Students investigated the effect of light intensity on the rate of photosynthesis by varying the distance of a halogen lamp from a piece of Elodea pondweed. They measured the rate of photosynthesis by recording the volume of oxygen gas produced in mm3\text{mm}^3mm3 over a 5-minute period. Table 1 shows their results.
| Distance of lamp in cm | Trial 1 | Trial 2 | Trial 3 | Mean |
|---|---|---|---|---|
| 15 | 82 | 86 | 84 | PPP |
| 30 | 54 | 55 | 53 | 54.0 |
| 45 | 32 | 30 | 31 | 31.0 |
| 60 | 18 | 49 | 16 | 17.0 |
| 75 | 8 | 9 | 7 | 8.0 |
Calculate the mean value PPP.
Identify the anomalous result in Table 1 at a distance of 60 cm.
Explain how the students used the results in Table 1 to calculate the mean value of 17.0 for the distance of 60 cm.
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.