Molecular Biology MCQs Multiple Choice Questions with Answers

1. The biology that deals with the structure and function of the macromolecules e.g. proteins and nucleic acids is known as:
a. Microbiology
b. Molecular biology
c. Biotechnology
d. Environmental biology
Answer: b. Molecular biology

2. How many bio-elements account for 99% of the total mass?
a. Seven
b. Three
c. Six
d. Ten
Answer: c. Six

3. At which position on the ribose ring is the base group attached to the nitrogen base group?
a. 5′
b. 3′
c. 2′
d. 1′
Answer: d. 1′

4. The primary cell wall is made up of:
a. Inorganic salts
b. Silica and waxes
c. Cellulose
d. Chitin, Lignin
Answer: c. Cellulose

5. Colloidion is a colloidal solution of:
a. Sucrose in water
b. Cellulose nitrate in water
c. Cellulose in water
d. Cellulose nitrate in ethyl alcohol
Answer: b. Cellulose nitrate in water

6. Rough endoplasmic reticulum (RER) are involved in the synthesis of:
a. Lipids
b. Proteins
c. Fats
d. Carbohydrates
Answer: b. Proteins

7. Peroxisome is enriched with:
a. Oxydative enzymes
b. Reductive enzymes
c. Isomeric enzymes
d. Ligase enzymes
Answer: a. Oxydative enzymes

Recommended: Molecular Biology Practice Test

8. Okazaki fragments give rise to…?
a. Master strand
b. Sense strand
c. Lagging strand
d. Leading strand
Answer: c. Lagging strand

9. What is lac operon?
a. Arabinose operon
b. Repressible operon
c. Inducible operon
d. Overlapping genes
Answer: c. Inducible operon

10. The hydrogen bond between cytosine and guanine are:
a. 1
b. 2
c. 3
d. 4
Answer: c. 3

11. Hereditary information is indicated by:
a. Number of nucleic acid
b. Position of nucleic acids
c. Sequence of nucleic acids
d. All of these
Answer: c. Sequence of nucleic acids

12. A tRNA recognizes ribosomes by:
a. TC loop
b. DHU loop
c. Anti-Codon
d. AA-site
Answer: a. TC loop

13. The function of the beta subunit of polymerase is:
a. Catalytic binding
b. Template binding
c. Promoter binding
d. Cation binding
Answer: a. Catalytic binding

14. Which of the sigma factors is heat stable?
a. σ 32
b. σ 54
c. σ 70
d. σ 28
Answer: a. σ 32

15. True replication of DNA is possible due to…?
a. Phosphate backbone
b. Hydrogen bonding
c. Complementary base pairing rule
d. None of these
Answer: c. Complementary base pairing rule

16. The usual method of DNA replication is:
a. Conservative
b. Semiconservative
c. Dispersive
d. Non-conservative
Answer: b. Semiconservative

17. Which of the following enzyme is used to join DNA fragments?
a. Primase
b. Ligase
c. Terminase
d. DNA polymerase
Answer: b. Ligase

18. Which of the following enzyme is used in the unwinding of DNA?
a. Topoisomerase
b. Ligase
c. Exonuclease
d. Helicase
Answer: d. Helicase

19. Which of the following processes does not occur in prokaryotes??
a. Transcription
b. Translation
c. Replication
d. Splicing
Answer: d. Splicing

20. An enzyme that uses viral RNA as a template for the synthesis of DNA is:
a. DNA polymerase
b. DNA synthetase
c. RNA replicase
d. Reverse transcriptase
Answer: d. Reverse transcriptase

21. DNA synthesis can be measured by estimating the incorporation of radiolabeled:
a. Thymine
b. Guanine
c. Adenine
d. Cytosine
Answer: a. Thymine

22. How many RNA polymerases are present in a bacterial system??
a. One
b. Two
c. Seven
d. Five
Answer: a. One

23. The method of DNA replication, in which two strands of DNA separate and synthesize new strands are known as:
a. Conservative
b. Semiconservative
c. Dispersive
d. Non-conservative
Answer: b. Semiconservative

24. What are the fragments of DNA called that are synthesized on the lagging strand?
a. Satellite segments
b. Okazaki fragments
c. Kornberg segment
d. Double-helix segment
Answer: b. Okazaki fragments

25. The bond between a phosphate group and the ribose sugar group in RNA is known as:
a. Phosphodiester linkage
b. Glycosidic bond
c. Peptide bond
d. Amide bond
Answer: b. Glycosidic bond

