Question

The Bt toxin in genetically engineered Bt cotton kills the pest by:

• A. Creating pores in the midgut
• B. Damaging the respiratory system
• C. Degenerating the nervous system
• D. Altering the pH of body fluids

Answer 1

The Correct Option is A

Bt cotton is a genetically modified variety of cotton that produces an insecticidal toxin derived from the bacterium Bacillus thuringiensis (Bt). This Bt toxin is specifically designed to target certain pests, primarily the larval stages of moths and butterflies, which can cause significant damage to cotton crops. The Bt toxin functions as follows:

1. Ingestion by Pests: When pests such as bollworms feed on Bt cotton, they ingest the Bt toxin present in the plant.
2. Activation of Bt Toxin: Inside the pest's alkaline gut, the Bt toxin gets activated. This transformation is crucial because only the activated toxin can affect the pest.
3. Binding to Midgut Cells: The activated Bt toxin binds to specific receptors on the surface of the midgut cells of the pest.
4. Creating Pores in the Midgut: Once bound, the Bt toxin causes the formation of pores or holes in the wall of the midgut cells. This ultimately disrupts the cellular integrity of the midgut.
5. Death of Pest: The formation of pores leads to cell leakage and subsequently collapses the gut wall integrity, resulting in septicemia and death of the pest.

This mechanism of action is highly selective and does not affect mammals or non-target organisms, making Bt cotton an effective and environmentally friendly pest control solution.

Based on this explanation, the correct answer is: Creating pores in the midgut.