Site of PGA formation in `C_3` plants & `C_4` plants respectively

Options

A. Mesophyll cells & Mesophyll cells
B. Bundle sheath cells & Mesophyll cells
C. Mesophyllcells & Bundles sheath cells
D. Guardcells & Mesophyll cells

Answer

To answer the question regarding the site of PGA (3-phosphoglycerate) formation in C3 and C4 plants, we will break down the information step by step.

### Step-by-Step Solution:

1. **Understanding C3 and C4 Plants**:
- C3 plants primarily utilize the Calvin cycle for photosynthesis, where the first stable product formed is 3-phosphoglycerate (PGA).
- C4 plants have an additional step in their photosynthetic process, where carbon dioxide is initially fixed into a four-carbon compound before entering the Calvin cycle.

2. **Identifying the Site of PGA Formation**:
- In C3 plants, the PGA formation occurs in the **mesophyll cells**. These cells are where the Calvin cycle takes place directly.
- In C4 plants, the initial carbon fixation occurs in the **mesophyll cells** as well, but the conversion to PGA happens in the **bundle sheath cells**. The bundle sheath cells surround the vascular tissue and are involved in the Calvin cycle after the initial fixation.

3. **Conclusion**:
- Therefore, the site of PGA formation in C3 plants is the **mesophyll cells**, and in C4 plants, it is the **bundle sheath cells**.

4. **Final Answer**:
- The correct answer to the question is **C: mesophyll cells and bundle sheath cells**.