Assess students' understanding of molecular mechanisms controlling the E. coli lac operon in response to glucose and lactose availability, including lac repressor/allolactose induction, cAMP–CRP activation, catabolite repression and inducer exclusion, promoter/operator interactions, predicted gene expression states under no sugar, lactose only, glucose only, and both sugars, and interpretation of simple lacZ/β‑galactosidase experimental readouts.