MDCAT Biology MCQ #464

In the carbon fixation stage of the Calvin cycle, which molecule acts as the initial acceptor of carbon dioxide from the atmosphere?

MDCAT Biology MCQ #464

  1. Question 1

    Q1. In the carbon fixation stage of the Calvin cycle, which molecule acts as the initial acceptor of carbon dioxide from the atmosphere?

    • A) 3-phosphoglycerate (PGA)
    • B) Ribulose bisphosphate (RuBP)
    • C) Glyceraldehyde-3-phosphate (G3P)
    • D) Oxaloacetate

    Answer: Ribulose bisphosphate (RuBP)

    Explanation: CO2 first reacts with the 5-carbon RuBP; PGA is the first stable 3-carbon product formed after the reaction.