The lac regulatory system is important to bacteria because the sugar lactose
A)cannot be made by bacteria unless the genes are turned on.
B)is the most common source of food;enzymes are needed all the time.
C)is only rarely available;producing enzymes all the time is costly.
D)is incorporated into the nucleic acid of the bacteria.
E)switches the system off and on whether lactose is present or not.

Question

Quizplus · Accepted Answer

The lac regulatory system is important because lactose is only rarely available as a source of food for bacteria, so producing enzymes all the time would be a waste of energy. The system turns on the necessary genes only when lactose is present.

The Lac Regulatory System Is Important to Bacteria Because the Sugar