48 exam-style questions on Cell respiration — topic C1.2 of Interaction and interdependence in the IB Biology syllabus — with answers and explanations. Samples below; the full set is free with an account.
In aerobic respiration, the majority of ATP is produced during
Answer: oxidative phosphorylation
Oxidative phosphorylation on the inner mitochondrial membrane yields the bulk of ATP via the electron transport chain and chemiosmosis.
State the net gain of ATP from glycolysis of one glucose molecule.
Answer: 2 ATP
Glycolysis uses 2 ATP in the phosphorylation of glucose and generates 4 ATP by substrate-level phosphorylation, giving a net gain of 2 ATP.
Determine what happens to pyruvate during anaerobic respiration in human muscle cells.
Answer: It is reduced to lactate, regenerating NAD+
In human muscle, pyruvate is reduced to lactate by accepting hydrogen from NADH, which regenerates NAD+ so that glycolysis can continue.
Distinguish the correct fate of the reduced coenzymes (NADH and FADH2) produced in the Krebs cycle.
Answer: They donate electrons to the electron transport chain to drive ATP synthesis
Reduced coenzymes carry electrons to the electron transport chain, where their energy is used to pump protons and ultimately synthesise ATP by chemiosmosis.
In yeast undergoing anaerobic respiration (fermentation), determine the products formed from pyruvate.
Answer: Ethanol and CO₂
Yeast decarboxylate pyruvate and reduce it to ethanol, releasing carbon dioxide; this regenerates NAD+ for continued glycolysis.
State why oxygen is essential for continued ATP production in aerobic respiration.
Answer: It is the final electron acceptor
Oxygen accepts electrons and protons at the end of the chain to form water; without it the chain backs up and oxidative phosphorylation stops.
That was 6 of 48 Cell respiration questions.
Practise all 48 freeStateAO1 · 1–2 marks
One word or one short sentence. No explanation, no working: the mark is for the fact itself.
OutlineAO2 · 1–4 marks
A brief account or summary: the main points in two or three sentences, no evaluation.
ExplainAO3 · 3–8 marks
Give reasons or causes: say what happens AND why, linking each step with 'because' or 'so that'.
48 Cell respiration questions — free with an account. Spaced repetition, streaks and full exam simulations included.
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