Biology Terminology (Quick Study Academic) [1 ed.] 1423221516, 9781423221517

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Essential, concise definitions designed for quick access to support the study of life

abiotic: Characteristic of nonliving entities ABO blood groups: Antigens A and B found on red blood cells; based on genetic inheritance; O is the absence of both A and B antigens; possible phenotypes (i.e., blood types) include A, B, AB, and O acclimation: Adapting physiologically to artificial or experimental conditions acclimatization: Adapting physiologically to natural or environmental conditions acoelomate: Animals with no internal body cavity between the digestive tract and external body coverings acquired immunity: Production of antibodies after exposure to antigens either naturally or through vaccination action potential: Sudden reversal of polarity across a cell membrane triggered by a stimulus that causes ion channels (e.g., Na) to open active immunity: Self-produced immunity; antibodies produced based on exposure to antigens; may last long periods of time, even years; See passive immunity active transport: Energy-requiring movement of materials across cell membranes; typically going against concentration gradients; See passive transport adaptation: Genetic characteristics (morphological, physiological, or behavioral) that increase the survival and reproductive rates of organisms adaptive radiation: Divergence of species types and phenotypes to exploit diversified habitats in ecosystems adenosine triphosphate (ATP): Primary energy molecule in cells of all organisms; sometimes called the energy currency of a cell adrenaline: Hormone from the adrenal medulla released during acute stress; also called epinephrine age structure: Age distribution of individuals in a population agonism: Aggressive behavior between individuals; typically competing for mating, feeding, or territories AIDS (acquired immunodeficiency syndrome): Effect of HIV infection; characterized by reduced immune response and concomitant increased chances of secondary infections alcoholic fermentation: Anaerobic ATP production by converting pyruvate to CO2 and ethyl alcohol algae: Photosynthetic, eukaryotic protists allantois: Associated structure of amniote embryo; functions in gas exchange and stores dissolved wastes alleles: Alternate phenotypes of genes allometric growth: Differential growth rates of body areas to develop distinct morphologies, e.g., appendages allopatric speciation: Population of a species is separated (e.g., by geography) into distinct subgroups that subsequently diverge into separate species; See sympatric speciation

alternation of generations: Life cycle of plants and some algae that includes multicellular diploid (sporophyte produces spores) and haploid (gametophyte produces gametes) stages: heteromorphic: sporophyte and gametophyte are different in form; isomorphic: sporophyte and gametophyte have the same form altruism: The performance of potentially harmful behavioral acts that may benefit other individuals amniocentesis: Procedure of sampling cells from the developing embryo and associated membranes for genetic analysis amniotic egg: Vertebrate, tetrapod egg type with protective structures and supportive membranes amoeboid: Cell types with morphology similar to that of amoebae; with pseudopodia, e.g., certain white blood cells anabolism: Type of metabolism where complex, large molecules are synthesized from smaller molecules anaerobic: Referring to the absence or nonuse of oxygen analogous structures: Similar characteristics (e.g., bird and bat wings) based on convergent evolution rather than close phylogenetic relationships; See homologous structures anatomy: Study of morphology androgen: Steroid hormones affecting male reproduction and development aneuploidy: Abnormal numbers of chromosomes angiosperm: Plant that produces seeds inside a flower anhydrobiosis: A form of cryptobiosis; organisms can withstand extreme desiccation (i.e., lack of water) within its cells Animalia: Kingdom of multicellular, eukaryotic heterotrophs; lack cell walls annual plant: Completes its life cycle in one growing season; may not persist beyond a year anoxybiosis: A form of cryptobiosis; organisms can survive with no oxygen within their cells antheridium: Area of male gamete production in plants and algae anthropoid: Primates consisting of monkeys, apes, and humans antibody (immunoglobulin): Proteins produced by white blood cells (B cells); important component of specific immunity; bind to antigens anticodon: Triplet sequence of nucleotides on tRNA that allow for the complementary base pairing with mRNA during protein synthesis antidiuretic hormone (ADH): Hypothalamic hormone that helps body retain water and increases blood pressure by increasing vasoconstriction; also known as vasopressin antigen: Substance (biotic or abiotic) that triggers immune system to produce antibodies antiparallel: Description of opposite direction of each side of the DNA molecule

antler: Branching, bony structures growing from the skulls of some mammals, e.g., deer apical meristem: Embryonic plant tissues at root and bud tips; allow for lengthening plant growth apoptosis: Programmed cell death in tissues aposematic coloration: Conspicuous color patterns on organisms warning others to avoid contact because of physical or chemical defenses appendicular skeleton: Bones of the appendages (e.g., legs, arms, wings) in vertebrates appendix: Digestive structure arising from the cecum; may have immune function; may be vestigial Archaea: Prokaryotic domain; distributed in many habitats, including harsh environments; See extremophiles archegonium: Female part of plant gametophyte in which gametes are produced archenteron: Embryonic gut formed during gastrulation; lined with endoderm arteriole: Blood vessel between arteries and capillaries artery: Blood vessel transporting blood from the heart arthropod: Animal with a hard exoskeleton; appendages have soft articulations at joints to allow for movement; body segments present artificial selection: Reproduction of organisms controlled or influenced by humans for selection of traits ascocarp: Spore-producing structure of ascomycete (sac) fungi asexual reproduction: Formation of new, genetically identical individuals from one individual via cell division or tissue budding associative learning (classical conditioning): Learning by associating separate stimuli or events ATP synthase: Enzyme embedded in membranes (in mitochondria and chloroplasts); catalyzes production of ATP using osmotic flow of protons that were generated primarily via electron transport systems (ETS) autoimmunity: The immune system attacks the organism’s own cells or tissues autonomic nervous system: Motor neurons that are typically under subconscious or automatic control, e.g., control of heart rate; See somatic nervous system, sympathetic division, parasympathetic division autosome: Chromosomes not involved in sex determination autotroph: Organisms that produce their own food molecules either using sunlight or inorganic chemicals axial skeleton: Bones that compose the main axis of the body axillary bud: Plant structure that form new branches or shoots; emerges at the point where a stem and leaf meet axon: Elongated extensions of neurons; important in transmitting nerve impulses

B cell (B lymphocyte): A white blood cell that differentiates in the bone marrow; produces antibodies bacillus: Rod-shaped bacteria Bacteria: Prokaryotic domain; extremely prolific and diverse bacteriophage (phage): Viruses specialized for bacteria Barr body: Inactivated, condensed X chromosome; found in female mammals with two X chromosomes in somatic cells basal metabolic rate (BMR): Resting metabolic rate base-pair substitution: Point mutation in which a nucleotide pair is substituted; may subsequently change the gene expression basidiocarp: Spore-producing structure of basidiomycete (club) fungi behavior: Actions of an animal, relating to its environment, e.g., finding mates, food behavioral ecology: Study of animal behavior in relation to its evolution and environment bilateral symmetry: Animals that have one plane/axis creating two mirror images on left and right side binary fission: Cell division and asexual reproduction by prokaryotes; produces two clone cells binomial nomenclature: System of assigning a two-word scientific name to organisms: 1st = genus, 2nd = species; e.g., Homo sapiens biodiversity (species diversity): Number (species richness) and relative abundance of species in a habitat bioenergetics: Energy flow through organisms and their environment biofilm: Accumulation of prokaryotes on a surface; metabolic cooperation may also occur

