Question

Suppose that the concentration of CO2 available for the Calvin cycle decreased by 50% (because the stomata closed to conserve water).
Which statement correctly describes how O2 production would be affected? (Assume that the light intensity does not change.)
A. The rate of O2 production would remain the same because the light reactions are independent of the Calvin cycle.
B. The rate of O2 production would decrease because the rate of ADP and NADP+ production by the Calvin cycle would decrease.
C. The rate of O2 production would decrease because the rate of G3P production by the Calvin cycle would decrease.
D. The rate of O2 production would remain the same because the light intensity did not change.

Answer 1

Answer:

The correct answer is B. The rate of O2 production would decrease because the rate of ADP and NADP+ production by the calvin cycle would decrease.

Explanation:

The light reactions and calvin cycle are dependant on each other. If concentration of CO2 is decreased, less ADP and NADP+ will be produced by the calvin cycle resulting in decrease O2 production.

The ADP and NADP+ molecules produced in calvin cyce are required by the light reactions where they get converted into ATP and NADPH respectively, ultimately producing oxygen.

Hence option B is correct.