# A species of moth lives in a forest. The moths vary in wing pattern — some have spotted wings and some have plain wings. The moths rest on tree bark during the day. Birds are the main predators of the moths. Explain how natural selection could lead to one wing pattern becoming more common in the moth population over many generations.

> OCR A-Level Biology B — Advancing Biology (H422) — 4.4 Populations and evolution · Explain · 5 marks

> In this forest, the tree bark has an uneven, mottled texture. Moths with spotted wings are harder for birds to see against the bark than moths with plain wings.

## Mark scheme (5 marks)

1. There is variation in wing pattern within the moth population
2. Spotted moths are better camouflaged / less visible to predators on the mottled bark
3. Plain-winged moths are more likely to be eaten by birds / have a selective disadvantage
4. Spotted moths are more likely to survive and reproduce, passing on the allele/gene for spotted wings to offspring
5. Over many generations, the proportion of spotted moths in the population increases

## Key terms

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

## Related

- [Revision notes for OCR A-Level Biology B — Advancing Biology (H422)](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/a-species-of-moth-lives-in-36110428) · Published by Druglandscape Ltd.