biogeochemical cycle: Nutrient pathways and transfers within biotic and abiotic portions of ecosystems, e.g., nitrogen cycle biogeography: Study of current and historical distribution of species bioinformatics: Use of computer/statistical applications to access large databases about DNA/gene/protein information biological accumulation: Substance (e.g., toxin) levels increase in an organism as it interacts with the environment, e.g., through eating or respiration biological clock: Intrinsic clock controlling biological rhythms of organisms; typically requires some current environmental cues to remain synchronized biological magnification:The process by which substances accumulate (e.g., toxins) as food is transferred between trophic levels; concentrations can exponentially increase at high trophic levels biomass: Amount of organic material in an organism or habitat biome: Major types of floral and faunal ecosystems assemblages based on temperature & rainfall amounts bioremediation: Using organisms to restore degraded or polluted ecosystems biosynthesis: Anabolic reactions used to synthesize large, complex biological molecules, e.g., synthesis of proteins from amino acid precursors biosphere: Collective habitats on Earth where life exists biotechnology: Using organisms to produce products and advance technology blastocyst: Embryonic blastula stage in mammals; implants in uterine lining in placental mammals

blastopore: Opening to primitive gut (archenteron) in the embryonic gastrula stage of animals blastula: Embryonic developmental stage of animals characterized by a hollow ball of many cells blood: Fluid connective tissue with blood cells, e.g., erythrocytes blood pressure: Hydrostatic pressure of blood inside blood vessels blood-brain barrier: Specialized blood vessels that inhibit transport of many substances into the brain; helps maintain homeostasis of brain fluids Bohr effect: Hemoglobin releases oxygen in active tissues, which have lower pH; See dissociation curve bone: Hardened connective tissue used for skeletal support; matrix contains minerals (hydroxyapatite) and collagen bottleneck effect: Rapid shift in the genetic composition of a population, typically from a natural disaster; genetic composition of surviving individuals may differ significantly from that of the original Bowman’s capsule: Structure in vertebrate kidney that initially filters the blood; part of a nephron brown adipose tissue (brown fat): Type of mammalian adipose tissue used to generate heat without shivering, primarily in hibernating animals and newborn infants; highly vascularized, creating darker coloration than white adipose tissue bryophyte: Nonvascular plants, which lack morphology to adapt well to terrestrial environments; includes mosses, liverworts and hornworts budding: Form of asexual reproduction in which new individuals are produced directly from an individual; buds may remain attached or separate and live independently

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C3 plant: Typical photosynthetic mechanism producing a 3-carbon intermediate during carbon fixation; does not function well in climates with high temperatures, drought, and lower CO2 levels C4 plant: Alternate photosynthetic mechanism producing a 4-carbon intermediate during carbon fixation; functions better than C3 plants in climates with high temperatures, drought, and lower CO2 levels, e.g., sugar cane Calvin cycle: Portion of photosynthesis that requires no light and fixes (converts) CO2 into food molecules CAM (crassulacean acid metabolism) plants: Alternate photosynthetic mechanism producing acid intermediate during carbon fixation; functions better than C3 plants in climates with high temperatures, drought, and lower CO2 levels, e.g., cactus plants Cambrian explosion: Beginning of Paleozoic era when animal evolution adaptively radiated into most modern animal forms camouflage: Characteristics (e.g., color patterns) that conceal the presence of an organism in its natural habitat cancer: Diseased tissues characterized by abnormal cell proliferation (division) rates capillary: Smallest blood vessel characterized by high permeability, thereby allowing exchange of materials between blood and tissues carbon fixation: Converting CO2 to organic molecules, e.g., glucose carcinogen: Any agent that triggers cancerous growths cardiac cycle: Rhythmic contraction and relaxation cycles of the heart cardiac muscle (striated muscle): Muscle type found in the heart cardiac output: Amount of blood pumped from the heart (primarily the left ventricle) every minute cardiovascular system: The heart and circulatory system carnivore: An organism that eats animals carotenoid: Accessory orange-yellow pigments that augment the wavelengths of light beyond what chlorophylls can absorb during photosynthesis carpel: Female reproductive organ of flowering plants carrier: A genetic situation were the gene forms (alleles) present in an individual are different, i.e., a heterozygous genotype that masks a potentially harmful recessive allele carrying capacity: Maximum population size for a specified area; symbolized by K cartilage: Flexible connective tissue found in skeletons; sometimes converted into bone (endochondral ossification) cell: Basic structural and functional unit of organisms cell cycle: Activity cycle of eukaryotic cells; includes interphase (G1, S, G2) and mitosis cell differentiation: Morphological and functional specialization of cells in the various types of tissues of the organism cell division: Cell reproduction; involves cytokinesis and typically mitosis cell-mediated immunity: Acquired immunity involving identification of foreign or infected cells that are destroyed by cytotoxic white blood cells cell plate: New cell wall structure produced during cytokinesis (cell division) in plant cells cell respiration: Process of oxidizing glucose (or other energy molecules) to drive the production of ATP cell theory: Concept that all organisms are made up of cells and come from cells cellulose: Structural carbohydrate compound in cell walls in plants cell wall: Nonliving, supportive membrane found in some microbes, fungi, and plants; located outside the plasma membrane

central nervous system (CNS): The brain and spinal cord of most animals centriole: Microtubular structures found in many eukaryotes; component of the centrosome centromere: Connection region between chromatids of a duplicated chromosome centrosome: Microtubule organizing center in eukaryotic cells cephalization: Concentration of sensory structures in the anterior-positioned head cervix: Inferior opening of uterus leading to the vagina chemiosmotic phosphorylation: Coupling of hydrogen ion (i.e., proton) osmotic flow to the production of ATP; electron transport systems (ETS) created hydrogen ion gradients with energized electrons from food molecules, e.g., glucose chemoautotroph: Organism that produces food molecules by using energy from inorganic compounds, e.g., bacteria at hydrothermal vents use hydrogen sulfide chemoheterotroph: Organism that obtains energy by consuming organic compounds chemoreceptor: Receptors that respond to chemical stimuli chiasma: Breakage and recombination point where chromatids of homologous chromosomes cross over chimera: A single organism with 2 or more genetically distinct types of cells from 2 or more distinct zygotes chitin: Structural carbohydrate compound of cell walls of fungi and exoskeletons of arthropods chlorophyll: Green photopigments used by photoautotrophs to synthesize food molecules chloroplast: Plastid-containing chlorophylls and accessory pigments; used for photosynthesis cholesterol: Lipid compound used in cell membranes and precursors for steroid hormones, e.g., estrogen and testosterone chondrichthyan: Cartilaginous fishes in the class Chondrichthyes; includes sharks, skates, and rays chordate: Animals in the phylum Chordata; possess at least embryonically a notochord, dorsal hollow nerve cord, pharyngeal slits, and postanal tail chorionic villi sampling (CVS): Tissue samples from the embryonic chorion layer are acquired and analyzed for chromosomal composition and potential genetic defects chromatin: DNA-protein complex found in eukaryotes; condition of DNA during interphase chromosome: DNA-protein complex appearing as condensed chromosomes during mitosis and meiosis; can also refer informally to DNA-protein complex at any stage in the cell cycle circadian rhythm: Cycling of physiological and behavioral activities around the 24-hour day-night cycle citric acid cycle (Krebs or TCA cycle): Stage of cell respiration where carbohydrate intermediates from glucose are oxidized to CO2 clade: A group of organisms, including the stem ancestor and its descendants classical conditioning: Learning involving the association of a stimulus to a behavior cleavage: Rapid cell division of a zygote; individual cell growth is limited cloaca: Common exit opening for 2 or more systems, 1 of which is digestive clone: Genetically identical cells closed circulatory system: Circulatory system in which blood stays primarily in blood vessels

