MCQOPTIONS
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MCQOPTIONS
This section includes 64 Mcqs, each offering curated multiple-choice questions to sharpen your Molecular Biology knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Which one of the following is not a function of a nucleotide? |
| A. | Nucleic acid monomer |
| B. | Ribozyme |
| C. | Energy carrier molecules |
| D. | Receptors |
| Answer» E. | |
| 2. |
Which of the following factors do not provide to the separation of DNA fragments during electrophoresis? |
| A. | Chargaff’s rule |
| B. | Matrix density |
| C. | Ethidium bromide |
| D. | Size |
| Answer» D. Size | |
| 3. |
According to Chargaff’s rule the two strands of DNA has ___________ |
| A. | Same molecular weight |
| B. | Same amount of A and G |
| C. | Different amount of A and G |
| D. | Different molecular weight |
| Answer» E. | |
| 4. |
Which macromolecule is not abundantly found though being of critical importance for biological mechanisms? |
| A. | Proteins |
| B. | Lipids |
| C. | Nucleic acids |
| D. | Polysaccharides |
| Answer» C. Nucleic acids | |
| 5. |
Building blocks of nucleic acids are ____________ |
| A. | Nucleotides |
| B. | Nucleosides |
| C. | Amino acids |
| D. | Histones |
| Answer» B. Nucleosides | |
| 6. |
Which of the following statements is not true about RNA? |
| A. | Does not have a double stranded structure |
| B. | Thymine is present |
| C. | Does not obey Chargaff’s rule |
| D. | The sugar contained in RNA is a ribose |
| Answer» C. Does not obey Chargaff’s rule | |
| 7. |
A nucleotide consists of |
| A. | a sugar, a base and a phosphate |
| B. | a sugar and a phosphate |
| C. | paired bases |
| D. | a sugar, a base and three phosphates |
| Answer» B. a sugar and a phosphate | |
| 8. |
What happens in hyperchromicity? |
| A. | When DNA is in bound form, there is decrease in absorption of UV light |
| B. | When DNA is in bound form, there is increase in absorption of UV light |
| C. | When DNA is in unbound form, it is more stable |
| D. | When DNA is in unbound form, there is increase in absorption of UV light |
| Answer» E. | |
| 9. |
What happens in hypochromicity? |
| A. | When DNA is in bound form, there is decrease in absorption of UV light |
| B. | When DNA is in bound form, there is increase in absorption of UV light |
| C. | When DNA is in unbound form, it is more stable |
| D. | When DNA is in unbound form, there is decrease in absorption of UV light |
| Answer» B. When DNA is in bound form, there is increase in absorption of UV light | |
| 10. |
Which one of the following nucleic acids has a left handed helix? |
| A. | M-RNA |
| B. | T-RNA |
| C. | A-DNA |
| D. | Z-DNA |
| Answer» E. | |
| 11. |
Which of the following nucleotides is not present in RNA? |
| A. | AMP |
| B. | GMP |
| C. | CMP |
| D. | TMP |
| Answer» E. | |
| 12. |
Which of the following is true about Z-DNA helix? |
| A. | It has alternating GC sequences |
| B. | It is a permanent conformation of DNA |
| C. | It tends to be found at the 3’ end of the genes |
| D. | It has fewer base pairs per turn than B-DNA |
| Answer» B. It is a permanent conformation of DNA | |
| 13. |
Which ratio is constant for DNA? |
| A. | A + G / T + C |
| B. | A + T / G + C |
| C. | A + C / U + G |
| D. | A + U / G + C |
| Answer» B. A + T / G + C | |
| 14. |
Which of the following amino acids interact with the DNA or RNA backbone (i.e. phosphate)? |
| A. | Ile and Val |
| B. | Lys and Arg |
| C. | Leu and Ala |
| D. | Cys and Met |
| Answer» C. Leu and Ala | |
| 15. |
Which of the following amino acids can interact with the DNA or RNA nucleotide bases via hydrogen bonding? |
| A. | Asn and Gln |
| B. | Cys and Met |
| C. | Lys and Leu |
| D. | Ile and Val |
| Answer» B. Cys and Met | |
| 16. |
Cleavage of DNA by EcoRI endonuclease results in the formation of |
| A. | two 3'-OH ends and two 5'-phosphate ends |
| B. | one 3'-OH end and one 5'-phosphate end |
| C. | two 3'-phosphate ends and two 3'-OH ends |
| D. | one 3'-OH end and two 5'-phosphate end |
