and which ones are false (F)? 1. True 2. True 3. False 4. True 5. False 6. True 7. False 8. False 9. False 10. False 11. True 12. True 13. 14. True

True

______________________________________________________________________________________________________________________________

7th Biology

161

3.TISSUES FORMATIVE WORKSHEET Q.No Key Q.No Key Q.No Key Q.No Key

1 A 11 B 21 C 31 D

2 D 12 B 22 A 32 A

3 A 13 C 23 B 33 D

4 B 14 B 24 C 34 B

5 A 15 C 25 B 35 C

6 C 16 D 26 D 36 B

7 A 17 B 27 C 37 A

8 D 18 D 28 A

9 A 19 C 29 C

10 D 20 A 30 C

7 B 17 D 27 D

8 D 18 B 28 A

9 A 19 C 29 A

10 B 20 C 30 B

7 A

8 A

9 A

10 A

CONCEPTIVE WORKSHEET Q.No Key Q.No Key Q.No Key Q.No Key

1 B 11 B 21 B 31 B

2 C 12 D 22 D 32 C

3 C 13 B 23 D 33 D

4 B 14 C 24 B 34 C

5 A 15 C 25 A 35 A

6 C 16 C 26 C

SUMMATIVE WORKSHEET Multiple Choice Questions Q.No 1 2 Key C B

3 A

4 C

5 A

6 B

Fill in the blanks 1. Muscular tissues 2. Skeletal 3. Neurons 4. Brain, spinal cord 5. Smooth (or unstriated) 6. Muscular tissue 7. Vascular tissue 8. Xylem 9. Phloem 10. Meristematic 11. Meristematic Name the tissue found in the following: 1. Meristematic 2. Dermal tissue 3. Epithelial tissue 4. Muscular tissue 5. Connective tissue 6. Nervous tissue 7. Parenchyma Find the odd one out, giving reasons: 1. Plasma 2. Blood 3. Epithelium 4. Xylem 5. Collenchyma Which of the following statements are true (T) and which ones are false (F)? 1. T 2. T 3. F 4. F 5. F 6. T 7. T 8. T 9. T 10. T 11. T

______________________________________________________________________________________________________________________________

Key

162

4. LIFE UNDER A MICROSCOPE (MICROORGANISMS) FORMATIVE WORKSHEET Q.No Key Q.No Key Q.No Key Q.No Key Q.No Key Q.No Key

1 B 11 A 21 B 31 A 41 D 51 C

2 A 12 C 22 D 32 C 42 D 52 B

3 D 13 C 23 B 33 C 43 A 53 D

4 ABC 14 A 24 D 34 B 44 C 54 D

5 B 15 D 25 A 35 A 45 B

6 D 16 D 26 B 36 B 46 D

7 C 17 C 27 A 37 C 47 C

8 C 18 C 28 A 38 C 48 A

9 ABD 19 A 29 D 39 B 49 D

10 D 20 A 30 C 40 D 50 C

7 C 17 A 27 D 37 AB

8 B 18 BC 28 B 38 C

9 A 19 B 29 A 39 D

10 A 20 D 30 D 40 C

7 C

8 B

9 C

10 B

CONCEPTIVE WORKSHEET Q.No Key Q.No Key Q.No Key Q.No Key Q.No Key

1 A 11 D 21 B 31 D 41 C

2 D 12 A 22 A 32 D 42 B

3 B 13 B 23 B 33 D

4 C 14 C 24 A 34 AB

5 B 15 A 25 B 35 ABCD

6 B 16 D 26 D 36 D

SUMMATIVE WORKSHEET

Multiple Choice Questions Q.No Key Q.No Key

1 A 11 A

2 B 12 B

3 D

4 A

5 C

6 A

Mushrooms red alga yeast Silica

3. 6. 9. 12.

Fill in the blanks 1. 4. 7. 10.

Microscope Kelp smaller bacteriophage

2. 5. 8. 11.

chlorphyll hyphae binary fission pathogens

Name the following: 1. 4. 6.

8. 12. 13. 14.

Lactobacillus 2. Penicillium 3. Yeast heterocyst 5. Yeast Cholera, typhoid, tuberculosis, diphtheria, plague Ringworm (skin disease) and Rusts in plants Malaria, dysentery, sleeping sickness Common cold, chickenpox, smallpox, measles, polio, rabies Alexander flemming 9. Idli, Dosa, Bread 10. Rhizobium Amoeba, Paramecium, Euglena, Plasmodium, Trypanosoma. Salmonella and Clostridium. Aspergillus and Penicillium

11.

Plasmodium

______________________________________________________________________________________________________________________________

7th Biology

163 Find the odd one out. 1. flowering plants

2.

bread mould

3.

Mushroom

Match the statements in Column A with those in Column B. 1.

a – r, b – t, c – p, d – q, e – s

Which of the following statements are true (T) and which ones are false (F)? 1.

