Equal soil samples were kept for 48 hours at different oxygen concentrations. Each sample started with the same amounts of ammonium compounds and nitrate ions. No plants were present.
| Oxygen concentration in soil (%) | Nitrate ions after 48 hours (mg per kg of soil) |
|---|---|
| 8 | 42 |
| 1 | 14 |
Explain how these results support the prediction that plants growing in soil with 1% oxygen would grow less than plants growing in soil with 8% oxygen.
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.