# Biodiversity is important for the stability of ecosystems. Explain why a reduction in biodiversity can have serious consequences for an ecosystem, including the impact on food webs and the long-term survival of species.

> Edexcel A-Level Biology A: Salters-Nuffield (9BN0) — 2.5 Biodiversity · Explain · 5 marks

> In recent decades, human activities such as deforestation, pollution and overuse of pesticides have caused a significant decline in the number of species found in many ecosystems worldwide.

## Mark scheme (5 marks)

1. Biodiversity refers to the variety of different species found in an ecosystem / area
2. Reducing the number of species disrupts food webs because removal of one species affects the organisms that feed on it or are fed upon by it
3. A less biodiverse ecosystem is less stable / more vulnerable to change, because there are fewer alternative species to fill ecological roles
4. Loss of species reduces the gene pool / genetic diversity available, reducing the ability of species to adapt to environmental change
5. Once a species becomes extinct, it is lost permanently, so biodiversity loss is irreversible and further reduces ecosystem stability over time

## Key terms

- [biodiversity](https://www.gradenine.co.uk/glossary/biodiversity)
- [food web](https://www.gradenine.co.uk/glossary/food-web)

## Related

- [Revision notes for Edexcel A-Level Biology A: Salters-Nuffield (9BN0)](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/biodiversity-is-important-for-the-stability-9e15a825) · Published by Druglandscape Ltd.