The substrate for photorespiration is

Options

A. Phosphoenol pyruvic acid
B. Ribulose bi phosphate
C. ATP
D. RuBis CO

Answer

To determine the substrate for photorespiration, we need to understand the process and the role of the enzyme involved. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Understanding Photorespiration**:
- Photorespiration is a process that occurs in plants, particularly in C3 and C4 plants. It is a metabolic pathway that occurs when the enzyme Rubisco reacts with oxygen instead of carbon dioxide.

2. **Identifying the Role of Rubisco**:
- The enzyme responsible for the initial step of both photosynthesis and photorespiration is Ribulose bisphosphate carboxylase/oxygenase, commonly known as Rubisco. This enzyme can catalyze reactions with both CO2 and O2.

3. **Substrates Involved**:
- In the case of photorespiration, Rubisco binds to O2 instead of CO2. The substrate for photorespiration is the molecule that Rubisco acts upon during this process.

4. **Analyzing the Options**:
- The options given are:
- A) Phosphoenolpyruvic acid
- B) Ribulose bisphosphate
- C) ATP
- D) Rubisco
- Among these, Ribulose bisphosphate (RuBP) is the substrate that Rubisco acts upon during the process of photorespiration.

5. **Conclusion**:
- Therefore, the substrate for photorespiration is **Ribulose bisphosphate (RuBP)**.

### Final Answer:
The substrate for photorespiration is **Ribulose bisphosphate (RuBP)**.

---