MCQOPTIONS
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MCQOPTIONS
This section includes 267 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
During conventional transformation experiments E. coli cells and plasmid DNA interacts in an environment of |
| A. | high temperature and Ca++ |
| B. | low temperature and Ca++ |
| C. | high temperature and Mg++ |
| D. | low temperature and Mg++ |
| Answer» C. high temperature and Mg++ | |
| 52. |
Which type of splicing reaction requires a guanine nucleoside or nucleotide cofactor that is not used as a source of energy? |
| A. | Spliceosomal |
| B. | Group I |
| C. | Group II |
| D. | Group IV |
| Answer» C. Group II | |
| 53. |
Which of the following is not a structural motif in DNA binding proteins? |
| A. | bZIP |
| B. | helix-turn-helix |
| C. | TFIID |
| D. | zinc finger |
| Answer» D. zinc finger | |
| 54. |
Which of the following is the smallest of the RNAs? |
| A. | Messenger RNA |
| B. | Transfer RNAs |
| C. | Ribosomal RNAs |
| D. | All of these |
| Answer» C. Ribosomal RNAs | |
| 55. |
After one replication in 15N, how many bands should be observed in a cesium chloride gradient? |
| A. | One |
| B. | Two |
| C. | Three |
| D. | A smear |
| Answer» B. Two | |
| 56. |
Which of the following process generates a new copy of the transposable element at a new location of DNA? |
| A. | Homologous genetic recombination |
| B. | Site specific recombination |
| C. | Non-homologous recombination |
| D. | Replicative recombination |
| Answer» E. | |
| 57. |
Which is the third elongation step in bacteria? |
| A. | Peptide bond formation |
| B. | Binding of an incoming aminoacyl t-RNA |
| C. | Translocation |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 58. |
Proteins which help to open the double helix for DNA synthesis are |
| A. | DNA helicases |
| B. | single stranded binding proteins |
| C. | ligase |
| D. | DNA topoisomerase |
| Answer» B. single stranded binding proteins | |
| 59. |
Processive synthesis is a characteristic feature of |
| A. | all DNA polymerases. |
| B. | DNA Pol III at a replication fork. |
| C. | removal of RNA primers on Okasaki fragments. |
| D. | DNA mismatch repair |
| Answer» C. removal of RNA primers on Okasaki fragments. | |
| 60. |
Cellular DNA is uncondensed throughout |
| A. | Prophase |
| B. | Interphase |
| C. | Telophase |
| D. | Anaphase |
| Answer» C. Telophase | |
| 61. |
70S prokaryotic ribosome is the complex of |
| A. | 30S + 50S |
| B. | 30S + 40S |
| C. | 20S + 60S |
| D. | 20S + 30S |
| Answer» B. 30S + 40S | |
| 62. |
Automated DNA sequencing uses the chain termination method |
| A. | but with an oligonucleotide primer labeled with a fluorescent dye |
| B. | but with a polynucleotide primer labeled with a fluorescent dye |
| C. | with no primer |
| D. | either (b) or (c) |
| Answer» B. but with a polynucleotide primer labeled with a fluorescent dye | |
| 63. |
Which of the following is RNA-dependent RNA polymerase? |
| A. | Reverse transcriptase |
| B. | RNA polymerase I |
| C. | RNA polymerase II |
| D. | RNA replicase |
| Answer» E. | |
| 64. |
Which of the following promotes branch migration at higher rates than does Rec-A? |
| A. | Rec-B |
| B. | Rec-C |
| C. | Rec-D |
| D. | Ruv-A and Ruv-B |
| Answer» E. | |
| 65. |
In which of the following cases the first base of anticodon pairs with only one codon? |
| A. | When the first base of anticodon is A or C |
| B. | When the first base of anticodon is A or G |
