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AQA A-Level Biology Paper 2 Comprehensive
Practice Exam 2026/2027 Specification (7402):
Verified Questions and A+ Answers – Pass
Guaranteed - A+ Graded
Section A: Multiple-Choice Questions
(15 marks – 1 mark per question)
Q1: Which of the following correctly describes the immediate fate of electrons released during
photolysis of water in the light-dependent reactions of photosynthesis?
A. They reduce NADP directly to form reduced NADP
B. They replace electrons lost by photosystem II, which then excite photosystem I electrons
C. They combine with hydrogen ions to form hydrogen gas
D. They are used to phosphorylate ADP to ATP directly
Correct Answer: B
Rationale: Photolysis of water replaces electrons lost from photosystem II (P680). These
replacement electrons are passed along the electron transport chain, providing energy for proton
pumping and eventually replacing electrons lost by photosystem I (P700). Option A is incorrect
because electrons from photolysis do not directly reduce NADP—they must pass through the
electron transport chain first. Option C is incorrect as hydrogen gas is not produced in
photosynthesis. Option D is incorrect because electrons do not directly phosphorylate ADP;
chemiosmosis drives ATP synthesis. [AQA 3.5.1]
Q2: During the Calvin cycle, for every 3 molecules of CO₂ fixed, how many molecules of triose
phosphate (TP) are produced, and how many leave the cycle to produce hexose sugars?
A. 6 TP produced; 6 TP leave
B. 6 TP produced; 1 TP leaves
C. 3 TP produced; 1 TP leaves
D. 3 TP produced; 3 TP leave
Correct Answer: B
Rationale: For every 3 CO₂ molecules fixed, 6 molecules of TP are produced (via 6 turns of the
cycle involving 6 RuBP). However, only 1 TP molecule leaves the cycle to form hexose sugars
,2
(requiring 2 TP to form 1 hexose). The remaining 5 TP molecules are used to regenerate 3 RuBP
molecules to maintain the cycle. Option A is incorrect because not all TP leaves—regeneration is
essential. Options C and D underestimate the total TP production. [AQA 3.5.1]
Q3: In oxidative phosphorylation, what is the role of oxygen?
A. To phosphorylate ADP directly to form ATP
B. To act as the final electron acceptor, forming water with protons
C. To pump protons across the inner mitochondrial membrane
D. To oxidize NADH and FADH₂ directly
Correct Answer: B
Rationale: Oxygen acts as the final electron acceptor at the end of the electron transport chain,
combining with electrons and protons (H⁺) to form water. This maintains the proton gradient by
removing electrons from the chain. Option A is incorrect—oxygen does not phosphorylate ADP.
Option C is incorrect—proton pumping is driven by electron transport, not oxygen directly.
Option D is incorrect—NADH and FADH₂ are oxidized by dehydrogenase enzymes at complex I
and II, not by oxygen. [AQA 3.5.2]
Q4: A respirometer experiment shows an organism consumes 0.6 dm³ of O₂ and produces 0.4
dm³ of CO₂ over the same time period. What is the respiratory quotient (RQ)?
A. 0.67
B. 1.0
C. 1.5
D. 0.4
Correct Answer: A
Rationale: RQ = Volume of CO₂ produced ÷ Volume of O₂ consumed = 0.4 ÷ 0.6 = 0.67. An RQ
of 0.7 indicates lipid respiration; 1.0 indicates carbohydrate; >1.0 indicates anaerobic respiration
or conversion of carbohydrate to fat. Option B would indicate pure carbohydrate metabolism.
Option C is mathematically incorrect. Option D inverts the calculation. [AQA 3.5.2]
Q5: Which statement correctly describes the relationship between gross primary production
(GPP) and net primary production (NPP)?
A. NPP = GPP + plant respiration losses
B. NPP = GPP − plant respiration losses
C. GPP = NPP − plant respiration losses
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D. NPP represents only the energy consumed by herbivores
Correct Answer: B
Rationale: NPP represents the energy stored in plant biomass after respiratory losses (R) are
subtracted from GPP: NPP = GPP − R. This is the energy available to primary consumers.
