In autumn, leaves fall from the trees in a forest and collect on the ground.
Describe how the carbon in the dead leaves is returned to the air.
Explain why the decomposition of dead leaves is important for the growth of the trees.
In very cold places, a thick layer of dead leaves builds up on the ground.
Explain why.
Large areas of forest are being cut down and burned.
Explain how this increases the concentration of carbon dioxide in the air.
44 exam-style questions on Edexcel GCSE Biology 9.3 Material cycles and decomposition, covering 9.3.1 Cycling of materials through ecosystems, 9.3.2 The carbon cycle, 9.3.3 The water cycle, 9.3.4 The nitrogen cycle, 9.3.5 Indicator species and pollution, 9.3.6 Decomposition in preservation and composting, and 9.3.7 Rate changes in decay of biological material. Each one has a worked solution and a mark scheme showing where the marks go.