Outline how light intensity affects the rate of photosynthesis, with reference to the Calvin cycle and effects on the concentrations of GP, GALP and RuBP.

Light is needed to provide energy for the light dependent reactions of photosynthesis. A greater light intensity will provide more energy for these reactions to occur. At a low light intensity, the products of the light dependent reactions, ATP and NADPH will be in short supply. As a result, the ATP and NADPH dependent reactions which involves the conversion of GP to GALP, and the ATP dependent reactions which involves the conversion of GALP to RuBP would both be inhibited, causing an accumulation of GP and a decrease in GALP and RuBP.