| C. | When the first base of anticodon is inosine |
| D. | When the first base of anticodon is G or U |
| Answer» B. When the first base of anticodon is A or G | |
| 66. |
Which of the following species lack a 'classical' histone H1? |
| A. | Saccharomyces cerevisiae |
| B. | Strongylocentrotus purpuratus |
| C. | Xenopus laevis |
| D. | Arabidopsis thaliana |
| Answer» B. Strongylocentrotus purpuratus | |
| 67. |
Which of the following has beads on a string structure? |
| A. | Chromosomes |
| B. | Chromatin |
| C. | Nucleosomes |
| D. | Heterochromatin |
| Answer» D. Heterochromatin | |
| 68. |
TBP stands for? |
| A. | TATA box polymerase |
| B. | TATA-box binding protein |
| C. | Transcription associated factor |
| D. | Transcription factor binding protein |
| Answer» C. Transcription associated factor | |
| 69. |
The lowest level of chromosome organization is |
| A. | Nucleosome |
| B. | Solenoid |
| C. | 30nm fiber |
| D. | None of these |
| Answer» B. Solenoid | |
| 70. |
Reverse transcriptase does not catalyze |
| A. | RNA-dependent DNA synthesis |
| B. | RNA degradation |
| C. | DNA-dependent DNA synthesis |
| D. | DNA-dependent RNA synthesis |
| Answer» E. | |
| 71. |
The type of topoisomerases which generally relaxes DNA by removing negative supercoiling is |
| A. | Type I |
| B. | Type II |
| C. | Type III |
| D. | Type IV |
| Answer» B. Type II | |
| 72. |
Which of the following is an active site on its single polypeptide chain for DNA Polymerase I? |
| A. | 5' → 3' polymerase |
| B. | 3' → 5' exonuclease |
| C. | 5' → 3' exonuclease |
| D. | all of the above |
| Answer» B. 3' → 5' exonuclease | |
| 73. |
The melting of 40-45 bp at the oriC site of E. coli requires |
| A. | DNA + ATP + HU |
| B. | DNA + ATP + HU + DNAb |
| C. | DNA+ ATP + HU + DNAb + DNAa |
| D. | DNA + ATP + HU + DNAb + DNAa + Pol III holoenzyme |
| Answer» B. DNA + ATP + HU + DNAb | |
| 74. |
Which site of the tRNA molecule binds to the mRNA molecule? |
| A. | Anticodon |
| B. | Codon |
| C. | Amino acid |
| D. | 5 prime end |
| Answer» B. Codon | |
| 75. |
Which of the following process occurs between DNA molecules of very similar sequences? |
| A. | Homologous genetic recombination |
| B. | Site specific recombination |
| C. | Non-homologous recombination |
| D. | Replicative recombination |
| Answer» B. Site specific recombination | |
| 76. |
About what proportion of mitochondrial proteins are encoded by nuclear DNA? |
| A. | More than 95% |
| B. | 50% |
| C. | 1% |
| D. | 1.5% |
| Answer» B. 50% | |
| 77. |
How many amino acid residues are there in ubiquitin? |
| A. | 72 |
| B. | 73 |
| C. | 75 |
| D. | 76 |
| Answer» E. | |
| 78. |
Wobble hypothesis was first proposed by |
| A. | Nirenberg |
| B. | Watson and Crick |
| C. | Watson |
| D. | Crick |
| Answer» E. | |
| 79. |
In RNA, uracil pairs with |
| A. | adenine |
| B. | cytosine |
| C. | thymine |
| D. | guanine |
| Answer» B. cytosine | |
| 80. |
Which of following RNA characteristically contains unusual purines and pyrimidmes? |
| A. | rRNA |
| B. | nRNA |
| C. | mRNA |
| D. | tRNA |
| Answer» E. | |
| 81. |
Which of the following RNAs bind to an amino acid? |
| A. | mRNA |
| B. | tRNA |
| C. | rRNA |
| D. | hnRNA |
| Answer» C. rRNA | |
| 82. |
The growing polypeptide chain is released from the ribosomes when |
| A. | a chain terminating codon is reached |
| B. | a chain terminating tRNA binds to the ribosome |
| C. | the 7-methyl guanosine cap is reached |
