Fixation of one molecule of `Co_(2)` through Calvin cycle requires

Options

A. 3 ATP and 3 NAD`H_(2)` molecules
B. 3 ATP and 2 NADP`H_(2)` molecules
C. 2 ATP and I NADP`H_(2)` molecule
D. 1 ATP and 2 NADP`H_(2)` molecules

Answer

To determine the fixation of one molecule of CO₂ through the Calvin cycle, we need to analyze the process step by step.

### Step-by-Step Solution:

1. **Understanding the Calvin Cycle**: The Calvin cycle consists of three main stages: carbon fixation, reduction, and regeneration. In this cycle, carbon dioxide (CO₂) is fixed into organic molecules.

2. **Carbon Fixation**: In the first stage, CO₂ is combined with ribulose-1,5-bisphosphate (RuBP) to form 3-phosphoglycerate (3-PGA). This process occurs with the help of the enzyme RuBisCO.

3. **Energy Requirements**: The Calvin cycle requires energy in the form of ATP and reducing power in the form of NADPH. These are produced during the light-dependent reactions of photosynthesis.

4. **Calculating Requirements for CO₂ Fixation**:
- For every three molecules of CO₂ that enter the Calvin cycle, a total of 9 ATP and 6 NADPH are used.
- Therefore, to fix one molecule of CO₂, we need to divide these amounts by 3.

5. **Final Calculation**:
- **ATP Required**: 9 ATP / 3 CO₂ = 3 ATP
- **NADPH Required**: 6 NADPH / 3 CO₂ = 2 NADPH

6. **Conclusion**: Thus, the fixation of one molecule of CO₂ through the Calvin cycle requires **3 ATP and 2 NADPH**.

### Final Answer:
The fixation of one molecule of CO₂ through the Calvin cycle requires **3 ATP and 2 NADPH**.

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