# Describe how a mutation can lead to extinction of a species if natural selection occurs too slowly.

> WJEC GCSE Biology (Wales) — 2.4.2 Evolution and natural selection · Describe · 4 marks

> A small population of beetles lives in a forest. Over time, the temperature of the forest environment rises significantly. A mutation occurs in some individuals that affects their ability to regulate body temperature.

## Mark scheme (4 marks)

1. A mutation is a random change in DNA / which increases variation
2. If the mutation does not produce an advantageous phenotype / the organisms are not well suited to the new environmental conditions
3. Individuals without a beneficial allele are less likely to survive and reproduce / fewer advantageous alleles are passed to offspring
4. If natural selection is too slow, the whole species dies out before it can adapt / this leads to extinction

## Key terms

- [mutation](https://www.gradenine.co.uk/glossary/mutation)
- [natural selection](https://www.gradenine.co.uk/glossary/natural-selection)
- [extinction](https://www.gradenine.co.uk/glossary/extinction)

## Related

- [Revision notes for WJEC GCSE Biology (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" 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/describe-how-a-mutation-can-lead-e347f465) · Published by Druglandscape Ltd.