# A peat bog is a waterlogged ecosystem where dead plant material accumulates over thousands of years rather than fully decomposing. Explain why dead plant material accumulates in a peat bog instead of being fully broken down, and explain what would happen to the rate of decomposition if the peat bog dried out.

> OCR A-Level Biology B — Advancing Biology (H422) — 4.3 Energy budgets and ecosystems · Explain · 5 marks

> Peat bogs cover around 3% of the Earth's land surface and store vast amounts of carbon. Scientists are concerned about the effects of draining peat bogs for agriculture.

## Mark scheme (5 marks)

1. The waterlogged conditions mean there is little or no oxygen available
2. Decomposers / microorganisms cannot carry out aerobic decomposition without oxygen
3. Anaerobic decomposition is much slower than aerobic decomposition, so material accumulates
4. If the bog dried out, oxygen availability would increase
5. The rate of decomposition would increase because aerobic decomposition / decomposers would be more active

## Key terms

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

## Related

- [Revision notes for OCR A-Level Biology B — Advancing Biology (H422)](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-peat-bog-is-a-waterlogged-e853f4f5) · Published by Druglandscape Ltd.