Cie Igcse Biology Key Terms

Front 1

absorption

Back 1

the movement of digested food molecules

through the wall of the intestine into the blood or lymph

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accommodation

Back 4

the change of shape of the lens, in

order to focus on objects at different distances

Front 5

active immunity

Back 5

defence against a pathogen by

antibody production in the body

Front 6

active site

Back 6

the part of an enzyme molecule into which

its substrate fi ts

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active transport

Back 7

the movement of molecules and ions

in or out of a cell through the cell membrane, from a

region of their lower concentration to a region of their

higher concentration against a concentration gradient,

using energy released during respiration

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adaptation

Back 8

a feature of an organism

that helps it survive in its environment

Front 9

adaptive features

Back 9

the inherited functional features of an

organism that increase its fi tness

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adipose tissue

Back 10

tissue made up of cells in which fat is

stored

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adrenaline

Back 11

a hormone secreted by the adrenal glands,

which prepares the body for ‘fl ight or fi ght’

Front 12

adult stem cell

Back 12

a cell in an adult that can give rise to a

limited range of specialised cells

Front 13

aerobic respiration

Back 13

the release of a relatively large

amount of energy in cells by the breakdown of nutrient

molecules in the presence of oxygen

Front 14

alimentary canal

Back 14

part of the digestive system; a long

tube running from mouth to anus

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alveolus (plural: alveoli)

Back 15

an air sac in the lungs, where

gas exchange occurs

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amino acids

Back 16

molecules that can link together in long

chains to form proteins; they contain carbon, hydrogen,

oxygen and nitrogen, and sometimes sulfur

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amniotic fluid

Back 17

fluid secreted by the amnion, which

supports and protects a developing fetus

Front 18

amylase

Back 18

an enzyme which breaks down starch to

maltose

Front 19

anaerobic respiration

Back 19

the release of a relatively

small amount of energy by the breakdown of nutrient

molecules in the absence of oxygen

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anatomy

Back 20

the detailed body structure of an organism

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allele

Back 21

any of two or more alternative forms

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anther

Back 22

the part of a stamen in which pollen is produced

Front 23

antibiotic

Back 23

a drug that kills bacteria in the human body,

without damaging human cells

Front 24

antibodies

Back 24

chemicals secreted by lymphocytes, which

attach to antigens and help to destroy them

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antigens

Back 25

chemicals on the surfaces of pathogens, which

are recognised as foreign by the body

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artery

Back 26

a blood vessel that carries blood away from the

heart

Front 27

artificial selection

Back 27

the choice by a farmer or grower of

only the ‘best’ parents to breed, generation aft er generation

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asexual reproduction

Back 28

the process resulting in the

production of genetically identical off spring from one

parent

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assimilation

Back 29

the movement of digested food molecules

into the cells of the body where they are used, becoming

part of the cells

Front 30

atrioventricular valves

Back 30

valves between the atria and

ventricles in the heart that prevent blood fl owing from

the ventricles into the atria

Front 31

auto-immune disease

Back 31

a disease caused by a person’s

own immune system attacking parts of their body

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auxin

Back 32

a plant hormone which causes cells to elongate

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axon

Back 33

a nerve fibre that conducts impulses away from

the cell body