Step 1: Functions of the lac operon genes.
- 'i' gene: Encodes the repressor protein.
- 'z' gene: Encodes $\beta$-galactosidase, an enzyme that hydrolyzes lactose.
- 'a' gene: Encodes transacetylase.
- 'y' gene: Encodes lac permease, a transporter protein facilitating lactose uptake.
| List I | List II | ||
|---|---|---|---|
| A | Two or more alternative forms of a gene | I | Back cross |
| B | Cross of F1 progeny with homozygous recessive parent | II | Ploidy |
| C | Cross of F progeny with any of the parents | III | Allele |
| D | Number of chromosome sets in plant | IV | Test cross |