In Bt cotton, the Bt toxin present in plant tissue as pro-toxin is converted into active toxin due to

Options

A. Acidic pH of the insect gut
B. Action of gut micro-organisms
C. Presence of conversion factors in insect gut
D. Alkaline pH of the insect gut

Answer

### Step-by-Step Text Solution

1. **Understanding Bt Cotton**: Bt cotton is a genetically modified organism (GMO) that has been engineered to express a toxin from the bacterium *Bacillus thuringiensis* (Bt). This toxin is effective against certain insect pests.

2. **Role of the Toxin**: The toxin produced by *Bacillus thuringiensis* is initially in an inactive form known as a protoxin. This form is not harmful until it undergoes a transformation.

3. **Ingestion by Insects**: When an insect feeds on Bt cotton, it ingests the protoxin present in the plant tissue.

4. **Activation of the Toxin**: The conversion of the protoxin into the active toxin occurs in the insect's gut. Specifically, this transformation is triggered by the alkaline pH conditions found in the gut of the insect.

5. **Mechanism of Action**: Once activated, the toxin binds to the gut wall of the insect, leading to swelling and the formation of pores in the gut lining. This disrupts the gut function, ultimately resulting in the death of the insect.

6. **Conclusion**: Therefore, the correct answer to the question is that the protoxin is converted into the active toxin due to the alkaline pH of the insect gut.