cnidarians: Animals with gelatinous body and nematocysts, e.g., jellies, sea anemones, and corals cnidocyte: Specialized cell types in cnidarians, with nematocysts (stinging structures) cochlea: Organ of hearing in many vertebrates coccus: Spherical-shaped bacteria codominance: Genetic condition in which two different alleles are both expressed as a phenotype codon: Basic unit of the genetic code; consists of three nucleotides that code for amino acids to build proteins coelom: Internal body cavity lined entirely with mesoderm; coelomate animals coenocytic: Multinucleated cell, e.g., primitive fungal hyphae coevolution: Interactions between two different species influences the evolution of both species collagen: Protein fibers found in connective tissues of animals competitive exclusion: When 1 of 2 competing species is eliminated by the other species due to competitive differences complete digestive tract: GI tract with 2 openings; mouth and anus complete dominance: Genetic condition in which only 1 of 2 alleles is expressed as a phenotype cone cell: Photoreceptor involved in color vision and visual acuity; See rod cell congeneric: Individuals of the same genus conspecific: Individuals of the same species conifer: A gymnosperm plant that produces reproductive structures called cones, e.g., pine trees conjugation: Exchange of DNA between 2 single-celled organisms that are temporarily joined connective tissue: Supportive tissues in animals with relatively few cells embedded in a matrix convergent evolution: Development of similar adaptations by unrelated species, e.g., bird vs. bat wings corpus luteum: Follicle that has just released its developing oocyte; produces steroid hormones (progesterone and estrogen) that prevent development and release of any additional oocytes cotyledon: Modified seed leaf of plant embryo; occurs individually (monocots) and in 2 attached halves (dicots) countercurrent exchange: Opposite flow of fluids to maximize respiration or heat retention crista: Inner membrane of mitochondria; site of the electron transport system (ETS) crossing over: Exchange of DNA portions between 2 homologous chromosomes: occurs during meiosis cross-pollination: Transfer of pollen between flowers on different plants of the same species cryptobiosis: Organisms shift temporarily to a state of suspended animation or no metabolism based on levels of water, oxygen, toxins, or temperature cuticle: External covering found in some organisms, e.g., waxy coat on leaves or exoskeleton of arthropods cyanobacterium: Photosynthetic prokaryotes cytokinesis: Splitting of a cell into 2 distinct cells; associated with mitosis and meiosis cytoplasm: Contents inside a cell, except for the nucleus cytoskeleton: Internal support and transport structure in cells; composed of proteins, including microtubules cytosol: Fluid portion of the cytoplasm; contains many dissolved substances

deciduous: Woody plants that shed their leaves after each growing season decomposer: Organisms that derive their nutrients from dead organisms or castaway materials, e.g., leaves or wastes deletion: Removal of either the nucleotide sequence from a gene or whole sections of chromosomes demography: Analysis of birth and death rates in populations dendrite: Relatively short extensions from the cell body of a neuron; receives nerve impulses density dependent: Population density directly affects a characteristic density independent: Population density does not directly affect a characteristic deoxyribonucleic acid (DNA): Double helix, macromolecule involved in genetics and inheritance depolarization: Disruption of the normal polarized state of a cell; reversal of the resting membrane potential of a negative cellular interior and positive exterior dermis: Connective tissue layer of the skin below the epidermis; highly vascularized and innervated determinate cleavage: Cell fate is determined relatively early in embryonic development of an animal; characteristic of protostomes determinate growth: Growth of an organism reaches a maximum determined size

detritivore: Consumes detritus (organic debris) deuterostome: Animals characterized by similar developmental pathways, including a 2nd embryonic opening in the gastrula forming the mouth diaphragm: Conical muscle used in respiration by changing the pressure in the thoracic cavity diatom: Photosynthetic alga characterized by glass-like cell wall coverings; extremely abundant and produce significant amounts of oxygen diffusion: Movement of a substance from an area of its high concentration to low concentration digestion: Breaking down food both mechanically and chemically allowing for absorption in the GI tract dihybrid cross: Cross involving two individuals with the same heterozygous genotype for two traits, e.g., AaBb × AaBb dikaryotic: Cells with nuclei from 2 different individuals; fungal mycelia typically have 2 haploid nuclei in part of their life history dinoflagellate: Photosynthetic alga typically possessing 2 flagella, which triggers spinning during locomotion; can lose flagella and live in the tissues of some animals, e.g., corals dioecious: Male and female reproductive organs are found in separate individuals diploblastic: Animal possessing 2 distinct tissue layers diploid: Cell possessing 2 sets of each type of chromosome

dispersal: Movement of individuals throughout a geographic area dissociation curve: Figure showing the amount of oxygen bound to hemoglobin under varying conditions, e.g., partial pressure of oxygen, pH disturbance: Environmental factors, such as fire, can dramatically alter biological community composition diurnal: Organismal activity levels peaking during the day and subsiding at night DNA fingerprint: Nonclonal individuals possess unique genetic compositions DNA ligase: Enzyme that attaches Okazaki fragments that were synthesized along the lagging strand of the DNA DNA polymerase: Enzyme that synthesizes new DNA by following the DNA base pairing rules of A with T and C with G domain: 1) Broadest taxonomic category for organisms; includes Archaea, Bacteria, and Eukarya; 2) independent portion of protein dominant allele: An allele that is expressed whenever present in a genotype dormancy: Condition of low metabolic rate double fertilization: Fertilization in angiosperm plants typically involves 2 sperm; 1 fertilizes the egg and the 2nd activates a cell to produce endosperm (which serves as a food source for embryo)

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Down syndrome: Disease resulting from having an extra duplication: Chromosomal mutation resulting in the chromosome 21 (i.e., 3 instead of 2); results in physical and duplication of chromosomal fragments; occurs during mental disabilities crossing over

E

ecdysis (molting): Periodic shedding of the exoskeleton allowing for growth, e.g., arthropods ecdysone: Steroid hormone that triggers molting in arthropods ecdysozoan: Phylogenetically-related animals that molt echinoderm: Spiny-skinned, marine animals, including sea urchins and sand dollars ecological niche: The specific role of an organism in its environment, including where it lives, resources used, and interactions with other species ecological succession: Sequence of species colonization in a habitat; usually initiated after a disturbance ecology: Relationships of organisms to their environment ecosystem: Interacting unit of biotic communities and abiotic environments ecotone: Transition area between two ecosystems or biomes, e.g., transition from desert to grassland ectoderm: Outer embryonic germ or tissue layer of an animal ectothermic: Organisms that use primarily abiotic characteristics (e.g., sunlight) and behavior to regulate body temperature egg (ovum): Female gamete ejaculation: Release of sperm and semen from the male reproductive organs electrocardiogram (ECG or EKG): Recording electrical activity of the heart during diastole and systole electron transport chain: Sequence of molecules embedded in membranes of chloroplasts and mitochondria involved in transporting protons by moving electrons in redox reactions; used to create proton gradients for generation of ATP embryo: Development of the zygote, eventually creating the adult individual endangered species: Species that are close to extinction endemic species: Species that are characterized by living in a specific geographic area endocrine gland: Chemicals are released into the blood for distribution to target tissues throughout the body endocytosis: Bringing materials into the cell interior endoderm: Inner embryonic germ or tissue layer of an animal endometrium: Inner lining of the uterus, where embryo implants in placental mammals endoplasmic reticulum (ER): Membranous organelles in eukaryotic cells; with attached ribosomes (rough ER or RER; makes proteins) or without ribosomes (smooth ER or SER; makes lipids, carbohydrates; detoxification) endorphin: Hormone involved in pain relief and exhilaration endoskeleton: Internal skeletal support, e.g., bones in humans endosperm: Nutrient portion of flowering plant seed; initiated by sperm during double fertilization endothermic: Animals that use metabolic reactions to produce heat for thermoregulation

