# A species of ground-dwelling beetle lives in a woodland. The beetles vary in shell colour, ranging from pale brown to dark brown. Owls are the main predator of these beetles and hunt by sight during the day. Over many generations, the average shell colour of the beetle population becomes significantly darker. Explain how natural selection could lead to this change in the beetle population.

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

> A species of ground-dwelling beetle lives in a woodland. The beetles vary in shell colour, ranging from pale brown to dark brown. Owls are the main predator of these beetles and hunt by sight during the day. Over many generations, the average shell colour of the beetle population becomes significantly darker.

## Mark scheme (5 marks)

1. There is variation in shell colour within the beetle population
2. Darker beetles are better camouflaged against the woodland floor / less easily seen by owls
3. Pale brown beetles are more likely to be eaten by owls / have a higher predation rate
4. Darker beetles are more likely to survive and reproduce, passing on the allele(s) / genes for dark colouration to offspring
5. Over many generations the proportion / frequency of darker beetles in the population increases

## Key terms

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

## 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-ground-dwelling-beetle-lives-e77b0fe3) · Published by Druglandscape Ltd.