Primary carboxylation occurs in `C_(3)` and `C_(4)` plants with the help of

Options

A. `PEP` carboxylase and pyruvate carboxylase
B. `PEP` carboxylase and `RuBP` carboxylase
C. `RuBP` carboxylase and `PEP` carboxylase
D. `RuBP` carboxylase and pyruvate carboxylase.

Answer

To solve the question about primary carboxylation in C3 and C4 plants, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Carboxylation**:
- Carboxylation is a chemical reaction where carbon dioxide (CO2) is incorporated into an organic compound. This process is crucial for photosynthesis as it helps in the formation of carbohydrates.

2. **Identify the Types of Plants**:
- There are two main types of plants based on their photosynthetic pathways: C3 plants and C4 plants.

3. **Primary Carboxylation in C3 Plants**:
- In C3 plants, the primary carboxylation occurs when CO2 is fixed to ribulose bisphosphate (RuBP) using the enzyme ribulose bisphosphate carboxylase (commonly known as Rubisco).
- This reaction produces 3-phosphoglycerate (3-PGA), a three-carbon compound.

4. **Primary Carboxylation in C4 Plants**:
- In C4 plants, the primary carboxylation occurs when CO2 is fixed to phosphoenolpyruvate (PEP) using the enzyme phosphoenolpyruvate carboxylase (PEP carboxylase).
- This reaction produces oxaloacetate, a four-carbon compound.

5. **Identify the Correct Enzymes**:
- For C3 plants, the enzyme is Rubisco (RUBP carboxylase).
- For C4 plants, the enzyme is PEP carboxylase.

6. **Evaluate the Options**:
- The question provides several options regarding which enzymes are involved in primary carboxylation in C3 and C4 plants.
- The correct answer would include both RUBP carboxylase and PEP carboxylase.

### Conclusion:
The correct answer to the question is: **RUBP carboxylase and PEP carboxylase**.

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