Biology - An Illustrated Guide to Science (794127), страница 36
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It cannot be furtherdecomposed by hydrolysis.motor neuron A neuron that carries impulses from thecentral nervous system to muscles or glands.muscle Tissue the contraction of which causesmovement.mutation A variation caused by a change to anorganism’s genetic material.mycelium The body of a fungus made up of manythousands of branching connected hyphae.NAD See nicotinamide adenine dinucleotideNADH See nicotinamide adenine dinucleotidephosphate.NADP See nicotinamide adenine dinucleotidephosphate.nematode Any of a group of mainly parasitic worms.nephron The functional unit of the kidney.
Nephronsare long microscopic tubules that produce urine fromblood.neuron A nerve cell.neurotransmitter A chemical that carries informationacross the small gap at a synapse.nicotinamide adenine dinucleotide A coenzyme thatfunctions as a hydrogen carrier in a wide range of redoxreactions.nicotinamide adenine dinucleotide phosphate Acoenzyme, functioning as a hydrogen carrier, importantin the creation of ATP. NADH is the reduced form.nitrogen cycle The cycling of nitrogen through livingsystems as proteins, nitrates, and nitrites, etc.nucleic acid An organic substance found in cells that isinvolved in the storage of inherited information. It isthe collective name for DNA and RNA.© Diagram Visual Information Ltd.KEY WORDS202© Diagram Visual Information Ltd.KEY WORDSnucleotide A molecule formed from a sugar, aphosphate group, and a nitrogenous base. It is the basicbuilding block of DNA and RNA.nucleus The control center of a cell.
It contains thegenetic material.objective lens The lens near the specimen in a lightmicroscope.ocular lens The eyepiece lens in a light microscope.olfactory neuron A nerve cell that detects chemicals inthe nasal cavity and so provides the sense of smell.oogonium A cell that divides by mitosis to produceprimary oocytes.operon The collection of structural genes that worktogether with associated repressor and operator genesto control the production of a particular characteristic.optic cortex The part of the brain concerned with theinterpretation of nerve impulses from the eyes.optic nerve The nerve taking information from the eyesto the optic cortex in the brain.organelle A specialized structure in the cell that carriesout a particular function, e.g., the nucleus,mitochondria, or chloroplasts.organic matter Material produced by living organisms.osculum In Porifera, a large pore that lets water out ofthe body.osmoregulation Regulation of salt and water balance.osmosis The passage of a solvent (usually water)through a semipermeable membrane.
The movement isfrom a higher concentrated solution to a lowerconcentrated solution until the concentrations of bothsolutions reach equilibrium.otolith A particle of calcium carbonate in the inner earthat when displaced signals position and movement ofthe head.ovary The female organ that produces the egg.ovule The structure in plants in which the femalegamete is fertilized. It will develop into a seed.ovum The mature female gamete or egg cell prior tofertilization.papilla A small lump or knob arising from a surface,such as that on the surface of the tongue.parasite An organism that gets its food from a host butdoes not kill the host in the process.parasympathetic nervous system Part of the autonomicnervous system that regulates the routine functions ofthe body such as digestion, elimination, and heartbeat.passive transport Movement of chemicals down aconcentration gradient.
Passive transport does notrequire an energy input from an organism.pathogen A microorganism that causes disease.pedipalp A pair of specialized legs at the front of aspider used to manipulate food and clean the body.pentadactyl limb A limb based on a pattern of one boneleading to two bones and on to hands or feet ending infive digits.peptide Two or more amino acids linked by a peptidebond.peptide bond A link between two peptides in a proteinmolecule. It is formed between the carboxyl group ofone amino acid and the amino group of another.peripheral nervous system The nerves outside the brainand spinal cord.permeability The ability of a compound to diffuseacross a membrane.phagocytosis The engulfing and ingestion of materialsby a cell.phenotype The external features of an organism.
