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Molecular Basis of Inheritance · Question 5

RE-NEET (UG) 2026MCQMedium📈 Topic in 88% papers+4−1
1

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

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

Answer

(2) Gene i is constitutively expressed

Solution

(1) Incorrect: As per NCERT, lactose (not galactose) is the inducer of the lac operon.

(2) Correct: The repressor of the operon is synthesised (all the time – constitutively) from the i gene.

(3) Incorrect: Lactose (inducer) binds the repressor and inactivates it, so the repressor cannot bind the operator.

(4) Incorrect: The structural genes z, y and a are transcribed from a common promoter; the regulatory gene i has its own promoter.

Answer: (2)

RE-NEET (UG) 2026

Keep practising — Molecular Basis of Inheritance

2

Which of the following enzymes synthesizes precursor mRNA?

  1. DNA polymerase
  2. RNA polymerase I
  3. RNA polymerase II
  4. RNA polymerase III
RE-NEET (UG) 2026
3

Which chromosome in the human genome has the highest number of genes?

  1. Chromosome 1
  2. Chromosome 10
  3. Chromosome X
  4. Chromosome Y
NEET (UG) 2025
4

Match List-I with List-II Choose the correct answer from the options given below:

  1. A-IV, B-III, C-I, D-II
  2. A-III, B-II, C-IV, D-I
  3. A-II, B-IV, C-I, D-III
  4. A-IV, B-II, C-I, D-III
NEET (UG) 2025
5

Which of the following are the post-transcriptional events in a eukaryotic cell? Choose the correct answer from the options given below :

  1. B, C, E only
  2. C, D, E only
  3. A, B, C only
  4. B, C, D only
NEET (UG) 2025
6

Given below are two statements: In the light of the above statements, choose the most appropriate answer from the options given below :

  1. Statement I is correct but statement II is incorrect
  2. Statement I is incorrect but statement II is correct
  3. Both statement I and statement II are correct
  4. Both statement I and statement II are incorrect
NEET (UG) 2025
7

Given below are two statements : In the light of the above statements, choose the most appropriate answer from the options given below :

  1. Statement I is correct but statement II is incorrect
  2. Statement I is incorrect but statement II is correct
  3. Both statement I and statement II are correct
  4. Both statement I and statement II are incorrect
NEET (UG) 2025
8

Who proposed that the genetic code for amino acids should be made up of three nucleotides?

  1. Jacques Monod
  2. Franklin Stahl
  3. George Gamow
  4. Francis Crick
NEET (UG) 2025
9

Histones are enriched with -

  1. Phenylalanine & Leucine
  2. Phenylalanine & Arginine
  3. Lysine & Arginine
  4. Leucine & Lysine
NEET (UG) 2025
10

Which factor is important for termination of transcription?

  1. (rho)
  2. (gamma)
  3. (alpha)
  4. (sigma)
NEET (UG) 2025
11

The lactose present in the growth medium of bacteria is transported to the cell by the action of

  1. Beta-galactosidase
  2. Acetylase
  3. Permease
  4. Polymerase
NEET (UG) 2024

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