# A farmer stores freshly cut silage (grass) in sealed, airtight bales. After several months, the silage is opened and the grass material is largely unchanged, with very little decomposition having taken place. Explain why sealing the silage in airtight bales greatly reduces the rate of decomposition.

> Edexcel A-Level Biology A: Salters-Nuffield (9BN0) — 5.5 Decomposition and decay · Explain · 5 marks

> Silage is a method of preserving grass by packing it tightly into sealed, airtight plastic bales. Farmers rely on this technique to store animal feed for winter months. The sealed bales prevent decomposers from breaking down the grass rapidly.

## Mark scheme (5 marks)

1. Decomposers (bacteria and fungi) are responsible for breaking down the organic material
2. Sealing the bale removes/excludes oxygen, creating anaerobic conditions
3. Most decomposers require oxygen for aerobic respiration to release energy for growth and reproduction
4. Without oxygen, decomposers cannot respire aerobically, so their metabolic activity / growth is greatly reduced
5. Therefore, the enzymes produced by decomposers to digest the organic material are not released / are produced at a much lower rate, slowing decomposition

## 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-stores-freshly-cut-silage-12348dbe) · Published by Druglandscape Ltd.