After several weeks of no rain during the summer you observe

After several weeks of no rain during the summer, you observe that leaves of some plants are wilted. Which of the following would you expect to observe at the cellular level with respect to photosynthesis?

Select one:

a. More glucose is going to be produced to compensate for the absence of water.

b. The rate of the oxidation and reduction of the thylakoid electron transport chain will be greater than normal.

c. Less NADPH will be produced.

d. More ATP is going to be synthesized by ATP synthase in the chloroplasts.

Solution

When we look into the molecular mechanism of wilting we will find that wilting is due to excessive loss of water through stomata in hot summer day. If we recall the light reaction we will find that the upon photon absorption H₂O is cleaved into molecular oxygen, Protons and electrons. These electrons move to NADP⁺ via electron transport chain and thus reduce NADP⁺ to NADPH.

So answer will be less NADPH will be produced