False It is a caused by a protozoan i.e., Plasmodium. False It was Louis Pasteur who first stated the "germ theory of disease". True False Plague is a deadly infectious disease that is caused by the enterobacteria yersinia pestis False It is obtained from red alga. False Phycology is study of algae. True True

2. 3. 4. 5. 6. 7. 8.

5. NUTRITION IN PLANTS AND ANIMALS FORMATIVE WORKSHEET Q. No Key Q. No Key Q. No Key Q. No Key Q. No Key Q. No Key

1 C 11 B 21 A 31 C 41 A 51 D

2 C 12 12a A C 22 A 32 * 42 C 52 D

14.

500,000,000

16.

a) False b) True c) True

3 D 13 C

14 D 23 A 33 D 43 D 53 A

4 AB 13a 14a C * 24 A 34 B 44 C 54 B

5 C 15 B 25 A 35 B 45 C 55 D

6 A 16 A 26 * 36 A 46 D 56 B

7 C 17 * 27 * 37 D 47 D 57 A

8 A 18 * 28 C 38 D 48 B 58 A

9 A 19 C 29 C 39 C 49 A 59 D

10 C 20 * 30 A 40 D 50 C 60 B

17. A B C D Outer membrane Inner membrane Stoma Thylakoid

E Granum

18. A Guard cells

B Chloroplasts

C Epidermal cell

D Nucleus

E Stoma

______________________________________________________________________________________________________________________________

Key

164 CONCEPTIVE WORKSHEET

1. 2. 3. 4. 5. 6. 7.

Food Nutrition Autotrophic nutrition and Heterotrophic nutrition. Photosynthesis Autotrophic nutrition Autotrophs Charles Reid Barnes Carbon dioxide + Water

8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35.

sunlight and chlorophyll

Starch + Oxygen

Carbon dioxide Water Starch and oxygen Photosynthesis Chlorophyll Pigment. Stomata Xylem Phloem a) True b) False Heterotrophic. Heterotrophs Parasitic plants, symbioitic plants, saprophytic plants, insectvorous plants Host Cuscuta and mistletoe Rafflesia Whitish Saprophytic Asia and throughout North America Fungi Insectivorous plants are plants that derive some or most of their nutrients by trapping and consuming animals, mainly insects. Pitcher plant Sundew (Drosera) Rhizobium Leaf Lichens are an association between a fungus and an algae. Bacteria Q. No Key Q. No Key

36 C 46 C

37 B 47 A

38 C

39 D

40 D

41 A

42 C

43 B

44 D

45 B

SUMMATIVE WORKSHEET Multiple Choice Questions Q.No Key

1 B

2 B

3 A

4 A

5 B

______________________________________________________________________________________________________________________________

7th Biology

165 Fill in the blanks: 1. proteins 2. 4. rice and milk 5. 7. Calcium and phosphorous 8. 10. vitamin D 11. 13. food 14. 16. balanced diet 17. 19. oxygen 20. 22. chlorophyll , chloroplast 23.

Facts 78 Energy Goiter vitamin C rice and bread Iodine stomata

3. 6. 9. 12. 15. 18. 21.

balanced proteins K calories scurvy carbon dioxide, water and sun light bule-black

Which of the following statements are true (T) and which ones are false (F)? 1. T 2. F 3. F 4. F 5. T 6. T 7. F 8. T 9. T 10. F 11. T Name the following: 1. Carbohydrates and fats 2. proteins 3. vitamins and minerals 4. bread, milk , cheese, egg, meat etc 5. (a) Wheat, Rice, Maize, Potato, Bread, Honey, Common sugar, Milk, Banana (b) Pulses (peas, soyabean), Egg, Meat, Paneer, Cheese, Groundnut, Milk, Fish (c) Butter, Cheese Vegetable oil (coconut oil, Groundnut oil, Sunflower oil), Nuts, Milk, Animal fat from meat 6. (a) Night-blindness (poor night vision) (b) Anaemia (c) Scurvy (bleeding of gums and swelling of joints) (d) Goitre (enlarged thyroid), Abnormal metabolism 7. (a) phosphorous, iodine and fluorine (b) calcium, phosphorus, potassium (c) sodium and iodine 8. chlorophyll 9. carbon dioxide 10. Drosera Match the statements in column A with those in column B. 1. 1-b, 2-c, 3-a, 4-e, 5-d