enzyme: Biological catalysts; proteins and RNA (ribozymes) enzyme-substrate complex: Structure formed when substrate is held within the active site of the enzyme; initiates the chemical reaction epidermis: Outer tissue layer of animals and nonwoody plants epigenetic inheritance: Traits based on non-nucleic acid (i.e., genes are not involved) factors epinephrine: Hormone from the adrenal medulla released during acute stress; also called adrenaline epiphyte: Plant that grows on the surface of other plants epistasis: One gene alters the expression of another completely different type of gene erythrocyte: Red blood cells; transport gases (oxygen and carbon dioxide) in the circulatory system estivation: Metabolic inactivity of an animal to withstand extended hot and dry conditions estrogen: Steroid hormone class; important for female reproductive system and general growth estrus: Reproductive sexual activity correlated to ovulation estuary: Aquatic ecosystem characterized by a mixture of freshwater and seawater ethology: Study of the functional aspects of animal behavior eudicot: Major group of plants with two embryonic seed leaves; mostly replaces the term “dicots”; See monocots Eukarya: Eukaryotic domain; contains protists, fungi, plants and animals eukaryotic cell: Cells with nuclei and other organelles eumetazoan: Animals with true, well-defined tissues euryhaline: Aquatic organism that tolerates significant changes in salt concentrations; See stenohaline eutrophication: Increased nutrients, such as nitrogen and phosphorus, enter an ecosystem; can trigger algal blooms evapotranspiration: Evaporation of water from the land and plant surfaces evolution: Concept that all organisms are related to each other and have a common ancestor excretion: Removal of nitrogenous waste materials by an animal exocytosis: Exporting materials out of the cell exon: Portions of Messenger RNA that are actually expressed; See intron exoskeleton: External skeletal support, e.g., arthropod coverings exponential population growth: Population growth characterized by rapid, sustained increases; J-shaped growth curve extant: Species that still exist extinct: Species that no longer exist extracellular digestion: Food materials are broken down outside the cells from which the enzymes are released extremophile: Archeans that live in extreme environments, e.g., halophiles live in hypersaline conditions

F1 generation: 1st generation of heterozygous offspring produced from homozygous parents with alternate phenotypes F2 generation: 2nd generation of offspring produced from crossing F1 individuals facilitated diffusion: Form of diffusion involving membrane carriers fast block to polyspermy: Egg cell membrane depolarizes after a sperm has penetrated the egg cell membrane to prevent additional sperm from attempting to fertilize fast-twitch muscle fibers: Muscle fibers characterized by rapid contraction rate fermentation: Production of ATP without the use of an electron transport system; metabolic products are typically either ethanol or lactic acid, depending on the organism; form of substrate-level phosphorylation fertilization: Fusion of gametes to form zygote; See syngamy fetus: The developing human embryo after two months, when the major organs and morphology necessary for the adult are in place filtration: Fluid formed (filtrate) by filtering blood via the excretory system fission: A form of asexual reproduction where an individual splits into two separate and functional individuals fitness: Genetic characteristics that increase chances of survival and contributing to the future gene pool of a population through reproduction

fixed action pattern: Instinctive, sequence of behaviors triggered by a stimulus flower: Sexual reproductive structure in angiosperms with modified leaves (typically having nongreen colors) fluid mosaic model: Cell membranes have a mosaic of proteins in the fluid-like phospholipids bilayer follicle-stimulating hormone (FSH): Pituitary hormone that stimulates egg production in females and sperm production in males food chain: Food and energy transfers between trophic levels in ecosystems; from producers to consumers food web: Feeding connections within an ecosystem; typically complex foraging: Behavior associated with getting and consuming food fossil record: Chronological record of fossilized organisms founder effect: Relatively few individuals isolated from the main population establish a new population, which may cause a genetic drift or shift from the typical characteristics of the initial population fragmentation: A form of asexual reproduction where an individual splits into many separate and functional individuals fruit: Modified ovary of a flower that contains dormant seeds; typically modified with sugars to attract animal seed dispersers Fungi: Kingdom of multicellular, eukaryotic heterotrophs; cell walls are usually present

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gametangium: Plant or algal structure that produces gametes: female portion is archegonium; male form is antheridium gamete: Haploid cells—egg and sperm—that combine (syngamy) during sexual reproduction, resulting in a diploid zygote gametogenesis: Production of gametes gametophyte: Haploid, gamete-producing stage in organisms with alternation of generations life histories gastrula: Embryonic developmental stage characterized by an emerging tube or GI tract with one opening called the blastopore gastrulation: Formation of the gastrula stage by invagination (i.e., inward growth) of the blastula gated ion channel: Protein that opens and closes to help regulate ion and charge distributions across the cell membrane gene: Functional unit of heredity; nucleotide sequences in DNA or RNA (in certain viruses) gene cloning: Making exact copies of a gene gene flow: Alterations to the gene pool of a population via additions or removals of alleles via immigration and emigration of individuals gene pool: All the genes in a population gene therapy: Use of genes to treat a genetic disease genetic drift: Allelic frequency change in a population because of random fluctuations genetic engineering: Manipulation of an individual’s genome genetic map: Location of genes on a chromosome genetic recombination: Pairing of new alleles during crossing over genetics: Study of heredity genome: Complete genetic composition of a species genomic imprinting: Expression of an allele based on whether it came from the male or female parent genomics: Study of the functions of genes genotype: Specific alleles of a gene present in an individual geographic variation: Deviations in gene pools of geographically distinct populations geologic record: Earth’s history divided into major time frames based primarily on significant geologic events germ layers: Animal embryonic tissue layers; See ectoderm, mesoderm, endoderm germinal tissue: Involved in production of gametes gestation: Development of animal embryo inside the female (i.e., pregnancy in humans) glucagon: Hormone from pancreas that increases blood glucose levels; See insulin glycogen: Animal starch; common in the liver and muscle cells glycolysis: Initial step of cell respiration; glucose oxidized into 2 pyruvate molecules Golgi apparatus: Organelle in eukaryotes; packages and transports materials produced in endoplasmic reticulum; synthesizes carbohydrates gonadotropin: Hormones that stimulate production in the ovaries and testes, e.g., follicle-stimulating hormone (FSH) and Luteinizing hormone (LH) gonads: Organs in animals that produce gametes Gram stain: Stains that can distinguish different species of prokaryotes, e.g., Gram-positive and Gram-negative gravid: Full of fertilized eggs; pregnant gravitropism: Plant growth response to gravity; used to establish root growth into the soil growth hormone (GH): Hormone from the pituitary that affects growth and development in many tissues gustation: Process of sensing taste gymnosperm: Plant that produces seeds exposed on a modified leaf; does not produce a flower