26. Which of the following does not play a role in DNA replication?
a. Helicase
b. DNA polymerase
c. Single-stranded binding protein
d. Guanyl transferase
Answer: d. Guanyl transferase

27. Choose the correct statement regarding the Splicing process:
a. Remove introns and conserve exons
b. Remove exons and conserve introns
c. Remove mutated regions of primary transcript RNA
d. Add multiple adenosine bases to the end of a primary RNA
Answer: a. Remove introns and conserve exons

28. Which of the following is not a characteristic of eukaryotic DNA transcription??
a. Multiple RNA polymerases
b. Strict promoter sequences
c. TATA-binding protein
d. Transcription factors
Answer: b. Strict promoter sequences

29. Which of the following codons cannot be recognized by a Transfer RNA (tRNA) molecule?
a. UAA
b. UUU
c. AUG
d. CGA
Answer: b. UUU

30. What is the rate of DNA transcription?
a. 80 nucleotides per second
b. 200 nucleotides per second
c. 40 nucleotides per second
d. 60 nucleotides per second
Answer: d. 60 nucleotides per second

31. Different codons that encode the same amino acid are known as…?
a. Similar codons
b. Synonymous codons
c. Degenerates
d. Complements
Answer: b. Synonymous codons

32. Which of the following is not a characteristic of a tRNA molecule?
a. D arm
b. T arm
c. Beta arm
d. Anti-codon arm
Answer: c. Beta arm

33. What group of nitrogenous bases do adenine and guanine belong?
a. Large
b. Small
c. Pyrimidines
d. Purines
Answer: d. Purines

34. What is the rate of mammalian DNA replication?
a. 500 nucleotides per second
b. 100 nucleotides per second
c. 10 nucleotides per second
d. 50 nucleotides per second
Answer: d. 50 nucleotides per second

35. The end of transcription is signaled by:
a. Terminator
b. Stop codon
c. RNA polymerase runs out
d. The end of the DNA chain
Answer: a. Terminator

36. The initiation codon is:
a. AUG
b. UUU
c. UGA
d. UAG
Answer: a. AUG

37. Which of the following is not a component of a nucleotide?
a. Phosphate group
b. Anti-codon
c. Ribose sugar
d. Nitrogen base
Answer: b. Anti-codon

38. What is the rate of mutation per round of DNA replication??
a. 1 in 1,000 base pairs
b. 1 in 1,000,000,000 base pairs
c. 1 in 1,000,000 base pairs
d. 1 in 10,000 base pairs
Answer: b. 1 in 1,000,000,000 base pairs

39. Which of the subunits of RNA polymerase holoenzyme is responsible for promoter recognition?
a. The beta subunit
b. The gamma subunit
c. The sigma subunit
d. The delta subunit
Answer: c. The sigma subunit

40. Choose the correct example of missense mutation:
a. UAC to UAG
b. AAA to UAA
c. UGC to UCC
d. UAA to UGA
Answer: c. UGC to UCC

41. Which of the following bases is not present in DNA??
a. Thymine
b. Adenine
c. Guanine
d. Uracil
Answer: d. Uracil

42. Which sequence is present at the 10 region of the promoter?
c. CAA
Answer: a. TATAAT

43. According to the wobble hypothesis; a U in the 5′ position of the anticodon can pair with:
a. A, C, or G
b. A or G
c. Only A
d. U or C
Answer: b. A or G

44. What is the name of the enzyme responsible for helping charge tRNA molecules?
a. Guanyl transferase
b. Polymerase
c. Aminoacyl-tRNA synthase
d. Helicase
Answer: c. Aminoacyl-tRNA synthase

45. The strand on which DNA replication is continuous is known as:
a. Lagging strand
b. Major strand
c. Leading strand
d. Minor strand
Answer: c. Leading strand

46. Which of the following is the sequence recognized by poly (A) polymerase?
a. CAA
Answer: d. AAUAAA

47. A mutation changes the original base sequence of DNA, GATAGCCG to a new sequence GGTAGCCG. What is the type of mutation?
a. Transition
b. Transversion
c. Inversion
d. Translocation
Answer: a. Transition

48. The 3′ end of a tRNA molecule contains which of the following sequences?
a. CAA
b. AUG
d. UAA
Answer: a. CAA

49. How many hydrogen bonds are formed between one A:T base pair?
a. 1
b. 2
c. 5
d. 10
Answer: b. 2

50. A gene with 600 nucleotides will code for how many amino acids??
a. 600
b. 200
c. 500
d. 900
Answer: b. 200

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