A mutant is found in which the operon is uninducible. Assuming the affected gene makes a protein, what kind of

Answer 1

One mutation would be to mutate the repressor protein so that it no longer binds lactose. Then, it will always be bound to the operator region of the operon so that transcription is always blocked.

Other mutations either in the operator or in the repressor protein gene could make the operon always be "on" and thus uninducible, too.