Three stages of Calvin cycle are

Options

A. Carboxylation, oxidation and reduction
B. Oxidation, reduction and carboxylation
C. Carboxylation, reduction and oxidation
D. Carboxylation, reduction and regenartion

Answer

**Step-by-Step Solution:**

1. **Understanding the Calvin Cycle**: The Calvin cycle is a crucial part of photosynthesis in higher plants, where carbon dioxide is fixed and converted into glucose. It consists of three main stages.

2. **Identifying the Stages**:
- **Carboxylation**: This is the first stage of the Calvin cycle. In this stage, carbon dioxide (CO2) is fixed by combining with ribulose 1,5-bisphosphate (RUBP). The enzyme responsible for this reaction is Rubisco (Ribulose 1,5-Bisphosphate Carboxylase Oxygenase), which catalyzes the reaction to form 3-phosphoglycerate (3-PGA).

- **Reduction**: The second stage involves the reduction of 3-PGA into glyceraldehyde-3-phosphate (G3P) using ATP and NADPH produced in the light-dependent reactions of photosynthesis. This stage is crucial for the synthesis of carbohydrates like glucose and sucrose.

- **Regeneration**: The final stage is the regeneration of RUBP from G3P. This step also requires ATP. The regeneration of RUBP is essential for the cycle to continue, allowing for the fixation of more CO2.

3. **Conclusion**: The three stages of the Calvin cycle, in the correct order, are:
- Carboxylation
- Reduction
- Regeneration

4. **Correct Option**: Based on the stages identified, the correct answer is "Carboxylation, Reduction, and Regeneration."

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