A2 2 2022-style respiration question (reduced-content series) · 6 marks
Describe the role of the electron transport chain in oxidative phosphorylation.
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CCEA A2 Biology 2022 past paper and mark scheme
Summer 2022 is part of the current CCEA GCE Biology (2016) specification, so every question style in it is still examinable. Reduced content — check what was removed before using it as a full mock. The papers and mark schemes themselves are published by CCEA; BioCCEA is an independent study tool and is not endorsed by CCEA.
What you sit in A2 2022
A2 1: Physiology, Co-ordination and Control, and Ecosystems
A2 1 written paper (2 hours)
Homeostasis and the kidney, nervous transmission, muscle contraction, hormonal co-ordination, photosynthesis, respiration and ecosystems.
A2 1 topic list and exam focusA2 2: Biochemistry, Genetics and Evolutionary Trends
A2 2 written paper (2 hours)
Respiration and ATP, monohybrid and dihybrid inheritance, sex linkage, population genetics, natural selection, speciation and gene technology.
A2 2 topic list and exam focusA2 3: Practical Skills in A2 Biology
A2 3 practical booklet plus a written practical-skills paper (1 hour 15 minutes)
Designing valid investigations, precision and error, statistical treatment of biological data and evaluating limitations.
A2 3 topic list and exam focus
How to sit the 2022 paper properly
- 1Print the paper and sit it in one block, to time, with no notes. A paper done in pieces tells you nothing about your exam performance.
- 2Mark it with the official CCEA mark scheme in front of you and award a mark only where the scheme's point is actually made.
- 3Log every dropped mark by unit topic, not by question number, so patterns appear across papers.
- 4Rewrite the two worst answers in full, using mark-scheme wording, then re-mark them.
- 5Come back to the same paper three weeks later and redo only the questions you lost marks on.
Sit the A2 2022 style questions
Answer each one under exam conditions. Your wording is marked against every mark scheme point before the full-mark answer appears.
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These questions are written in the style of the CCEA GCE Biology (2016) papers and are not reproduced from any live paper. CCEA owns the copyright in its question papers and mark schemes — always download the official paper and mark scheme from CCEA and use these worked answers alongside them. BioCCEA is an independent study tool and is not endorsed by CCEA.
Worked A2 2022 questions with mark schemes
Question styles that carried the most marks in the Summer 2022 papers, each with the full list of creditworthy mark scheme points, a model answer at full marks, and the marking point candidates most often missed.
A2 2 2022-style respiration question (reduced-content series) · 6 marks
Describe the role of the electron transport chain in oxidative phosphorylation.
Command word: Describe — how to answer itMark scheme — 6 creditworthy points
- Reduced NAD and reduced FAD are oxidised, releasing hydrogen atoms which split into protons and electrons
- Electrons pass along carriers in the inner mitochondrial membrane, losing energy at each transfer
- Energy released pumps protons from the matrix into the intermembrane space
- A proton gradient / electrochemical gradient is established across the inner membrane
- Protons return to the matrix through ATP synthase — chemiosmosis — producing ATP
- Oxygen is the final electron acceptor, combining with protons and electrons to form water
Full-mark answer
Reduced NAD and reduced FAD are oxidised at the inner mitochondrial membrane, releasing hydrogen atoms that split into protons and electrons. The electrons pass along a chain of carriers, losing energy at each transfer, and this energy is used to pump protons from the matrix into the intermembrane space. This establishes an electrochemical proton gradient across the inner mitochondrial membrane. Protons then diffuse back into the matrix through ATP synthase, and this chemiosmotic flow drives the phosphorylation of ADP to ATP. At the end of the chain oxygen acts as the final electron acceptor, combining with protons and electrons to form water.
Examiner insight: Name the compartments — matrix and intermembrane space. 'Across the membrane' without direction does not secure the pumping mark.
A2 2 2022-style comparison question · 4 marks
Compare the ATP yield of aerobic and anaerobic respiration in a muscle cell and explain the difference.
Command word: Explain — how to answer itMark scheme — 4 creditworthy points
- Aerobic respiration yields about 32–38 ATP per glucose; anaerobic yields 2 ATP per glucose
- In anaerobic respiration only glycolysis occurs / no Krebs cycle or electron transport chain
- Because no oxygen is available as the final electron acceptor, so no oxidative phosphorylation
- Pyruvate is reduced to lactate to reoxidise NAD so glycolysis can continue
Full-mark answer
Aerobic respiration yields around 32 to 38 molecules of ATP per glucose, whereas anaerobic respiration in a muscle cell yields only 2. In anaerobic conditions only glycolysis occurs, because there is no oxygen to act as the final electron acceptor, so the electron transport chain stops and no oxidative phosphorylation takes place; the Krebs cycle also stops. Pyruvate is instead reduced to lactate, which reoxidises reduced NAD so that glycolysis, and therefore a small amount of substrate-level ATP production, can continue.
Examiner insight: Quote figures for both routes — a comparison without numbers loses the first mark. The lactate mark must mention reoxidising NAD, not just 'to remove pyruvate'.
A2 2 2022-style nerve impulse question (reduced-content series) · 6 marks
Explain how a resting potential is established across the membrane of an axon, and explain why myelination increases the speed of conduction.
Command word: Explain — how to answer itMark scheme — 7 creditworthy points
- Sodium-potassium pumps actively transport 3 Na+ out for every 2 K+ in, using ATP
- This makes the inside of the axon negative relative to the outside
- The membrane is more permeable to K+, which diffuses out through potassium channels
- Large negatively charged proteins remain inside the axon
- A potential difference of about -70 mV is established (polarised membrane)
- Myelin is an insulating sheath, so depolarisation can only occur at the nodes of Ranvier
- The impulse jumps from node to node - saltatory conduction - which is faster than continuous conduction
Full-mark answer
Sodium-potassium pumps in the axon membrane actively transport three sodium ions out of the axon for every two potassium ions in, using ATP, so more positive ions leave than enter. The membrane is also more permeable to potassium ions, which diffuse back out through potassium channels, and large negatively charged proteins remain trapped inside. Together these establish a potential difference of about -70 mV, with the inside negative relative to the outside - the membrane is polarised. Myelin formed by Schwann cells is an electrical insulator, so ions cannot cross the membrane except at the nodes of Ranvier. Depolarisation therefore occurs only at the nodes and the impulse appears to jump from node to node, which is called saltatory conduction and is much faster than the continuous wave of depolarisation seen in a non-myelinated axon.
Examiner insight: The 3:2 stoichiometry and the differential permeability to potassium are separate marks. For the myelin half, the word 'saltatory' alone earns nothing without the node-to-node explanation.
These questions are written in the style of the CCEA GCE Biology (2016) papers and are not reproduced from any live paper. CCEA owns the copyright in its question papers and mark schemes — always download the official paper and mark scheme from CCEA and use these worked answers alongside them. BioCCEA is an independent study tool and is not endorsed by CCEA.
Download the official CCEA paper and mark schemePractise the A2 2022 paper in the app
These open BioCCEA with A2 already selected, so you can sit questions in this paper's style and have them marked against the CCEA mark scheme.
Get your 2022 answers marked
Photograph a written answer from this paper and see it marked line by line in CCEA mark-scheme language, with the exact phrase you needed to earn each missing mark.