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

Options

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

Answer

**Step-by-Step Solution:**

1. **Understanding Bt Cotton**: Bt cotton is a genetically modified organism (GMO) that has been engineered to express a gene from the bacterium *Bacillus thuringiensis* (Bt). This gene encodes for a protein that acts as an insecticide.

2. **Nature of Bt Toxin**: In Bt cotton, the toxin produced is initially in an inactive form known as 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 along with the plant material.

4. **Environment of Insect Gut**: The protoxin reaches the gut of the insect, where it encounters the gut environment. The gut of many insects, including those that feed on Bt cotton, has an alkaline pH.

5. **Conversion to Active Toxin**: The alkaline pH of the insect gut is crucial because it facilitates the conversion of the protoxin into its active form. This active toxin is what exerts the insecticidal effect, leading to the death of the pest.

6. **Conclusion**: Therefore, the conversion of the Bt toxin from protoxin to active toxin in Bt cotton occurs due to the alkaline pH of the insect gut.

**Final Answer**: The Bt toxin present in plant tissue as protoxin is converted into active toxin due to the alkaline pH of the insect gut.

---