glossary of biology terms

7/28/2019 Glossary of Biology Terms

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Glossary of Biology terms

abscission layer

a layer of easily-ruptured tissue in a leafstalk which causes leaves to drop in the

autumn

Adaptive radiation

divergent evolution caused by the adaptingof populations to new conditions, notexperienced by previous generations; seealso divergent evolution

ADH

anti-diuretic hormone, released by thepituitary gland to cause increased waterretention by kidney nephrons

Adhesion

forces which cause molecules to adhere toplant surfaces such as xylem vessels

adrenaline

a hormone or chemical messenger whichstimulates the nervous system andmetabolism especially in times of stress

AIDS (acquired immunodeficiency syndrome)

reduced immunity caused by infection withHIV

aleurone layer

a layer under the epidermis of a barley seedwhich can produce amylase under the controlof GA

allele frequency

preponderance of alternative versions of


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genes

Amino acids

the basic units of proteins. They consist ofthe elements C, H, O and N

Angiosperms

flowering plants

antibodies

proteins synthesised in response to foreignantigens

antidiuretic hormone (ADH)

the hormone released by the pituitary glandto cause increased water retention by kidneynephrons

antigens

any substances that cause the immunesystem to produce antibodies. They may be

foreign or made within the body

antimicrobial proteins

peptide chains which deter pathogens

antiparallel

running in opposite direction to

apical meristemsgrowth of the apical (terminal) bud at theexpense of lateral buds

Apical meristems

growing points (regions of mitosis) found atthe tips of plant stems or roots allowing


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increase in length

appeasement display

behaviour used to divert the threat posed by

a dominant animal

artificial environment

surroundings approximating to thosenaturally found

artificial selection

breeding is controlled by Man so thatselected genetic lines survive

avoidance behaviour

behaviour which reduces threat displays fromdominant animals

behavioural

relating to reponses of the whole organism toits environment

buddingproducing new cels by mitosis as budsforming on the parent cell, eg. in Yeast

calcicoles

plants which prefer calcium-rich soil

calcifuges

plants which avoid calcium-rich soil

callus

a group dividing cells which may develop intoa new plant

cambium


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(plural: cambia) a region of mitosis

capsid

the outer part of a virus

captive breeding

the use of zoos or reserves to allow capturedorganisms to produce offspring underprotected conditions

carbon fixation

combination of carbon with hydrogen in thesecond phase of photosynthesis

Cell banks

laboratory preserved reserves of cells

cellulase

an enzyme which digests cellulose sugar

characteristic banding pattern

sequence of bands usual in that species

chloride secretory cells

cells which can release chlorine ions

climax, or mature, community

the last populations establishing themselves.These are long-lived.

clonesgroups of genetically identical individualsproduced from one parent by mitosis,perhaps using micropropagation

codon

a triplet of exposed bases on a length of


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mRNA

Cohesion

forces which cause molecules to stick to one

another

compensation point

any point at which photosynthetic rate andrate of respiration exactly balance oneanother out, usually once in the morning asphotosynthesis speeds up and once in theearly evening as phtosynthesis is retarded bylack of light and heat

Competition

the need for the same resources

continental drift

the gradual moving apart of continents dueto plate tectonics

convergent evolution

the evolution of similar adaptive features inunrelated groups of organisms

critical period

the number of hours of darkness in any 24hour period which is crucial in triggeringflowering

cuticle

a waxy, waterproof layer on the epidermis ofa leaf or stem

Cyanogenic plants

plants such as clover which release cyanidein response to grazing


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the shape of a DNA molecule, see

Duplication

repetition of a series of nucleotides

Ecological barriers

impediments to interbreeding which resultfrom differences in ecology such as freshwater inflow separating two regions of saltwater

ecological niche

the position of an organism in the food web

ectotherms

animals whose body temperature is largelydependent on external ambient temperature

effector

cells, muscles or glands which performresponses to stimuli

effector cells

any muscle cell or gland cell that performs aresponse to a stimulus

embryo

the early stages of development of a plantroot and shoot found in the seed

endosperm

starchy food store of a barley seed

endotherms

animals whose body temperature iscontrolled internally. These are the birds and


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mammals.

