# Explain why farmers use selective breeding to produce new varieties of wheat with higher grain yields, and describe one disadvantage of this process.

> AQA GCSE Biology (8461) — 4.6.2 Variation and evolution · Explain · 4 marks

> Farmers have used selective breeding for thousands of years to improve crop plants. Modern wheat varieties produce far more grain per plant than wild wheat ancestors.

## Mark scheme (4 marks)

1. Farmers choose/select plants with the highest grain yield (desirable characteristic) and breed them together
2. This is repeated over many generations so that offspring inherit the alleles for high yield
3. A disadvantage is that it reduces genetic variation in the population (inbreeding)
4. This means the population is more vulnerable to a new disease or change in environment (because few/no individuals carry resistant alleles)

## Key terms

- [selective breeding](https://www.gradenine.co.uk/glossary/selective-breeding)

## Related

- [Revision notes for AQA GCSE Biology (8461)](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-why-farmers-use-selective-breeding-7d330b92) · Published by Druglandscape Ltd.