Students investigated the effect of carbon dioxide concentration on the rate of photosynthesis in a suspension of the microalgae Chlorella vulgaris. They measured the rate of oxygen production in microlitres per minute (μl min−1\mu\text{l}\ \text{min}^{-1}μl min−1). The results are shown in the table below:
| Carbon dioxide concentration (mmol dm−3\text{mmol}\ \text{dm}^{-3}mmol dm−3) | Rate of oxygen production (μl min−1\mu\text{l}\ \text{min}^{-1}μl min−1) | |||
|---|---|---|---|---|
| Test 1 | Test 2 | Test 3 | Mean | |
| 0.2 | 4.1 | 4.7 | 4.4 | ZZZ |
| 0.4 | 8.8 | 8.5 | 8.2 | 8.5 |
| 0.6 | 12.1 | 12.9 | 12.5 | 12.5 |
| 0.8 | 16.2 | 15.8 | 16.6 | 16.2 |
| 1.0 | 18.1 | 18.5 | 18.0 | 18.2 |
| 1.2 | 18.4 | 2.1 | 18.6 | 18.5 |
Calculate the mean value ZZZ shown in the table. Show your working.
Identify the anomalous result in the table by stating the carbon dioxide concentration and the test number.
Explain how the students should deal with this anomalous result when calculating the mean for that concentration.
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.