definitions - set 2

Question 1

cellulose

Answer 1

a polysaccharide carbohydrate which forms fibres and is found in the cell walls of plant cells

Question 2

central nervous system

Answer 2

the brain and spinal chord

Question 3

chemical digestion

Answer 3

the breakdown of large molecules of food into smaller ones, done by enzymes

Question 4

chlorophyll

Answer 4

a green, light-absorbing pigment found inside chloroplasts in plant cells

Question 5

chloroplasts

Answer 5

an organlelle found in some plant cells, which contains chlorophyll and where photosynthesis takes place

Question 6

chromosome

Answer 6

a thread-like structure of DNA, made up of a string of genes

Question 7

cholera

Answer 7

a disease caused by a waterborne nacterium. which causes severe diarrhoea

Question 8

chyme

Answer 8

the partly-digested food, that moves from the stomach into the small intestine

Question 9

cilia

Answer 9

tiny extentions on the surface of a cell, which can wave in unison and cause fluids to move

Question 10

ciliary muscle

Answer 10

a ring of muscle around the lens, which can change its shape

Question 11

cirrhosis

Answer 11

a disease of the liver in which the cells are permanently damaged

Question 12

clone

Answer 12

a group of genetically identical organisms

Question 13

codominance

Answer 13

a situation in which both alleles in a heterozygote have an effect on the phenotype

Question 14

common ancestor

Answer 14

a species that lived long ago that is thought to be a distant ancestor of two or more species living today

Question 15

community

Answer 15

all the organisms, of all the different species, living in an area at the same time

Question 16

cone cell

Answer 16

a light-sensitive cell in the retina, which responds to light of a particular color

Question 17

consumer

Answer 17

an organism that getsits energy from feeding on other organisms

Question 18

continuous variation

Answer 18

differences in the features of a group of organisms in which there are no definite categories; each individual’s features can lie anywhere between two extremes

Question 19

coronary heart disease

Answer 19

a condition in which the coronary arteries become partly blocked

Question 20

corpus luteum

Answer 20

the structure that forms in an ovary after an egg has been released; it secretes progesterone

Question 21

cortex

Answer 21

in a kidney, the outer layer; in a plant stem or root, aa tissue made of typical plant cells (usually, however, without chloroplasts)

Question 22

cotyledons

Answer 22

food storage structures in a seed, which sometimes come above ground during germination and begin to photosynthesise

Question 23

cross-pollination

Answer 23

the transfer of pollen from the anther of one plant to the stigma of another plant of the same species

Question 24

cuticle

Answer 24

a layer of wax on a leaf

Question 25

cytoplasm

Answer 25

jelly-like material that is found in cells

Question 26

deamination

Answer 26

a metabolic reaction that takes place in the liver, in which the nitrogen-containing part of amino acids is removed to form urea, followed by the release of energy from the remainder of the amino acid

Question 27

death phase

Answer 27

a stage where the number in a population falls rapidly towards zero

Question 28

decomposer

Answer 28

an organism that gets its energy from dead or waste organic matter

Question 29

deforestation

Answer 29

the destruction of large areas of forest

Question 30

denatured

Answer 30

an enzyme is said to be denatured when its molecule has changed shape so much that the substrate can no longer fit into it

Question 31

denitrifying bacteria

Answer 31

bacteria that obtain their energy by converting nitrate ions into nitrogen gas

Question 32

deoxygenated blood

Answer 32

blood containing only a little oxygen

Question 33

depressant

Answer 33

a drug that inhibits the nervous system and slows it down

Question 34

dialysis

Answer 34

exchange of substances between two solutions through a partially permeable membrane; dialysis machines are used in the treatment of people with kidney failure

Question 35

diastole

Answer 35

the stage of a heart beat in which the muscles in the heart relax

Question 36

dichotomous

Answer 36

branching into two

Question 37

diffusion

Answer 37

the net movement of molecules from a region of their higher concentration to a region of their lower concentration down a concentration gradient, as a result of their random movement

Question 38

digestion

Answer 38

the break-down of large, insoluble food molecules into small molecules using mechanical and chemical processes

Question 39

diploid

Answer 39

having two sets of chromosmoes

Question 40

disaccharide

Answer 40

a complex sugar; a carbohydrate whose molecules are made of two sugar units

Question 41

discontinuous variation

Answer 41

differences in the features of a group of organisms where each fits into one of a few clearly defined categories

Question 42

DNA

Answer 42

the chemical from which genes and chromosomes are made

Question 43

dominant

Answer 43

an allele that is expressed if it is present (e.g. T or G)

Question 44

dormant

Answer 44

a condition in which an organism shuts its metabolism down, so that it can survive in adverse conditions

Question 45

double circulatory system

Answer 45

a system in which blood passes twice through the heart on one complete circuit of the body

Question 46

drug

Answer 46

any substance taken into the body that modifies or affects chemical reactions in the body

Question 47

ecosystem

Answer 47

a unit containing all of the organisms and their environment, interacting together, in a given area e.g. decomposing log or a lake

Question 48

ectothermic

Answer 48

unable to regulate body temperature physiologically; the organism's temperature varies with that of its environment

Question 49

effector

Answer 49

a part of the body that responds to a stimulus, e.g. a muscle or a gland

Question 50

egestion

Answer 50

the passing out of food that has not been digested, as feaces, through the anus