Thephenotype depends on the genotype of the organismand the action of the environment.phloem In plants, specialized transporting cells thatform tubules to carry sugars and organic materials fromthe leaves to all other parts of the organism.photosynthesis In green plants, the production of sugarand oxygen from carbon dioxide and water using lightas an external energy source.pistil (1) Another name for carpel, the femalereproductive organ of flowering plants consisting of thestigma, style, and ovary. (2) The part of the flower madeup of one or more carpels.pituitary gland A small pea-sized gland hanging fromthe base of the brain that produces a range ofhormones to control other endocrine glands.placenta The vascular organ that allows materials to beexchanged between a mother and a fetus in the uterus.plasma The clear, fluid portion of the blood in whichplatelets and blood cells are suspended.plasma membrane The membrane surrounding allliving cells that is composed of lipid and proteinmolecules.plasmid A circular molecule of DNA found in somebacteria.platelet A small, sub-cellular component in the bloodconcerned with clotting.pollen In flowering plants, the microspores containingthe male gamete.polypeptide A molecule formed by a long string ofamino acids joined by peptide bonds.
Proteins arecomposed of polypeptides.polypeptide chain A chain of amino acids joined bypeptide bonds.polyribosomes A series of ribosomes arranged along apiece of endoplasmic reticulum to form a chain ofribosomes.polysaccharide An insoluble, long-chained carbohydrateusually used for storage or cell structure, e.g., cellulose,starch, and glycogen.predator An animal that hunts and kills other animals.premolar A crushing tooth located in front of themolars and behind each cuspid.primary oocyte A cell formed while the female was anembryo that divides by meiosis to produce ova.producer An organism that makes organic material.prophase The first stage of cell division in which thechromosomes become visible in the nucleus.203protein An organic molecule composed of one or morechains of amino acids.
Proteins have fundamentalstructural and metabolic roles in cells and tissues.pseudopodium An extension of the cell in an ameba.pupa In insects, a phase between larva and adult inwhich the organism undergoes major tissuereorganization.pyrenoid Small structures in the chloroplast concernedwith the formation of starch.radial symmetry A body that can be divided along thesame axis through several planes to form two halvesthat are near mirror images of each other.recessive In genetics, the feature that does not appearwhen a gene contains two different alleles.red blood corpuscle A disc-shaped cell without anucleus, filled with hemoglobin, and found only in theblood.respiration The chemical process by which organismsmake energy from food.restriction enzyme An enzyme that recognizes specific,short nucleotide sequences and can cut DNA moleculesinto shorter portions.ribosome An organelle involved in the manufacture ofprotein.root hair In plants, an extension of a cell in the rootepidermis.
Root hairs massively increase the surfacearea of the root available for the uptake of water andmineral salts.rough endoplasmic reticulum A complex network ofsacs and tubes in cells. It contains ribosomes involved inthe synthesis of proteins.secondary thickening Extra strengthening in stems laiddown as they age to allow taller stems.secondary oocyte On oocyte after first meiotic division.It eventually matures into an ovum and a polar body.seed In plants, the structure formed from a fertilizedovule. The seed is the dormant phase of the plant lifecycle and is used to spread new plants.segment One of several or many similar bodycompartments.
Insects show segmented bodies.selective reabsorption Reabsorption of particularsubstances, and not others, by cells lining the nephronsin the kidney.semen The fluid, manufactured in the male urinogenitalsystem, that contains sperm.semicircular canal One of the three fluid-filled canals inthe inner ear that are concerned with the sense ofbalance and movement detection.seminiferous tubule A tube in the testis that producesspermatozoa.semipermeable membrane A membrane that allows thepassage of small but not large molecules.sensory neuron A neuron that carries impulses fromsense organs to the central nervous system.sexual reproduction Reproduction that involves twosexes producing gametes that join together to producethe next generation.sinoatrial node An area of the left atrium of the heartthat is the source of the signal that controls contractionof muscles in the walls of the heart.smooth endoplasmic reticulum A complex network ofsacs and tubes in cells involved in lipid synthesis.smooth muscle Muscle, such as that found in the bloodvessels or intestine, that performs automatic tasks viacontraction.solute A substance that is dissolved in anothersubstance.species A taxonomic group whose members caninterbreed.specimen (1) An individual used as a representative tostudy the properties of a whole.
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