Class 12 Biology Chapter 6: Molecular Basis of Inheritance – 100 MCQs with Answers
1. The DNA is a polymer of:
Answer: B) Nucleotides
2. Who proposed the double helix model of DNA?
Answer: A) Watson and Crick
3. Purines are:
Answer: B) Adenine and Guanine
4. Which is a pyrimidine base in RNA only?
Answer: C) Uracil
5. DNA replication is:
Answer: B) Semiconservative
6. DNA polymerase adds nucleotides in direction:
Answer: B) 5’ → 3’
7. Okazaki fragments are joined by:
Answer: B) DNA ligase
8. Hershey-Chase experiment involved:
Answer: B) Bacteria and viruses
9. Which type of RNA carries amino acids?
Answer: B) tRNA
10. A gene is:
Answer: B) DNA segment
11. The backbone of DNA is made up of:
Answer: B) Phosphate and sugar
12. Which RNA is most abundant in cells?
Answer: C) rRNA
13. The first step of gene expression is:
Answer: B) Transcription
14. The bond between bases A and T is:
Answer: B) Two hydrogen bonds
15. The coding segments of eukaryotic DNA are:
Answer: B) Exons
16. Chromatin is composed of:
Answer: A) DNA and protein
17. DNA is present in which organelle?
Answer: D) All above
18. Removal of introns is called:
Answer: B) Splicing
19. The enzyme in transcription is:
Answer: B) RNA polymerase
20. The central dogma of molecular biology is:
Answer: B) DNA → RNA → Protein
21. The process of making RNA from DNA is called:
Answer: B) Transcription
22. In prokaryotes, transcription and translation:
Answer: A) Are coupled
23. The start codon is:
Answer: B) AUG
24. Griffith’s experiment proved:
Answer: C) Transformation principle
25. Which is an enzyme for DNA synthesis?
Answer: A) DNA polymerase
26. What are Chargaff’s rules about base pairing?
Answer: A) A = T, G = C
27. DNA is synthesised from which direction?
Answer: B) 5’ → 3’
28. Which is stop codon?
Answer: B) UAG
29. DNA fingerprinting is based on:
Answer: A) Satellite DNA
30. The length of one complete turn of DNA is:
Answer: A) 34 Å
31. RNA differs from DNA by:
Answer: D) All
32. Number of nucleotides in one turn of DNA:
Answer: A) 10
33. The enzyme helicase helps in:
Answer: A) Unwinding DNA
34. Human genome has about:
Answer: B) 3 billion base pairs
35. Nucleosome core particle is wrapped by:
Answer: B) 146 bp DNA
36. The first eukaryotic gene cloned was of:
Answer: D) Human
37. In eukaryotic cell, transcription occurs in:
Answer: B) Nucleus
38. The process of forming mRNA from DNA:
Answer: B) Transcription
39. Principal of DNA fingerprinting was developed by:
Answer: C) Alec Jeffreys
40. Meselson and Stahl proved DNA replication is:
Answer: C) Semiconservative
41. Removal of RNA primer is done by:
Answer: B) DNA polymerase I
42. DNA double helix model was based on:
Answer: B) X-ray diffraction
43. Spliceosome is associated with:
Answer: B) RNA splicing
44. Promoter site is important during:
Answer: B) Transcription
45. RNA primer is synthesized by:
Answer: A) Primase
46. TATA Box is a:
Answer: A) Promoter region
47. The enzyme reverse transcriptase is present in:
Answer: B) Retroviruses
48. mRNA codon for methionine:
Answer: A) AUG
49. DNA as genetic material was proved by:
Answer: A) Hershey-Chase
50. Stop codons do NOT code for:
Answer: C) Any amino acid
51. Mutations are changes in:
Answer: A) Nucleotide sequence
52. ‘Wobble hypothesis’ is related to:
Answer: C) tRNA anticodon
53. DNA fingerprinting technique involves:
Answer: B) VNTR analysis
54. Genetic code is:
Answer: B) Universal
55. Eukaryotic mRNA processing involves:
Answer: D) All
56. Mutagens are agents inducing:
Answer: B) Mutation
57. The nucleosome model of chromatin was proposed by:
Answer: B) Kornberg
58. RNA splicing removes:
Answer: B) Introns
59. The site of translation in cell:
Answer: B) Ribosome
60. Antiparallel strands mean:
Answer: B) Opposite direction
61. The repeating unit of chromatin is:
Answer: B) Nucleosome
62. Number of hydrogen bonds between G and C:
Answer: C) Three
63. DNA that can transfer between bacteria is:
Answer: A) Plasmid
64. The function of rRNA is:
Answer: B) Structure of ribosome
65. mRNA is synthesized from DNA template by:
Answer: B) RNA polymerase
66. Which is NOT a stop codon?
Answer: D) AUG
67. Proteins are synthesized at:
Answer: B) Ribosome
68. Polysome is a:
Answer: A) Group of ribosomes on mRNA
69. DNA and RNA differ in:
Answer: D) All
70. The backbone of RNA is:
Answer: A) Sugar-phosphate
71. Griffith’s experiment worked with:
Answer: C) Pneumococcus
72. Proteins are synthesized from:
Answer: A) mRNA template
73. Anticodon is present on:
Answer: C) tRNA
74. Released polypeptide chain detaches at:
Answer: B) Stop codon
75. Hybridization probes are labelled fragments of:
Answer: A) DNA
76. Sense strand of DNA has sequence:
Answer: B) Same as mRNA
77. VNTRs stand for:
Answer: A) Variable Number of Tandem Repeats
78. Which of the following is NOT true about genetic code?
Answer: D) Overlapping
79. Ribozymes are:
Answer: A) Enzymatic RNA
80. Pribnow box is found in:
Answer: A) Prokaryotes
81. Direction of coding on sense strand is:
Answer: B) 5’ → 3’
82. Which is not a function of tRNA?
Answer: C) Providing mRNA template
83. Telomerase synthesizes:
Answer: A) Chromosome ends
84. The sequence coding for a single amino acid is called:
Answer: A) Codon
85. RNA primer is required for:
Answer: A) DNA replication
86. The percentage of purine is equal to:
Answer: A) Pyrimidine
87. In bacteria, DNA replication is:
Answer: B) Bidirectional
88. Which is NOT an enzyme in DNA replication?
Answer: D) Sucrase
89. In eukaryotes, gene regulation is by:
Answer: B) Histone modification
90. The coding sequence in mRNA for protein is:
Answer: A) Exon
91. Avery–McLeod–McCarty experiment showed:
Answer: B) DNA is hereditary material
92. Sanger’s method is used for:
Answer: B) DNA sequencing
93. Replication origins in eukaryotes:
Answer: B) Multiple
94. PCR stands for:
Answer: B) Polymerase Chain Reaction
95. Central dogma of genetics is proposed by:
Answer: B) Crick
96. In eukaryotes, split genes were discovered by:
Answer: B) Sharp and Roberts
97. A nucleoside consists of:
Answer: A) Sugar and base
98. DNA replication in mitochondria is:
Answer: B) Circular
99. First step in gene expression is:
Answer: A) Transcription
100. The enzyme joining DNA fragments is:
Answer: A)