PEP is primary `CO_(2)` acceptor in

Options

A. `C_4` plants
B. `C_3` plants
C. `C_2` plants
D. Both `C_3 & C_4` plants

Answer

To determine where PEP (phosphoenolpyruvate) acts as the primary CO2 acceptor, we need to analyze the options given in the question.

### Step-by-Step Solution:

1. **Understand the Role of PEP**:
- PEP is a three-carbon compound that plays a crucial role in the process of photosynthesis, particularly in certain types of plants.

2. **Identify the Types of Plants**:
- The question provides four options: C4 plants, C3 plants, C2 plants, and both C3 and C4 plants.

3. **Focus on C4 Plants**:
- In C4 plants, the initial fixation of CO2 occurs in the mesophyll cells. This is a key characteristic of C4 photosynthesis.

4. **Enzyme Involvement**:
- The enzyme responsible for the initial fixation of CO2 in C4 plants is PEP carboxylase. This enzyme catalyzes the reaction between CO2 and PEP.

5. **Formation of Oxaloacetic Acid**:
- When CO2 combines with PEP in the presence of PEP carboxylase, it forms oxaloacetic acid (OAA), which is a four-carbon compound. This is a crucial step in the C4 pathway.

6. **Conclusion**:
- Based on the above points, we conclude that PEP is the primary CO2 acceptor in C4 plants.

### Final Answer:
PEP is the primary CO2 acceptor in **C4 plants**.

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