Topic: Gene regulation: lac operon· Genetics and Evolution

Which of the following is required as inducer(s) for the expression of Lac operon ?

1. glucose

2. galactose

3. lactose

4. lactose and galactose

Doubtly Asked 30 Oct 2026 NEET UG 2016 Phase 1 Practice test neet Save WhatsApp Report

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Answer: 3. lactose

Key idea: In the lac operon, lactose (as allolactose) is the inducer.

It binds the repressor protein, which then leaves the operator, so RNA polymerase can transcribe the structural genes (lacZ, lacY, lacA). Glucose and galactose do not act as inducers.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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Which of the following is required as inducer(s) for the expression of Lac operon ?

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