Enzyme responsible for primary carboxylation in `C_(4)` plants is

Options

A. PEP carboxylase
B. Succinic dehydrogenase
C. RuBP carboxylase oxygenase
D. Hexokinase

Answer

To solve the question regarding the enzyme responsible for primary carboxylation in C4 plants, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding C4 Plants**:
- C4 plants utilize a specific pathway known as the C4 pathway for photosynthesis. This pathway is characterized by the initial fixation of carbon dioxide.

2. **Identifying Primary Carboxylation**:
- In C4 plants, the primary carboxylation occurs when carbon dioxide is fixed to phosphoenolpyruvate (PEP), which is a 3-carbon compound.

3. **Enzyme Involved**:
- The enzyme responsible for this primary carboxylation reaction is crucial to the C4 pathway. The reaction produces oxaloacetic acid (OAA), a 4-carbon compound.

4. **Evaluating the Options**:
- The options provided are:
1. PEP carboxylase
2. Succinic dehydrogenase
3. RUBP carboxylase-oxygenase
4. Hexokinase

5. **Analyzing Each Option**:
- **PEP carboxylase**: This enzyme catalyzes the reaction of PEP with CO2 to form oxaloacetic acid. This is the correct answer.
- **Succinic dehydrogenase**: This enzyme is involved in the Krebs cycle and does not participate in the C4 pathway. Thus, it is incorrect.
- **RUBP carboxylase-oxygenase**: This enzyme is primarily associated with C3 plants, not C4 plants, making it incorrect.
- **Hexokinase**: This enzyme phosphorylates hexoses and is not involved in the carboxylation process in C4 plants, hence it is also incorrect.

6. **Conclusion**:
- The enzyme responsible for primary carboxylation in C4 plants is **PEP carboxylase**.

### Final Answer:
The enzyme responsible for primary carboxylation in C4 plants is **PEP carboxylase**.

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