| Answer» B. one 3'-OH end and one 5'-phosphate end | |
| 17. |
DNA denaturation is measured by absorbance at ___________ |
| A. | 220nm |
| B. | 230nm |
| C. | 250nm |
| D. | 260nm |
| Answer» E. | |
| 18. |
Which of the following is a purine? |
| A. | Cytosine |
| B. | Adenine |
| C. | Thymine |
| D. | Uracil |
| Answer» C. Thymine | |
| 19. |
Thymidine |
| A. | can participate in hydrophobic interactions due to its methyl group |
| B. | is replaced by uracil in RNA |
| C. | normally forms two hydrogen bonds with adenosine |
| D. | all of the above |
| Answer» E. | |
| 20. |
Different DNA polymerases play distinct roles in DNA replication and repair in both prokaryotic and eukaryotic cells. All known DNA polymerases synthesize DNA only in the __________ by the addition of dNTPs to a performed primer strand of DNA. |
| A. | positive direction |
| B. | 3' to 5' direction |
| C. | 5' to 3' direction |
| D. | negative direction |
| Answer» D. negative direction | |
| 21. |
Identify the purine base of nucleic acids in the following. |
| A. | Cytosine |
| B. | Thymine |
| C. | Uracil |
| D. | Adenine |
| Answer» E. | |
| 22. |
The most stabilizing force for nucleic acids is |
| A. | hydrogen bonds |
| B. | electrostatic bond |
| C. | Van der Waals |
| D. | conformational entropy |
| Answer» D. conformational entropy | |
| 23. |
Which of the following leads to disruption of nucleosomal structure? |
| A. | Acetylation |
| B. | Carboxylation |
| C. | Phosphorylation |
| D. | Methylation |
| Answer» E. | |
| 24. |
A purine with an amine (NH₂) group on the 6th carbon is |
| A. | adenine |
| B. | cytosine |
| C. | thymine |
| D. | guanine |
| Answer» B. cytosine | |
| 25. |
Which of the following nucleotides is not present in DNA? |
| A. | AMP |
| B. | GMP |
| C. | CMP |
| D. | UMP |
| Answer» E. | |
| 26. |
Which of the following is found on RNA but not DNA? |
| A. | Uracil |
| B. | Deoxyribose |
| C. | Phosphate |
| D. | Adenine |
| Answer» B. Deoxyribose | |
| 27. |
The glycosidic bonds in DNA and RNA |
| A. | connect the sugar to the base |
| B. | can be hydrolyzed by OH- ion |
| C. | stabilize Watson-Crick H-bonds |
| D. | are free to rotate over about 180° |
| Answer» B. can be hydrolyzed by OH- ion | |
| 28. |
Number of hydrogen bonds between guanine and cytosine? |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» D. 4 | |
| 29. |
The type II restriction endonucleases, bind to DNA sites |
| A. | using H-bonds for specificity |
| B. | that are usually palindromic |
| C. | using non-sequence-dependent backbone interactions |
| D. | all of the above |
| Answer» E. | |
| 30. |
Which of the following statements is true? |
| A. | Sugar component of a nucleotide is ribose |
| B. | Sugar component of a nucleotide is deoxyribose |
| C. | The bases in nucleotides are attached to a pentose sugar moiety by a glycosidic linkage |
| D. | The sugar molecule of the nucleotide is in L-configuration |
| Answer» D. The sugar molecule of the nucleotide is in L-configuration | |
| 31. |
Which of the following involves carrying genetic information from DNA for protein synthesis? |
| A. | m-RNA |
| B. | t-RNA |
| C. | r-RNA |
| D. | sn-RNA |
| Answer» B. t-RNA | |
| 32. |
The unfavourable free energy associated with not satisfying a hydrogen bond after formation of the double helix is approximately |
| A. | 10 kJ/mol |
| B. | 20 kJ/mol |
| C. | 25 kJ/mol |
| D. | 30 kJ/mol |
| Answer» C. 25 kJ/mol | |
| 33. |
What is the composition of nucleotide? |
| A. | a sugar + a phosphate |
| B. | a base + a sugar |
| C. | a base + a phosphate |
| D. | a base + a sugar + phosphate |
| Answer» E. | |
| 34. |
Which of the following is false about denaturation? |
| A. | Disruption of hydrogen bonds |
| B. | Disruption of phosphodiester linkage |
| C. | Loss of helical structure of DNA |
| D. | It is resulted as a result of change in pH or increase in temperature |
| Answer» C. Loss of helical structure of DNA | |
| 35. |
Arrangement of nucleotides in DNA can be seen by ____________ |
| A. | Ultracentrifuge |
