MDCAT Biology MCQ #288

An experimental herbicide binds to the plastoquinone binding site of Photosystem II. What is the most immediate effect on the light reactions?

MDCAT Biology MCQ #288

  1. Question 1

    Q1. An experimental herbicide binds to the plastoquinone binding site of Photosystem II. What is the most immediate effect on the light reactions?

    • A) Inhibition of photolysis
    • B) Enhanced cyclic flow
    • C) Increased NADPH production
    • D) Reduction of NADP+

    Answer: Inhibition of photolysis

    Explanation: PSII blockage stops water splitting and oxygen release; cyclic flow is tempting but it only involves PSI and cytochrome.