The enzyme RuBP carboxylase

Options

A. Activity occurs in `C_(3) and C_(4)` plants
B. Is present in inner thylakoid membrane
C. Is low temperature sensitive enzyme
D. Show greater affinity for `CO_(2)`

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Enzyme**: The enzyme in question is RuBP carboxylase, commonly referred to as Rubisco. It plays a crucial role in the process of photosynthesis, specifically in the fixation of carbon dioxide.

2. **Function of Rubisco**: Rubisco catalyzes the first step of the Calvin cycle, which is a series of light-independent reactions in photosynthesis. This enzyme facilitates the conversion of ribulose bisphosphate (RuBP) and carbon dioxide into 3-phosphoglycerate (3-PGA).

3. **Location of Rubisco**:
- In C3 plants, Rubisco is found in the mesophyll cells.
- In C4 plants, it is located in the bundle sheath cells.
This indicates that Rubisco is present in both C3 and C4 plants.

4. **Evaluating the Statements**:
- **Statement A**: "Activity occurs in C3 and C4 plants." - This statement is correct as established.
- **Statement B**: "Present in inner thylakoid membrane." - This statement is incorrect; Rubisco is not located in the thylakoid membrane.
- **Statement C**: "It is a low temperature sensitive enzyme." - This statement is also incorrect; Rubisco is not particularly sensitive to low temperatures.
- **Statement D**: "It shows greater affinity for carbon dioxide." - While Rubisco does have an affinity for carbon dioxide, it also has a tendency to react with oxygen, which can lead to photorespiration. Thus, this statement is misleading.

5. **Conclusion**: Based on the analysis, the only correct statement regarding RuBP carboxylase is that its activity occurs in both C3 and C4 plants. Therefore, the correct answer is option A.

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