OCR a level biology Q&A
Abiotic components - Answer-Components of an ecosystem that are non living
Abiotic factors - Answer-Non living components of an ecosystem that effect other living organisms
Acetycholine - Answer-Chemical that acts as a transmitter that diffuses across synaptic cleft
Acetycholinesterase - Answer-Enzyme in synaptic cleft that breaks down acetycholine. After it has
triggered an action potential in the post synaptic neurone, acetycholine must be broken down otherwise
it would remain in the synaptic cleft and continue to open sodium ion channels in the post synaptic
membrane causing action potentials
Acinus (plural acini) - Answer-Small group of exocrine cells in a sac like structure. in the pancreas these
surround a tubule and secrete into the tubule
Action potential - Answer-A brief reversal of teh potential across the membrane of a neurone causing a
peak of +40mV compared to the resting potential of -60mV
Adenyl cyclase - Answer-An intracellular enzyme that converts ATP to cyclic AMP (CAMP)
ADP - Answer-Adenosine diphosphate
Adrenal cortex - Answer-Outer layer of the adrenal gland
Adrenal gland - Answer-One of the pair of glands lying above kidneys, which release adrenaline and a
number of hormones known as corticoids (or corticosteroids) such as aldosterone
Adrenaline - Answer-Hormone released from medulla of adrenal glands which stimulates body to
prepare for fight or flight
,Adrenal medulla - Answer-Inner layer of adrenal gland
Adrenocorticotropic hormone (ACTH) - Answer-Hormone released by pituitary gland which stimulates
adrenal cortex to produce corticosteroid hormones
Actin and myosin - Answer-Proteins involved in muscular contraction
Agar - Answer-Polysacharide of galactose obtained from seaweed which is used to thicken a medium into
a gel.
Agarose - Answer-Type of sugar that can incorporated into a type of agar gel
Alkaloids - Answer-Organic nitrogen containing bases that have important physiological effects on
animals, includes nicotine, quinine, strychnine and morphine
Allele - Answer-Version of a gene
Allele frequency - Answer-Propotion of a particular allele within the gene pool
Allopatric speciation - Answer-Formation of 2 different species from one original one due to geographic
isolation
Alpha cells - Answer-Cells found in islets of langerhans that secrete glucagon
Ammonification - Answer-Production of ammonia by bacterial action in the decay of nitrgenous organic
matter
AMP - Answer-Adeonside monophosphate
Aneuploidy - Answer-Abnormal chromosome number
, Antagonist - Answer-Something that works against the other in opposite pairs, such as in the muscles
that are arranged in opposing pairs, so one contracts and the other elongates
ADH (antidiuretic hormone) - Answer-Hormone made in hypothalamus, stored and released from
pituitary gland, that controls permeability of collecting duct in walls of kidneys
Apical dominance - Answer-Inhibition of lateral buds fruther down shoot by chemicals produced by
apicial bud at tip of plant shoot.
Apoptosis - Answer-Programmed cell death
Artificial selection - Answer-Selective breeding of organisms to produce desired phenotypes
Ascending limb - Answer-Part of loop of Henle that carries fluid back into distal tubule in cortex
ATP - Answer-Adenosine triphosphate
Autoimmune response - Answer-Response in which body's immune system attacks and destroys some of
its own cells.
Autonomic nervous stsrem - Answer-Part of nervous system responsible for controlling involuntary
motor activities of body
Autoradiograms - Answer-Photographs made when photographic film is exposed to molecules labelled
with radioactivity
Autosomal linkage - Answer-Gene loci present on the same autosome (non sex chromosome) are often
inherited together
Autosome - Answer-Chromosome not concerned with sex determination
Abiotic components - Answer-Components of an ecosystem that are non living
Abiotic factors - Answer-Non living components of an ecosystem that effect other living organisms
Acetycholine - Answer-Chemical that acts as a transmitter that diffuses across synaptic cleft
Acetycholinesterase - Answer-Enzyme in synaptic cleft that breaks down acetycholine. After it has
triggered an action potential in the post synaptic neurone, acetycholine must be broken down otherwise
it would remain in the synaptic cleft and continue to open sodium ion channels in the post synaptic
membrane causing action potentials
Acinus (plural acini) - Answer-Small group of exocrine cells in a sac like structure. in the pancreas these
surround a tubule and secrete into the tubule
Action potential - Answer-A brief reversal of teh potential across the membrane of a neurone causing a
peak of +40mV compared to the resting potential of -60mV
Adenyl cyclase - Answer-An intracellular enzyme that converts ATP to cyclic AMP (CAMP)
ADP - Answer-Adenosine diphosphate
Adrenal cortex - Answer-Outer layer of the adrenal gland
Adrenal gland - Answer-One of the pair of glands lying above kidneys, which release adrenaline and a
number of hormones known as corticoids (or corticosteroids) such as aldosterone
Adrenaline - Answer-Hormone released from medulla of adrenal glands which stimulates body to
prepare for fight or flight
,Adrenal medulla - Answer-Inner layer of adrenal gland
Adrenocorticotropic hormone (ACTH) - Answer-Hormone released by pituitary gland which stimulates
adrenal cortex to produce corticosteroid hormones
Actin and myosin - Answer-Proteins involved in muscular contraction
Agar - Answer-Polysacharide of galactose obtained from seaweed which is used to thicken a medium into
a gel.
Agarose - Answer-Type of sugar that can incorporated into a type of agar gel
Alkaloids - Answer-Organic nitrogen containing bases that have important physiological effects on
animals, includes nicotine, quinine, strychnine and morphine
Allele - Answer-Version of a gene
Allele frequency - Answer-Propotion of a particular allele within the gene pool
Allopatric speciation - Answer-Formation of 2 different species from one original one due to geographic
isolation
Alpha cells - Answer-Cells found in islets of langerhans that secrete glucagon
Ammonification - Answer-Production of ammonia by bacterial action in the decay of nitrgenous organic
matter
AMP - Answer-Adeonside monophosphate
Aneuploidy - Answer-Abnormal chromosome number
, Antagonist - Answer-Something that works against the other in opposite pairs, such as in the muscles
that are arranged in opposing pairs, so one contracts and the other elongates
ADH (antidiuretic hormone) - Answer-Hormone made in hypothalamus, stored and released from
pituitary gland, that controls permeability of collecting duct in walls of kidneys
Apical dominance - Answer-Inhibition of lateral buds fruther down shoot by chemicals produced by
apicial bud at tip of plant shoot.
Apoptosis - Answer-Programmed cell death
Artificial selection - Answer-Selective breeding of organisms to produce desired phenotypes
Ascending limb - Answer-Part of loop of Henle that carries fluid back into distal tubule in cortex
ATP - Answer-Adenosine triphosphate
Autoimmune response - Answer-Response in which body's immune system attacks and destroys some of
its own cells.
Autonomic nervous stsrem - Answer-Part of nervous system responsible for controlling involuntary
motor activities of body
Autoradiograms - Answer-Photographs made when photographic film is exposed to molecules labelled
with radioactivity
Autosomal linkage - Answer-Gene loci present on the same autosome (non sex chromosome) are often
inherited together
Autosome - Answer-Chromosome not concerned with sex determination
