NEET 2026 (cancelled) · Question 101 · Class 12

Molecular Basis of Inheritance

In the *lac* operon, the *z* gene codes for :

  1. (A)the repressor of *lac* operon
  2. (B)transacetylase
  3. (C)permease
  4. (D)beta-galactosidase

The NCERT line that answers it

Verbatim line

The *z* gene codes for beta-galactosidase ( $\beta$ -gal), which is primarily responsible for the hydrolysis of the disaccharide, lactose into its monomeric units, galactose and glucose.

Chapter
Molecular Basis of Inheritance
Section
5.8.1 The Lac operon

The answer appears as a continuous sentence in NCERT. This is that sentence.

How this line gives the answer

0, emb=1.0, combined=1.0). Verified: high — The span explicitly states that the z gene codes for beta-galactosidase, which directly matches option D and distinguishes it from the other options.

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Question text is reproduced from the published NEET 2026 (cancelled) paper for study and commentary. NCERT text is quoted, not redistributed; textbooks remain at ncert.nic.in. Our mapping method, including its measured error rates, is published at /methodology.