Given below are two statements: one is labelled as Assertion and the other is labelled as Reason. Assertion: Addition of lactose to the culture medium of E. coli switches on the lac operon. Reason: Lactose binds to the operator region, preventing the repressor protein from binding to it. In the light of the above statements, choose the most appropriate answer from the options given below:

Step-by-step solution

The Assertion is true because lactose acts as an inducer for the lac operon; its addition to the culture medium switches on the operon to allow the metabolism of lactose. The Reason is false because lactose does not bind to the operator region. Instead, it binds to the repressor protein, inactivating it so that the repressor cannot bind to the operator region. This allows RNA polymerase to access the promoter and initiate transcription. Answer: Assertion is true but Reason is false.