envelope

an outer part

Enzyme induction

the switching on of a gene or group ofgenes to cause production of an enzyme as itis required

enzymes

chemicals which promote reactions byforming enzyme/substrate complexes at

active sites

etiolated

growth of a stem featuring yellow colour,long internodes and a plumular hook occuringwhen plants are grown in darkness

Extinction

total loss of a species

Fatty acids

molecules which combine with glycerol tomake fats

filter feeding

the use of a syphon effect to suck planktonor bacteria into specialised feeders such assome molluscs

fitness

ability to survive

Foetal Alcohol Syndrome (FAS)

a condition causing mental and physicalretardation of children of mothers who are


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alcoholic

Foraging

systematic searching for food, such as when

an animal quarters a field

function

job

Galls

areas of plant tissue which isolate damagedareas or parasitic organisms

gene poolpopulation of genotypes available for mixingthrough mating

genetic code

the sequence of nucleotides in a DNAmolecule determines the sequence on mRNAand this codes for the sequence of aminoacids in a protein

Genetic engineering

the use of organisms which have had DNAinserted by Man to produce selected products

Geographical barriers

impediments to interbreeding which resultfrom accidents of geography such as distanceor mountainous regions which preventpopulations meeting

gibberellic acid (GA)

a plant growth substance which promotes cell


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elongation and causes production of amylasein germinating seeds

glomeruli

knots of tiny blood capillaries found in theBowmans capsules of nephrons

glucose

a six carbon sugar which is the product ofphotosynthesis and the substrate ofrespiration

glycogen

the storage product formed by the action ofinsulin on glucose

glycolysis

the breakdown of glucose (sugar) into 2molecules of pyruvic acid

grazer

an animal which spends many hours feedingon plants

growth curve

a graph showing growth in sze over anorganisms lifetime

guard cells

kidney shaped cells found in pairs to formstomata

habituated

a term decribing an animal which has learnedto ignore a specific, repetitive, harmlessstimulus

haemoglobin


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a globular protein containing iron whichassociates readily with oxygen whenavailable

Henle the loop of Henle is a part of the nephronwhich folds back on itself allowing acountercurrent exchange system between thetwo portions which lie parallel to one another

Human immunodeficiency virus (HIV)

a virus which disrupts the immune system byinvading white blood cells

hybrid plants

plants produced using genes of differentvarieties or species

hydrogen carriers

molecules such as NAD which easily bind toHydrogen when available

Hydrophytes

plants adapted to live in wet conditions suchas in ponds

hypertonic

solution A (or cell A) is hypertonic to solutionB (or cell B) if it has less water, that is more

solute, than solution B (or cell B)

hypothalamus

part of the brain adjacent to the pituitarygland which monitors and regulatestemperature and water balance


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a hormone produced in the pancreas whichconverts excess glucose to glycogen

internal environment

conditions within all the different cells andfluids in the body

interspecific

between species

intraspecific

within one species

Inversionreversal

Inversion mutation

reversal of a sequence of nucleotides or alength of DNA

islets of Langerhans

cells in the pancreas which produce insulin

and glucagon

isotonic

equal in concentration

Jacob-Monod hypothesis of gene action

the theory, observed in bacteria, that geneswork in functional groups to control use ofresources

kidneys

osmoregulatory organs; they remove ureaand excess water from the blood


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lac operon

the group of genes responsible in bacteria forregulation of lactose digestion bybetagalactosidase enzyme

Lateral meristems

growing points (regions of mitosis) foundinside plant stems or roots allowing increasein girth

learned behaviour

behaviour copied by observation in socialgroups

liver

a large organ with many functions, includingstoring vitamins and iron, deaminatingexcess amino acids to form urea, and storingglycogen

Long-day plants

plants which use lengthening days as atrigger for flowering; there is a critical

number of hours which must be exceeded.

