A compost heap is warm and very wet. Its centre is tightly packed and has little oxygen. Decay is slow.
Which change is most likely to increase aerobic decay, and why?
Add more water and compress the heap, increasing moisture while keeping the decomposers close to their food.
Seal the heap and retain its moisture, reducing gas exchange while keeping the decomposers at a suitable temperature.
Mix in dry coarse material and turn the heap, reducing waterlogging while allowing more air to enter its centre.
Spread out the heap until completely dry, increasing gas exchange while removing the excess water from its centre.
40 exam-style questions on AQA GCSE Biology 7.2 Organisation of an ecosystem, covering 7.2.1 Levels of organisation, 7.2.2 How materials are cycled, 7.2.3 Decomposition, and 7.2.4 Impact of environmental change (HT only). Each one has a worked solution and a mark scheme showing where the marks go.