A student records the time for identical milk mixtures containing lipase to reach the same pH endpoint.
| Temperature / ∘C^{\circ}\mathrm{C}∘C | Time in trial 1 / s | Time in trial 2 / s | Time in trial 3 / s |
|---|---|---|---|
| 20 | 140 | 150 | 160 |
| 30 | 90 | 100 | 110 |
The student calculates relative rate as 1÷mean time1 \div \text{mean time}1÷mean time .
What is the percentage increase in relative rate between 20∘C20^{\circ}\mathrm{C}20∘C and 30∘C30^{\circ}\mathrm{C}30∘C ?
33.3%
66.7%
150%
50.0%
40 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.