In Calvin cycle, to form one molecule of glucose how many number of ATP and NADPH molecules are utilized?

Options

A. 12ATP and 9NADPH
B. 6ATP and 4NADPH
C. 18ATP and 12NADPH
D. 20ATP and 24NADPH

Answer

To determine how many ATP and NADPH molecules are utilized in the Calvin cycle to form one molecule of glucose, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Calvin Cycle**: The Calvin cycle is a series of biochemical reactions that take place in the stroma of chloroplasts in photosynthetic organisms. It is responsible for fixing carbon dioxide and converting it into glucose.

2. **Carbon Fixation**: In the first step, carbon dioxide (CO2) is fixed by ribulose bisphosphate (RuBP) in the presence of the enzyme ribulose bisphosphate carboxylase/oxygenase (Rubisco), resulting in the formation of 3-phosphoglycerate (3-PGA).

3. **Reduction Phase**: The 3-PGA molecules are then reduced to glyceraldehyde-3-phosphate (G3P) using ATP and NADPH. For every 2 molecules of 3-PGA formed, 2 ATP and 2 NADPH are consumed.

4. **Regeneration of RuBP**: The G3P molecules are used to regenerate RuBP, which requires additional ATP. Specifically, for every G3P molecule that is converted back to RuBP, 1 ATP is used.

5. **Calculating for One Glucose Molecule**:
- To form one molecule of glucose (C6H12O6), six carbon atoms are required. Since each turn of the Calvin cycle fixes one carbon atom (from one CO2), the cycle must turn 6 times.
- Each cycle uses 3 ATP and 2 NADPH. Therefore, for 6 cycles:
- ATP: 6 cycles × 3 ATP/cycle = 18 ATP
- NADPH: 6 cycles × 2 NADPH/cycle = 12 NADPH

6. **Final Answer**: Thus, to form one molecule of glucose, a total of **18 ATP** and **12 NADPH** molecules are utilized in the Calvin cycle.

### Summary:
To form one molecule of glucose in the Calvin cycle, **18 ATP** and **12 NADPH** are required.

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