This deep dive covers Conditions Affecting the Rate of Decomposition within Decomposition for GCSE Biology. Topic 4: Decomposition It is section 3 of 11 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 3 of 11
Practice
15 questions
Recall
20 flashcards
🌡️ Conditions Affecting the Rate of Decomposition
Because decomposition depends on enzyme activity by microorganisms, any factor that affects those enzymes will affect how fast decomposition occurs:
- Temperature — warmer conditions increase kinetic energy of molecules, raising the rate of enzyme-substrate collisions and speeding decomposition. The optimum temperature for most soil decomposers is approximately 37 °C. Above this temperature, enzymes are denatured — the active site permanently changes shape and decomposition slows dramatically.
- Oxygen — most decomposer bacteria and fungi are aerobic and require oxygen for respiration. Anaerobic conditions (e.g., waterlogged soil, compacted compost) severely reduce decomposition rate because only less-efficient anaerobic decomposers can function.
- Moisture — water is needed as a solvent for enzyme secretion and for decomposers' own metabolic reactions. Very dry conditions kill or inactivate decomposers; optimal moisture content maximises enzyme activity and decomposer growth.
- pH — most soil decomposers have an optimal pH of approximately 7 (neutral). Highly acidic or alkaline conditions alter the charge distribution on enzyme active sites, reducing enzyme efficiency and slowing decomposition.