Outline the biochemical differences between C4 plants and C3 plants.
The C4 route for carbon dioxide fixation was established in 1966 by Hatch and Slack. In their study, they recorded the rates of carbon dioxide fixation at high light intensities in leaves taken from both temperate and tropical grasses. They also determined the activities of two carboxylase enzymes in the leaves, ribulose bisphosphate carboxylase (rubisco) and PEP carboxylase. Every rate was measured at $30\,^{\circ}\text{C}$. Some of their findings are presented in Table 2.1.
Using Table 2.1, compare the rates of carbon dioxide fixation in C3 and C4 grasses.
Describe the function of rubisco in the Calvin cycle.
Using Table 2.1, suggest reasons for the differences in activity of the two carboxylase enzymes in C3 and C4 grasses.
It has been calculated that, to make one molecule of glucose, the C3 pathway uses $18$ molecules of ATP and the C4 pathway uses $30$. Suggest why C4 plants can afford this high cost of ATP.