# Describe the role of nitrifying bacteria and denitrifying bacteria in the nitrogen cycle.

> Pearson Edexcel International GCSE Biology (4BI1) — 4.3 Cycles within ecosystems · Describe · 4 marks

## Mark scheme (4 marks)

1. Nitrifying bacteria convert ammonia to nitrates (in the soil)
2. Nitrifying bacteria are found in the soil
3. Denitrifying bacteria convert nitrates (in the soil) into nitrogen gas
4. Denitrifying bacteria return nitrogen gas to the atmosphere

## Key terms

- [nitrifying bacteria](https://www.gradenine.co.uk/glossary/nitrifying-bacteria)
- [denitrifying bacteria](https://www.gradenine.co.uk/glossary/denitrifying-bacteria)
- [nitrogen cycle](https://www.gradenine.co.uk/glossary/nitrogen-cycle)

## Related

- [Revision notes for Pearson Edexcel International GCSE Biology (4BI1)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-the-role-of-nitrifying-bacteria-02f69307) · Published by Druglandscape Ltd.