A grower measured the rate of photosynthesis of tomato plants at different light intensities. She made the measurements at two carbon dioxide concentrations, 0.04 % and 0.40 %. The temperature was kept at 20 °C throughout.
Figure: The rate of photosynthesis of tomato plants at different light intensities, measured at two carbon dioxide concentrations
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Both curves have the same shape between light intensities of 0 and 3 arbitrary units.
Explain what this shows about the factor limiting the rate of photosynthesis at these light intensities.
Explain why the curve for 0.04 % carbon dioxide becomes horizontal above a light intensity of 3 arbitrary units.
The grower raises the temperature of the greenhouse from 20 °C to 25 °C. The rate of photosynthesis at a light intensity of 8 arbitrary units and 0.04 % carbon dioxide does not increase.
Suggest why.
54 exam-style questions on AQA GCSE Biology 4.1 Photosynthesis, covering 4.1.1 Photosynthetic reaction, 4.1.2 Rate of photosynthesis, and 4.1.3 Uses of glucose from photosynthesis. Each one has a worked solution and a mark scheme showing where the marks go.