AQA A LEVEL BIOLOGY PAPER 2
7402-2 MARK SCHEME MS FINAL TEST
2026 QUESTIONS WITH CORRECT
ANSWERS GRADED A+
◍ What is homeostasis?.
Answer: The maintenance of a constant internal environment.
◍ What is a stimulus?.
Answer: A change in your environment than requires a response. e.g Light,
sound, touch, pressure, pain, chemical or temperature.
◍ What do the receptors do?.
Answer: Detect the stimulus or change in environment.
◍ What happens after the receptors?.
Answer: Receptors send messages to the CNS via the sensory neurone.
◍ 2010 TZ1 2. (a) Glucose and galactose are examples of monosaccharides.
State one other example of amonosaccharide. (b) The equation below shows
the production of glucose and galactose from lactose. (i) There are several
different types of carbohydrate. State which type of carbohydrate lactose is.
(ii) State the type of chemical reaction that occurs when lactose is digested
into glucose and galactose. (c) Lactase is widely used in food processing.
Explain three reasons for converting lactose to glucose and galactose during
food processing. (d) Simple laboratory experiments show that when the
enzyme lactase is mixed with lactose,the initial rate of reaction is highest at
48°
C. In food processing, lactase is used at a much lower temperature, often at
5°
, C. Suggest reasons for using lactase at relatively low temperatures..
Answer: (a) fructose/ribose/deoxyribose/ribulose/other monosaccharides
apart from glucose and galactose (b) (i) disaccharide (ii) hydrolysis (c) it
allows people who are lactose intolerant/have difficulty digesting lactose
toconsume milk (products); galactose and glucose taste sweeter than lactose
reducing need for additionalsweetener (in flavoured milk products);
galactose and glucose are more soluble than lactose / gives smoother texture
/reduces crystalization in ice cream; (bacteria) ferment glucose and
galactose more rapidly (than lactose) shorteningproduction time (of
yogurt/cottage cheese); (d) less denaturation / enzymes last longer at lower
temperatures;lower energy costs / less energy to achieve 5° C compared to
48° C;reduces bacterial growth / reduces (milk) spoilage;to form products
more slowly / to control rate of reaction;
◍ What makes up the central nervous system?.
Answer: The brain or spinal cord
◍ 2010 TZ2 2. (c) Describe the movement of water across membranes. (d)
State the role of water in photosynthesis..
Answer: (c) osmosis / moves passively; from regions of low solute/high
water potential/concentration to high soluteconcentration / low water
potential/concentration; passes through protein
channels/aquaporins/selectively-permeable membrane; (d) water molecules
undergo photolysis/are split by light energy; forms oxygen as a by-product;
hydrogen helps power the fixation of carbon (into organic molecules);
◍ What is an effector?.
Answer: Muscles or glands that bring about a response.
◍ What do the muscles and glands do in response to stimuli?.
Answer: Muscles contract and glands secrete chemical
substances(hormones).
◍ 2010 TZ2 4. (a) State a word equation for anaerobic cell respiration in
humans..
Answer: (a) pyruvate/pyruvic acid lactate/lactic acid; glucose
, (pyruvate/pyruvic acid) lactate/lactic acid
◍ 2010 Nov2. (d) Explain, using one example, how non-disjunction in meiosis
can lead to changes in chromosome number..
Answer: (d) pair of homologous chromosomes moves in same direction/does
not separateduring anaphase I / chromatids move in same direction/do not
separate duringanaphase II;leaving a cell with an (some) extra
chromosome(s)/missing chromosome(s); an example; (e.g. Down syndrome
/ trisomy 21);
◍ What is a sensory neurone?.
Answer: A neurone that carry information from the receptors to the CNS.
◍ 2010 Nov3. (a) List two functions of membrane proteins..
Answer: (a) hormone binding sites / receptors; (immobilized) enzymes; cell
adhesion; cell (to cell) communication; passive transport/channels; active
transport/pumps; facilitate diffusion; carry electrons;
◍ What is a relay neurone?.
Answer: Neurones that carry impulses from the sensory neurone to the
motor neurone.
◍ What is a motor neurone?.
Answer: Neurones that carry information from the CNS to the effectors.
◍ What is the nervous system?.
Answer: It is a system that allows you to react to your surroundings.
◍ 2011 TZ1 4. (b) State two characteristics of stem cells that can be used to
distinguish them from otherbody cells.(c) Outline one therapeutic use of
stem cells..
