MDCAT Biology MCQ #212

On a hot, dry day, a C3 plant closes its stomata, leading to photorespiration. How does Rubisco behave differently in this scenario?

MDCAT Biology MCQ #212

  1. Question 1

    Q1. On a hot, dry day, a C3 plant closes its stomata, leading to photorespiration. How does Rubisco behave differently in this scenario?

    • A) It fixes CO2 into a 4-carbon compound
    • B) It produces two molecules of G3P
    • C) It adds oxygen to RuBP instead of CO2
    • D) It occurs only in the bundle sheath cells

    Answer: It adds oxygen to RuBP instead of CO2

    Explanation: Rubisco acts as a carboxylase when CO2 is high, but switches to oxygenase activity during photorespiration when O2 levels rise.