MCQOPTIONS
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MCQOPTIONS
This section includes 107 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
DNA polymerases II and III lack |
| A. | 5' → 3' exonuclease activity |
| B. | 5' → 3' endonuclease activity |
| C. | partially 5' → 3' exonuclease activity |
| D. | partially 5' → 3' endonuclease activity |
| Answer» B. 5' → 3' endonuclease activity | |
| 2. |
What is the approximate size (in kb) of the genome? |
| A. | 3000 kilobase |
| B. | 4500 kilobase |
| C. | 5500 kilobase |
| D. | 6500 kilobase |
| Answer» C. 5500 kilobase | |
| 3. |
DNA gyrase in |
| A. | adds positive supercoils to chromosomal DNA |
| B. | can be inhibited with antibiotics |
| C. | is required only at the |
| D. | site |
| E. | performs the same function as helicase in eukaryotes |
| Answer» C. is required only at the | |
| 4. |
Replication in is initiated by the generation of short RNA primers using |
| A. | RNA polymerase |
| B. | primase |
| C. | reverse transcriptase |
| D. | both (a) and (b) |
| Answer» E. | |
| 5. |
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. | |
| 6. |
During conventional transformation experiments 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 | |
| 7. |
The RNA primers used to initiate replication in |
| A. | result in Okazaki fragments on leading strand |
| B. | are removed by Pol I |
| C. | are joined together by DNA ligase |
| D. | are removed by helicase + ATP |
| Answer» C. are joined together by DNA ligase | |
| 8. |
The melting of 40-45 bp at the oriC site of 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 | |
| 9. |
After one replication in N, how many bands should be observed in a cesium chloride gradient? |
| A. | One |
| B. | Two |
| C. | Three |
| D. | A smear |
| Answer» B. Two | |
| 10. |
The accepted hypothesis for DNA replication is |
| A. | conservative theory |
| B. | dispersive theory |
| C. | semi-conservative theory |
| D. | evolutionary theory |
| Answer» D. evolutionary theory | |
| 11. |
When DNA polymerase is in contact with guanine in the parental strand, what does it add to the growing daughter strand? |
| A. | Phosphate |
| B. | Cytosine |
| C. | Uracil |
| D. | Guanine |
| Answer» C. Uracil | |
| 12. |
The overall conclusion of the Hershey-Chase experiment was that |
| A. | DNA was responsible for heredity |
| B. | proteins and DNA were responsible for heredity |
| C. | the ratio of Adenine to thymine was always the same |
| D. | phage DNA was similar to bacterial DNA |
| Answer» B. proteins and DNA were responsible for heredity | |
| 13. |
In DNA double helix, the two DNA chains are held together by |
| A. | covalent bonds between the pair of bases |
| B. | hydrogen bonds between the pair of bases |
| C. | ionic bonds between the pair of bases |
| D. | none of the above |
| Answer» C. ionic bonds between the pair of bases | |
| 14. |
A cesium chloride will separate DNA molecules by |
| A. | absorption |
| B. | resorption |
| C. | density |
| D. | adhesion |
| Answer» D. adhesion | |
| 15. |
Which of the following enzyme adds complementary bases during replication? |
| A. | Helicase |
| B. | Synthesase |
| C. | Replicase |
| D. | Polymerase |
| Answer» E. | |
| 16. |
Taylor, Woods and Hughes labeled Vicia DNA by allowing new DNA synthesis in the presence of radioactive thymine. After DNA replication (S phase of the cell cycle), it was observed that |
| A. | only one chromatid of a chromosome was labeled |
| B. | both chromatids of a chromosome were labeled |
| C. | both (a) and (b) |
| D. | neither chromatid was labeled |
| Answer» C. both (a) and (b) | |
| 17. |
The 5' and 3' numbers are related to the |
| A. | length of the DNA strand |
| B. | carbon number in sugar |
| C. | the number of phosphates |
| D. | the base pair rule |
| Answer» C. the number of phosphates | |
| 18. |
Messelsen and Stahl model of replication was called |
| A. | conservative replication |
| B. | semi-conservative replication |
| C. | dispersive replication |
| D. | Cri du Chat |
| Answer» C. dispersive replication | |
| 19. |
Enzymes, responsible for unraveling short segments of DNA is |
| A. | DNA polymerase |
| B. | helicase |
| C. | DNA ligase |
| D. | primase |
| Answer» C. DNA ligase | |
| 20. |
DNA replication takes place in which direction? |
