Class 12 · Biology · CBSE Board · 2016–2025

Molecular Basis of Inheritance — Class 12 Biology PYQs

96 questions from this chapter, asked in 8 Class 12 exams between 2016–2025 — every question paper set included, duplicates removed.

96questions
8Class 12 exams
2016–2025years covered
1 / 2 / 3 / 4 / 5mark values asked

Questions asked per year

202512 Qs202415 Qs202314 Qs202019 Qs201910 Qs201817 Qs201710 Qs20167 Qs

Practice questions

Q1MCQ20251 mark
AnswerLogic

Which one of the following enzymes are used in the digestion of the RNA primer during DNA replication in E. coli ?
[Max Marks: 1 | Sets: 57/2/3]

(A)DNA polymerase I
(B)DNA polymerase II
(C)DNA polymerase III
(D)DNA polymerase IV
Q2MCQ20251 mark
AnswerLogic

A change in nucleotide sequence of a DNA segment is known as :
[Max Marks: 1 | Sets: 57/1/1]

(A)Mutagen
(B)Genetic drift
(C)Chromosomal aberration
(D)Gene mutation
Q3MCQ20251 mark
AnswerLogic

Which one of the following enzymes is also known as 'molecular scissors' ?
[Max Marks: 1 | Sets: 57/2/2]

(A)DNA ligase
(B)Endonuclease
(C)DNA polymerase
(D)RNA polymerase
Q4MCQ20251 mark
AnswerLogic

How many lactose molecules bind to the lac repressor to inactivate it ?
[Max Marks: 1 | Sets: 57/1/2]

(A)One
(B)Two
(C)Three
(D)Four
Q5MCQ20251 mark
AnswerLogic

How many proteins are involved in the digestion of RNA primer during DNA replication in E. coli ?
[Max Marks: 1 | Sets: 57/2/1]

(A)One
(B)Two
(C)Three
(D)Five
Q6MCQ20251 mark
AnswerLogic

How many genes are involved in the metabolism of lactose in a bacterial cell ?
[Max Marks: 1 | Sets: 57/1/3]

(A)Three
(B)Four
(C)Two
(D)One
Q7MCQ20255 marks
AnswerLogic

[Max Marks: 5 | Set: 57/2/3]

(A)(a) Explain the relationship between 'genes' and 'DNA'.
(B)Explain the functioning of a 'Lac operon' in a bacterial cell when lactose is provided in the growth medium.
(C)List the two observations made by Griffith in his experiment to prove that 'DNA is the genetic material'.
(D)List the salient features of the 'Genetic Code'.
OR
Q8MCQ20255 marks
AnswerLogic
(A)(a) Explain the discovery of 'DNA is the genetic material' in bacteria.
(B)Distinguish between the anticodon of a tRNA and the codon of mRNA.
(C)Draw a labelled diagram of transcription unit in a prokaryotic cell. OR
(B)(a) Why is the genetic code referred to as 'degenerate code' and 'universal code'?
(B)With the help of a suitable diagram, explain the replication fork that occurs during the process of DNA replication.
(C)What is meant by the term 'semi-conservative DNA replication' ? [Max Marks: 5 | Set: 57/2/2]
Q9MCQ20255 marks
AnswerLogic
(A)(a) Name the DNA polymerases that are involved in the process of DNA replication in a prokaryotic cell.
(B)What is the function of DNA ligase during this process ?
(C)Mention the proteins that are associated with DNA and help in the organisation of DNA. OR
(B)(a) What is 'transcription'? List the three steps involved in this process in a bacterial cell.
(B)Name the enzyme and the substrate that binds to RNA polymerase during transcription.
(C)Explain the meaning of the term 'translation'. [Max Marks: 5 | Sets: 57/1/3]
Q10MCQ20255 marks
AnswerLogic
(A)(a) Explain the 'DNA as the genetic material' demonstrated by Alfred Hershey and Martha Chase.
(B)Explain how the action of RNA polymerase differs from that of DNA polymerase in a bacterial cell. OR
(B)(a) What is an operon ? Explain the functioning of an inducible operon using a suitable example.
(B)Name the enzyme associated with the process of transcription in bacteria. [Max Marks: 5 | Sets: 57/1/1]

Why practise Molecular Basis of Inheritance PYQs?

Molecular Basis of Inheritance has appeared in 8 Class 12 Biology exams we track between 2016–2025, with questions worth 1, 2, 3, 4, 5 marks. CBSE Board examiners consistently reuse concepts and question patterns from this topic — practising its previous year questions is the most reliable way to know exactly what to expect in your exam.

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