Photorespiration , usually occurs in :-

Options

A. one-cell organelles
B. two cell organelles
C. three cell organelles
D. four cell organelles

Explanation

To solve the question regarding where photorespiration usually occurs, we can break it down into the following steps:

### Step 1: Understand the Process of Photorespiration
Photorespiration is a process that occurs in plants where the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (commonly known as rubisco) reacts with oxygen instead of carbon dioxide. This typically happens when the concentration of oxygen is high and the concentration of carbon dioxide is low.

**Hint:** Remember that rubisco can function as both a carboxylase and an oxygenase depending on the concentration of CO2 and O2.

### Step 2: Identify the Role of Rubisco
Rubisco is crucial for the process of photosynthesis and photorespiration. In photorespiration, rubisco catalyzes the reaction of ribulose-1,5-bisphosphate (RuBP) with oxygen, leading to the production of phosphoglycolate and phosphoglycerate.

**Hint:** Focus on the dual role of rubisco and how it affects the process based on the gas concentrations.

### Step 3: Recognize the Organelles Involved
Photorespiration involves three specific organelles:
1. **Chloroplasts** - where the initial reaction occurs.
2. **Peroxisomes** - where glycolate is metabolized.
3. **Mitochondria** - where further processing of the products occurs.

**Hint:** Think about the cellular locations where the different stages of photorespiration take place.

### Step 4: Conclude the Answer
Since photorespiration requires the involvement of chloroplasts, peroxisomes, and mitochondria, the correct answer to the question is that photorespiration usually occurs in **three organelles**.

**Hint:** Count the organelles involved in the process to confirm your answer.

### Final Answer
Photorespiration usually occurs in **three organelles**: chloroplasts, peroxisomes, and mitochondria.