# A population of giraffes lives in a grassland habitat where food at ground level becomes increasingly scarce. Some giraffes have longer necks than others due to genetic variation. Explain how natural selection could lead to a population of giraffes with longer necks over many generations.

> OCR GCSE Biology A: Gateway Science (J247) — B5.2 Natural selection and evolution · Explain · 4 marks

> In a grassland habitat, vegetation at ground level is becoming increasingly scarce. Giraffes in the population vary in neck length due to mutations in their DNA.

## Mark scheme (4 marks)

1. There is genetic variation in neck length within the population (due to mutation)
2. Giraffes with longer necks can reach more food / are better suited to the environment
3. Longer-necked giraffes are more likely to survive and reproduce
4. The alleles for longer necks are passed on to offspring, so over many generations the frequency of the longer-neck allele increases in the population

## Key terms

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

## Related

- [Revision notes for OCR GCSE Biology A: Gateway Science (J247)](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-population-of-giraffes-lives-in-0a0edfbe) · Published by Druglandscape Ltd.