Genes that are involved in turning on or off the transcription of a set of structural genes are called:

In the $lac$ operon, what does the term "$lac$" refer to?

In the $lac$ operon concept of gene expression,allolactose acts as:

Who proposed the operon model for the first time?

At what level does gene expression not occur?

Given below are two statements:
Statement $I$: In lac operon,the repressor protein binds to the promoter region of the operon and prevents $\text{RNA}$ polymerase from transcribing the operon.
Statement $II$: Regulation of lac operon can also be visualized as regulation of enzyme synthesis by its substrate.
In the light of the above statements,choose the correct answer from the options given below: