# A farmer converts a large area of species-rich grassland into a monoculture crop field, growing only wheat. Explain how this change reduces biodiversity and suggest why a reduction in biodiversity in this area could affect the stability of the local ecosystem.

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

> Biodiversity refers to the variety of living organisms in an area. Ecosystems with high biodiversity tend to be more stable and resilient than those with low biodiversity.

## Mark scheme (5 marks)

1. Converting grassland to a monoculture reduces the variety of plant species present
2. Fewer plant species means fewer habitats / food sources available, so animal species (invertebrates, insects, birds) are also lost
3. Use of pesticides / herbicides to maintain the monoculture further kills non-crop species, reducing biodiversity
4. In an ecosystem with low biodiversity, there are fewer species in food webs / food chains, so the ecosystem is less stable
5. If one species is lost from a low-biodiversity ecosystem, there are fewer alternative species to fulfil that role, so other species may also be lost / the ecosystem may collapse

## Key terms

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

## 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/a-farmer-converts-a-large-area-449fc9af) · Published by Druglandscape Ltd.