Explain how the biochemistry of C4 plants is different from that of C3 plants.
Hatch and Slack worked out the C4 pathway for carbon dioxide fixation in 1966. In their study they compared the rates of carbon dioxide fixation at high light intensities in leaves taken from both temperate and tropical grasses. They also measured the activity 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 shown in Table 2.1.
Using Table 2.1, compare the rates at which carbon dioxide is fixed 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 produce one molecule of glucose, the C3 pathway uses 18 molecules of ATP and the C4 pathway uses 30 molecules of ATP. Explain why C4 plants can afford this high cost of ATP.