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    Question

    How many ATP molecules are required in the C₄

     pathway for the synthesis of one molecule of glucose?
    A 6 Correct Answer Incorrect Answer
    B 12 Correct Answer Incorrect Answer
    C 18 Correct Answer Incorrect Answer
    D 36 Correct Answer Incorrect Answer
    E 30 Correct Answer Incorrect Answer

    Solution

    In the C₄ pathway (Hatch-Slack pathway), the synthesis of one molecule of glucose requires a total of 30 ATP molecules . Here's a breakdown of how this energy is utilized: ATP Requirements:

    1. C₄ Cycle (Initial CO₂ Fixation in Mesophyll Cells):
      • 2 ATP molecules are consumed to regenerate phosphoenolpyruvate (PEP) from pyruvate for every CO₂ molecule fixed in the C₄ cycle.
      • For the production of one glucose molecule, 6 CO₂ molecules are required, so 6 × 2 = 12 ATP are used in the C₄ cycle.
    2. Calvin Cycle (C₃ Pathway in Bundle-Sheath Cells):
      • The Calvin cycle requires 18 ATP molecules to synthesize one glucose molecule (as in the C₃ pathway).
    Total ATP:
    • 12 ATP from the C₄ cycle + 18 ATP from the Calvin cycle = 30 ATP molecules.

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