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NEET2026ZoologyMolecular Basis of InheritanceActual

Which of the following statements about lac-operon is correct ?

Options

  1. AGalactose can act as an inducer of lac operon
  2. BGene i is constitutively expressed
  3. CLactose activates repressor to bind to the operator
  4. DGenes i , z , y and a share single common promoter

Correct answer

B. Gene i is constitutively expressed

Step-by-step solution

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

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