# Describe how carbon is cycled between the atmosphere and living organisms, including the roles of photosynthesis, respiration, decomposition and combustion.

> Cambridge International IGCSE Biology (0610) — 19.3 Nutrient cycles · Describe · 4 marks

## Mark scheme (4 marks)

1. Carbon dioxide is removed from the atmosphere by plants during photosynthesis and incorporated into organic molecules such as carbohydrates or proteins.
2. Carbon is passed through the food chain when organisms feed on one another / is transferred between trophic levels by feeding / ingestion.
3. Carbon is returned to the atmosphere as carbon dioxide by respiration in living organisms (plants, animals and decomposers).
4. Carbon stored in fossil fuels is released as carbon dioxide by combustion, OR carbon in dead organisms is returned to the atmosphere by decomposition.

## Key terms

- [photosynthesis](https://www.gradenine.co.uk/glossary/photosynthesis)
- [respiration](https://www.gradenine.co.uk/glossary/respiration)
- [decomposition](https://www.gradenine.co.uk/glossary/decomposition)
- [combustion](https://www.gradenine.co.uk/glossary/combustion)

## Related

- [Revision notes for Cambridge International IGCSE Biology (0610)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-carbon-is-cycled-between-3a0f8d58) · Published by Druglandscape Ltd.