Describe the role of ATP in cells, including how it is made and how it transfers energy to cellular processes.

AQA A-Level Biology (7402) — 3.1.6 ATP · Describe · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (5 marks)

ATP is a small molecule that stores and transfers energy in cells.
1. It is produced during cellular respiration, mainly in the mitochondria, by substrate‑level phosphorylation and oxidative phosphorylation.
2. When ATP is hydrolysed to ADP and inorganic phosphate, a high‑energy bond is broken and the released energy is used to power cellular processes such as muscle contraction, active transport, protein synthesis and cell division.
3. The ADP and phosphate can be recombined, using energy from respiration, to regenerate ATP, allowing the molecule to be recycled continuously.

Examiner tips

  • Use the word ‘hydrolysed’ and mention ADP + Pi; include both respiration and the energy‑releasing step; give at least two examples of processes powered by ATP.
  • Show the cycle: synthesis → hydrolysis → regeneration; keep the answer concise and use correct terminology.

Mark scheme (5 marks)

  1. ATP is a molecule that stores / transfers energy (in cells)
  2. ATP is made during respiration
  3. ATP is broken down (hydrolysed) / ATP releases energy when it is broken down into ADP and phosphate
  4. The energy released from ATP is used to power cellular processes (e.g. muscle contraction / active transport / protein synthesis / cell division)
  5. ADP and phosphate can be rejoined / recombined (using energy from respiration) to reform ATP — ATP can be continuously recycled / regenerated

Key terms in this question

ATP

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