NEETZoologyBiotechnology and Its Applications
A cotton bollworm feeds on a transgenic cotton plant that expresses the cryIIAb gene. Which of the following correctly describes the primary physiological mechanism that leads to the death of this specific pest?
Options
- AThe acidic pH of the insect gut activates the protoxin, which then binds to the foregut and prevents feeding.
- BThe expressed protein is ineffective against the cotton bollworm, but it causes starvation by blocking the ins
- CThe alkaline pH of the insect midgut solubilises the inactive protoxin into an active form that creates pores
- DThe active toxin is absorbed into the insect's haemolymph where it inhibits cellular respiration and ATP synth
Correct answer
C. The alkaline pH of the insect midgut solubilises the inactive protoxin into an active form that creates pores
Step-by-step solution
The gene cryIIAb encodes a Bt toxin protein that specifically targets and controls the cotton bollworm. When the insect ingests the plant tissue, the Bt toxin exists as an inactive protoxin. It is converted into an active form of toxin due to the alkaline pH of the insect's midgut, which solubilises the protein crystals. The activated toxin then binds to the surface of the midgut epithelial cells, creating pores that cause cell swelling and lysis, eventually leading to the death of the insect. Options stating acidi