MCQOPTIONS
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MCQOPTIONS
This section includes 41 Mcqs, each offering curated multiple-choice questions to sharpen your Life Sciences knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Which of the following possesses both 5'-3' and 3'-5' exonuclease activity? |
| A. | Kornberg enzyme |
| B. | DNA polymerase III |
| C. | Taq DNA polymerase |
| D. | None of these |
| Answer» B. DNA polymerase III | |
| 2. |
Which of the following lacks 3'-5' exonuclease activity? |
| A. | Short fragment of DNA polymerase I |
| B. | Taq DNA polymerase |
| C. | T4 DNA ligase |
| D. | All of the above |
| Answer» E. | |
| 3. |
Name the protein, which is responsible for the formation of RNA primer? |
| A. | Topoisomerase |
| B. | Gyrase |
| C. | Helicase |
| D. | Primase |
| Answer» E. | |
| 4. |
Which enzyme used to join bits of DNA? |
| A. | DNA polymerase |
| B. | DNA ligase |
| C. | Endonuclease |
| D. | Primase |
| Answer» C. Endonuclease | |
| 5. |
Which of the following enzymes is the principal replication enzyme in E. coli? |
| A. | DNA polymerase I |
| B. | DNA polymerase II |
| C. | DNA polymerase III |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 6. |
DNA unwinding is done by ____________ |
| A. | Ligase |
| B. | Helicase |
| C. | Topoisomerase |
| D. | Hexonuclease |
| Answer» C. Topoisomerase | |
| 7. |
What is the reaction in DNA replication catalyzed by DNA ligase? |
| A. | Addition of new nucleotides to the leading strand |
| B. | Addition of new nucleotide to the lagging strand |
| C. | Formation of a phosphodiester bond between the 3’-OH of one Okazaki fragment and the 5’-phosphate of the next on the lagging strand |
| D. | Base pairing of the template and the newly formed DNA strand |
| Answer» D. Base pairing of the template and the newly formed DNA strand | |
| 8. |
Eukaryotes differ from prokaryote in mechanism of DNA replication due to ____________ |
| A. | Use of DNA primer rather than RNA primer |
| B. | Different enzyme for synthesis of lagging and leading strand |
| C. | Discontinuous rather than semi-discontinuous replication |
| D. | Unidirectional rather than semi-discontinuous replication |
| Answer» D. Unidirectional rather than semi-discontinuous replication | |
| 9. |
Semi-conservative DNA replication was first demonstrated in ____________ |
| A. | Drosophila melanogaster |
| B. | Escherichia coli |
| C. | Streptococcus pneumonae |
| D. | Drosophila melanogaster |
| Answer» B. Escherichia coli | |
| 10. |
What is DNA replication? |
| A. | Conservative |
| B. | Non-conservative |
| C. | Semi-conservative |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 11. |
Which of the following enzyme is responsible for initiating DNA replication? |
| A. | polymerase |
| B. | ligase |
| C. | primase |
| D. | gyrase |
| Answer» D. gyrase | |
| 12. |
Which enzyme joins the Okazaki fragments into a continuous strand? |
| A. | gyrase |
| B. | topoisomerase |
| C. | ligase |
| D. | helicase |
| Answer» D. helicase | |
| 13. |
Who made the discovery that one DNA strand is synthesized discontinuously in fragments? |
| A. | Francis Crick |
| B. | Reiji Okazaki |
| C. | James Watson |
| D. | Louis Pasteur |
| Answer» C. James Watson | |
| 14. |
The lagging strand is synthesized discontinuously. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 15. |
How many copies (approximately) of DNA polymerase III are present in a typical bacterial cell? |
| A. | 10 |
| B. | 50 |
| C. | 100 |
| D. | 200 |
| Answer» B. 50 | |
| 16. |
When was DNA polymerase III discovered as the major enzyme behind DNA replication in bacteria? |
| A. | 1949 |
| B. | 1959 |
| C. | 1969 |
| D. | 1989 |
| Answer» D. 1989 | |
| 17. |
Which enzyme removes the positive supercoils generated when the replication fork? |
| A. | helicase |
| B. | endonuclease |
| C. | exonuclease |
| D. | gyrase |
| Answer» E. | |
| 18. |
Movement of the replication fork generates ________________ in the unreplicated portion of DNA. |
| A. | positive supercoils |
| B. | negative supercoils |
| C. | untranslated regions |
| D. | amino acid substitutions |
| Answer» B. negative supercoils | |
| 19. |
The bacterial oriC is the __________________ |
| A. | specific sequence |
| B. | transcription factor |
| C. | enzyme |
| D. | polypeptide |
| Answer» B. transcription factor | |
| 20. |
Temperature-sensitive mutants can not replicate their chromosomes at non-permissive temperatures. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 21. |
Which isotopes were used by the researchers who first confirmed the semiconservative nature of DNA replication? |
| A. | Nitrogen |
| B. | Carbon |
| C. | Oxygen |
| D. | Sulfur |
