OCR A Level Biology Paper 1 ( AS & A LEVEL) Exam Paper + Mark Scheme
Revision Essential
(Enzyme) cofactors - ✔✔✔-Non-protein components that are required for enzyme catalysis;
called a coenzyme if it is organic molecule
ABA (abscisic acid) - ✔✔✔-Maintains dormancy of seeds/buds, stimulates cold responses e.g.
antifreeze proteins, stomatal closure (DOES NOT CAUSE ABSCISSION)
Abscission - ✔✔✔-Leaf fall
Acetylcholine - ✔✔✔-An excitatory neurotransmitter that enables learning and memory and
also triggers muscle contraction; after it binds it is broken down by an enzyme to be reabsorbed
Acetylcholinesterase - ✔✔✔-Enzyme that breaks down acetylcholine in the synaptic cleft to
Choline and Ethanoic acid
Actin - ✔✔✔-Thinner myofilament, has binding site for myosin head
Action of adrenaline - ✔✔✔-Can't enter cell because hydrophilic; binds to receptor on the cell
surface membrane; activates the enzyme adenyl cyclase; this converts ATP to cAMP; cAMP is
the second messenger in the cell, causes an effect inside the cell by activating protein kinases
which convert glycogen to glucose
Action potential - ✔✔✔-Nerve impulse; the membrane repolarises then depolarises again due
to ion movement
Activation energy - ✔✔✔-Minimum amount of energy required to start a chemical reaction;
enzymes lower this
Active site - ✔✔✔-Region on an enzyme that binds to a substrate
,OCR A Level Biology Paper 1 ( AS & A LEVEL) Exam Paper + Mark Scheme
Revision Essential
Active transport - ✔✔✔-Requires energy; moves material across a cell membrane against a
concentration gradient; ATP binds to carrier protein, releasing energy, which changes the shape
of it to force the material to the other side of the membrane
Adaptations of exchange surfaces - ✔✔✔-Large surface area, thin membrane to provide a short
diffusion path, good ventilation, good blood supply
ADH - ✔✔✔-Antidiuretic hormone, increases the permeability of the distal convoluted tubule
causing the body to reabsorb more water
ADH action - ✔✔✔-Binds to receptor on cell surface which triggers cAMP formation, cAMP
causes cascade reactions which cause aquaporin vesicles to insert into the membranes
ADH negative feedback loop - ✔✔✔-The hypothalamus produces ADH, which is stored in the
posterior pituitary, when osmoreceptors in hypothalamus detect low water the ADH is
stimulated to release more and cause more reabsorption of water, and vice-versa: when
osmoreceptors detect high water, little to no ADH is released
Adrenal cortex - ✔✔✔-Outer section of adrenal glands; secretes cortisol and aldosterone (vital
to life)
Adrenal medulla - ✔✔✔-Inner section of adrenal glands; secretes adrenaline (helps body react
to stress)
Adrenaline - ✔✔✔-Secreted by adrenal medulla; increases heart rate as well as blood glucose
by glycogenolysis; release stimulated by sympathetic nervous system
Alchohol dehydrogenase - ✔✔✔-Enzyme that breaks down ethanol to ethanal, in the liver
,OCR A Level Biology Paper 1 ( AS & A LEVEL) Exam Paper + Mark Scheme
Revision Essential
Alcholic fermentation - ✔✔✔-Anaerobic carbohydrate breakdown often in yeast that produces
ATP and ethanol, production of ethanol regenerates NAD to allow more formation of pyruvate,
however there is decarboxylation so the pyruvate cannot be recovered once oxygen is available
Alkaloids - ✔✔✔-Nitrogenous molecules which can act as drugs or poisons and taste bitter
All-or-nothing - ✔✔✔-If potential does not reach the threshold value, an action potential will
not be formed; all potentials are the same 'size' (therefore intensity of stimulus is conveyed with
frequency)
Allele - ✔✔✔-Different forms of a gene
Allosteric site - ✔✔✔-A site on an enzyme other than the active site, to which a specific
