Photorespiratioin in `C_(3)` plants starts from

Options

A. Phosphoglycerate
B. Glycerate
C. Glycine
D. Phosphoglycolate

Answer

To answer the question "Photorespiration in C3 plants starts from," we will follow these steps:

### Step 1: Understand Photorespiration
Photorespiration is a process that occurs in plants, particularly in C3 plants, where oxygen (O2) is consumed and carbon dioxide (CO2) is released. This process is often considered wasteful because it can reduce the efficiency of photosynthesis.

**Hint:** Remember that photorespiration is a process that competes with photosynthesis and is more prominent in C3 plants.

### Step 2: Identify the Role of Rubisco
In C3 plants, the enzyme ribulose bisphosphate carboxylase/oxygenase (commonly known as Rubisco) plays a crucial role. It catalyzes the reaction between ribulose bisphosphate (RuBP) and CO2 to form two molecules of 3-phosphoglycerate (3-PGA). However, Rubisco can also bind to O2, leading to a different pathway.

**Hint:** Rubisco is the enzyme that can bind both CO2 and O2, which is key to understanding the start of photorespiration.

### Step 3: Formation of Phosphoglycolate
When Rubisco binds to O2 instead of CO2, it leads to the formation of phosphoglycolate instead of 3-PGA. Phosphoglycolate is a two-carbon compound that initiates the photorespiratory pathway.

**Hint:** Focus on the product formed when Rubisco reacts with O2, as this is crucial for identifying the starting point of photorespiration.

### Step 4: Conclude the Starting Point
Since photorespiration begins with the formation of phosphoglycolate, we can conclude that the process starts from this compound in C3 plants.

**Hint:** The key compound that marks the beginning of photorespiration in C3 plants is phosphoglycolate.

### Final Answer
Photorespiration in C3 plants starts from **phosphoglycolate**.