Zoology - Molecular Basis of Inheritance Question with Solution | TestHub

The $i$ gene in the lac operon codes for the repressor protein. It is a regulatory gene that is constitutively expressed, meaning it is transcribed continuously to maintain a basal level of repressor in the cell.

Galactose does not act as an inducer of the lac operon; lactose or allolactose serves as the inducer.

Lactose binds to the repressor protein and inactivates it, preventing it from binding to the operator region.

Genes $z$, $y$, and $a$ are structural genes that share a single common promoter, whereas the $i$ gene has its own separate promoter.

Answer: Gene $i$ is constitutively expressed