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In the absence of lactose, the lac operon is:
AMaximally transcribed
BTranscribed at high levels even without lactose
CPermanently deleted from the genome
DRepressed — the i gene product (lac repressor) binds the operator and prevents transcription
Answer & Solution
Correct answer: D. Repressed — the i gene product (lac repressor) binds the operator and prevents transcription
Default state of lac operon (no lactose) = **repressed**. The repressor (i gene product) constitutively binds the operator. Transcription only occurs when lactose is present (inducer) AND glucose is absent (positive regulation by CAP-cAMP — beyond NCERT class XII scope).
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