During lactose metabolism in $E. coli$,the repressor protein binds to the ...........

In the medium where $E$. coli was growing, lactose was added, which induced the lac operon. Then, why does the lac operon shut down some time after the addition of lactose in the medium?

Wild type $E. coli$ cells are growing in a normal medium with glucose. They are transferred to a medium containing only lactose as the sugar. Which one of the following changes takes place?

Identify the $INCORRECT$ statement with reference to the regulation of gene expression.

An environmental agent that triggers transcription from an operon is a:

In a negative operon,