How is the cell in diagram b effectively using its resources?

since lactose is absent, the repressor protein is blocking the genes and stopping transcription.

since lactose is present, the repressor protein will begin transcription.

the cell continually produces the enzymes needed to break down lactose.

rna polymerase is transcribing the genes since lactose is present.

Since lactose is absent, the repressor protein is blocking the genes and stopping transcription.

Option A.

Lac operon or lactose operon is the genetic mechanism of the cell to produce the enzyme digesting lactose by production of lactase enzymes. The bacterial cell has this mechanism of lac operon which controls the production of definite amount of lactase only in presence of lactose, to minimize the wastage of proteins.

In the lac operon, there are cap sites, promoter region, operator region, and the genes producing enzymes. In presence of lactose, protein produced from the promoter attaches with the lactose which acts as inducer and frees up the operator sites for RNA polymerase to act. But in absence of glucose, the operator site remains blocked, as in figure B, restricting the lactase production.

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands