Biology 2nd Edition by Robert Brooker, Eric Widmaier ,Linda Graham ,Peter Stiling

Exercise 13

For the lac operon, what would be the expected effects of a mutation in the operator site that prevented the binding of the repressor protein
A) The operon would always be turned on.
B) The operon would always be turned off.
C) The operon would always be turned on, except when glucose is present.
D) The operon would be turned on only in the presence of lactose.
E) The operon would be turned on only in the presence of lactose and the absence of glucose.