6. DIGESTION FORMATIVE WORKSHEET Q.No Key Q.No Key Q.No Key Q.No Key Q.No Key Q.No Key Q.No Key

1 A 11 B 21 D 31 B 41 C 51 A 61 D

2 D 12 C 22 A 32 B 42 B 52 B 62 B

3 B 13 B 23 D 33 C 43 D 53 B

4 D 14 D 24 A 34 C 44 D 54 D

5 A 15 D 25 B 35 * 45 B 55 D

6 B 16 A 26 D 36 B 46 A 56 A

7 A 17 B 27 B 37 C 47 A 57 A

8 B 18 B 28 D 38 D 48 D 58 C

9 A 19 A 29 C 39 D 49 A 59 D

10 A 20 A 30 A 40 A 50 B 60 D

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Key

166 CONCEPTIVE WORKSHEET Q.No Key Q.No Key Q.No Key Q.No Key Q.No Key

1 C 11 C 21 D 31 A 41 B

2 A 12 C 22 A 32 A 42 C

3 C 13 C 23 C 33 A 43 A

4 C 14 B 24 C 34 C 44 D

5 D 15 C 25 D 35 C 45 D

6 A 16 C 26 D 36 B 46 D

7 A 17 A 27 C 37 A 47 B

8 C 18 D 28 B 38 B 48 B

9 D 19 B 29 A 39 A

10 D 20 D 30 A 40 C

SUMMATIVE WORKSHEET Multiple Choice Questions Q.No 1 2 3 4 5 6 7 Key C A C C B B C Fill in the blanks: 1. salivary glands 2. 12 3. incisors 4. enzymes 5. digestion 6. spleen 7. Ingestion, Digestion, Absorption, Assimilation and Egestion 8. enamel 9. root 10. cannies Name the following: 1. i. Mouth and mouth cavity ii. Oesophagus (gullet) iii. Stomach iv. Small Intestine v. Large Intestine vi. Anus 2. Incisors, Canines, Premolars and Molars 3. Mouth-saliva Pancreas-insulin Stomach-gastric juice Small intestine-amylase (ptyalin) Which of the following statements are true (T) and which ones are false (F)? 1. T 2. F 3. T 4. F 5. F 6. F

8 B

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7th Biology

167

7. RESPIRATION AND EXCRETION FORMATIVE WORKSHEET Q.No Key Q.No Key Q.No Key Q.No Key

1 A 11 A 21 B 31 D

2 D 12 B 22 B 32 C

3 A 13 A 23 B 33 A

4 A 14 A 24 B 34 B

5 D 15 B 25 C 35 `B

6 D 16 C 26 C

7 A 17 B 27 C

8 A 18 C 28 B

9 A 19 B 29 D

10 C 20 D 30 D

7 A 17 D 27 A

8 C 18 C 28 A

9 C 19 A

10 C 20 C

7 A

8 C

9 B

10 C

CONCEPTIVE WORKSHEET Q.No Key Q.No Key Q.No Key

1 C 11 A 21 D

2 A 12 C 22 D

3 D 13 A 23 D

4 C 14 A 24 D

5 B 15 B 25 B

6 B 16 C 26 B

SUMMATIVE WORKSHEET Multiple Choice Questions Q.No Key

1 B

2 C

3 A

4 C

5 A

6 B

Fill in the blanks: 1. carbon dioxide and water 2. Hemoglobin 4. diffusion 5. Excretion 7. lungs 8. Nephrons 10. spiracles 11. Gills 13. carbon dioxide and water 14. respiration Write True or False in front of the statements given below: 1. T 2. F 3.

3. 6. 9. 12.

yeast and bacteria urea and salt ureter alveoli

F

4.

T

8. MOVEMENT IN ANIMALS AND PLANTS FORMATIVE WORKSHEET Q.No Key Q.No Key Q.No Key Q.No Key Q.No Key Q.No Key

1 ABCD 11 B 21 A 31 C 41 A 51 C

2 C 12 C 22 B 32 B 42 C 52 A

3 C 13 C 23 D 33 A 43 C

4 B 14 D 24 B 34 B 44 A

5 B 15 A 25 A 35 D 45 B

6 B 16 D 26 D 36 C 46 AB

7 C 17 B 27 A 37 A 47 C

8 D 18 D 28 B 38 A 48 A

9 B 19 D 29 D 39 A 49 C

10 A 20 D 30 D 40 C 50 B

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Key

168 CONCEPTIVE WORKSHEET Q.No Key Q.No Key Q.No Key Q.No Key Q.No Key

1 A 11 D 21 A 31 A 41 D

2 D 12 D 22 B 32 B 42 D

3 D 13 C 23 A 33 C

4 C 14 A 24 A 34 A

5 C 15 A 25 B 35 A

6 C 16 D 26 B 36 A

7 A 17 A 27 D 37 D

8 D 18 B 28 C 38 AB

5 A

6 C

9 B 19 A 29 A 39 A

10 C 20 A 30 D 40 C

SUMMATIVE WORKSHEET Multiple Choice Questions Q.No Key Fill in the blanks: 1. bones 2. contracts 3. relaxes 4. immovabale joints 5. towards 6. thigmotropism

1 D

2 B

3 A

4 B

Name the structures associated with locomotion in the following organisms: 1. Amoeba - pseudopodia 2. Paramecium - cilia 3. Euglena - flagellum 4. Hydra - tentacles 5. Fish - fins and tail 6. Reptiles - scales 7. Birds - wings 8. Frog - hind limbs with webbed feet Name the joints found in / between 1. Teeth and gum - bony socket 2. Finger - Hinge 3. Skull - Fixed 4. Knee - Hinge 5. Shoulder - Ball and socket

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