Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The lac operon is completely turned off in the absence of an inducer, with absolutely no basal level of expression. Reason (R): Lactose cannot enter the bacterial cell if permease is completely absent. In the light of the above statements, choose the most appropriate answer from the options given b

Step-by-step solution

NCERT explicitly states that a very low level of expression of the lac operon has to be present in the cell all the time. Therefore, the Assertion is false because the operon is never completely shut down with zero expression. This basal level of expression ensures that a small amount of permease (the product of the y gene) is always available in the cell membrane. The Reason is true because permease is essential for the transport of lactose into the cell. If permease were completely absent, lactose from the surrou