Question

Number of turns of Calvin cycle required for synthesis of one glucose molecule is ___________.

• A. One
• B. Four
• C. Two
• D. Six

Hint:

Each Calvin cycle turn fixes one CO\textsubscript{2}; glucose needs six CO\textsubscript{2} molecules.

Answer 1

The Correct Option is D

Step 1: Understanding the Calvin cycle.
The Calvin cycle is the dark reaction of photosynthesis where atmospheric CO\textsubscript{2} is fixed into carbohydrates using ATP and NADPH.
Step 2: Carbon requirement for glucose formation.
One turn of the Calvin cycle fixes one molecule of CO\textsubscript{2}.
Glucose is a six-carbon compound, so six molecules of CO\textsubscript{2} are required.
Step 3: Analysis of options.
(A) One: Incorrect — fixes only one carbon atom.
(B) Four: Incorrect — insufficient for glucose formation.
(C) Two: Incorrect — forms only a three-carbon compound.
(D) Six: Correct — six turns are required to form one glucose molecule.
Step 4: Conclusion.
Six turns of the Calvin cycle are required for the synthesis of one glucose molecule.