A marine biologist grows equal masses of sea lettuce, an alga, in six tanks. The concentration of dissolved carbon dioxide, light intensity and temperature can be controlled independently.
The table shows the mean rate of oxygen production in each tank.
| Tank | Light intensity / W m⁻² | Dissolved carbon dioxide concentration / mg dm⁻³ | Temperature / °C | Oxygen production rate / cm³ h⁻¹ |
|---|---|---|---|---|
| P | 20 | 2.0 | 24 | 3 |
| Q | 20 | 8.0 | 30 | 3 |
| R | 100 | 2.0 | 24 | 9 |
| S | 100 | 8.0 | 24 | 14 |
| T | 100 | 8.0 | 30 | 18 |
| U | 100 | 8.0 | 42 | 4 |
Explain how the results show that light intensity, carbon dioxide concentration and temperature interact to limit the rate of photosynthesis.
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.