Explain how the hydrolysis of ATP provides energy for cellular processes, and state two examples of processes in cells that require this energy.

AQA A-Level Biology (7402) — 3.1.6 ATP · Explain · 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 hydrolysed by water to give ADP and inorganic phosphate (Pi). The bond between the terminal phosphate and the rest of the molecule is high‑energy, so when it breaks energy is released. This energy is transferred to drive cellular processes. Examples: muscle contraction and active transport.

Examiner tips

Use the phrase ‘hydrolysed by water’ and ‘high‑energy bond’ to hit the key points. Include the conversion to ADP + Pi and the release of energy. Give two specific cellular processes to earn the final mark. Keep the answer concise and use UK spelling.

Common mistakes

Writing ‘ATP is broken down’ without mentioning water or Pi. Using vague terms like ‘energy is released’ without linking it to the terminal phosphate bond. Giving only one example of a cellular process.

Mark scheme (5 marks)

ATP is hydrolysed / broken down by water (hydrolysis)
ATP is converted to ADP and (inorganic) phosphate / Pi
Energy is released (from the bond between the terminal phosphate and ADP) when hydrolysis occurs
This released energy is transferred to (drive) cellular processes
Any two correct examples of cellular processes requiring ATP, e.g. muscle contraction / active transport / protein synthesis / DNA replication / cell division (1 mark for each, max 2, but only 1 mark available here as final point)

Key terms in this question

hydrolysis · ATP · cellular processes