Calvin cycle operates in

Options

A. `C_3` plants , `C_4` plants ,CAM plants
B. `C_3` plants only
C. `C_4` plants , CAM plants only
D. `C_3 and C_4` plants only

Answer

**Step-by-Step Solution:**

1. **Understanding the Calvin Cycle**: The Calvin cycle is a crucial part of photosynthesis that occurs in plants. It is often referred to as the "dark reactions" because it does not directly require light to occur, although it relies on the products of the light-dependent reactions.

2. **Identifying the Process**: The Calvin cycle involves three main stages:
- **Carboxylation**: The enzyme RuBisCO catalyzes the fixation of carbon dioxide to ribulose bisphosphate (RuBP).
- **Reduction**: ATP and NADPH produced in the light reactions are used to convert 3-phosphoglycerate (3-PGA) into glyceraldehyde-3-phosphate (G3P).
- **Regeneration**: Some G3P molecules are used to regenerate RuBP, allowing the cycle to continue.

3. **Location of the Calvin Cycle**: The Calvin cycle takes place in the stroma of chloroplasts in plant cells. This is where the necessary enzymes and substrates are located.

4. **Types of Plants**: The Calvin cycle operates in all types of photosynthetic plants, including:
- **C3 plants**: These plants primarily use the Calvin cycle for carbon fixation.
- **C4 plants**: These plants also utilize the Calvin cycle but have an additional mechanism to concentrate CO2.
- **CAM plants**: These plants fix CO2 at night and also utilize the Calvin cycle during the day.

5. **Conclusion**: Since the Calvin cycle is present in C3, C4, and CAM plants, the correct answer to the question is that it operates in all of these types of plants.

**Final Answer**: The Calvin cycle operates in C3 plants, C4 plants, and CAM plants.

---