Explain why a stable community contains both producers and decomposers.

AQA GCSE Biology (8461) — 4.7.2 Organisation of an ecosystem · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Producers carry out photosynthesis, converting CO₂ and H₂O into organic matter and biomass.
They supply the community with the biomass, energy and food that consumers need.
Decomposers break down dead plant and animal material, returning the organic matter to the environment.
In doing so they release mineral ions back into the soil and water, making nutrients available again for producers to use.

Examiner tips

Use the word ‘producers’ and ‘decomposers’ explicitly. Show the flow: photosynthesis → biomass → food for consumers → decomposition → nutrient recycling. Keep each point short and to the point to hit all four marks.

Common mistakes

Mixing up producers with consumers; forgetting to mention decomposers’ role in nutrient recycling. Using vague terms like ‘food’ without linking it to biomass or energy. Omitting the fact that decomposers return mineral ions to the soil.

Mark scheme (4 marks)

Producers photosynthesise / convert carbon dioxide and water into organic matter / biomass
Producers provide biomass / energy / food for consumers in the community
Decomposers break down dead plant and animal material / organic matter
Decomposers return mineral ions to the soil / environment so that producers can use them (for growth)

Key terms in this question

producers · decomposers · community