ReNEET 2026 · Biology · Q153Molecular Basis of InheritanceIn our bank: Strong match · 88%
Which of the following statements about the lac-operon is correct?
- A.Gene i is constitutively expressed✓
- B.Lactose activates the repressor to bind to the operator
- C.Genes i, z, y and a share a single common promoter
- D.Galactose can act as an inducer of the lac operon
Correct Answer
(A) Gene i is constitutively expressed
Solution & Explanation
The regulatory gene i is expressed constitutively (always on) to make the repressor. Lactose (its isomer allolactose), not galactose, is the inducer and it INACTIVATES the repressor (so the repressor binds operator only in the ABSENCE of lactose). The structural genes z, y, a share a promoter, but gene i has its own promoter. So only statement (1) is correct.
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