In `C_(4)` -pathway initial carbon dioxide fixaion occurs in chloroplasts of

Options

A. Guard cells
B. mesophyll
C. bundle sheath
D. all the above

Answer

**Step-by-Step Solution:**

1. **Understanding the C4 Pathway**: The C4 pathway is a photosynthetic process that occurs in certain plants, known as C4 plants, which include species like maize, sorghum, and sugarcane. This pathway is characterized by the initial fixation of carbon dioxide (CO2) in a specific type of cell.

2. **Identifying the Cells Involved**: In C4 plants, the leaf anatomy is specialized. The key types of cells involved in the C4 pathway are:
- **Mesophyll Cells**: These cells are located in the upper part of the leaf and are responsible for the initial fixation of CO2.
- **Bundle Sheath Cells**: These cells surround the vascular tissue and are involved in further processing of the fixed carbon.
- **Guard Cells**: These cells surround the stomata and regulate gas exchange but are not directly involved in the initial fixation of CO2.

3. **Initial CO2 Fixation**: The question asks where the initial fixation of CO2 occurs in the C4 pathway. It is important to note that the initial fixation takes place in the mesophyll cells, where CO2 is combined with phosphoenolpyruvate (PEP) to form a C4 acid.

4. **Conclusion**: Based on the information, the correct answer to the question is that the initial carbon dioxide fixation in the C4 pathway occurs in the chloroplasts of **mesophyll cells**.

**Final Answer**: Mesophyll cells.

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