lymphocytes

cells involved in producing humoralantibodies (B-lymphocytes) and in cell-mediated responses (T-lymphocytes)

lysis

bursting, eg. the release of daughter

viruses from a host cell. See also glycolysis

lysozyme

an enzyme produced in tears to defend


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against pathogens

macro-elements

elements such as N, S, P, K, Ca, Mg which

are required in relatively large quantities byplants

mass extinctions

large scale losses of species and genera

maximum sustainable yield (MSY)

the highest harvest of plants or animalswhich can continue over time without

detriment ot the population harvested

membranous envelope

a coating formed by a membrane

memory cells

cells (B cells) which produce a secondaryimmune response as they are activated bylow levels of antigen

meristem

a growing point in a plant, ie. a place wheremitosis produces new cells (see cambia)

meristems

growing points in plants, ie. places wheremitosis produces new cells (see cambium)

messenger RNA (mRNA)the nucleic acid which carries the geneticcode to the ribosomes


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metabolic pathway

a series of reactions which build up (anabolic)products or break down (catabolic)substrates

metabolic water

water released during respiration in allrespiring cells (check the equation)

micropropagation

the use of plant tissue other than seeds togrow new plants allowing mass production ofuniform crops

mitosis

nuclear division

mobile

able to move

monocytes

large, long-lived white blood cells which

become macrophages which engulf virusesand bacteria

NAD

A co-enzyme which easily attaches toHydrogen atoms, but releases them whenthey are required

national park

an area reserved for wildlife by governmentlegislation

natural environment

native surroundings


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nutrient

a mineral such as nitrogen, phosphorous orpotassium, or a chemical which releasesminerals to a plant

obligate intracellular parasites

organisms which require to live in the cells ofhosts

operator gene

the gene which switches on the structuralgene when appropriate

operon

a group of regulator, operator and structuralgenes which operate as a unit

order

sequence

osmoregulation

the mechanisms used by organisms tomaintain water and solute balance

Osmoregulation

control of water and solute concentrationswithin tolerable limits

osmosis

movement of water from high to lowconcentration through a semi permeablemembrane

pancreas


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an organ which both releases enzymes, suchas amylase, and also hormones, insulin andglucagon

peptide bonds connections between amino acids

perennial

living for several years

pesticides

chemicals applied to kill pests

Phagocyteswhite blood cells called macrophages

Phagocytosis

the process by which macrophages engulfbacteria which invade tissues

phenotypes that are beneficial

constitutions which allow individuals to

exploit resources and circumstances betterthan their competitors

phenylalanine

an amino acid

phenylalanine hydroxylase (PAH)

the enzyme which cannot be produced in theinherited disorder phenylketonuria

Phenylketonuria (PKU)

(PKU) is an inherited metabolic disorder (orinborn error of metabolism) which results ininability to convert phenylalanaine to tyrosine


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photoperiodism

the response of an organism to changingdaylength

photophosphorylationthe production of ATP using light energy

photosynthesis

the production of glucose and oxygen in thechloroplasts of a green plant using lightenergy to combine carbon dioxide withhydrogen extracted from water

physiological

relating to responses and secretions of bodyorgans

physiological homeostasis

mechanism used to maintain a stable internalenvironment

phytoalexins

chemicals produced by plants when they areattacked by parasites in the same way thatantibodies protect animals

pioneer community

the first populations establishing themselves.These are short-lived.

pituitary glandthe master gland, found in the brain, whichreleases growth hormone, TSH and ADH,among others

plant growth hormones

substances which promote or inhibit the


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development of plant tissues, depending onconcentrations

plasmodesmata

pores in a cell membrane (plasmalemma)connecting adjacent cells

plasmolysed

shrunken due to loss of water

polymers

long molecules composed of repeated units(monomers)

polypeptide chains

several amino acids joined by peptide bonds

primary growth

first increase in size due to production andenlargement of new cells at the cambiawithin a vein (vascular bundle)

primary immune response

first defensive reaction on detection of anantigen. It is usually weak and slow.

