NEET 2011 Biology question

Bacillus thuringiensis forms protein crystals which contain insecticidal protein.

(1)Binds with epithelial cells of midgut of the insect pest ultimately killing itCorrect
(2)is coded by several genes including the gene cry
(3)is activated by acid pH of the foregut of the insect pest.
(4)does not kill the carrier bacterium which is itself resistant to this toxin

Answer: (1)

Solution

The Cry proteins of Bt are present in the bacterium as inactive protoxins. When an insect larva ingests them, the alkaline pH of the insect gut solubilises the crystals and activates the toxin; the active toxin binds to the surface of the midgut epithelial cells, creates pores, causes cell swelling and lysis, and

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Question ID VK-090687