# Explain how nitrogen from the atmosphere becomes available to plants, and why this process is essential for plant growth.

> Eduqas GCSE Biology — 1.6.2 Nutrient cycles · Explain · 4 marks

> Plants need nitrogen to make proteins, but they cannot use nitrogen gas directly from the atmosphere. Certain bacteria play a key role in making nitrogen available to plants.

## Mark scheme (4 marks)

1. Nitrogen-fixing bacteria convert nitrogen gas into nitrates (or ammonia/ammonium compounds)
2. These nitrates are absorbed by plants through their roots
3. Plants use nitrates to make amino acids / proteins
4. Without sufficient nitrates, plants cannot make enough protein, leading to poor/stunted growth

## Related

- [Revision notes for Eduqas GCSE Biology](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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