H

habitat: Area in which species occupy in an ecosystem haploid: Cell possessing 1 set of each type of chromosome helper T cell: Enhances immune response by stimulating antibody and cell-mediated responses hemocyanin: Copper-based respiratory pigment found in the blood of some invertebrates, e.g., arthropods and mollusks hemoglobin: Iron-based respiratory pigment found in the blood of many animals hemolymph: Body fluid found in animals with an open circulatory system hemophilia: Genetic disease in which blood clotting abilities are limited herbaceous: Plants that do not produce woody tissues herbivore: Animal that eats plants heredity: Inheritance of traits hermaphrodite: Organism with both male and female reproductive organs simultaneously or sequentially (protogyny = female first; protandry = male first); See monoecious heterosporous: Plant sporophyte that produces two types of spores; microspore develops into male gametophyte; megaspore develops into female gametophyte heterotroph: Organisms that cannot produce their own food molecules and must locate food heterozygote advantage: Reproductive success is associated with a heterozygous genotype; helps maintain variation in populations

heterozygous: Genotype with two different alleles hibernation: Metabolic inactivity of an animal to withstand extended cold conditions high-density lipoprotein (HDL): Cholesterol transport molecule in the blood. Carries less cholesterol than low-density lipoprotein (LDL) histone: Proteins important in eukaryotic chromosome structure; See nucleosome HIV (human immunodeficiency virus): Retrovirus that causes AIDS in humans homeostasis: Process of maintaining constant conditions in an organism, e.g., temperature regulation hominid: Humans and our recent ancestors hominoid: Humans and great apes homologous chromosomes: Pairs of the same type of chromosome; one came from each parent homologous structures: Body parts in different species are similar because of recent, common ancestors, e.g., appendages of fishes, birds and mammals; See analogous structures homosporous: Plant sporophyte that produces only one type of spore, which develops into a gametophyte that produces both male and female gametes homozygous: Genotype with two identical alleles hormone: Chemical messenger that affects function, and is distributed within an individual via the blood or interstitial fluids human chorionic gonadotropin (HCG): Hormone released by embryonic membranes (chorion) that keeps the corpus luteum functioning to prevent further development of follicles and release of ova; released into maternal blood system, and detected in early pregnancy tests Human Genome Project: Mapping the entire DNA sequence of the human genome humoral immune response: Acquired immunity involving identification of foreign or infected cells that are destroyed by molecules in the blood, e.g., antibody reactions hydrostatic skeleton: Structural support of an organism based on the pressure of the internal fluids on the tissues, e.g., sea anemones and jellyfishes hypertonic: Solution with a higher solute concentration than another solution (which is hypotonic) hypothalamus: Inferior section of vertebrate brain; multiple functions, including homeostasis, hormone production, and regulation hypotonic: Solution with a lower solute concentration than another solution (which is hypertonic)

I

immigration: Movement of individuals into an area immunoglobulin (Ig): Proteins that form antibodies in vitro fertilization: Fertilization of an egg in the laboratory and subsequent artificial implantation in the uterus incomplete dominance: Phenotype of a heterozygous genotype is intermediate, i.e., both alleles contributed to the phenotype indeterminate cleavage: Cell fate is determined relatively late in embryonic development of an animal; characteristic of deuterostomes indeterminate growth: Growth of an organism has no maximum, determined size innate behavior: Genetically programmed behaviors; not learned innate immunity: Mechanisms of immune defense present prior to birth; does not require prior exposure; See acquired immunity insertion: Mutation involving nucleotides inserted into a gene insulin: Hormone from pancreas that decreases blood glucose levels; also stimulates macromolecule synthesis integration: Processing of neural sensory signals in the central nervous system (CNS)

J

juxtaglomerular apparatus: Tissues that regulate blood pressure into the glomerulus of a nephron; releases renin to counteract low blood pressure or volume juxtamedullary nephron: Loop of Henle extends deep into the renal pelvis of the kidney; can create highly concentrated urine

K

karyogamy: Fusion of two nuclei; 2nd phase of syngamy karyotype: Chromosome types displayed as homologues pairs; 23 pairs in humans; can show chromosomal aneuploids keystone species: Organisms that play a critical role in maintaining the integrity of the community kin selection: Evolutionary concept that individuals engage in altruistic behaviors because related individuals share more common genes

kinesis: Movement or activity rate change in response to a stimulus; e.g., cytokinesis kingdom: Broad taxonomic category for organisms; below domain level Krebs cycle: Final step of cell respiration; pyruvate molecules are oxidized to CO2; See citric acid cycle K-selection: Populations that favor reproductive strategies with relatively few offspring but maximized parental care to ensure survival of offspring

labor: Rhythmic uterine contractions that push the baby out of the female’s vagina during parturition (i.e., childbirth) lactation: Production of milk by mammary glands lactic acid: By-product of fermentation of pyruvate during anaerobic conditions lagging strand: During DNA replication, the side of the molecule that must be synthesized in fragments (Okazaki); See leading strand larva: Juvenile form of some animals that typically are morphologically and physiologically distinct from the adult lateral line system: Lateral mechanoreceptors that detect water movements in fishes and aquatic amphibians lateral meristem: Plant tissue responsible for growth in diameter; e.g., vascular cambium Law of Independent Assortment (Mendel’s 2nd law): Alleles of genes on different kinds of chromosomes will assort independently Law of Segregation (Mendel’s 1st law): Alleles of genes separate during the formation of gametes, which only get one allele of the two leading strand: During DNA replication, the side of the molecule that is synthesized continuously without interruption; See lagging strand leukocyte: White blood cells; immune defense function Leydig cell: Testosterone-producing cells located between seminiferous tubules of testes lichen: Symbiotic association between a fungus and alga or cyanobacterium life cycle: Stages in the reproductive history of an organism life history: Changes in an organism from birth until death life table: Mortality rates for age groups in a population light-dependent reactions: Photosynthetic reactions requiring light; produce ATP and NADPH; release oxygen light-harvesting complex: Structure in chloroplasts used to capture sunlight during photosynthesis

light-independent reactions: Photosynthetic reactions that do not require light; produce carbohydrates from CO2 limnology: Study of freshwater ecosystems linked genes: Genes on the same chromosome liver: Major organ in vertebrates with multiple functions, including detoxification of toxins in the blood and bile formation locus: Specific location of a gene on a chromosome logistic population growth: Population growth characterized by an initial increase followed by a relatively stable population size as the carrying capacity is reached; S-shaped growth curve lophotrochozoan: Phylogenetically-related animals that possess a lophophore feeding structure and trochophore larvae low-density lipoprotein (LDL): Cholesterol transport molecule in the blood. Carries more cholesterol than high-density lipoprotein (HDL) luteinizing hormone (LH): Pituitary hormone that stimulates ovulation and formation of the corpus luteum in females, and Leydid cells in males to produce testosterone; also called interstitial cell stimulating hormone (ICSH) in males lymphatic system: Vascular system with lymph nodes; returns excess fluids (lymph) from the blood, transports lipids from digestive tract to the blood, integral part of the immune system lymphocyte: White blood cell involved in acquired immunity; See B cells lysogenic cycle: Stage when bacteriophage virus inserts its genome into the genome of the host bacterium lysosome: Organelle that contains hydrolytic enzymes for intracellular digestion lysozyme: Antibacterial enzyme produced in bodily secretions of animals lytic cycle: Stage when bacteriophage virus replicates, releasing viruses and destroying the host bacterial cell

