A gardener turns over a compost heap with a fork every week.
Which statement explains why this increases the rate of decomposition?
It removes water, so the microorganisms can respire more quickly.
It adds oxygen, so the microorganisms can respire aerobically.
It lowers the temperature, so their enzymes are not denatured.
It adds carbon dioxide, so the microorganisms can photosynthesise.
111 exam-style questions on OCR GCSE Biology 4.1 Ecosystems, covering 4.1.1 Cycling of materials in ecosystems, 4.1.2 Microorganisms in cycling materials, 4.1.3 The carbon and water cycles, 4.1.4 Factors affecting decomposition, 4.1.5 Levels of organisation in an ecosystem, 4.1.6 Abiotic and biotic factors affecting communities, 4.1.7 Interdependence and competition, 4.1.8 Trophic levels, 4.1.9 Pyramids of biomass, and 4.1.10 Efficiency of biomass transfers. Each one has a worked solution and a mark scheme showing where the marks go.