substance binds, changing the shape and activity of the enzyme
Alpha cells - ✔✔✔-Secrete glucagon
Alveoli - ✔✔✔-Tiny sacs of lung tissue specialised for the movement of gases between air and
blood; large SA:V, thin, ventilated, good blood supply
Amino acids - ✔✔✔-Organic compound containing a carboxyl (—COOH), a Hydrogen, an amino
(—NH2) and a variable R group; monomer of proteins
Amount of bonds for basic elements - ✔✔✔-Carbon can have 4 bonds; Nitrogen can have 3
bonds; Oxygen can have 2 bonds; Hydrogen can have 1 bond
, OCR A Level Biology Paper 1 ( AS & A LEVEL) Exam Paper + Mark Scheme
Revision Essential
Anaphase - ✔✔✔-The chromosomes separate and move to opposite ends of the cell; spindles
separates the chromatids by the centromeres
Anaphase I - ✔✔✔-Homologous chromosomes are pulled to opposite ends of the cell
(chromatids DO NOT separate, each duplicated chromosome still has two chromatids)
Anaphase II - ✔✔✔-Sister chromatids separate and move towards opposite poles
Androgens - ✔✔✔-Secreted by adrenal cortex; not as much as from the ovaries and testes
Antagonism - ✔✔✔-When hormones have opposite effects
Antennae pigments - ✔✔✔-Chlorophyll B, xanthophylls, carotenoids: funnel light energy to
reaction center pigments (chlorophyll A)
Anterior pituitary gland - ✔✔✔-Produces hormones with actions related to metabolism,
reproduction, growth and others (ACTH - cortisol production)
Antiparallel - ✔✔✔-Description of the opposite arrangement of the sugar-phosphate
backbones in a DNA double helix
Apical dominance - ✔✔✔-Tendency for growth to be concentrated at the tip of a plant shoot;
auxins stimulate growth in the apical shoot but inhibit it in the lateral shoots
Apoplast pathway - ✔✔✔-Route taken by water between the cells or through the cell walls in a
plant
Aquaporins - ✔✔✔-Water channel proteins
Revision Essential
(Enzyme) cofactors - ✔✔✔-Non-protein components that are required for enzyme catalysis;
called a coenzyme if it is organic molecule
ABA (abscisic acid) - ✔✔✔-Maintains dormancy of seeds/buds, stimulates cold responses e.g.
antifreeze proteins, stomatal closure (DOES NOT CAUSE ABSCISSION)
Abscission - ✔✔✔-Leaf fall
Acetylcholine - ✔✔✔-An excitatory neurotransmitter that enables learning and memory and
also triggers muscle contraction; after it binds it is broken down by an enzyme to be reabsorbed
Acetylcholinesterase - ✔✔✔-Enzyme that breaks down acetylcholine in the synaptic cleft to
Choline and Ethanoic acid
Actin - ✔✔✔-Thinner myofilament, has binding site for myosin head
Action of adrenaline - ✔✔✔-Can't enter cell because hydrophilic; binds to receptor on the cell
surface membrane; activates the enzyme adenyl cyclase; this converts ATP to cAMP; cAMP is
the second messenger in the cell, causes an effect inside the cell by activating protein kinases
which convert glycogen to glucose
Action potential - ✔✔✔-Nerve impulse; the membrane repolarises then depolarises again due
to ion movement
Activation energy - ✔✔✔-Minimum amount of energy required to start a chemical reaction;
enzymes lower this
Active site - ✔✔✔-Region on an enzyme that binds to a substrate
,OCR A Level Biology Paper 1 ( AS & A LEVEL) Exam Paper + Mark Scheme
Revision Essential
Active transport - ✔✔✔-Requires energy; moves material across a cell membrane against a
concentration gradient; ATP binds to carrier protein, releasing energy, which changes the shape
of it to force the material to the other side of the membrane
Adaptations of exchange surfaces - ✔✔✔-Large surface area, thin membrane to provide a short
diffusion path, good ventilation, good blood supply