L

integumentary system: Outer covering of many animals interphase: Portion of cell cycle with main metabolic activity (G1); synthesis of DNA (S); Production of microtubules for mitosis or meiosis (G2) intersexual selection: Selection of an individual—among many—of the opposite sex for mating; typically females select males interspecific competition: Interactions between individuals of different species for limited resources interstitial fluid: Fluids occupying spaces between cells of tissues intracellular digestion: Phagocytized food in vacuoles merge with lysosomes inside the cell wherein chemical digestion will occur introduced species: Human introduction of species into habitats in new geographic areas; also called exotic or invasive species intron: Intervening sequences of Messenger RNA that are not expressed and must be removed; See exons inversion: Chromosomal mutation resulting in a chromosomal fragment inserted in the wrong direction; occurs during crossing over invertebrate: Animal without a vertebral column; most animals isotonic: Solution with the same solute concentration of another solution

M

macroevolution: Major evolutionary change; jawed fishes from jawless fishes; See microevolution macromolecule: Large organic molecules; polymers from monomers; carbohydrates, lipids, proteins and nucleic acids macrophage: Phagocytic cell; major role in immunity malignant tumor: Cancerous tumor that interrupts normal tissue and organ function Malpighian tubule: Excretory system found in insects; empties contents into digestive tract mammal: Animal with hair and mammary glands for milk production to nourish their young marsupial: Mammal that produces young that complete their embryonic development in a pouch (marsupium) on the mother’s body, e.g., kangaroo and koala mechanoreceptor: Specialized sensory receptor that detects changes in pressure, motion or sound meiosis: Two-step cell division process that reduces the chromosome number (from diploid to haploid) and creates genetic variation melanocyte: Epidermal cell that produces melanin, a dark pigment melatonin: Hormone found in many organisms; regulates circadian rhythms, including sleep/wake cycles membrane potential: Charge differences between the interior and exterior of cells based on anion and cation distributions memory cell: Lymphocytes that retain the “memory” of previous exposure to an antigen resulting in a prolonged defense; See vaccine 4

menopause: When ovulation and menstruation cease menstrual cycle: Periodic shedding of the uterine lining (endometrium) in the reproductive cycle of higher female primates in the absence of fertilization and implantation meristem: Persistent embryonic plant tissue mesoderm: Middle embryonic germ or tissue layer of an animal messenger RNA (mRNA): Nucleic acid made from DNA sequence; used by ribosomes to synthesize proteins coded by genes metabolic pathway: Sequence of chemical reactions in biological systems, e.g., Krebs cycle metabolic rate: Rate of energy consumption by an organism metabolism: Net of all chemical reactions in an organism; includes both anabolic and catabolic reactions metamorphosis: Change in morphology (form) in the life history of an organism associated with reaching sexual maturity, e.g., insect larval caterpillars metamorphose into butterflies metanephridium: Excretory organ found in some animals; e.g., annelids and molluscs metastasis: Dispersal of cancerous cells to locations potentially far from the original tumor microevolution: Changes in gene allele frequencies in populations due to mutations, genetic drift, gene flow and natural (or artificial) selection microtubule: Protein (tubulin) component of cilia, flagella and cytoskeleton mimicry: Evolution of similar characteristics between different species mitochondrion: Organelle that produces ATP via cell respiration

M (continued )

mitosis: Division and replication of the nuclear material (DNA) into two identical nuclei; cytokinesis typically occurs creating two identical cells mixotroph: Organisms that are both autotrophic and heterotrophic molecular clock: Estimate of evolutionary timing based on rates of genomic evolution monocots: Major group of plants with one embryonic seed leaf See eudicots monoecious: Male and female reproductive organs are found in the same individual, See hermaphrodite monohybrid: Cross involving two individuals with the same heterozygous genotype for one trait, e.g., Aa × Aa monophyletic: Groups of species with a common, recent ancestor, See polyphyletic, paraphyletic morphogenesis: Development of the organism’s shape and body structures morula: Embryonic developmental stage characterized by a solid ball of many cells motor neuron: Transmits nerve signal from the CNS to the PNS, which triggers a response, e.g., muscle contraction muscle tissue: Contractile cells; skeletal, cardiac and smooth mycorrhiza: Mutualistic symbiosis involving fungi and the roots of plants myelin sheath: Lipid insulation found along nerve axons; speeds up conduction rates by forcing nerve impulses to jump to areas without myelin (nodes of Ranvier) myoglobin: Iron-based respiratory pigment found in the muscle tissue of many animals

N

natural selection: Differential survival of offspring with different phenotypes based on interactions with the environment negative feedback: Physiological response to maintain homeostasis by counteracting the direction of change in a variable, e.g., ambient high temperatures triggers cooling mechanisms in the body; See positive feedback nephron: Structural unit of the vertebrate kidney nerve: Bundle of nerve cells surrounded by connective tissue nervous tissue: Neurons and supportive cells neuron: Nerve cell; conducts electrical signals neurosecretory cell: Special nerve cells that release hormones, e.g., in hypothalamus neurotransmitter: Chemical released from one neuron (presynaptic) travels across the synapse to bind to receptors on other neurons (postsynaptic) for stimulation or inhibition nitrogen fixation: Converting N2 to more usable forms, such as ammonia (NH3); requires the enzyme nitrogenase produced by some prokaryotes; some plants house such microbes in root nodules nondisjunction: Failure of homologous chromosomes or chromatids of duplicated chromosomes to separate; See aneuploidy nonshivering thermogenesis: Role of mitochondrial activity switches from primarily producing ATP to heat production; See brown adipose tissue norepinephrine: Hormone from the adrenal medulla released during acute stress; also called noradrenaline notochord: Elongate, flexible, supportive structure in chordate animals; replaced by vertebral column in higher chordates nucleoid: Dense area of DNA in prokaryotes; lacks nuclear membrane nucleolus: Structure in nucleus for ribosome assembly nucleosome: Structural unit of eukaryotic chromosomes consisting of two full loops of DNA around a histone core nucleotide: Monomer units of nucleic acids; thymine, adenine, cytosine, guanine and uracil nucleus: Membrane-bound organelle containing chromosomes

O

Okazaki fragment: See lagging strand olfaction: Smell reception omnivore: Heterotroph that consumes both animals and plants oncogene: Activated genes that trigger cancer in tissues oogenesis: Meiosis in animal females producing eggs (ova) open circulatory system: Circulatory system in which blood or hemolymph is not generally transported in vessels but rather directly in the tissues organ: Groups of different tissues working collectively for bodily functions organ system: Groups of different organs

working collectively for bodily functions organelle: Structure inside cell with specialized functions osmoconformer: Animal that allows its bodily fluids to match the osmotic composition of its aquatic environment osmoregulator: Animal that maintains a relatively stable osmotic level independently of its aquatic environment osmosis: Diffusion of water across a semipermeable cell membrane osteichthyan: Bony fishes in the class Osteichthyes; includes most fishes osteoblast: Bone-forming cell ovary: Female reproductive structure produc-

