Enzymes `PEP` carboxylase and `RuBP` carboxylase are located in chloroplasts of

Options

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

Answer

To determine the plants in which the enzymes PEP carboxylase and RuBP carboxylase are located in the chloroplasts, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the enzymes and their functions**:
- **PEP carboxylase**: This enzyme is crucial for the initial fixation of carbon dioxide in the photosynthetic pathway. It catalyzes the reaction that forms oxaloacetic acid (OAA) from phosphoenolpyruvate (PEP) and carbon dioxide.
- **RuBP carboxylase (also known as Rubisco)**: This enzyme plays a key role in the Calvin cycle, where it catalyzes the reaction between ribulose bisphosphate (RuBP) and carbon dioxide to form 3-phosphoglycerate (3-PGA).

2. **Determine the location of PEP carboxylase**:
- PEP carboxylase is found in the mesophyll cells of **C4 plants** and **CAM plants**. It is not present in C3 plants.

3. **Determine the location of RuBP carboxylase**:
- RuBP carboxylase is found in the chloroplasts of **C3 plants**, **C4 plants**, and **CAM plants**. This enzyme is essential for carbon fixation in all three types of plants.

4. **Analyze the options**:
- **Option A (C3 plants)**: PEP carboxylase is not present; therefore, this option is incorrect.
- **Option B (CAM plants)**: Both enzymes are present; hence, this option is correct.
- **Option C (C4 plants)**: Both enzymes are present; hence, this option is also correct.
- **Option D (both B and C)**: Since both CAM and C4 plants contain both enzymes, this option is correct.

5. **Conclusion**:
- The correct answer is **Option D (both B and C)**, as both PEP carboxylase and RuBP carboxylase are located in the chloroplasts of CAM and C4 plants.