Figure 11.10 shows the effect of light on the rate of photosynthesis. Based on the graph, answer the following questions: (a) At which point/s (A, B or C) in the curve light is a limiting factor? (b) What could be the limiting factor/s in region A? (c) What do C and D represent on the curve?

Light is the limiting factor at points A and B on the curve, where the rate of photosynthesis rises with increasing light intensity

In region A (the initial, steeply rising part of the curve) the low photon flux density limits the supply of excitation energy to the photosystems, so light intensity (quality, quantity and duration) is the primary limiting factor

Point C represents the light-saturation point, at which further increases in light intensity do not increase the photosynthetic rate because another factor (e.g., CO₂ concentration or enzyme capacity) has become limiting

Point D marks the onset of photoinhibition, where excess light causes damage to chlorophyll and the photosynthetic apparatus, leading to a decline in net photosynthesis