# Explain how both biotic and abiotic factors can affect the size of a population of rabbits living in a field.

> OCR GCSE Biology A: Gateway Science (J247) — B4.1 Ecosystems · Explain · 4 marks

> Rabbits live in a field as part of an ecosystem alongside grasses, foxes and various pathogens. The size of the rabbit population changes throughout the year.

## Mark scheme (4 marks)

1. A biotic factor such as predation (by foxes) reduces the rabbit population
2. A second biotic factor (e.g. food availability / pathogens / competition) also affects population size with a correct explanation
3. An abiotic factor such as temperature / light intensity / moisture / soil mineral content is correctly identified
4. Correct explanation of how the named abiotic factor affects the rabbit population, linked through its effect on the ecosystem (e.g. plant/grass growth)

## Key terms

- [biotic factors](https://www.gradenine.co.uk/glossary/biotic-factors)
- [abiotic factors](https://www.gradenine.co.uk/glossary/abiotic-factors)

## 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/explain-how-both-biotic-and-abiotic-5121c1ca) · Published by Druglandscape Ltd.