Students investigated the effect of temperature on the rate of photosynthesis in pondweed by measuring the volume of oxygen produced per hour. The results are shown in the table below:
| Temperature in ∘C^{\circ}\text{C}∘C | Rate of photosynthesis in cm3/hour\text{cm}^3/\text{hour}cm3/hour | |||
|---|---|---|---|---|
| Test 1 | Test 2 | Test 3 | Mean | |
| 15 | 12.4 | 11.8 | 12.1 | YYY |
| 20 | 22.3 | 21.9 | 23.0 | 22.4 |
| 25 | 34.5 | 33.8 | 34.9 | 34.4 |
| 30 | 46.2 | 47.1 | 45.9 | 46.4 |
| 35 | 38.2 | 39.5 | 38.7 | 38.8 |
| 40 | 1.5 | 12.8 | 1.8 | 1.7 |
Calculate the mean value YYY shown in the table. Show your working.
Identify the anomalous result in the table by stating its temperature and test number.
Explain how the students should deal with this anomalous result when calculating the mean for that temperature.
State one key factor that the students should have kept constant in this investigation to ensure valid results.
54 exam-style questions on AQA GCSE Biology 4.1 Photosynthesis, covering 4.1.1 Photosynthetic reaction, 4.1.2 Rate of photosynthesis, and 4.1.3 Uses of glucose from photosynthesis. Each one has a worked solution and a mark scheme showing where the marks go.