| Answer» B. Carbon | |
| 22. |
How many types of replication models were considered before the semiconservative nature of DNA replication was confirmed? |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» D. 4 | |
| 23. |
NAME_THE_PROTEIN,_WHICH_IS_RESPONSIBLE_FOR_THE_FORMATION_OF_RNA_PRIMER??$ |
| A. | Topoisomerase |
| B. | Gyrase |
| C. | Helicase |
| D. | Primase |
| Answer» E. | |
| 24. |
WHICH_OF_THE_FOLLOWING_ENZYMES_IS_THE_PRINCIPAL_REPLICATION_ENZYME_IN_E._COLI??$ |
| A. | DNA polymerase I |
| B. | DNA polymerase II |
| C. | DNA polymerase III |
| D. | None of these |
| Answer» D. None of these | |
| 25. |
The_enzyme_used_to_join_bits_of_DNA_is$ |
| A. | DNA polymerase |
| B. | DNA ligase |
| C. | Endonuclease |
| D. | Primase |
| Answer» C. Endonuclease | |
| 26. |
Which of the following would relax negatively supercoiled DNA? |
| A. | DNA gyrase |
| B. | Type I topoisomerase |
| C. | Collagen |
| D. | Elastin |
| Answer» C. Collagen | |
| 27. |
DNA unwinding is done b? |
| A. | Ligase |
| B. | Helicase |
| C. | Topoisomerase |
| D. | Hexonuclease |
| Answer» C. Topoisomerase | |
| 28. |
Name the protein, which is used for termination of replication? |
| A. | DnaC |
| B. | SSB |
| C. | Tus protein |
| D. | DNA polymerase |
| Answer» D. DNA polymerase | |
| 29. |
Which of the following enzymes remove supercoiling in replicating DNA ahead of the replication fork? |
| A. | DNA polymerases |
| B. | Helicases |
| C. | Primases |
| D. | Topoisomerases |
| Answer» E. | |
| 30. |
Which of the following protein is required for connecting Okazaki fragments? |
| A. | Scaffold protein |
| B. | Helicase |
| C. | Primase |
| D. | DNA gyrase |
| Answer» E. | |
| 31. |
Which of the following reactions is required for proofreading during DNA replication by DNA polymerase III? |
| A. | 5’ to 3’ exonuclease activity |
| B. | 3’ to 5’ exonuclease activity |
| C. | 3’ to 5’ endonuclease activity |
| D. | 5’ to 3’ endonuclease activity |
| Answer» C. 3‚Äö√Ñ√∂‚àö√ë‚àö¬• to 5‚Äö√Ñ√∂‚àö√ë‚àö¬• endonuclease activity | |
| 32. |
Which of the following protein does not involve in the initiation of replication? |
| A. | DnaA |
| B. | SSB (Single strand binding protein) |
| C. | DnaB |
| D. | DnaF |
| Answer» E. | |
| 33. |
The reaction in DNA replication catalyzed by DNA ligase is |
| A. | Addition of new nucleotides to the leading strand |
| B. | Addition of new nucleotide to the lagging strand |
| C. | Formation of a phosphodiester bond between the 3’-OH of one Okazaki fragment and the 5’-phosphate of the next on the lagging strand |
| D. | Base pairing of the template and the newly formed DNA strand |
| Answer» D. Base pairing of the template and the newly formed DNA strand | |
| 34. |
How many numbers of replicon is found in E.coli? |
| A. | Five replicon |
| B. | Two replicon |
| C. | Single replicon |
| D. | Multiple replicon |
| Answer» D. Multiple replicon | |
| 35. |
Which of the following is true about DNA polymerase? |
| A. | It can synthesize DNA in the 5’ to 3’ direction |
| B. | It can synthesize DNA in the 3’ to 5’ direction |
| C. | It can synthesize mRNA in the 3’ to 5’ direction |
| D. | It can synthesize mRNA in the 5’ to 3’ direction |
| Answer» B. It can synthesize DNA in the 3‚Äö√Ñ√∂‚àö√ë‚àö¬• to 5‚Äö√Ñ√∂‚àö√ë‚àö¬• direction | |
| 36. |
What is the origin of replication? |
| A. | Particular site at which DNA replication starts |
| B. | Site which prevents initiation |
| C. | Random location on the DNA |
| D. | Site at which replication terminated |
| Answer» B. Site which prevents initiation | |
| 37. |
Eukaryotes differ from prokaryote in mechanism of DNA replication due to |
| A. | Use of DNA primer rather than RNA primer |
| B. | Different enzyme for synthesis of lagging and leading strand |
| C. | Discontinuous rather than semi-discontinuous replication |
| D. | Unidirectional rather than semi-discontinuous replication |
| Answer» D. Unidirectional rather than semi-discontinuous replication | |
| 38. |
What is a mode of replication in E.coli? |
| A. | Intermediate |
| B. | Dispersive |
| C. | Conservative |
| D. | Semiconservative |
| Answer» E. | |
| 39. |
Semi-conservative DNA replication was first demonstrated in |
| A. | Drosophila melanogaster |
| B. | Escherichia coli |
| C. | Streptococcus pneumonae |
| D. | Drosophila melanogaster |
| Answer» B. Escherichia coli | |
| 40. |
Base sequence of each parental strand considered to synthesis new complementary strand. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 41. |
Double-helix structure of DNA is discovered by___________ |
| A. | Gobind Khurana |
| B. | Nirenberg |
| C. | Watson and Crick |
| D. | Darwin |
| Answer» D. Darwin | |