question_answer 8)

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

Answer:

(i) Points B-C of the curve, the rate did not increase with an increase in its concentration, because light becomes a limiting factor under these conditions. (ii) In A region, the rate of photosynthesis shows proportionate increase up to a certain CO2 concentration, beyond, which the rate again becomes constant. (iii) Points C and D represent that if the light intensity is doubled, CO2 concentration again becomes limiting factor beyond this concentration.