A grower uses two raised beds containing the same type of soil.
Both beds are planted with bean plants that develop root nodules.
At harvest, the grower treats the beds differently:
| bed | treatment |
|---|---|
| A | only the bean pods are removed; the roots and stems are cut up and mixed into the soil |
| B | the whole bean plants, including the roots, are removed |
Both soils are then kept moist and well aerated for six weeks. The nitrate concentration becomes higher in bed A than in bed B.
Explain why the nitrate concentration becomes higher in bed A than in bed B.
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.