Option A incorrectly adds respiration. Option C rearranges the equation incorrectly. Option D is
incorrect—NPP includes all stored energy, not just that consumed by herbivores. [AQA 3.5.3]
Q6: In the nitrogen cycle, which microorganisms are responsible for converting ammonium ions
to nitrite ions?
A. Nitrobacter
B. Rhizobium
C. Nitrosomonas
D. Pseudomonas
Correct Answer: C
Rationale: Nitrosomonas bacteria carry out the first stage of nitrification: oxidizing ammonium
ions (NH₄⁺) to nitrite ions (NO₂⁻). Option A (Nitrobacter) converts nitrite to nitrate (second
stage). Option B (Rhizobium) fixes atmospheric nitrogen. Option D (Pseudomonas) carries out
denitrification under anaerobic conditions, converting nitrate to nitrogen gas. [AQA 3.5.4]
Q7: In a synapse, which ion movement is primarily responsible for the release of
neurotransmitter into the synaptic cleft?
A. Influx of Na⁺ into the presynaptic neurone
B. Influx of Ca²⁺ into the presynaptic neurone
C. Efflux of K⁺ from the presynaptic neurone
D. Influx of Cl⁻ into the presynaptic neurone
Correct Answer: B
Rationale: Depolarization of the presynaptic membrane opens voltage-gated calcium channels.
The influx of Ca²⁺ triggers synaptic vesicles to fuse with the presynaptic membrane, releasing
neurotransmitter via exocytosis. Option A (Na⁺ influx) causes depolarization but does not
directly trigger vesicle release. Option C (K⁺ efflux) causes repolarization. Option D (Cl⁻ influx)
typically hyperpolarizes the membrane and inhibits transmission. [AQA 3.6.2]
Q8: Which structural feature of rod cells in the retina enables them to function effectively in low
light intensities?
AQA A-Level Biology Paper 2 Comprehensive
Practice Exam 2026/2027 Specification (7402):
Verified Questions and A+ Answers – Pass
Guaranteed - A+ Graded
Section A: Multiple-Choice Questions
(15 marks – 1 mark per question)
Q1: Which of the following correctly describes the immediate fate of electrons released during
photolysis of water in the light-dependent reactions of photosynthesis?
A. They reduce NADP directly to form reduced NADP
B. They replace electrons lost by photosystem II, which then excite photosystem I electrons
C. They combine with hydrogen ions to form hydrogen gas
D. They are used to phosphorylate ADP to ATP directly
Correct Answer: B
Rationale: Photolysis of water replaces electrons lost from photosystem II (P680). These
replacement electrons are passed along the electron transport chain, providing energy for proton
pumping and eventually replacing electrons lost by photosystem I (P700). Option A is incorrect
because electrons from photolysis do not directly reduce NADP—they must pass through the
electron transport chain first. Option C is incorrect as hydrogen gas is not produced in
photosynthesis. Option D is incorrect because electrons do not directly phosphorylate ADP;
chemiosmosis drives ATP synthesis. [AQA 3.5.1]
Q2: During the Calvin cycle, for every 3 molecules of CO₂ fixed, how many molecules of triose
phosphate (TP) are produced, and how many leave the cycle to produce hexose sugars?
A. 6 TP produced; 6 TP leave
B. 6 TP produced; 1 TP leaves
C. 3 TP produced; 1 TP leaves
D. 3 TP produced; 3 TP leave
Correct Answer: B
Rationale: For every 3 CO₂ molecules fixed, 6 molecules of TP are produced (via 6 turns of the
cycle involving 6 RuBP). However, only 1 TP molecule leaves the cycle to form hexose sugars
,2
(requiring 2 TP to form 1 hexose). The remaining 5 TP molecules are used to regenerate 3 RuBP
molecules to maintain the cycle. Option A is incorrect because not all TP leaves—regeneration is
essential. Options C and D underestimate the total TP production. [AQA 3.5.1]
Q3: In oxidative phosphorylation, what is the role of oxygen?
