# Explain why enzymes are described as biological catalysts and why the shape of an enzyme is important for its function.

> Pearson Edexcel A-Level Biology A (9BI0) — Topic 1 Biological Molecules · Explain · 5 marks

> Enzymes are proteins found in all living organisms. They are involved in many reactions, including the breakdown of food molecules during digestion.

## Mark scheme (5 marks)

1. Enzymes speed up chemical reactions
2. Enzymes are not used up / changed in the reaction
3. Enzymes have an active site with a specific shape
4. Only a specific substrate can fit into / bind to the active site
5. If the shape of the active site changes (denaturation), the enzyme can no longer function / the substrate cannot bind

## Key terms

- [enzyme](https://www.gradenine.co.uk/glossary/enzyme)
- [catalyst](https://www.gradenine.co.uk/glossary/catalyst)

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" 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/explain-why-enzymes-are-described-as-57a2544f) · Published by Druglandscape Ltd.