| D. | the poly A tail is reached |
| Answer» B. a chain terminating tRNA binds to the ribosome | |
| 83. |
RNA instability in alkaline solutions is due to |
| A. | adenine |
| B. | ribose |
| C. | uracil |
| D. | single strand nature |
| Answer» C. uracil | |
| 84. |
The peptidyl transferase reaction occurs |
| A. | on the large subunit |
| B. | on the small subunit |
| C. | between the subunit |
| D. | none of these |
| Answer» B. on the small subunit | |
| 85. |
Number of autosomes in humans is |
| A. | 21 pairs |
| B. | 44 |
| C. | 46 |
| D. | 48 |
| Answer» C. 46 | |
| 86. |
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 | |
| 87. |
Okazaki fragments occur on the __________ and are bonded together by __________ |
| A. | Leading strand, polymerase |
| B. | mRNA, anticodons |
| C. | Lagging strand, ligase |
| D. | tRNA, polymerase |
| Answer» D. tRNA, polymerase | |
| 88. |
The mRNA from which of the following would contain a poly-A tail? |
| A. | A restriction endonuclease from E. coli |
| B. | Bacterial alpha-amylase |
| C. | Human insulin |
| D. | Bacteriophage DNA ligase |
| Answer» D. Bacteriophage DNA ligase | |
| 89. |
Repressors bind to |
| A. | Promoter |
| B. | Enhancer |
| C. | Operator |
| D. | Hormone response element |
| Answer» D. Hormone response element | |
| 90. |
Which of the following is called a resolvase? |
| A. | Ruv-C |
| B. | Ruv-A |
| C. | Ruv-B |
| D. | Rec-A |
| Answer» B. Ruv-A | |
| 91. |
RNA primer is removed from the Okazaki fragment by |
| A. | DNA polymerase I |
| B. | DNA polymerase II |
| C. | DNA polymerase III |
| D. | RNA polymerase |
| Answer» B. DNA polymerase II | |
| 92. |
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 | |
| 93. |
Which of the following introns have self-splicing activity? |
| A. | Group I and group II |
| B. | Group II and group III |
| C. | Group III and group IV |
| D. | Group I and group III |
| Answer» B. Group II and group III | |
| 94. |
The enzyme used to join bits of DNA is |
| A. | DNA polymerase |
| B. | DNA ligase |
| C. | Endonuclease |
| D. | Primase |
| Answer» C. Endonuclease | |
| 95. |
The packing ratio of nucleosomes is about |
| A. | 6 |
| B. | 8 |
| C. | 7 |
| D. | 9 |
| Answer» D. 9 | |
| 96. |
The function of enzyme involved in base excision repair is |
| A. | Addition of correct base |
| B. | Addition of correct nucleotide |
| C. | Removal of incorrect base |
| D. | Removal of phosphodiester bond |
| Answer» D. Removal of phosphodiester bond | |
| 97. |
Which of the following inactivates the 60S subunit of eukaryotic ribosomes? |
| A. | Chloramphenicol |
| B. | Cycloheximide |
| C. | Diphtheria toxin |
| D. | Ricin |
| Answer» E. | |
| 98. |
What modified base is at the 5' extremity of a capped eukaryotic m-RNA? |
| A. | 1-methyl-adenosine |
| B. | 2'-O-methyl-guanosine |
| C. | 7-methyl-guanosine |
| D. | 1-methyl-guanosine |
| Answer» D. 1-methyl-guanosine | |
| 99. |
Which of the following mechanisms will remove uracil and incorporate the correct base? |
| A. | Direct repair |
| B. | Base excision repair |
| C. | Mismatch repair |
| D. | Nucleotide excision repair |
| Answer» C. Mismatch repair | |
| 100. |
Without telomerase, what would happen to the ends of chromosomes after each round of replication? |
| A. | Chromosomes would become progressively shorter |
| B. | Nothing would happen |
| C. | Chromosomes would get longer |
| D. | none of the above |
| Answer» B. Nothing would happen | |