Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Bacillus thuringiensis is not killed by the B t toxin protein it produces. Reason (R): The toxin exists as an inactive protoxin that requires the alkaline pH of the insect midgut to become active and create cytolytic pores. In the light of the above statements, choose the correct answer from the op

Step-by-step solution

The Assertion is true because the bacterium Bacillus thuringiensis produces the B t toxin but is not harmed by it. The Reason is also true and correctly explains the Assertion. The B t toxin protein exists as an inactive protoxin within the bacterium. It only becomes an active, pore-forming toxin when it is ingested by an insect and exposed to the alkaline pH of the insect's midgut, which solubilizes the protein crystals. Since the bacterium lacks this alkaline environment, the toxin remains inactive and does not k