This topic summary covers Topic Summary: Decomposition within Decomposition for GCSE Biology. Topic 4: Decomposition It is section 11 of 11 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 11 of 11
Practice
15 questions
Recall
20 flashcards
Topic Summary: Decomposition
Key Terms
- Decomposer: Bacteria or fungi — secrete enzymes, absorb products
- Detritivore: Animal that feeds on dead material (e.g., earthworm)
- Saprotrophic: External digestion then absorption
- Compost: Decomposed organic matter used as soil improver
- Biogas: Methane + CO₂ from anaerobic decomposition
TOMP Factors
- Temperature: Faster up to ~37 °C optimum; denaturation above
- Oxygen: Aerobic conditions needed for most decomposers
- Moisture: Water needed for enzyme activity
- pH: Neutral optimum; acid/alkali reduces activity
- Peat bogs: anaerobic + acidic = very slow decomposition
Must-Know Facts
- Both bacteria AND fungi are decomposers
- Decomposers secrete enzymes externally (saprotrophic nutrition)
- Decomposition returns mineral ions to soil for plant uptake
- Compost heaps: warm + moist + aerated = fastest decomposition
- Biogas generators: anaerobic conditions needed for methane
- Decomposition is essential to carbon cycle and nutrient recycling