Answer: (b) retain the capacity to divide;they are undifferentiated /
unspecialized;have the ability to differentiate (along different pathways) /
are multipotent/pluripotent/totipotent; (c) named source of stem cells e.g.
bone marrow / cord blood / inner cell mass of embryo / embryonic stem
cells;name of condition that is treated using the stem cells e.g. leukaemia /
heart disease / diabetes / other possibility;one precise detail of how the stem
, cells replace/ replenish (differentiated) cells that are the cause of the
condition; Example: Source: stem cells obtained from bone marrow;
Condition: leukaemia; Detail: patient's bone marrow cells (are killed and)
replaced with the stem cells;
◍ How do signals travel across a synapse?.
Answer: The chemical or neurotransmitter diffuses across the synapse and
binds to a complementary receptor on the neurone (postsynaptic). This
causes an electrical impulse to travel down the next neurone.
◍ 2011 TZ16. (c) Explain the causes and consequences of sickle-cell anemia..
Answer: (c) (point) mutation of gene for hemoglobin; CTC to CAC / GAG
to GTG / substitution of T/thymine with A/adenine; mRNA copy of gene is
GUG instead of GAG; valine instead of glutamic acid; (in homozygotes) red
blood cells become sickle-shaped; (in homozygotes) less oxygen carried; (in
homozygotes) red blood cells do not survive long / burst / block blood
vessels/capillaries / circulatory problems may cause pain/organ
failure/example of symptom; heterozygotes have malaria resistance;
◍ 2011 TZ2 2. (a) Identify the structure labelled
I. (b) Explain briefly how materials produced in the structure labelled I are
transported to theplasma membrane. (c) Outline the function of the
mitochondria in the cell. (d) Suggest why the two labelled mitochondria are
different shapes in the micrograph..
Answer: . (a) rough endoplasmic reticulum/RER/rough ER / ribosome(b)
vesicles are formed (from the rough ER); they are received by Golgi
apparatus; Golgi apparatus forms vesicles that transport substances to
membrane(c) aerobic respiration takes place in the mitochondria; important
for energy/ATP production; pyruvate broken down into carbon dioxide and
water(d) they are cut in different planes / due to three-dimensional
nature/shape
◍ 2011 TZ2 4. (a) State the evidence provided by the karyotype that shows
this person has Down syndrome. (b) Outline how Down syndrome occurs
due to meiosis. (c) Determine, giving a reason, the sex of the person in the
7402-2 MARK SCHEME MS FINAL TEST
2026 QUESTIONS WITH CORRECT
ANSWERS GRADED A+
◍ What is homeostasis?.
Answer: The maintenance of a constant internal environment.
◍ What is a stimulus?.
Answer: A change in your environment than requires a response. e.g Light,
sound, touch, pressure, pain, chemical or temperature.
◍ What do the receptors do?.
Answer: Detect the stimulus or change in environment.
◍ What happens after the receptors?.
Answer: Receptors send messages to the CNS via the sensory neurone.
◍ 2010 TZ1 2. (a) Glucose and galactose are examples of monosaccharides.
State one other example of amonosaccharide. (b) The equation below shows
the production of glucose and galactose from lactose. (i) There are several
different types of carbohydrate. State which type of carbohydrate lactose is.
(ii) State the type of chemical reaction that occurs when lactose is digested
into glucose and galactose. (c) Lactase is widely used in food processing.
Explain three reasons for converting lactose to glucose and galactose during
food processing. (d) Simple laboratory experiments show that when the
enzyme lactase is mixed with lactose,the initial rate of reaction is highest at
48°
C. In food processing, lactase is used at a much lower temperature, often at
5°
, C. Suggest reasons for using lactase at relatively low temperatures..
Answer: (a) fructose/ribose/deoxyribose/ribulose/other monosaccharides
apart from glucose and galactose (b) (i) disaccharide (ii) hydrolysis (c) it
allows people who are lactose intolerant/have difficulty digesting lactose
toconsume milk (products); galactose and glucose taste sweeter than lactose
reducing need for additionalsweetener (in flavoured milk products);
galactose and glucose are more soluble than lactose / gives smoother texture
/reduces crystalization in ice cream; (bacteria) ferment glucose and
galactose more rapidly (than lactose) shorteningproduction time (of
yogurt/cottage cheese); (d) less denaturation / enzymes last longer at lower
temperatures;lower energy costs / less energy to achieve 5° C compared to
48° C;reduces bacterial growth / reduces (milk) spoilage;to form products
more slowly / to control rate of reaction;
◍ What makes up the central nervous system?.
Answer: The brain or spinal cord
◍ 2010 TZ2 2. (c) Describe the movement of water across membranes. (d)
State the role of water in photosynthesis..