Primary succession

changes in the types of species which occupyan initially barren area through time

protein coat

outer part of a virus

protoplasts

nucleoplasm and cytoplasm


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pursuit time

time spent pursuing prey

ranking order

the organisation of a hierarchy of dominancewithin a group of social animals

receptor

name applied to cells which monitor changesin environment

recombinant plasmids

circular portions of DNA containing genes

inserted artificially

Regeneration

regrowth of amputated parts in lowerorganisms such as starfish and spiders

regulator

describing a gene of an operon which causesa repressor molecule to inhibit action of an

operator gene

repressor molecule

the compound produced under the control ofa regulator gene to inhibit operator geneexpression

Reproductive barriers

impediments to interbreeding arising fromdifferences in courtship ritual or in breedingseason

Resin

gum

reverse transcriptase


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an enzyme used by pathogens to generateDNA from RNA using the host cells resources

reversed stomatal rhythm

specialised behaviour of desert plants whichcauses the stomata to open at night ratherthan in the daytime

ribose

a sugar which forms part of an RNAnucleotide

ribosomes

structures found in the cytoplasm andattached to ER where protein synthesisoccurs

rickets

bone deformity due to lack of vitamin D orcalcium

RNAa nucleic acid containing phosphate, ribosesugar, adenine, uracil, guanine and cytosine

root pressure

the apparent push of water up through a cutstem from the roots

search time

time spent foraging

secondary growth

increase in width of a stem or root due toactivity of lateral meristems. This is themethod by which trees add annual rings as


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they grow perennially.

secondary immune response

defensive reaction on second or subsequent

exposure to an antigen. It is fast and strong.

Secondary succession

changes in the types of species which occupya previously colonised area through time

selected

allowing advantage

selective behaviourchoosing prey of the optimum size andavailability

semi-conservativemethod of replication whereby each new DNAdouble helix consists of one strand of originalDNA, and one newly constructed sequence ofnucleotides

sessile

unable to move

shade plants plants which thrive in poorly-illuminatedsituations

Short-day plants

plants which use shortening days as a triggerfor flowering; there is a critical number of


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hours which must not be exceeded.

short-term modification

a change in learned behaviour lasting only a

short time as it has not been practised

social behaviour

behaviour which affects relationships

social signals

behaviour communicating status or mood

somatic cell hybrid

a cross between two species arising from thefusion of cells other that gametes

somatic fusion

the joining of two plant cells, other thangametes, which have had their cell wallsremoved so that their contents fuse together

speciation

formation of a new species

species

a group of organisms which can breed toproduce fertile, viable offspring

specific immune response

cancelling of one type of antigen byantibodies which match only that single

pathogen

stomata

pores, mainly found on the undersurfaces ofleaves, which allow gas exchange


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strong bonds

conections between molecules, such ascovalent bonds, which are not easily broken

structural genesgenes responsible for the transcription ofmRNA, leading to enzyme production

structure

1: a particular organelle within a cell, eg.nucleus, nucleolus; 2: the way in which amolecule or an organelle or organ is built,eg.proteins are made of amino acids

struggle to survive

competition for resources

Substitution mutation

the replacement of one nucleotide by another

Succession

the series of changes in the types of species

which occupy a given area through time

sun plants

plants which thrive in sunny situations

territory

an area defended by an animal, or by a pair,usually to allow breeding behaviour

thalidomidea morning-sickness drug which caused limband other deformities in foetuses

thermostat

receptors in the hypothalamus which detectblood temperature and receive nervous


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Transpiration

release of water by stomata

transpiration pull

movement of water through the xylem of aplant due to solar evaporation through thestomata

transpiration stream

the flow of water through the xylem of aplant caused by transpiration loss at theleaves

triplet code three exposed bases on a length of DNA orRNA forming a code for matching bases

type

kind

tyrosine

an amino acid

unidirectional

in one direction only

uracil

an organic base forming part of RNAnucleotides

variations

differences

vasoconstriction

contraction in diameter of a blood vessel,


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glossary of biology terms

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