The first acceptor of `CO_(2) ` in `C _(4)` pathway is (A) RuBP carboxylase (B) PEP carboxylase (C) RuBP oxygenase (D) RuP carboxylase

Options

A. RuBP carboxylase
B. PEP carboxylase
C. RuBP oxygenase
D. RuP carboxylase

Answer

To solve the question regarding the first acceptor of CO2 in the C4 pathway, we can follow these steps:

### Step 1: Understand the C4 Pathway
The C4 pathway is a photosynthetic process that involves carbon fixation. It is named for the first stable product formed, which is a four-carbon compound (oxaloacetate).

**Hint:** Remember that the C4 pathway is characterized by the formation of a four-carbon compound.

### Step 2: Identify the Initial Acceptors of CO2
In the C4 pathway, the initial acceptor of CO2 is a three-carbon compound known as phosphoenolpyruvate (PEP).

**Hint:** Look for the three-carbon compound that plays a role in accepting CO2 in the C4 pathway.

### Step 3: Recognize the Enzyme Involved
The enzyme that catalyzes the reaction where CO2 is fixed to phosphoenolpyruvate is called phosphoenolpyruvate carboxylase (PEP carboxylase).

**Hint:** Focus on the enzyme that facilitates the reaction between CO2 and phosphoenolpyruvate.

### Step 4: Evaluate the Given Options
Now, let's evaluate the options provided in the question:
- (A) RuBP carboxylase: This is involved in the Calvin cycle, not the C4 pathway.
- (B) PEP carboxylase: This is the correct enzyme that catalyzes the reaction in the C4 pathway.
- (C) RuBP oxygenase: This is also related to the Calvin cycle and not the C4 pathway.
- (D) RuP carboxylase: This is not a recognized enzyme in the context of the C4 pathway.

**Hint:** Eliminate options that are related to the Calvin cycle and focus on the enzyme specific to the C4 pathway.

### Conclusion
The first acceptor of CO2 in the C4 pathway is phosphoenolpyruvate, and the enzyme that catalyzes this reaction is phosphoenolpyruvate carboxylase. Therefore, the correct answer is:

**(B) PEP carboxylase.**