The first carbon dioxide acceptor in `C_(4)`-plants is

Options

A. RuDP carboxylase
B. Phosphoric acid
C. RUBISCO
D. PEP-Carboxylase

Answer

To solve the question regarding the first carbon dioxide acceptor in C4 plants, we can follow these steps:

### Step 1: Understand the C4 Photosynthesis Pathway
C4 plants utilize a unique photosynthetic pathway that differs from C3 plants. In C4 photosynthesis, carbon dioxide is initially fixed into a four-carbon compound.

**Hint**: Remember that C4 plants have a special mechanism to efficiently capture CO2, especially in hot and dry environments.

### Step 2: Identify the Primary Carbon Dioxide Acceptor
In C4 plants, the first compound that CO2 combines with is phosphoenolpyruvate (PEP), which is a three-carbon compound.

**Hint**: Look for the three-carbon compound that acts as the initial acceptor of CO2 in the C4 pathway.

### Step 3: Recognize the Role of Enzymes
The enzyme responsible for catalyzing the reaction where CO2 is added to phosphoenolpyruvate is called PEP carboxylase (PEPC). This enzyme facilitates the carboxylation of PEP to form oxaloacetic acid (OAA), a four-carbon compound.

**Hint**: Enzymes play a crucial role in biochemical reactions; identify which enzyme is involved in the carboxylation process.

### Step 4: Conclusion
The first carbon dioxide acceptor in C4 plants is phosphoenolpyruvate (PEP), and the enzyme that catalyzes this reaction is PEP carboxylase.

**Final Answer**: The first carbon dioxide acceptor in C4 plants is phosphoenolpyruvate (PEP), and the correct option is PEP carboxylase.

### Summary of Steps:
1. Understand the C4 pathway.
2. Identify the primary carbon dioxide acceptor (PEP).
3. Recognize the role of PEP carboxylase in the process.
4. Conclude with the correct answer.