Scientists incubated equal masses of the same soil for 14 days without plants. The oxygen availability was different in the two samples.
| sample | oxygen availability | nitrate concentration on day 0 in mg kg−1\mathrm{mg\,kg^{-1}}mgkg−1 | nitrate concentration on day 14 in mg kg−1\mathrm{mg\,kg^{-1}}mgkg−1 |
|---|---|---|---|
| A | high | 52 | 49 |
| B | low | 52 | 20 |
After 14 days, both samples were placed under the same suitable conditions and identical seedlings were planted in them. No fertiliser was added and nitrate was the limiting factor for growth.
Explain the nitrate results and how they would affect the growth of seedlings in sample B compared with sample A.
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.