# Explain how the removal of a top predator from an ecosystem can affect the populations of organisms at lower trophic levels.

> Pearson Edexcel International GCSE Biology (4BI1) — 4.1 The organism in the environment · Explain · 4 marks

> In a grassland ecosystem, a food chain exists in which grass is eaten by rabbits, and rabbits are eaten by foxes. Foxes are the top predators in this ecosystem.

## Mark scheme (4 marks)

1. Removal of foxes means the rabbit population is no longer controlled / rabbit population increases (as predation pressure is removed)
2. Increased rabbit population leads to greater consumption of grass / grass is eaten more rapidly
3. Grass (producer) population decreases
4. This illustrates that a change in one trophic level affects other trophic levels / biotic factors in an ecosystem affect population distribution

## Key terms

- [trophic level](https://www.gradenine.co.uk/glossary/trophic-level)
- [predator](https://www.gradenine.co.uk/glossary/predator)
- [population](https://www.gradenine.co.uk/glossary/population)

## Related

- [Revision notes for Pearson Edexcel International GCSE Biology (4BI1)](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-the-removal-of-a-a8d37250) · Published by Druglandscape Ltd.