(a(i))[1]
State the limiting factor in region A on the graph.
(a(ii))[2]
Explain what the term limiting factor means.
(a(iii))[2]
Explain why there is no further increase in the rate of photosynthesis beyond point C.
(b)[4]
In many plants from temperate regions, the optimum temperature for photosynthesis is about $25^{\circ}\text{C}$. Suggest reasons why the rate of photosynthesis falls at temperatures above $25^{\circ}\text{C}$.