1. Molecular biology primarily deals with the study of:
(A) DNA, RNA, and proteins
(B) Cells and tissues
(C) Organ systems
(D) Evolution
2. The basic unit of genetic information is:
(A) Protein
(B) Chromosome
(C) Gene
(D) Codon
3. DNA stands for:
(A) Deoxyribonucleic acid
(B) Deoxyribose nucleic acid
(C) Dideoxyribonucleic acid
(D) Dinucleic acid
4. The structure of DNA was proposed by:
(A) Chargaff
(B) Meselson and Stahl
(C) Watson and Crick
(D) Franklin and Wilkins
5. DNA is a polymer of repeating units called:
(A) Amino acids
(B) Phospholipids
(C) Sugars
(D) Nucleotides
6. Each nucleotide of DNA consists of:
(A) Sugar, phosphate, protein
(B) Sugar, phosphate, nitrogenous base
(C) Sugar, base, lipid
(D) Base, protein, lipid
7. Which sugar is present in DNA?
(A) Ribose
(B) Deoxyribose
(C) Glucose
(D) Fructose
8. Which nitrogenous base is found only in DNA?
(A) Uracil
(B) Thymine
(C) Cytosine
(D) Adenine
9. Complementary base pairing in DNA involves:
(A) A–G and C–T
(B) A–T and G–C
(C) A–C and G–T
(D) A–U and G–C
10. Hydrogen bonds between A and T are:
(A) One
(B) Three
(C) Two
(D) Four
11. Hydrogen bonds between G and C are:
(A) One
(B) Three
(C) Two
(D) Four
12. DNA replication is:
(A) Conservative
(B) Semiconservative
(C) Dispersive
(D) Random
13. The semiconservative nature of DNA replication was proven by:
(A) Watson and Crick
(B) Hershey and Chase
(C) Griffith
(D) Meselson and Stahl
14. DNA replication occurs during which phase of cell cycle?
(A) G₁ phase
(B) S phase
(C) G₂ phase
(D) M phase
15. The enzyme responsible for unwinding DNA is:
(A) DNA ligase
(B) DNA polymerase
(C) Primase
(D) Helicase
16. RNA primer is synthesized by:
(A) Primase
(B) DNA polymerase III
(C) Ligase
(D) DNA polymerase I
17. The enzyme that joins Okazaki fragments is:
(A) Helicase
(B) Topoisomerase
(C) Polymerase
(D) Ligase
18. Okazaki fragments are formed on:
(A) Leading strand
(B) Parental strand
(C) Both strands
(D) Lagging strand
19. RNA differs from DNA by having:
(A) Deoxyribose
(B) Thymine
(C) Uracil
(D) Double strand
20. The enzyme responsible for transcription is:
(A) DNA polymerase
(B) RNA polymerase
(C) Reverse transcriptase
(D) Ligase
21. Transcription occurs in the:
(A) Cytoplasm only
(B) Nucleus (in eukaryotes)
(C) Ribosome
(D) Mitochondria only
22. The template strand in transcription is also called:
(A) Coding strand
(B) Sense strand
(C) Leading strand
(D) Antisense strand
23. The process of protein synthesis is known as:
(A) Transcription
(B) Mutation
(C) Replication
(D) Translation
24. Translation takes place on:
(A) Ribosomes
(B) Golgi apparatus
(C) Nucleus
(D) Lysosomes
25. A group of three nucleotides coding for one amino acid is called:
(A) Anticodon
(B) Intron
(C) Exon
(D) Codon
26. The start codon for protein synthesis is:
(A) UAA
(B) UGA
(C) UAG
(D) AUG
27. Which amino acid is coded by the start codon?
(A) Glycine
(B) Alanine
(C) Valine
(D) Methionine
28. Stop codons include:
(A) UAA, UAG, UGA
(B) UUU
(C) AUG
(D) AAA
29. tRNA carries:
(A) DNA
(B) Amino acids
(C) mRNA
(D) Ribosomes
30. The anticodon is present on:
(A) tRNA
(B) rRNA
(C) mRNA
(D) DNA
31. The genetic code is said to be universal because it:
(A) Changes in organisms
(B) Exists only in bacteria
(C) Is same in all organisms
(D) Exists only in plants
32. One gene–one enzyme hypothesis was proposed by:
(A) Watson and Crick
(B) Mendel
(C) Beadle and Tatum
(D) Morgan
33. Exons are:
(A) Non-coding regions
(B) Regulatory regions
(C) Mutated regions
(D) Coding regions
34. Introns are removed during:
(A) Replication
(B) RNA splicing
(C) Translation
(D) Mutation
35. Reverse transcription is the synthesis of:
(A) RNA from DNA
(B) Protein from RNA
(C) DNA from RNA
(D) RNA from protein
36. The enzyme reverse transcriptase is found in:
(A) Bacteria
(B) Plants
(C) Fungi
(D) Retroviruses
37. Operon model was proposed by:
(A) Watson and Crick
(B) Mendel
(C) Beadle and Tatum
(D) Jacob and Monod
38. Lac operon is found in:
(A) Yeast
(B) E. coli
(C) Virus
(D) Plants
39. The regulatory gene in lac operon produces:
(A) Enzyme
(B) Activator protein
(C) Structural protein
(D) Repressor protein
40. The inducer of lac operon is:
(A) Lactose
(B) Glucose
(C) Galactose
(D) Maltose
41. Mutation involving single base change is called:
(A) Point mutation
(B) Chromosomal mutation
(C) Frameshift mutation
(D) Deletion mutation
42. Silent mutation does not affect:
(A) DNA sequence
(B) Codon
(C) Gene
(D) Amino acid sequence
43. A mutation that shifts the reading frame is known as:
(A) Missense mutation
(B) Frameshift mutation
(C) Nonsense mutation
(D) Silent mutation
44. Molecular cloning involves:
(A) Recombinant DNA formation
(B) DNA amplification
(C) Cell division
(D) Protein digestion
45. Restriction enzymes are also called:
(A) Ligases
(B) Endonucleases
(C) Polymerases
(D) Helicases
46. Restriction enzymes cut DNA at:
(A) Random sites
(B) Specific sequences
(C) Promoter regions
(D) Telomeres
47. Plasmids are commonly found in:
(A) Bacteria
(B) Animals
(C) Plants
(D) Viruses
48. PCR stands for:
(A) Protein Chain Reaction
(B) Primer Chain Reaction
(C) Peptide Chain Reaction
(D) Polymerase Chain Reaction
49. The enzyme used in PCR is:
(A) DNA ligase
(B) RNA polymerase
(C) Taq DNA polymerase
(D) Helicase
50. Molecular biology techniques are widely used in:
(A) Agriculture only
(B) Medicine only
(C) Ecology
(D) Genetics and biotechnology