A biologist places equal masses of duckweed in two transparent chambers. The temperature is kept at a value known not to limit photosynthesis.
The table shows the mean rate of carbon dioxide uptake at two carbon dioxide concentrations and two light intensities.
| Carbon dioxide concentration in % | Carbon dioxide uptake at 80 arbitrary light units in mg h−1\mathrm{mg\,h^{-1}}mgh−1 | Carbon dioxide uptake at 320 arbitrary light units in mg h−1\mathrm{mg\,h^{-1}}mgh−1 |
|---|---|---|
| 0.04 | 1.5 | 2.4 |
| 0.08 | 1.6 | 4.8 |
Compare the effect of increasing the carbon dioxide concentration from 0.04% to 0.08% at the two light intensities.
Explain why increasing the carbon dioxide concentration has different effects at the two light intensities.
87 exam-style questions on Edexcel GCSE Biology 6.1 Photosynthesis, covering 6.1.1 Photosynthetic organisms as producers, 6.1.2a Limiting factors on the rate of photosynthesis, 6.1.2b Interactions of limiting factors on photosynthesis, and 6.1.3 Inverse square law and light intensity. Each one has a worked solution and a mark scheme showing where the marks go.