# Explain how a mutation in a gene can lead to a change in an organism's phenotype.

> Edexcel GCSE Biology (1BI0) — 3.5 Variation and mutation · Explain · 4 marks

> Mutations occur randomly in organisms and can have a range of effects. Some mutations alter an organism's observable characteristics whilst others have no noticeable effect.

## Mark scheme (4 marks)

1. A mutation is a random change in the base sequence of DNA
2. A gene codes for the production of a specific protein / the altered base sequence may change the protein produced
3. The altered protein may not function correctly / may have a different shape or function
4. This change in protein leads to a change in the organism's observable characteristics / phenotype

## Key terms

- [mutation](https://www.gradenine.co.uk/glossary/mutation)
- [gene](https://www.gradenine.co.uk/glossary/gene)
- [phenotype](https://www.gradenine.co.uk/glossary/phenotype)

## Related

- [Revision notes for Edexcel GCSE Biology (1BI0)](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-how-a-mutation-in-a-42f0aeb8) · Published by Druglandscape Ltd.