Which of the following factors leads to the conversion of the Bt toxin present in Bt cotton plant tissue into an active toxin? Choose the correct option:

Alkaline pH of the insect gut

The correct answer is (c) The alkaline pH of the insect gut.

In Bt cotton, the Bt toxin is present in the plant tissue as an inactive form called protoxin. When insects consume the Bt cotton, the alkaline pH of their gut triggers a series of reactions that lead to the conversion of the protoxin into an active toxin.

The alkaline environment of the insect gut causes the protoxin to undergo proteolytic cleavage. This cleavage process separates the protoxin into smaller fragments, one of which is the active form of the toxin. Once the active toxin is released, it binds to specific receptors present in the insect's gut lining, leading to the disruption of cell membranes and ultimately causing the death of the insect.

It is important to note that the acidic pH of the insect gut (option b) is not responsible for the activation of the Bt toxin. The alkaline pH is the key factor that triggers the conversion of the protoxin into the active toxin.

The action of gut microorganisms (option c) is not directly involved in the conversion of the Bt toxin. However, some gut microorganisms can potentially enhance the effectiveness of the Bt toxin by producing toxins of their own or by increasing the susceptibility of insects to the Bt toxin.

The presence of conversion factors in the insect gut (option d) is not a recognized mechanism for the activation of the Bt toxin. The conversion of the protoxin into the active toxin is primarily driven by the alkaline pH of the insect gut.