# A species of Arctic fox has thick white fur, which provides camouflage in snowy environments. Scientists observed that, over many generations, foxes with thinner brown fur became increasingly rare in the population. Explain how natural selection led to white fur becoming the most common phenotype in this Arctic fox population.

> OCR A-Level Biology B — Advancing Biology (H422) — 5.5 Communication and homeostasis · Explain · 5 marks

> Arctic foxes live in environments covered in snow for most of the year. Predators hunt the foxes, and foxes with better camouflage are more likely to survive.

## Mark scheme (5 marks)

1. There is variation in fur colour/thickness within the Arctic fox population
2. White fur provides better camouflage against the snow, so white-furred foxes are less likely to be eaten by predators
3. White-furred foxes are more likely to survive and reproduce / are more likely to live long enough to breed
4. White-furred foxes pass the allele(s) for white fur to their offspring
5. Over many generations, the frequency of the allele for white fur increases in the population / brown fur allele becomes less common

## Key terms

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

## 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-arctic-fox-has-2fde83a3) · Published by Druglandscape Ltd.