# Explain how the use of pesticides on farmland can reduce the population of organisms at higher levels in a food chain.

> Eduqas GCSE Biology — 1.6.3 Human impact on the environment · Explain · 4 marks

> Farmers often spray crops with pesticides to kill insects that damage their plants. Some of these pesticides do not break down easily in the environment.

## Mark scheme (4 marks)

1. Pesticides are absorbed by / accumulate in small organisms (e.g. insects/invertebrates) at the base of the food chain
2. Pesticides are not broken down / are persistent, so they build up (accumulate) in body tissues
3. The concentration of pesticide increases at each level of the food chain (bioaccumulation / biological magnification)
4. High concentrations of pesticide in top predators cause death / reproductive failure / population decline

## Key terms

- [pesticide](https://www.gradenine.co.uk/glossary/pesticide)
- [food chain](https://www.gradenine.co.uk/glossary/food-chain)

## Related

- [Revision notes for Eduqas GCSE Biology](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-use-of-pesticides-8a60faef) · Published by Druglandscape Ltd.