# Explain how natural selection leads to a population of animals becoming better adapted to their environment over many generations.

> Pearson Edexcel A-Level Biology A (9BI0) — 2.6 Adaptation and natural selection · Explain · 5 marks

> In a population of moths, individuals vary in their body colour. Some moths are pale and some are darker. Birds hunt moths by sight. In an environment where tree bark is dark, darker moths are less easily spotted by predators.

## Mark scheme (5 marks)

1. There is variation in the population (e.g. in body colour)
2. Darker moths are better camouflaged / less likely to be seen by predators on dark bark
3. Darker moths are more likely to survive (and reproduce) / pale moths are more likely to be eaten
4. Darker moths pass on the alleles / genes for darker colouring to their offspring
5. Over many generations the proportion of darker moths in the population increases

## Key terms

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

## 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-how-natural-selection-leads-to-c22d505a) · Published by Druglandscape Ltd.