Which of the following best describes the biological role of the lac operon? a) It prevents other sugars from being metabolized until all available lactose has been used. b) It ensures that a cell dedicates resources to the production of enzymes involved in lactose metabolism only when lactose is available in the environment. c) It ensures that a cell produces enzymes involved in lactose metabolism in a constitutive manner. d) It ensures that bacterial cells produce lactose only when no other food sources are available.

Answer: B

Explanation:

The biological role of the lac operon is that it ensures that a cell dedicates resources to the production of enzymes involved in lactose metabolism only when lactose is available in the environment.

The lac operon coordinate the transport and metabolism of lactose in Escherichia coli and other bacteria.

The lacZ gene encodes beta-galactosidase, the enzyme that hyrolyzes lactose to galactose and glucose.

The lacY gene is responsible for the production of permease which transport lactose and galactose into the cell.

The lacA gene codes for thiogalactoside transacetylase.