A researcher investigates the effect of light intensity on photosynthesis in established bean plants. Identical lighting panels are fixed above groups of plants in two matching growth cabinets. Metal pipes run around the inside of each cabinet, and water can be circulated through the pipes.
The researcher carries out a pilot investigation at the same light-intensity setting in both cabinets. All other conditions are kept the same. Separate matching samples are used to estimate the initial mean dry mass of the plants.
| Water circulated through pipes | Mean temperature in cabinet (°C) | Mean increase in dry mass per plant after 7 days (g) |
|---|---|---|
| yes | 20 | 0.70 |
| no | 27 | 1.05 |
The researcher then plans to investigate four different light intensities.
Explain why water should be circulated through the pipes throughout the planned investigation. Use the pilot results in your answer.
117 exam-style questions on OCR GCSE Biology 1.4 Photosynthesis, covering 1.4.1 Photosynthesisers as biomass producers, 1.4.2 Factors affecting the rate of photosynthesis, and 1.4.3 Limiting factors in photosynthesis. Each one has a worked solution and a mark scheme showing where the marks go.