A student investigates the effect of light intensity on the rate of photosynthesis in pondweed. The student changes the distance of a lamp from the pondweed. A heat filter keeps the temperature of the water the same. The table shows the results. Table
| Distance of lamp from pondweed in cm\text{cm}cm | 40 | 30 | 20 | 15 | 10 | 5 |
|---|---|---|---|---|---|---|
| Number of bubbles per minute | 6 | 11 | 24 | 38 | 52 | 53 |
| Which statement explains the results between 10 cm and 5 cm? |
The light intensity does not change when the lamp is moved closer.
Another factor, such as carbon dioxide concentration, is now limiting.
The chlorophyll in the pondweed has been damaged by the bright light.
The pondweed has used up all the water it needs for photosynthesis.
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.