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.
| 1. |
Which out of the following statements is true about human genome? |
| A. | The human genome is believed to contain approximately 50,000 protein coding genes |
| B. | All non-protein coding sequences in the genome are believed to be non-functional DNA |
| C. | About 1.6% of the human genome encodes protein sequences |
| D. | Intros are the sections of protein coding genes that actually encode amino acid sequences |
| Answer» D. Intros are the sections of protein coding genes that actually encode amino acid sequences | |
| 2. |
The site on a bacterial chromosome that marks the initiation point for chromosome replication is called |
| A. | Ori |
| B. | a promoter |
| C. | Pro |
| D. | an initiation codon |
| Answer» B. a promoter | |
| 3. |
Eukaryotic mRNA binding to the ribosomes is facilitated by __________ . |
| A. | the Shine Dalgarno sequence |
| B. | the 7-methyl guanosine cap |
| C. | tRNA |
| D. | poly A tail |
| Answer» C. tRNA | |
| 4. |
What proportion of the human genome is made up of repetitive DNA sequences? |
| A. | 15% |
| B. | 1% |
| C. | 90% |
| D. | 50% |
| Answer» E. | |
| 5. |
The DNA is negatively super coiled, complexes to histone, |
| A. | HU |
| B. | HSP-1 |
| C. | H-NS |
| D. | All of these |
| Answer» E. | |
| 6. |
Chromatin is composed of |
| A. | DNA |
| B. | DNA and proteins |
| C. | DNA, RNA and proteins |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 7. |
The enzyme responsible for breaking the hydrogen bonds, and thus separating the DNA strands during DNA synthesis is |
| A. | DNA polymerase |
| B. | strandase |
| C. | helicase |
| D. | none of these |
| Answer» D. none of these | |
| 8. |
What is the exact name of the classical Watson-Crick double helix DNA? |
| A. | A-DNA |
| B. | B-DNA |
| C. | Z-DNA |
| D. | X-DNA |
| Answer» C. Z-DNA | |
| 9. |
Under-winding is measured in terms of |
| A. | Supercoiling |
| B. | Linking difference |
| C. | Positive supercoiling |
| D. | Negative supercoiling |
| Answer» C. Positive supercoiling | |
| 10. |
Which polymerase is active in DNA repairing |
| A. | Polymerase I |
| B. | Polymerase II |
| C. | Polymerase III |
| D. | none of these |
| Answer» C. Polymerase III | |
| 11. |
Which is required for protein synthesis? |
| A. | tRNA |
| B. | mRNA |
| C. | rRNA |
| D. | All of these |
| Answer» E. | |
| 12. |
Binding of the prokaryotic DNA dependent RNA polymerase to promoter site is inhibited by |
| A. | Rifampicin |
| B. | Tetracycline |
| C. | Puromycin |
| D. | Streptomycin |
| Answer» B. Tetracycline | |
| 13. |
The enzyme responsible for the removal of supercoiling in replicating DNA ahead of the replication fork is |
| A. | Topoisomerase |
| B. | Primase |
| C. | DNA polymerase |
| D. | Helicase |
| Answer» B. Primase | |
| 14. |
Translation in prokaryotes begins by the formation of a 30S initiation complex between the |
| A. | 30S ribosomal subunit, mRNA, initiation factors and N-fMet tRNA |
| B. | 30S ribosomal subunit, tRNA and initiation factors |
| C. | 30S ribosomal subunit and mRNA only |
| D. | 30S ribosomal subunit, mRNA and initiation factors |
| Answer» B. 30S ribosomal subunit, tRNA and initiation factors | |
| 15. |
Changing twist from relaxed state requires adding energy and increases the |
| A. | Forces in molecule |
| B. | Stress along molecule |
| C. | Strain over molecule |
| D. | None of the above |
| Answer» C. Strain over molecule | |
| 16. |
The DNA polymerase involved in base excision repair is |
| A. | DNA polymerase α |
| B. | DNA polymerase β |
| C. | DNA polymerase σ |
| D. | DNA polymerase γ |
| Answer» C. DNA polymerase σ | |
| 17. |
The rapid appearance of HIV-1 strains that are resistant to AIDS drugs is due in part to which of the following property of its reverse transcriptase? |
| A. | AZT (zidovudine) is too expensive to be taken in effective doses |
| B. | The RNase H domain of p66 causes error prone synthesis |
