[Campbell Biology P.247] Suppose an organism has a mutation that renders its NADP+ reductase... | Practice Question

Suppose an organism has a mutation that renders its NADP+ reductase enzyme non-functional. Assuming all other components of the light reactions are intact, which of the following would be the most direct consequence?

  • A: An increase in ATP production due to a buildup of electrons.
  • B: A reduced supply of NADPH, impairing the Calvin cycle.
  • C: An accumulation of protons in the stroma, leading to an inverse proton gradient.
  • D: The complete halt of all electron flow from Photosystem I.

Explanation

According to paragraph 8, the NADP+ reductase enzyme is responsible for catalyzing the transfer of electrons from ferredoxin Fd to NADP+, leading to the reduction of NADP+ to NADPH. NADPH is a crucial reducing agent for the Calvin cycle. If this enzyme is non-functional, the organism would be unable to produce NADPH, directly impairing its ability to carry out the Calvin cycle and synthesize carbohydrates.