Explain what is meant by a limiting factor in relation to photosynthesis.
Suggest why the air in the soil and the air around the leaves of the plants were separated.
In one investigation, two groups of plants, A and B, were raised from seed at different carbon dioxide concentrations: A - normal atmospheric concentration of carbon dioxide $(0.033\%)$. B - normal atmospheric concentration of carbon dioxide $\times 2\ (0.066\%)$. Then, while each group of plants remained in its own carbon dioxide concentration, their rates of photosynthesis were measured at several different light intensities. The results are shown in Fig. 2.1 on page 5.
Using Fig. 2.1, describe and explain, in terms of limiting factors, the results from the plants in set A.
Explain the difference between the results of set A and set B at high light intensities.
In a second investigation, two groups of plants, C and D, were raised from seed, as before, in different carbon dioxide concentrations: • C - normal atmospheric concentration of carbon dioxide ($0.033\%$) • D - normal atmospheric concentration of carbon dioxide $\times 2$ ($0.066\%$). When the plants had matured, the conditions in the growth chambers were altered to investigate the rate of photosynthesis of each group of plants in different concentrations of carbon dioxide. The results are shown in Fig. 2.2. Suggest explanations for the higher rate of photosynthesis per unit area of leaf shown by the plants in set D compared with those in set C.
Suggest explanations for the higher rate of photosynthesis per unit area of leaf shown by the plants in set D compared with those in set C.