Explain the role of decomposers in the carbon cycle.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Decomposers break down dead organic matter, faeces and urine.
They respire the carbon‑containing compounds.
Carbon dioxide is released into the atmosphere during this respiration.
Thus carbon is returned to the air, making it available for plant photosynthesis.
They respire the carbon‑containing compounds.
Carbon dioxide is released into the atmosphere during this respiration.
Thus carbon is returned to the air, making it available for plant photosynthesis.
Examiner tips
- Use the exact phrase "break down dead organic matter". Show the respiration step and CO₂ release. Link the return of CO₂ to plant use. Keep answer to four short points.
Common mistakes
- Confusing decomposers with producers. Omitting the respiration step. Using vague terms like "break down" without specifying dead matter.
Mark scheme (4 marks)
- Decomposers break down dead organic matter / dead organisms / faeces / urine
- Decomposers respire the organic compounds / carbon-containing compounds
- Carbon dioxide is released into the atmosphere / air during respiration
- This returns carbon to the atmosphere / makes carbon available to plants for photosynthesis
Key terms in this question
Related
- All Eduqas GCSE Biology revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
More Nutrient cycles questions
- Explain how carbon from carbon dioxide in the atmosphere becomes part of the bod…
- Explain how nitrogen from the atmosphere becomes available to plants, and why th…
- Describe the role of microorganisms in the nitrogen cycle.
- Explain why removing all the decomposers from a woodland ecosystem would eventua…