NEET Biology · Chapter-wise PYQs

Molecular Basis of Inheritance NEET PYQs (2005–2026) with Solutions

Molecular Basis of Inheritance has appeared in 22 of the 22 NEET and AIPMT papers from 2005 to 2026, with 98 questions in all: about 4.5 per paper on average. The last five papers (2022–2026) had 29 questions from it.

The most-asked topics are DNA and RNA (25), Transcription (22) and Genetic Code and Translation (14).

NEET MIND's syllabus map rates Molecular Basis of Inheritance as high weightage: about 6 questions (24 marks) in a NEET paper.

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Free account: 15 PYQs from Molecular Basis of Inheritance with explanations and progress tracking. Premium unlocks all 98.

PYQs in this chapter
98
Papers it appeared in
22 of 22
Average per paper
4.5
NEET weightage
High

10 solved Molecular Basis of Inheritance PYQs

Real NEET and AIPMT questions from this chapter, newest first. Try each one, then open the answer and the step-by-step explanation.

  1. Question 1 (NEET 2026)

    NEET 2026EasyDNA and RNA
    The correct statement with regard to the secondary structure of DNA/RNA is:
    1. Option A: RNA possesses a single strand helix structure and contains thymine as one of the four bases
    2. Option B: DNA possesses a double strand helix structure and contains thymine as one of the four bases
    3. Option C: RNA possesses a double strand helix structure and contains uracil as one of the four bases
    4. Option D: DNA possesses a single strand helix structure and contains uracil as one of the four bases
    Show answer & explanation

    Correct answer: (B) DNA possesses a double strand helix structure and contains thymine as one of the four bases

    Explanation

    DNA has a double helical structure and contains adenine, guanine, cytosine and thymine. RNA is generally single stranded and contains uracil instead of thymine. Hence option (B) is correct.

  2. Question 2 (NEET 2026)

    NEET 2026EasyGene Regulation
    In the lac operon, the z gene codes for:
    1. Option A: Permease
    2. Option B: Transacetylase
    3. Option C: beta-galactosidase
    4. Option D: The repressor of lac operon
    Show answer & explanation

    Correct answer: (C) beta-galactosidase

    Explanation

    In lac operon: z gene → β-galactosidase, y gene → permease, a gene → transacetylase. Hence option (C) is correct.

  3. Question 3 (NEET 2026)

    NEET 2026MediumTranscription
    Which of the following statements are correct with reference to a transcription unit? A. A transcription unit in DNA is defined primarily by three regions : promoter, structural gene and terminator. B. The promoter is said to be located towards the 5'-end of the structural gene. C. The promoter is a DNA sequence that provides binding site for RNA polymerase. D. The promoter defines the template and coding strands. E. The terminator is located towards the 3'-end of the coding strand and it defines the end of the process of transcription. Choose the correct answer from the options given below:
    1. Option A: A, B, C and D only
    2. Option B: A, C, D and E only
    3. Option C: B, C, D and E only
    4. Option D: A, B, C, D and E
    Show answer & explanation

    Correct answer: (D) A, B, C, D and E

    Explanation

    A transcription unit contains promoter, structural gene and terminator. The promoter lies toward the 5′ end, binds RNA polymerase and determines coding/template strands. Terminator lies toward the 3′ end and signals transcription termination. Hence all statements are correct.

  4. Question 4 (NEET 2026)

    NEET 2026MediumHuman Genome Project and DNA Fingerprinting
    Arrange the following steps of DNA fingerprinting in a correct sequence. A. Isolation of DNA and its digestion by restriction endonucleases. B. Hybridisation using a labelled VNTR probe. C. Transferring of separated DNA fragments to synthetic membranes. D. Detection of hybridised DNA fragments by autoradiography. E. Separation of DNA fragments by electrophoresis. Choose the correct answer from the options given below :
    1. Option A: A, B, D, C, E
    2. Option B: A, D, B, E, C
    3. Option C: A, E, C, B, D
    4. Option D: A, E, B, C, D
    Show answer & explanation

    Correct answer: (C) A, E, C, B, D

    Explanation

    The sequence of DNA fingerprinting steps is: DNA isolation and restriction digestion → electrophoresis → transfer to membrane (Southern blotting) → hybridisation with labelled VNTR probe → autoradiography detection.