Answer: (c) osmosis / moves passively; from regions of low solute/high
water potential/concentration to high soluteconcentration / low water
potential/concentration; passes through protein
channels/aquaporins/selectively-permeable membrane; (d) water molecules
undergo photolysis/are split by light energy; forms oxygen as a by-product;
hydrogen helps power the fixation of carbon (into organic molecules);
◍ What is an effector?.
Answer: Muscles or glands that bring about a response.
◍ What do the muscles and glands do in response to stimuli?.
Answer: Muscles contract and glands secrete chemical
substances(hormones).
◍ 2010 TZ2 4. (a) State a word equation for anaerobic cell respiration in
humans..
Answer: (a) pyruvate/pyruvic acid lactate/lactic acid; glucose
, (pyruvate/pyruvic acid) lactate/lactic acid
◍ 2010 Nov2. (d) Explain, using one example, how non-disjunction in meiosis
can lead to changes in chromosome number..
Answer: (d) pair of homologous chromosomes moves in same direction/does
not separateduring anaphase I / chromatids move in same direction/do not
separate duringanaphase II;leaving a cell with an (some) extra
chromosome(s)/missing chromosome(s); an example; (e.g. Down syndrome
/ trisomy 21);
◍ What is a sensory neurone?.
Answer: A neurone that carry information from the receptors to the CNS.
◍ 2010 Nov3. (a) List two functions of membrane proteins..
Answer: (a) hormone binding sites / receptors; (immobilized) enzymes; cell
adhesion; cell (to cell) communication; passive transport/channels; active
transport/pumps; facilitate diffusion; carry electrons;
◍ What is a relay neurone?.
Answer: Neurones that carry impulses from the sensory neurone to the
motor neurone.
◍ What is a motor neurone?.
Answer: Neurones that carry information from the CNS to the effectors.
◍ What is the nervous system?.
Answer: It is a system that allows you to react to your surroundings.
◍ 2011 TZ1 4. (b) State two characteristics of stem cells that can be used to
distinguish them from otherbody cells.(c) Outline one therapeutic use of
stem cells..
Answer: (b) retain the capacity to divide;they are undifferentiated /
unspecialized;have the ability to differentiate (along different pathways) /
are multipotent/pluripotent/totipotent; (c) named source of stem cells e.g.
bone marrow / cord blood / inner cell mass of embryo / embryonic stem
cells;name of condition that is treated using the stem cells e.g. leukaemia /
heart disease / diabetes / other possibility;one precise detail of how the stem
, cells replace/ replenish (differentiated) cells that are the cause of the
condition; Example: Source: stem cells obtained from bone marrow;
Condition: leukaemia; Detail: patient's bone marrow cells (are killed and)
replaced with the stem cells;
◍ How do signals travel across a synapse?.
Answer: The chemical or neurotransmitter diffuses across the synapse and
binds to a complementary receptor on the neurone (postsynaptic). This
causes an electrical impulse to travel down the next neurone.
◍ 2011 TZ16. (c) Explain the causes and consequences of sickle-cell anemia..
Answer: (c) (point) mutation of gene for hemoglobin; CTC to CAC / GAG
to GTG / substitution of T/thymine with A/adenine; mRNA copy of gene is
GUG instead of GAG; valine instead of glutamic acid; (in homozygotes) red
blood cells become sickle-shaped; (in homozygotes) less oxygen carried; (in
homozygotes) red blood cells do not survive long / burst / block blood
vessels/capillaries / circulatory problems may cause pain/organ
failure/example of symptom; heterozygotes have malaria resistance;
◍ 2011 TZ2 2. (a) Identify the structure labelled
I. (b) Explain briefly how materials produced in the structure labelled I are
transported to theplasma membrane. (c) Outline the function of the
mitochondria in the cell. (d) Suggest why the two labelled mitochondria are
different shapes in the micrograph..
Answer: . (a) rough endoplasmic reticulum/RER/rough ER / ribosome(b)
vesicles are formed (from the rough ER); they are received by Golgi
apparatus; Golgi apparatus forms vesicles that transport substances to
membrane(c) aerobic respiration takes place in the mitochondria; important
for energy/ATP production; pyruvate broken down into carbon dioxide and
water(d) they are cut in different planes / due to three-dimensional
nature/shape
◍ 2011 TZ2 4. (a) State the evidence provided by the karyotype that shows
this person has Down syndrome. (b) Outline how Down syndrome occurs
due to meiosis. (c) Determine, giving a reason, the sex of the person in the
