Bundle sheath cells

Options

A. Are rich in RuBisCO
B. Are rich in PEP carboxlase
C. Lack RubisCO
D. Lack both RuBisCO and PEP carboxylase

Answer

### Step-by-Step Solution:

1. **Understanding Bundle Sheath Cells**:
- Bundle sheath cells are specialized cells found in C4 plants. They play a crucial role in the photosynthetic process, particularly in the C4 pathway.

2. **C4 Plants and Kranz Anatomy**:
- In C4 plants, bundle sheath cells are arranged in a specific anatomical structure known as Kranz anatomy. This arrangement consists of bundle sheath cells surrounding vascular bundles, with mesophyll cells located outside of them.

3. **Enzymes in Bundle Sheath Cells**:
- The bundle sheath cells contain chloroplasts and are rich in the enzyme ribulose bisphosphate carboxylase/oxygenase (Rubisco). This enzyme is essential for the Calvin cycle, where it catalyzes the carboxylation of ribulose bisphosphate (RuBP).

4. **Enzymes in Mesophyll Cells**:
- In contrast, the mesophyll cells contain the enzyme phosphoenolpyruvate carboxylase (PEP carboxylase), which is responsible for the initial fixation of carbon dioxide into a 4-carbon compound.

5. **Evaluating the Options**:
- The question provides four options regarding the characteristics of bundle sheath cells:
- **Option 1**: Bundle sheath cells are rich in Rubisco. (True)
- **Option 2**: Bundle sheath cells are rich in PEP carboxylase. (False, as PEP carboxylase is found in mesophyll cells)
- **Option 3**: Bundle sheath cells lack Rubisco. (False, they contain Rubisco)
- **Option 4**: Bundle sheath cells lack both Rubisco and PEP carboxylase. (False, they contain Rubisco)

6. **Conclusion**:
- Based on the analysis, the correct answer is that bundle sheath cells are rich in Rubisco.