A. To phosphorylate ADP directly to form ATP
B. To act as the final electron acceptor, forming water with protons
C. To pump protons across the inner mitochondrial membrane
D. To oxidize NADH and FADH₂ directly
Correct Answer: B
Rationale: Oxygen acts as the final electron acceptor at the end of the electron transport chain,
combining with electrons and protons (H⁺) to form water. This maintains the proton gradient by
removing electrons from the chain. Option A is incorrect—oxygen does not phosphorylate ADP.
Option C is incorrect—proton pumping is driven by electron transport, not oxygen directly.
Option D is incorrect—NADH and FADH₂ are oxidized by dehydrogenase enzymes at complex I
and II, not by oxygen. [AQA 3.5.2]
Q4: A respirometer experiment shows an organism consumes 0.6 dm³ of O₂ and produces 0.4
dm³ of CO₂ over the same time period. What is the respiratory quotient (RQ)?
A. 0.67
B. 1.0
C. 1.5
D. 0.4
Correct Answer: A
Rationale: RQ = Volume of CO₂ produced ÷ Volume of O₂ consumed = 0.4 ÷ 0.6 = 0.67. An RQ
of 0.7 indicates lipid respiration; 1.0 indicates carbohydrate; >1.0 indicates anaerobic respiration
or conversion of carbohydrate to fat. Option B would indicate pure carbohydrate metabolism.
Option C is mathematically incorrect. Option D inverts the calculation. [AQA 3.5.2]
Q5: Which statement correctly describes the relationship between gross primary production
(GPP) and net primary production (NPP)?
A. NPP = GPP + plant respiration losses
B. NPP = GPP − plant respiration losses
C. GPP = NPP − plant respiration losses
, 3
D. NPP represents only the energy consumed by herbivores
Correct Answer: B
Rationale: NPP represents the energy stored in plant biomass after respiratory losses (R) are
subtracted from GPP: NPP = GPP − R. This is the energy available to primary consumers.
Option A incorrectly adds respiration. Option C rearranges the equation incorrectly. Option D is
incorrect—NPP includes all stored energy, not just that consumed by herbivores. [AQA 3.5.3]
Q6: In the nitrogen cycle, which microorganisms are responsible for converting ammonium ions
to nitrite ions?
A. Nitrobacter
B. Rhizobium
C. Nitrosomonas
D. Pseudomonas
Correct Answer: C
Rationale: Nitrosomonas bacteria carry out the first stage of nitrification: oxidizing ammonium
ions (NH₄⁺) to nitrite ions (NO₂⁻). Option A (Nitrobacter) converts nitrite to nitrate (second
stage). Option B (Rhizobium) fixes atmospheric nitrogen. Option D (Pseudomonas) carries out
denitrification under anaerobic conditions, converting nitrate to nitrogen gas. [AQA 3.5.4]
Q7: In a synapse, which ion movement is primarily responsible for the release of
neurotransmitter into the synaptic cleft?
A. Influx of Na⁺ into the presynaptic neurone
B. Influx of Ca²⁺ into the presynaptic neurone
C. Efflux of K⁺ from the presynaptic neurone
D. Influx of Cl⁻ into the presynaptic neurone
Correct Answer: B
Rationale: Depolarization of the presynaptic membrane opens voltage-gated calcium channels.
The influx of Ca²⁺ triggers synaptic vesicles to fuse with the presynaptic membrane, releasing
neurotransmitter via exocytosis. Option A (Na⁺ influx) causes depolarization but does not
directly trigger vesicle release. Option C (K⁺ efflux) causes repolarization. Option D (Cl⁻ influx)
typically hyperpolarizes the membrane and inhibits transmission. [AQA 3.6.2]
Q8: Which structural feature of rod cells in the retina enables them to function effectively in low
light intensities?
