A food producer grows radish seedlings in lightproof growing cabinets. The cabinets exclude outside light, so the lamps provide all the illumination.
Each tray contains 20 seedlings from the same batch and receives the same supply of water. The carbon dioxide concentration, lamp setting and temperature can be controlled.
The table shows the dry biomass produced by each tray during 12 days.
| tray | carbon dioxide concentration (%) | lamp setting | temperature (°C) | dry biomass produced (g) |
|---|---|---|---|---|
| 1 | 0.04 | low | 20 | 3.6 |
| 2 | 0.10 | low | 20 | 3.6 |
| 3 | 0.10 | high | 20 | 7.2 |
| 4 | 0.10 | high | 30 | 9.6 |
| 5 | 0.10 | high | 40 | 2.4 |
State the name of the pigment that absorbs light energy for photosynthesis.
Using the results for trays 1, 2 and 3, explain which factor limited biomass production in trays 1 and 2.
Describe the effect of temperature on the dry biomass produced when the lamp setting was high and the carbon dioxide concentration was 0.10%.
Maintaining a cabinet at 30 °C requires more heating than maintaining it at 20 °C.
Give one reason why the producer might choose to use 20 °C rather than 30 °C.
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.