  5. Question 5 (NEET 2026)

    NEET 2026MediumDNA and RNA
    Which of the following statements are correct with reference to packaging of DNA helix? A. Histones are organized to form a unit of eight molecules called histone octamer. B. Histones are negatively charged basic proteins. C. Histones are rich in the basic amino acid residues - lysine and arginine. D. The positively charged DNA is wrapped around the histone octamer to form nucleosome. E. The packaging of chromatin at higher levels requires an additional set of proteins called non-histone chromosomal proteins. Choose the correct answer from the options given below :
    1. Option A: A, C and E only
    2. Option B: B, D and E only
    3. Option C: C, D and E only
    4. Option D: A, B and D only
    Show answer & explanation

    Correct answer: (A) A, C and E only

    Explanation

    Histones form an octamer (2 each of H2A, H2B, H3 and H4). Histones are positively charged proteins rich in lysine and arginine. DNA is negatively charged and wraps around histone octamers. Higher-order chromatin packaging requires non-histone chromosomal proteins.

  6. Question 6 (NEET 2026)

    NEET 2026MediumLac operon regulation
    Which of the following statements about lac-operon is correct?
    1. Option A: Gene i is constitutively expressed
    2. Option B: Lactose activates repressor to bind to the operator
    3. Option C: Genes i, z, y and a share single common promoter
    4. Option D: Galactose can act as an inducer of lac operon
    Show answer & explanation

    Correct answer: (A) Gene i is constitutively expressed

    Explanation

    Option (A) is correct: the i gene codes for the repressor of the lac operon, and the repressor protein is synthesised all the time (constitutively) from the i gene. Option (B) is wrong: the inducer (lactose/allolactose) binds the repressor and inactivates it, so the repressor cannot bind the operator and transcription occurs. Option (C) is wrong: only the structural genes z, y and a are transcribed as one polycistronic unit from the lac promoter; the i gene is a separate regulatory gene with its own promoter. Option (D) is wrong: the inducer of the lac operon is lactose (allolactose), not galactose. Hence option (A).

  7. Question 7 (NEET 2026)

    NEET 2026EasyTranscription in eukaryotes: RNA polymerases
    Which of the following enzymes synthesizes precursor mRNA?
    1. Option A: RNA polymerase I
    2. Option B: RNA polymerase II
    3. Option C: RNA polymerase III
    4. Option D: DNA polymerase
    Show answer & explanation

    Correct answer: (B) RNA polymerase II

    Explanation

    In eukaryotes there are at least three RNA polymerases in the nucleus with a clear division of labour. RNA polymerase I transcribes rRNAs (28S, 18S and 5.8S); RNA polymerase III transcribes tRNA, 5S rRNA and snRNAs; RNA polymerase II transcribes the precursor of mRNA, the heterogeneous nuclear RNA (hnRNA), which is then capped, tailed and spliced. DNA polymerase makes DNA, not RNA. As the official solution states, the answer is RNA polymerase II, option (B).

  8. Question 8 (NEET 2025)

    NEET 2025MediumHuman Genome Project and DNA Fingerprinting
    Which chromosome in the human genome has the highest number of genes?
    1. Option A: Chromosome X
    2. Option B: Chromosome Y
    3. Option C: Chromosome 1
    4. Option D: Chromosome 10
    Show answer & explanation

    Correct answer: (C) Chromosome 1

    Explanation

    Chromosome 1 has the highest number of genes in the human genome.

  9. Question 9 (NEET 2025)

    NEET 2025EasyGenetic Code and Translation
    Who proposed that the genetic code for amino acids should be made up of three nucleotides?
    1. Option A: George Gamow
    2. Option B: Francis Crick
    3. Option C: Jacque Monod
    4. Option D: Franklin Stahl
    Show answer & explanation

    Correct answer: (A) George Gamow

    Explanation

    George Gamow proposed that the genetic code is triplet in nature, consisting of three nucleotides coding for one amino acid.

  10. Question 10 (NEET 2024)

    NEET 2024HardGenetic Discoveries
    Match List I with List II Choose the correct answer from the options given below:
    1. Option A: A-II, B-III, C-IV, D-I
    2. Option B: A-IV, B-I, C-II, D-III
    3. Option C: A-III, B-II, C-I, D-IV
    4. Option D: A-III, B-IV, C-I, D-II
    Show answer & explanation

    Correct answer: (D) A-III, B-IV, C-I, D-II

    Explanation

    Frederick Griffith discovered transformation, Jacob and Monod proposed the lac operon model, Har Gobind Khorana worked on deciphering genetic code, and Meselson & Stahl demonstrated semi-conservative DNA replication.

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