| C. | It lacks a proofreading exonuclease |
| D. | It has low affinity for the correct dNTP's |
| Answer» D. It has low affinity for the correct dNTP's | |
| 18. |
Which of the following amino acid starts all proteins synthesis? |
| A. | Glycine |
| B. | Proline |
| C. | Thymine |
| D. | Methionine |
| Answer» E. | |
| 19. |
Which of the following has unusual bases? |
| A. | mRNA |
| B. | tRNA |
| C. | rRNA |
| D. | hnRNA |
| Answer» C. rRNA | |
| 20. |
In DNA, nucleotides are covalently joined together by |
| A. | 3', 5' phosphodiester bonds to form a repetitive sugar-phosphate chain |
| B. | 2', 5' phosphodiester bonds to form a repetitive sugar-phosphate chain |
| C. | 2', 3' phosphodiester bonds to form a repetitive sugar-phosphate chain |
| D. | 3', 4' phosphodiester bonds to form a repetitive sugar-phosphate chain |
| Answer» B. 2', 5' phosphodiester bonds to form a repetitive sugar-phosphate chain | |
| 21. |
Which of the following plays a substantial role in linking together sister chromatids immediately after replication? |
| A. | Cohesins |
| B. | Condensins |
| C. | Histones |
| D. | Topoisomerases |
| Answer» B. Condensins | |
| 22. |
Which of the following contain only the sequences required for transposition and the genes for proteins that promote the process? |
| A. | Insertion sequences |
| B. | Complex transposons |
| C. | Transposons |
| D. | Chromosomes |
| Answer» B. Complex transposons | |
| 23. |
DNA with a G-C content of 50% will melt at approximately |
| A. | 60°C |
| B. | 70 °C |
| C. | 90 °C |
| D. | 100 °C |
| Answer» D. 100 °C | |
| 24. |
On the ribosome, mRNA binds |
| A. | between the subunits |
| B. | to the large subunit |
| C. | to the small subunit |
| D. | none of these |
| Answer» D. none of these | |
| 25. |
Which will require a higher temperature to denature? |
| A. | DNA with a high G-C content |
| B. | DNA with a high A-T content |
| C. | RNA with a high G-C content |
| D. | RNA with a high A-T content |
| Answer» B. DNA with a high A-T content | |
| 26. |
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’ to 5’ endonuclease activity | |
| 27. |
DNA polymerases I also has |
| A. | 5'-3' exonuclease activity |
| B. | 3'-5'exonuclease activity |
| C. | both (a) and (b) |
| D. | 5'-3' endonuclease activity |
| Answer» C. both (a) and (b) | |
| 28. |
TM refers to the temperature at which |
| A. | membranes are 50% fluid |
| B. | 50% of a DNA molecule is denatured |
| C. | 50% of a protein molecules are denatured |
| D. | all of the above |
| Answer» E. | |
| 29. |
Two features of the tRNA molecule associated, in converting the triplet codon to an amino acid, are |
| A. | in the T Loop and D stem and loop |
| B. | in the anticodon loop and D stem loop |
| C. | in the anticodon loop and the 3' CCA end |
| D. | none of the above |
| Answer» D. none of the above | |
| 30. |
The DNA threads which appear inside the nucleus at the time of cell division |
| A. | Spindle fibers |
| B. | Centrioles |
| C. | Asters |
| D. | Chromosomes |
| Answer» E. | |
| 31. |
Which of the following are short nucleotides strands made by DNA polymerase working in the opposite direction of the replication fork? |
| A. | Leading strands |
| B. | Okazaki fragments |
| C. | Primers |
| D. | Lagging strand |
| Answer» C. Primers | |
| 32. |
Which of the two organelles contain their own DNA and ribosomes? |
| A. | Mitochondria and chloroplast |
| B. | Endoplasmic reticulum and mitochondria |
| C. | Golgi complex and mitochondria |
| D. | Lysosomes and mitochondria |
| Answer» B. Endoplasmic reticulum and mitochondria | |
| 33. |
One hypothesis of DNA replication suggested that the parental DNA molecules are broken into fragments. Both strands of DNA in each of the daughter molecules are made up of an assortment of parental and new DNA. This statement refers to which hypothesis? |
| A. | Conservative theory |
| B. | Dispersive theory |
