Q. E.coli cells with a mutated z gene of the lac operon cannot grow in medium containing only lactose as the source of energy because
A) the lac operon is constitutively active in these cells
B) they cannot synthesise functional beta galactosidase
C) in the presence of glucose, E.coli cells do not utilise lactose
D) they cannot transport lactose from the medium into the cell.
Explanation
The correct answer is Option B: they cannot synthesise functional beta galactosidase.
A detailed explanation for this question is being prepared.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.