5. the blob operon produces enzymes that convert compound a into compound b. the operon is controlled by a regulatory gene s. normally these enzymes are synthesized only in the absence of compound b. if gene s is mutated, the enzymes are synthesized in the presence of b and in the absence of b. does gene s produce a repressor or an activator? is this operon inducible or repressible?

Repressor and repressible.

Explanation:

Operon may be defined as the functional unit of the DNA that contains the cluster of genes. These genes are transcribed by the single promoter and works as polycistronic gene.

The blob operon is inactive in the presence of the B. Here, Gene S may acts as a repressor protein and requires the  B compound to work as a corepressor. The blob operon acts as the repressible as it is inactive in the presence of B compound and become active only when the B compound is absent.

Thus, the answer is repressor and repressible.