# Compare the structure of ATP with the structure of ADP, and explain what happens during the interconversion of these two molecules.

> AQA A-Level Biology (7402) — 3.1.6 ATP · Compare · 5 marks

## Mark scheme (5 marks)

1. ATP has three phosphate groups whereas ADP has two phosphate groups
2. Both ATP and ADP contain a ribose sugar and an adenine base
3. When ATP is broken down / hydrolysed to ADP (and phosphate), energy is released
4. ADP is converted back to ATP by adding a phosphate group, which requires energy
5. ATP can be continuously recycled / regenerated so the same ATP molecules can be reused

## Key terms

- [ATP](https://www.gradenine.co.uk/glossary/atp)
- [ADP](https://www.gradenine.co.uk/glossary/adp)
- [interconversion](https://www.gradenine.co.uk/glossary/interconversion)

## Related

- [Revision notes for AQA A-Level Biology (7402)](https://www.gradenine.co.uk/learn)
- [How to answer "Compare" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/compare-the-structure-of-atp-with-22f5dcac) · Published by Druglandscape Ltd.