Which one of the following is not a feature of insecticidal protein c…

The correct answer is Option (4) → The activated toxin does not bind the surface of midgut epithelial cells which leads to pore formation, cell swelling and lysis.

Some strains of Bacillus thuringiensis form protein crystals that kill certain insects. The bacterium itself is not harmed, because inside it the protein stays inactive.

Option (1) When formed they exist as inactive protoxin. — A feature of the Bt protein crystals. The protein is made as an inactive protoxin, so it does not harm the bacterium.

Option (2) They are converted into an active form of toxin in the alkaline pH of the gut, which solubilize the crystals. — A feature of the Bt protein crystals. When an insect eats it, the alkaline pH of the insect gut dissolves the crystals and activates the toxin.

Option (3) They are effective against certain insects such as lepidopterans, coleopterans and dipterans. — A feature of the Bt protein crystals. Bt toxins kill certain insect groups: moth and butterfly caterpillars, beetles, and flies and mosquitoes.

Option (4) The activated toxin does not bind the surface of midgut epithelial cells which leads to pore formation, cell swelling and lysis. — Not a feature of the Bt protein crystals. The activated toxin does bind to the surface of the midgut epithelial cells. It makes pores in them, so they swell and burst, and the insect dies. NTA slipped “does not” into the book’s line, and a true fact turned false. Two little words can flip a whole option, so slow down at every “not”.

NCERT Extract:
Biotechnological Applications in Agriculture – …