MDCAT Biology MCQ #172

In the stroma of a C3 plant, which enzyme is responsible for the initial fixation of carbon dioxide into an organic molecule?

MDCAT Biology MCQ #172

  1. Question 1

    Q1. In the stroma of a C3 plant, which enzyme is responsible for the initial fixation of carbon dioxide into an organic molecule?

    • A) ATP synthase
    • B) Rubisco
    • C) NADP reductase
    • D) PEP carboxylase

    Answer: Rubisco

    Explanation: Rubisco fixes CO2 to RuBP during the first step of the Calvin cycle; PEP carboxylase is used in C4 plants, not C3.