# Explain why a stable ecosystem with high biodiversity is less likely to collapse than an ecosystem with low biodiversity when one species is removed.

> WJEC GCSE Biology (Wales) — 1.6.1 Ecosystems · Explain · 4 marks

## Mark scheme (4 marks)

1. In a high biodiversity ecosystem there are more species available to fill each role / niche
2. If one species is removed, another species can fulfil the same role / act as an alternative food source or predator
3. In a low biodiversity ecosystem, removal of one species means there is no replacement, so populations that depended on it are directly affected
4. This can cause a chain of population changes / collapse throughout the food web in the low biodiversity ecosystem

## Key terms

- [biodiversity](https://www.gradenine.co.uk/glossary/biodiversity)
- [ecosystem](https://www.gradenine.co.uk/glossary/ecosystem)
- [species](https://www.gradenine.co.uk/glossary/species)

## Related

- [Revision notes for WJEC GCSE Biology (Wales)](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-a-stable-ecosystem-with-374b3073) · Published by Druglandscape Ltd.