Scientists investigated dead reed material buried in lake sediment. In one container, narrow channels in the sediment allowed oxygenated water to reach the dead material. In the other container, compact sediment restricted the oxygen supply. Both containers were kept at the same temperature and started with the same mass of carbon in the dead material. The sample labels were lost.
The results are shown in the table.
| Time (days) | Carbon remaining in sample X (g) | Carbon remaining in sample Y (g) |
|---|---|---|
| 0 | 150 | 150 |
| 20 | 138 | 146 |
| 40 | 124 | 142 |
Explain which sample was from the container with channels and how keeping these conditions for several years would affect the carbon stored in the sediment.
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.