Phosphoenol pyruvate (PEP) is the primary `CO_(2)` acceptor in

Options

A. `C_(3)` plants
B. `C_(4)` plants
C. `C_(2)` plants
D. `C_(3) and C_(4) plants`

Answer

To solve the question "Phosphoenol pyruvate (PEP) is the primary CO2 acceptor in," we will follow these steps:

### Step 1: Understand the Role of PEP
Phosphoenol pyruvate (PEP) is a three-carbon molecule that plays a crucial role in the process of photosynthesis, particularly in certain types of plants.

**Hint:** Remember that PEP is involved in the initial steps of carbon fixation.

### Step 2: Identify the Types of Plants
There are different types of plants based on their photosynthetic pathways, primarily C3, C4, and CAM (Crassulacean Acid Metabolism) plants.

**Hint:** Think about the characteristics of C4 plants and how they differ from C3 and CAM plants.

### Step 3: Focus on C4 Plants
In C4 plants, the initial fixation of CO2 occurs in the mesophyll cells, where PEP acts as the primary CO2 acceptor. The enzyme responsible for this reaction is called PEP carboxylase.

**Hint:** C4 plants are known for their efficient CO2 fixation and have a specific enzyme that utilizes PEP.

### Step 4: The Reaction Involving PEP
When CO2 is fixed in C4 plants, PEP combines with CO2 in the presence of PEP carboxylase to form oxaloacetic acid (OAA), a four-carbon compound.

**Hint:** Remember the product formed when PEP combines with CO2.

### Step 5: Conclusion
Based on the above information, we can conclude that phosphoenol pyruvate (PEP) is the primary CO2 acceptor in C4 plants.

**Final Answer:** Hence, the correct answer is option second, C4 plants.

### Summary of Steps:
1. Understand the role of PEP in photosynthesis.
2. Identify different types of plants (C3, C4, CAM).
3. Focus on the role of PEP in C4 plants.
4. Recall the reaction that occurs with PEP and CO2.
5. Conclude that PEP is the primary CO2 acceptor in C4 plants.