This topic summary covers Knowledge Organiser within Decomposition for GCSE Biology. Topic 4: Decomposition It is section 11 of 12 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 12
Practice
15 questions
Recall
20 flashcards
Knowledge Organiser
Key Terms
- Decomposer: Bacteria or fungi — secrete enzymes, absorb products
- Detritivore: Animal that feeds on dead material (e.g., earthworm)
- Compost: Decomposed organic matter used as fertiliser
- Biogas: Methane + CO2 from anaerobic decomposition
- Saprotrophic: External digestion then absorption
Factors — TOMP
- Temperature: faster up to optimum (~37 degrees C), 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 (not swallowing prey)
- Decomposition returns mineral ions to soil for plant uptake
- Compost heaps: warm, moist, aerated = fastest decomposition
- Biogas generators: anaerobic conditions needed for methane production
- Decomposition links carbon cycle and nutrient recycling