ADH - ✔✔✔-Antidiuretic hormone, increases the permeability of the distal convoluted tubule
causing the body to reabsorb more water
ADH action - ✔✔✔-Binds to receptor on cell surface which triggers cAMP formation, cAMP
causes cascade reactions which cause aquaporin vesicles to insert into the membranes
ADH negative feedback loop - ✔✔✔-The hypothalamus produces ADH, which is stored in the
posterior pituitary, when osmoreceptors in hypothalamus detect low water the ADH is
stimulated to release more and cause more reabsorption of water, and vice-versa: when
osmoreceptors detect high water, little to no ADH is released
Adrenal cortex - ✔✔✔-Outer section of adrenal glands; secretes cortisol and aldosterone (vital
to life)
Adrenal medulla - ✔✔✔-Inner section of adrenal glands; secretes adrenaline (helps body react
to stress)
Adrenaline - ✔✔✔-Secreted by adrenal medulla; increases heart rate as well as blood glucose
by glycogenolysis; release stimulated by sympathetic nervous system
Alchohol dehydrogenase - ✔✔✔-Enzyme that breaks down ethanol to ethanal, in the liver
,OCR A Level Biology Paper 1 ( AS & A LEVEL) Exam Paper + Mark Scheme
Revision Essential
Alcholic fermentation - ✔✔✔-Anaerobic carbohydrate breakdown often in yeast that produces
ATP and ethanol, production of ethanol regenerates NAD to allow more formation of pyruvate,
however there is decarboxylation so the pyruvate cannot be recovered once oxygen is available
Alkaloids - ✔✔✔-Nitrogenous molecules which can act as drugs or poisons and taste bitter
All-or-nothing - ✔✔✔-If potential does not reach the threshold value, an action potential will
not be formed; all potentials are the same 'size' (therefore intensity of stimulus is conveyed with
frequency)
Allele - ✔✔✔-Different forms of a gene
Allosteric site - ✔✔✔-A site on an enzyme other than the active site, to which a specific
substance binds, changing the shape and activity of the enzyme
Alpha cells - ✔✔✔-Secrete glucagon
Alveoli - ✔✔✔-Tiny sacs of lung tissue specialised for the movement of gases between air and
blood; large SA:V, thin, ventilated, good blood supply
Amino acids - ✔✔✔-Organic compound containing a carboxyl (—COOH), a Hydrogen, an amino
(—NH2) and a variable R group; monomer of proteins
Amount of bonds for basic elements - ✔✔✔-Carbon can have 4 bonds; Nitrogen can have 3
bonds; Oxygen can have 2 bonds; Hydrogen can have 1 bond
, OCR A Level Biology Paper 1 ( AS & A LEVEL) Exam Paper + Mark Scheme
Revision Essential
Anaphase - ✔✔✔-The chromosomes separate and move to opposite ends of the cell; spindles
separates the chromatids by the centromeres
Anaphase I - ✔✔✔-Homologous chromosomes are pulled to opposite ends of the cell
(chromatids DO NOT separate, each duplicated chromosome still has two chromatids)
Anaphase II - ✔✔✔-Sister chromatids separate and move towards opposite poles
Androgens - ✔✔✔-Secreted by adrenal cortex; not as much as from the ovaries and testes
Antagonism - ✔✔✔-When hormones have opposite effects
Antennae pigments - ✔✔✔-Chlorophyll B, xanthophylls, carotenoids: funnel light energy to
reaction center pigments (chlorophyll A)
Anterior pituitary gland - ✔✔✔-Produces hormones with actions related to metabolism,
reproduction, growth and others (ACTH - cortisol production)
Antiparallel - ✔✔✔-Description of the opposite arrangement of the sugar-phosphate
backbones in a DNA double helix
Apical dominance - ✔✔✔-Tendency for growth to be concentrated at the tip of a plant shoot;
auxins stimulate growth in the apical shoot but inhibit it in the lateral shoots
Apoplast pathway - ✔✔✔-Route taken by water between the cells or through the cell walls in a
plant
Aquaporins - ✔✔✔-Water channel proteins
