# Explain how natural selection can lead to evolution in a population of organisms.

> AQA GCSE Biology (8461) — 4.6.2 Variation and evolution · Explain · 4 marks

> A population of bacteria is exposed to an antibiotic. Over many generations, the proportion of bacteria that survive antibiotic treatment increases.

## Mark scheme (4 marks)

1. Mutation produces genetic variants / some bacteria have a random change in DNA that gives resistance to the antibiotic
2. Bacteria with the advantageous trait (antibiotic resistance) are more likely to survive and reproduce
3. The allele for resistance is passed on to offspring / the frequency of the advantageous allele increases in the population over time
4. Over many generations the inherited traits of the population change / the population evolves to become resistant

## Key terms

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

## Related

- [Revision notes for AQA GCSE Biology (8461)](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-natural-selection-can-lead-e132766a) · Published by Druglandscape Ltd.