pacemaker (sinoatrial [SA] node): Intrinsic cells in the heart of mammals that maintain heart beat rates paedomorphosis: Organisms become adults reproductively while retaining juvenilelike characteristics paleontology: Study of fossils pancreas: Organ with both digestive and endocrine function Pangaea: Land masses were coalesced into this super continent at the beginning of the Mesozoic era paraphyletic: Groups of most species with a common, recent ancestor, See monophyletic, polyphyletic parasympathetic division: Portion of the autonomic nervous system; maintains activities during non-stress, e.g., increasing digestion while decreasing heart rate parazoan: Animal lacking true, developed tissues; e.g., sponges parthenogenesis: Development of an egg without fertilization parturition: Expulsion of the baby; birth passive immunity: Antibodies from other individuals provide temporary (weeks or months only) immune protection passive transport: Movement of materials across cell membranes that does not require energy input from the cell; movement is with the concentration gradient; See active transport pathogen: Agent that causes disease pedigree: Figure showing phenotypes of all known relatives penis: Structure in many animals used to deliver sperm into the female reproductive tract for fertilization perception: Cognition of stimuli by the CNS in animals perennial plant: Life history involves multiple years of growth and reproduction; may persist for hundreds or even thousands of years peripheral nervous system (PNS): Sensory and motor neuron outside the central nervous system peristalsis: Rhythmic contractions of muscles to either move materials in the digestive tract or propel an animal, e.g., annelid worms peroxisome: Involved in hydrogen peroxide synthesis and degradation

phagocytosis: Cells engulfing large particles; platelet (thrombocyte): Found in blood; function in clotting cell “eating” pharyngeal slits: Openings in all chordate pleiotropy: A gene having multiple phenoembryos, including humans; form gills in typic effects point mutation: A permanent change of a aquatic forms gene involving a single base nucleotide phenotype: Expression of a genotype pheromone: Chemical released by an organ- pollination: Pollen or male gametophyte is ism (typically an animal) that can influence the transferred abiotically (e.g., wind) or biotically (e.g., insect pollinator) to the female gametobehavior or physiology of conspecifics phloem: Vascular tissue of plants that phyte; fertilization of the egg inside an ovule can then follow transports food and nutrients photorespiration: During hot conditions, polygenic inheritance: Multiple genes with low CO2 levels, plants may begin to use contribute to a single phenotype oxygen and release CO2 rather than produce polyphyletic: Groups of species with several distinct recent ancestors; See monosugars during photosynthesis photosynthesis: Synthesis of food molecules phyletic, paraphyletic polyploidy: Possessing 3 or more sets of each from CO2 using sunlight energy phototropism: Growth response of plants kind of chromosome; See haploid, diploid population: Conspecifics in a localized to light phylogenetic tree: Tree-like figure showing habitat that could potentially reproduce positive feedback: Physiological response evolutionary relationships among species physiology: Studying the functional aspects to enhance the direction of change in a variable; e.g., uterine contractions cause of an organism’s structure phytoplankton: Aquatic, photosynthetic stronger contractions during childbirth; See organisms (small algae and cyanobacteria) negative feedback predation: Capturing and consuming prey pinocytosis: Cells engulfing dissolved pregnancy: Carrying an embryo in the uterus; particles; cell “drinking” See gravid pituitary gland: Endocrine gland releasing primary production: Ecosystems require many hormones from two major sections; autotrophic (usually photosynthetic) organisms anterior lobe (adenohypophysis) and postethat can produce organic compounds (food) rior lobe (neurohypophysis) prion: Proteins that act as infectious agents placenta: Structure that provides nutritional prokaryotic cell: Cells without nuclei and linkage between a fetus and the mother’s organelles blood supply protist: Mostly unicellular eukaryotes with Plantae: Kingdom of multicellular, eukary- plant-like, fungus-like, or animal-like forms otic autotrophs; cell walls are present protonephridium (flame cells): Excretory plasma: Liquid (water) portion of blood organ found in some animals, e.g., flatworms plasma cell: Lymphocyte that produces protostome development: Animals charantibodies acterized by similar developmental pathways, plasma (cell) membrane: Selectively per- including a first embryonic opening in the meable membrane of all cellular life gastrula forming the mouth plasmid: Small, circular DNA; accessory to protozoan: Animal-like protist, e.g., amoeba chromosomes in prokaryotes and some yeasts pseudocoelom: Internal body cavity lined plasmogamy: Fusion of cell membranes and partially with mesoderm; pseudocoelomate cytoplasm of 2 cells; 1st phase of syngamy animals plastid: Three similar types of plant organelle: chloroplast, leucoplast (store starch) and quadrat: Rectangular (usually) tool used to sample in ecology chromoplast (have non-green quantitative character: Trait based on polygenic inheripigments) tance and exhibits a broad range of phenotypes

P

R

radial symmetry: Animals that have multiple planes/axes creating mirror images recessive allele: An allele that is not expressed when present with a dominant allele in a genotype recombinant chromosome: Crossing over during meiosis can result in chromosomes with novel (i.e., different from either parental chromosomes) allele combinations red blood cell: See erythrocyte reflex: Neural reaction to a stimulus that is controlled autonomically regeneration: Replacing damaged or missing body parts, including pieces re-growing into a separate individuals; See asexual reproduction reproductive isolation: Biotic factors preventing closely related species from interbreeding reptile: Animal that lays amniotic eggs; includes snakes, lizards, turtles, alligators and birds 5

ing eggs in both animals and plants, e.g., flower oviduct: Tubes facilitating sperm and egg union in animals oviparous: Females lay fertilized, shelled eggs that hatch outside the body ovoviviparous: Female produces fertilized, shelled eggs that hatch inside the body where they continue to develop and are released during birth ovulation: Release of eggs (or immature oocytes) from the ovary ovule: Plant reproductive structure in ovaries; houses female gametophyte that produces eggs ovum (egg): Female gamete

Q

resource partitioning: Species occupying similar niches will likely use resources differentially to minimize competition and increase survival chances respiration: Gas exchange by organisms with the air or water to deliver oxygen to the tissues and expel CO2: See cell respiration retrovirus: RNA virus that inserts its nucleic acid into the DNA of the host cell using an enzyme reverse transcriptase; See transcription Rh factor: Antigen found on the surface of red blood cells in some humans and other primates; Rh positive = present; Rh negative = absent ribonucleic acid (RNA): Single-stranded macromolecule involved in transcription and translation of genes; multiple forms; genome of retroviruses ribosomal RNA (rRNA): Combine with proteins to form ribosomes ribosome: Organelle responsible for protein synthesis during translation

ribozyme: RNA that has enzymatic function RNA polymerase: Enzyme that synthesizes new RNA by following the RNA base pairing rules of A with U and C with G RNA processing: Removing noncoding introns and combining remaining exons prior to leaving the nucleus for subsequent translation by ribosomes

rod cell: Photoreceptor involved in low-light vision; See cone cell r-selection: Populations that favor reproductive strategies with many offspring but minimal to no parental care ruminant: Herbivorous animal with multichambered stomach specialized for breaking down cellulose by resident symbiotic microbes; includes cows, sheep, and giraffes

