# Describe the causes and types of outcome of mutations, and explain how mutations contribute to genetic variation within a species.

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

## Mark scheme (4 marks)

1. A mutation is a random change in the base sequence of DNA
2. Mutations may be beneficial, damaging, or neutral (all three required for this mark, or any two for half credit — award 1 mark for all three outcomes correctly stated)
3. Mutations introduce new alleles (versions of a gene) into a population
4. These new alleles can be passed on during sexual reproduction, increasing genetic variation in phenotypes across the species

## Key terms

- [mutation](https://www.gradenine.co.uk/glossary/mutation)
- [genetic variation](https://www.gradenine.co.uk/glossary/genetic-variation)

## Related

- [Revision notes for Edexcel GCSE Biology (1BI0)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-the-causes-and-types-of-b91b4fb3) · Published by Druglandscape Ltd.