A researcher uses two equal groups of cress seedlings. The temperature and starting carbon dioxide concentration are the same for both groups.
The table shows the carbon dioxide uptake at two light intensities.
| Light intensity | Carbon dioxide uptake in mg | Measurement time in minutes |
|---|---|---|
| Lower | 4.2 | 7 |
| Higher | 8.1 | 6 |
Calculate the percentage increase in the mean rate of carbon dioxide uptake when the light intensity is changed from the lower intensity to the higher intensity.
Show your working.
The researcher increases the light intensity above the higher intensity shown in the table. The mean rate of carbon dioxide uptake does not increase.
Explain this result.
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.