A scientist grows groups of 20 spinach plants in a sealed growth room. The light intensity, carbon dioxide concentration and temperature can be controlled independently.
The scientist measures the mean volume of oxygen produced by each group in one hour.
| Treatment | Light intensity in lux | Carbon dioxide concentration in % | Temperature in ∘C^\circ\text{C}∘C | Mean oxygen production in cm3 h−1\text{cm}^3\text{ h}^{-1}cm3 h−1 |
|---|---|---|---|---|
| P | 5000 | 0.04 | 14 | 24 |
| Q | 10000 | 0.04 | 14 | 40 |
| R | 10000 | 0.10 | 14 | 60 |
| S | 10000 | 0.10 | 22 | 84 |
| T | 15000 | 0.10 | 22 | 84 |
Explain what the results show about how the limiting factor changes as the conditions are changed from treatment P to treatment T.
The scientist expects the spinach plants in treatment S to produce more biomass than the plants in treatment R.
Explain why.
Suggest why treatment S may be more profitable than treatment T.
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.