Q. Bacillus thuringiensis forms protein crystals which contain insecticidal protein. This protein:
A) Is activated by acid pH of the foregut of the insect pest
B) Does not kill the carrier bacterium which is itself resistant to this toxin
C) Binds with epithelial cells of midgut of the insect pest ultimately killing it
D) Is coded by several genes including the gene cry
Explanation
[Solution from source] Bt protoxin is activated by the alkaline pH of the insect's gut; the active toxin binds to midgut epithelial cells, makes pores and kills the insect. The bacterium is not harmed because it keeps the toxin as an inactive protoxin, not because it is resistant, and acid pH does not activate it. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.