A student puts 50 g of dead leaves into a mesh bag and buries it in soil.
After 6 weeks, the mass of the leaves is 32 g.
What is the mean rate of decay of the leaves?
3.0 g per week3.0\ \text{g per week}3.0 g per week
5.3 g per week5.3\ \text{g per week}5.3 g per week
8.3 g per week8.3\ \text{g per week}8.3 g per week
18.0 g per week18.0\ \text{g per week}18.0 g per week
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.