secretion: Releasing synthesized molecules to function elsewhere in the body or to be removed via excretion seed: Plant embryo with a nutrient-filled tissue (cotyledon) enclosed in a protective seed coat selectively permeable: Plasma membranes do not allow equal access for substances attempting to cross the membrane semen: Collective fluid of ejaculate containing sperm and secretions from glands; e.g., seminal vesicles and prostate semiconservative model: DNA replication separating the two original sides of the double helix and adding nucleotides to create two new sides; duplicated chromosome is 50% conserved and 50% new. sensory neuron: Transmits nerve signal from the PNS to the CNS serial endosymbiosis theory (SET): Eukaryotes evolved by a sequence of symbioses involving prokaryotes; initially, mitochondria developed from an engulfed prokaryote; subsequently, chloroplasts developed from an engulfed photosynthetic prokaryote sex chromosome: Determines sex in most animals sex-linked gene: Genes located on the sex chromosomes sexual dimorphism: Individuals of each sex are distinguishable morphologically sexual reproduction: Formation of new individuals from two parents that create haploid gametes that combine to form a diploid zygote, which is genetically unique from both parents sexual selection: Adaptations that specifically increase chances for mating sinoatrial (SA) node: See pacemaker skeletal muscle (striated muscle): Muscle type found throughout the body; primarily for locomotion and support slow block to polyspermy: Fertilization membrane develops to prevent additional sperm from attempting to fertilize the egg smooth muscle: Muscle type lacking striations; involved in autonomic actions, e.g., digestive tract movements, blood vessel pressure changes somatic tissue: Nongerminal tissue; not involved in gamete production

somatic nervous system: Motor neurons that are typically under voluntary control, e.g., body movement involving skeletal muscle; See autonomic nervous system, sympathetic and parasympathetic division speciation: Evolution of new species species: Organisms with overall similar phenotypes allowing potential interbreeding species diversity: Number (richness) and relative abundance of a species in a habitat sperm: Male gamete; typically motile to locate ovum (egg) spermatogenesis: Meiosis in animal males producing sperm sporangium: Spore-producing structure in fungi and plants spore: Reproductive structure typically used for dispersal or survival in bacteria, protists, fungi and plants sporophyte: Diploid, spore-producing stage in organisms with alternation of generations life histories stamen: Male reproductive organ of flowering plants; houses male gametophyte that produces pollen and sperm stem cell: Formative cells in multicellular organisms; can be embryonic or adult stenohaline: Aquatic organism that cannot tolerate significant changes in salt concentrations; See euryhaline striated muscle: See cardiac muscle, skeletal muscle swim bladder: Gas-filled sac used for buoyancy by most bony fishes symbiosis: Different species living together, or having a significant association sympathetic division: Portion of the autonomic nervous system; maintains activities during periods of stress, e.g., fight or flight response sympatric speciation: Subgroups within a population (i.e., same geographic area) diverge into separate species; See allopatric speciation synapse: Gap between neurons, or neurons and muscles; See neurotransmitter syngamy: Fusion of gametes; See plasmogamy, karyogamy systematics: Analyzing the diversity and relationships of extant and extinct organisms

S

T

taxis: Movement response to a stimulus taxon: A specified classification unit, e.g., phylum Chordata is a taxon taxonomy: Classification and naming of organisms telomere: Protective endcaps of eukaryotic chromosomes territory: Defended area of an animal’s home range testes: Male reproductive structure producing sperm and steroid hormones testosterone: Steroid hormone class; important for male reproductive system and general growth tetrad: Duplicated, homologous chromosome pairs are attached during prophase of meiosis I, creating a complex of four chromatids tetrapod: Vertebrates with two pairs of locomotory appendages thermoregulation: Ability to maintain a relatively constant body temperature thyroid gland: Endocrine gland releasing hormones affecting body metabolism and bone development tissue: Cells working collectively to perform specific functions tonicity: Relative solute concentrations of two or more solutions; affects the net movement of water during osmosis; See hypotonic, hypertonic, isotonic torpor: Decreased state of physiological activity and metabolic rate; See hibernation

totipotent: Cells that have the ability to develop into any part of the organism transcription: Synthesis of RNA based on the DNA template transfer RNA (tRNA): Recognizes and transfers amino acids to ribosomes during translation translation: Proteins are synthesized from mRNA by ribosomes directing tRNA’s to bring in the designated amino acids transpiration: See evapotranspiration trimester: One of 3 developmental periods of pregnancy in humans triploblastic: Animal possessing three distinct tissue layers trophic structure: Organisms in ecosystems are classified based on how they gain and transfer energy, e.g., producers and consumers tropic hormone: Directly influences other endocrine glands, e.g., follicle stimulating hormone (FSH) tropism: Growth response to a stimulus, e.g., plants phototropic response to light true-breeding: Homozygous individuals crossed with each other for the same trait will give rise to offspring with the same genotype and phenotype (assuming no mutations) turgor pressure: Osmotic flow of water into a cell exerts a force inside the cell by increasing the pressure; plants can use such pressure for support of stems and leaves

U.S. $6.95 Author: Randy Brooks, Ph.D.

V

vaccine: Non-disease-forming antigens of a pathogen are injected into the body to initiate an immune response so that protection will be present if the real pathogen is encountered; See memory cell vagina: Structure in mammals used to receive the penis to facilitate delivery of sperm for fertilization variation: Phenotypic differences between conspecifics vascular bundle: Groupings of both xylem and phloem in vascular plants vascular plant: Plants with vessels transporting water, minerals, and food produced during photosynthesis; See xylem, phloem vasectomy: Severing the vas deferens to prevent passage of sperm to the urethra vasoconstriction: Decreasing the diameter of blood vessels; may increase blood pressure or decrease localized blood flow vasodilation: Increasing the diameter of blood vessels; may decrease blood pressure or increase localized blood flow vegetative reproduction: Asexual reproduction in plants vein: 1) Blood vessel transporting blood to the heart; 2) vascular bundle in a leaf ventricle: 1) Cavity that pumps blood away from the heart; 2) cavity in the brain of vertebrates vertebrate: Chordate animals with a vertebral column; fishes, amphibians, reptiles (including birds), and mammals vestigial structure: No longer has a significant function; rudimentary morphology; link to evolutionary past and common ancestry, e.g., body hair in humans viviparous: 1) Female produces fertilized eggs that attach to the uterus, develop inside the body, and are released during birth; called live birth; 2) seeds that germinate and develop directly from the parent plant vocal cord: Structures in the larynx of many vertebrates that produce sounds by vibrations induced by air passage

W

wetland: Transition between terrestrial and aquatic ecosystems wherein the sediment is saturated with water most of the time white blood cell: See leukocyte white adipose tissue (white fat): Type of mammalian adipose tissue used for general energy storage; See brown adipose tissue wild type: Normal genotypes and phenotypes found in populations wilting: Loss of turgor pressure in plants triggering drooping leaves and stems

X

xerophyte: Plants with adaptations for survival in arid climates xylem: Vascular tissue of plants that transports water and dissolved minerals

Y

yeast: A type of fungus that occurs as unicells yellow marrow: Fat storage area in long bones yolk: Stored nutrients in an egg; used as an energy source by the developing embryo

Z

zero population growth: Birth and death rate are equal in a population zygote: Fertilized egg; formed by syngamy

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NOTE TO STUDENT: This guide is intended for informational purposes only. Due to its condensed format, this guide cannot cover every aspect of the subject; rather, it is intended for use in conjunction with course work and assigned texts. BarCharts, Inc., its writers, editors, and design staff are not responsible or liable for the use or misuse of the information contained in this guide.

U

urea: Water-soluble, nitrogenous waste product excreted by some animals; major waste component of urine urethra: Tube that opens to the exterior allowing urine to be voided from the body; also allows for passage of semen in males during ejaculation uric acid: Water-insoluble, nitrogenous waste product excreted by some animals, e.g., insects and reptiles (including birds) urinary bladder: Temporary storage pouch for urine uterus: Female reproductive organ where fertilized eggs develop or are transported; mainly in mammals

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