| B. | X-Ray crystallography |
| C. | Light microscope |
| D. | Electron microscope |
| Answer» C. Light microscope | |
| 36. |
What is the composition of nucleoside? |
| A. | a sugar + a phosphate |
| B. | a base + a sugar |
| C. | a base + a phosphate |
| D. | a base + a sugar + phosphate |
| Answer» C. a base + a phosphate | |
| 37. |
A five carbon sugar lacking a hydrogen at the number 2 carbon is found in |
| A. | DNA |
| B. | RNA |
| C. | mRNA |
| D. | rDNA |
| Answer» B. RNA | |
| 38. |
The sugar molecule in a nucleotide is ____________ |
| A. | Pentose |
| B. | Hexose |
| C. | Tetrose |
| D. | Triose |
| Answer» B. Hexose | |
| 39. |
Group of adjacent nucleotides are joined by ____________ |
| A. | Phosphodiester bond |
| B. | Peptide bond |
| C. | Ionic bond |
| D. | Covalent bond |
| Answer» B. Peptide bond | |
| 40. |
Reverse transcripase from HIV does not |
| A. | uses RNA as a template |
| B. | has a 5' to 3' polymerase activity |
| C. | has a 3'- 5' exonuclease activity |
| D. | requires a primer |
| Answer» D. requires a primer | |
| 41. |
According to Chargaff’s rule, in a DNA molecule ____________ |
| A. | The amount of adenine and thymine is equal to the amount of guanine and cytosine |
| B. | The amount of adenine and guanine is equal to the amount of thymine and cytosine |
| C. | The amount of adenine and uracil is equal to the amount of guanine and cytosine |
| D. | The amount of adenine and guanine is equal to the amount of uracil and cytosine |
| Answer» B. The amount of adenine and guanine is equal to the amount of thymine and cytosine | |
| 42. |
The enzyme that joins DNA cuts is called |
| A. | joinase |
| B. | ligase |
| C. | DNA phosphorylase |
| D. | reverse transcriptase |
| Answer» C. DNA phosphorylase | |
| 43. |
Nucleotide bases and aromatic amino acids absorb light respectively at |
| A. | 280 and 260 nm |
| B. | 260 and 280 nm |
| C. | 270 and 280 nm |
| D. | 260 and 270 nm |
| Answer» C. 270 and 280 nm | |
| 44. |
Which of the following are not the components of RNA? |
| A. | Thymine |
| B. | Adenine |
| C. | Guanine |
| D. | Cytosine |
| Answer» B. Adenine | |
| 45. |
Which of the following is false about purine and pyrimidine bases? |
| A. | They are hydrophobic and relatively insoluble in water at the near-neutral pH of the cell |
| B. | At acidic or alkaline pH the bases become charged and their solubility in water increases |
| C. | Purines have two rings in their structure, but pyrimidine bases have only one ring |
| D. | At acidic or alkaline pH the bases become charged and their solubility in water decreases |
| Answer» E. | |
| 46. |
Which of the following is true about tₘ? |
| A. | It can be termed as renaturation temperature |
| B. | The higher the content of G ≡ C base pairs, the higher the tₘ |
| C. | The higher the content of A = T base pairs, the higher the tₘ |
| D. | The higher the content of G ≡ C base pairs, the lower the tₘ |
| Answer» C. The higher the content of A = T base pairs, the higher the tₘ | |
| 47. |
Nucleic acids can be analyzed experimentally by their |
| A. | molecular weight |
| B. | absorption of visible light |
| C. | absorption of uv light |
| D. | none of these |
| Answer» D. none of these | |
| 48. |
Which of the following is true about phosphodiester linkage? |
| A. | 5’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide |
| B. | 3’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the next nucleotide |
| C. | 5’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the next nucleotide |
| D. | 3’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide |
| Answer» B. 3’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the next nucleotide | |
| 49. |
Number of hydrogen bonds between adenine and thymine? |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» C. 3 | |
| 50. |
The sugar in RNA is __________ , the sugar in DNA is __________ |
| A. | deoxyribose, ribose |
| B. | ribose, deoxyribose |
| C. | ribose, phosphate |
| D. | ribose, uracil |
| Answer» C. ribose, phosphate | |