Leftover lentils are added to a compost container. The lentil proteins contain carbon and nitrogen. When the compost is ready, it is mixed with soil around a strawberry plant.
Some stages in the movement of the carbon and nitrogen are shown in the table.
| Element | Stages before uptake by the strawberry plant |
|---|---|
| carbon | carbon in lentil proteins → carbon compounds in microorganisms → carbon dioxide in the air |
| nitrogen | nitrogen in lentil proteins → ammonium compounds in the soil → nitrate ions in the soil |
A student states, ‘The strawberry plant takes in both the carbon and the nitrogen from the compost through its roots.’
Explain why the student's statement is only partly correct. Include how each element becomes part of new plant biomass.
101 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.