A researcher places equal masses of dead grass and decomposers in containers. Each container receives either a high or a low supply of oxygen.
The researcher records the time taken for each sample of dead grass to lose 2.0 g in mass.
| Oxygen supply | Time in trial 1 / h | Time in trial 2 / h | Time in trial 3 / h |
|---|---|---|---|
| High | 76 | 80 | 84 |
| Low | 120 | 125 | 130 |
Relative rate is calculated as 1÷mean time1 \div \text{mean time}1÷mean time.
What is the percentage decrease in relative rate when the oxygen supply changes from high to low?
64.0%
45.0%
56.3%
36.0%
83 exam-style questions on AQA GCSE Biology 7.2 Organisation of an ecosystem, covering 7.2.1 Levels of organisation, 7.2.2 How materials are cycled, 7.2.3 Decomposition, and 7.2.4 Impact of environmental change (HT only). Each one has a worked solution and a mark scheme showing where the marks go.