| C. | Semi-conservative theory |
| D. | Evolutionary theory |
| Answer» C. Semi-conservative theory | |
| 34. |
Which of the following is not a necessary component of translation? |
| A. | Anticodon |
| B. | mRNA |
| C. | Ligase |
| D. | Amino acid |
| Answer» D. Amino acid | |
| 35. |
Which of the following involves remarkable capacity of short segment of DNA to move from one place to another? |
| A. | DNA transposition |
| B. | DNA replication |
| C. | Translation |
| D. | Transcription |
| Answer» B. DNA replication | |
| 36. |
Over-twisting of a molecule results in |
| A. | Negative supercoiling |
| B. | Positive supercoiling |
| C. | Elongation |
| D. | Compression |
| Answer» C. Elongation | |
| 37. |
The direction of amino acid transfer to the growing polypeptide chain is |
| A. | from the A (aminoacyl tRNA site) site to the P (peptidyl tRNA site) site on the ribosome |
| B. | from the P site to the A site on the ribosome |
| C. | from the A site to the E (exit tRNA site) site on the ribosome |
| D. | from the P site to the E site on the ribosome |
| Answer» C. from the A site to the E (exit tRNA site) site on the ribosome | |
| 38. |
The sister chromatids separate at |
| A. | Prophase |
| B. | Metaphase |
| C. | Telophase |
| D. | Anaphase |
| Answer» E. | |
| 39. |
There is a single origin for DNA replication in bacteria. How many origins of replication are found in the much larger genomes of eukaryotes such as mammals? |
| A. | One |
| B. | About 100 |
| C. | Thousands and tens of thousands |
| D. | none of these |
| Answer» D. none of these | |
| 40. |
Bacteria have |
| A. | 70S ribosomes |
| B. | 60S ribosomes |
| C. | 50S ribosomes |
| D. | 80S ribosomes |
| Answer» B. 60S ribosomes | |
| 41. |
The role of mRNA in protein synthesis is |
| A. | It translates genetic code to a specific amino acid |
| B. | It modifies mRNA molecules prior to protein synthesis |
| C. | It provides genetic blueprint for the protein |
| D. | It catalyzes the process |
| Answer» D. It catalyzes the process | |
| 42. |
In how many steps protein biosynthesis takes place? |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 5 |
| Answer» E. | |
| 43. |
In which of the following cases the first base of anticodon pairs with three codons? |
| 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» D. When the first base of anticodon is G or U | |
| 44. |
HIV may not respond to |
| A. | Nucleoside analogues |
| B. | Protease inhibitors |
| C. | Neuraminidase inhibitors |
| D. | Reverse transcriptase inhibitors |
| Answer» D. Reverse transcriptase inhibitors | |
| 45. |
The first nucleic acid synthesizing enzyme discovered is |
| A. | Polynucleotide phosphorylase |
| B. | DNA polymerase |
| C. | RNA polymerase |
| D. | DNA ligase |
| Answer» B. DNA polymerase | |
| 46. |
Which type of homing is DNA-based? |
| A. | Group I intron |
| B. | Group II intron |
| C. | Group III intron |
| D. | Group IV intron |
| Answer» B. Group II intron | |
| 47. |
80S eukaryotic ribosome is the complex of |
| A. | 60S and 40S |
| B. | 40S and 20S |
| C. | 60S and 50S |
| D. | 30S and 20S |
| Answer» B. 40S and 20S | |
| 48. |
One of the following best describes the cap modification of eukaryotic mRNA |
| A. | Modified guanine nucleotide added to the 3’ end of the transcript |
| B. | Modified guanine nucleotide added to the 5’ end of the transcript |
| C. | String of adenine nucleotides added to the 3’ end of the transcript |
| D. | String of adenine nucleotides added to the 5’ end of the transcript |
| Answer» C. String of adenine nucleotides added to the 3’ end of the transcript | |
| 49. |
How many bases of nucleic acid determine a single amino acid? |
| A. | Four |
| B. | One |
| C. | Two |
| D. | Three |
| Answer» E. | |
| 50. |
In an agarose gel, DNA is moving from |
| A. | cathode to anode |
| B. | left to right |
| C. | anode to cathode |
| D. | A to B |
| Answer» B. left to right | |