Which is not a step in Calvin cycle ?

Options

A. Caboxylation
B. Reduction
C. Photophosporylation
D. Regeneration

Answer

**Step-by-Step Solution:**

1. **Understand the Calvin Cycle**: The Calvin cycle is a series of biochemical reactions that occur in plants and algae to convert carbon dioxide into glucose. It is also known as the dark reaction because it does not require light to occur.

2. **Identify the Steps of the Calvin Cycle**: The Calvin cycle consists of three main steps:
- **Carboxylation**: This is the first step where carbon dioxide is fixed into a 5-carbon sugar, ribulose bisphosphate (RuBP).
- **Reduction**: In this step, the fixed carbon is reduced to form glyceraldehyde-3-phosphate (G3P) using ATP and NADPH produced in the light-dependent reactions.
- **Regeneration**: The final step involves regenerating ribulose bisphosphate (RuBP) from G3P, allowing the cycle to continue.

3. **Evaluate the Options**: The options given are:
- Carboxylation
- Reduction
- Photophosphorylation
- Regeneration

4. **Analyze Each Option**:
- **Carboxylation**: This is a step in the Calvin cycle.
- **Reduction**: This is also a step in the Calvin cycle.
- **Photophosphorylation**: This process involves the conversion of ADP to ATP in the presence of light and is not a step in the Calvin cycle.
- **Regeneration**: This is a step in the Calvin cycle.

5. **Conclusion**: The step that is not part of the Calvin cycle is **Photophosphorylation**.

**Final Answer**: Photophosphorylation is not a step in the Calvin cycle.

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