Decomposer

How this is marked

The paying point is that decomposers feed on dead or waste organic matter, and bacteria and fungi are the named examples to give. Examiners reward linking them to nutrient cycling, for example releasing nitrogen or carbon dioxide back into the ecosystem. Students lose marks calling them 'consumers' or omitting that the material is dead or waste. Appears in Paper 4 food web, carbon cycle and nitrogen cycle questions.

In an exam answer

Describing their role: 'Decomposers such as bacteria and fungi feed on dead organic material, breaking it down and returning mineral nutrients to the soil for plants to absorb.'

Full topic guide: Organisms & their environment