| A. | 3' to 5' |
| B. | 5 'to 3' |
| C. | Randomly |
| D. | Vary from organism to organism |
| Answer» C. Randomly | |
| 21. |
The most common liquid volumes in molecular biology are measured in |
| A. | ml |
| B. | l |
| C. | nl |
| D. | 1 |
| Answer» C. nl | |
| 22. |
In DNA, there are |
| A. | five bases known as adenine, guanine, thymine, tryptophan and cytosine |
| B. | four bases known as adenine, guanine, thymine and cytosine |
| C. | three bases known as adenine, guanine and cytosine |
| D. | only two bases known as adenine and cytosine |
| Answer» C. three bases known as adenine, guanine and cytosine | |
| 23. |
Enzyme, responsible for proofreading base pairing is |
| A. | DNA polymerase |
| B. | Telomerase |
| C. | Primase |
| D. | DNA ligase |
| Answer» B. Telomerase | |
| 24. |
The nucleosome consists of histone |
| A. | octamer and 146 bp of DNA |
| B. | tetramer and 146 bp of DNA |
| C. | hexamer and 146 bp of DNA |
| D. | none of the above |
| Answer» B. tetramer and 146 bp of DNA | |
| 25. |
What is the only common methylation in the DNA of eukaryotes? |
| A. | Adenosine in GpA dinucleotides |
| B. | Guanosine in ApGpA trinucleotides |
| C. | Cytosine in CpG dinucleotides |
| D. | None of the above |
| Answer» D. None of the above | |
| 26. |
DNAs when charged, migrate in a gel towards the |
| A. | positive pole |
| B. | negative pole |
| C. | will not migrate |
| D. | none of these |
| Answer» B. negative pole | |
| 27. |
What is the approximate size (in kb) of the E. coli genome? |
| A. | 3000 kilobase |
| B. | 4500 kilobase |
| C. | 5500 kilobase |
| D. | 6500 kilobase |
| Answer» C. 5500 kilobase | |
| 28. |
In the study of one experiment it was found that the value of Tm for DNA is = 40 C. If the cell has 20% GC at the above Tm, then what will be value of 'Tm' if the GC% increases to 60%? |
| A. | Remains same |
| B. | Increases |
| C. | Decreases |
| D. | Can not be compared |
| Answer» C. Decreases | |
| 29. |
Which DNA polymerase removes RNA primers in DNA synthesis? |
| A. | Polymerase I |
| B. | Polymerase II |
| C. | Polymerase III |
| D. | none of these |
| Answer» B. Polymerase II | |
| 30. |
Okazaki fragments occur during |
| A. | transformation |
| B. | replication |
| C. | polymerase reaction |
| D. | synthesis |
| Answer» C. polymerase reaction | |
| 31. |
E.coli DNA polymerases II and III lack |
| A. | 5' 3' exonuclease activity |
| B. | 5' 3' endonuclease activity |
| C. | partially 5' 3' exonuclease activity |
| D. | partially 5' 3' endonuclease activity |
| Answer» B. 5' 3' endonuclease activity | |
| 32. |
In sperm heads, DNA is particularly highly condensed and the histones are replaced with small basic protein called |
| A. | protamines |
| B. | purines |
| C. | pyrimidines |
| D. | all of the above |
| Answer» B. purines | |
| 33. |
DNA can be sequenced by the |
| A. | chemical method |
| B. | chain termination procedure |
| C. | both (a) and (b) |
| D. | physical method |
| Answer» D. physical method | |
| 34. |
Which histone(s) are associated with the linker DNA of a nucleosome? |
| A. | Histone H1 |
| B. | Histones H2A and H2B |
| C. | Histone H3 |
| D. | Histone H4 |
| Answer» B. Histones H2A and H2B | |
| 35. |
Klenow fragment without free nucleotides exhibits |
| A. | exonuclease activity |
| B. | endonuclease activity |
| C. | nickase activity |
| D. | no activity |
| Answer» B. endonuclease activity | |
| 36. |
Proteins involved in opening a replication bubble are |
| A. | DNA helicases |
| B. | single stranded binding proteins |
| C. | ligase |
| D. | DNA topoisomerase |
| Answer» E. | |
| 37. |
The higher order structure of DNA shows symmetry, whereas the higher order structures of most proteins do not. Why isn't protein shape more regular like DNA? |
| A. | DNA has one main function in cells whereas proteins have many. |
| B. | The many different amino acid R groups on proteins confer many different shapes. |
| C. | Some S amino acids cause proteins to bend; others cause protein to flatten. |
| D. | All of the above |
| Answer» E. | |
| 38. |
What is the main damaging effect of UV radiation on DNA? |
| A. | Depurination |
| B. | Formation of thymine dimers |
| C. | Single strand break |
| D. | Dehydration |
| Answer» C. Single strand break | |
| 39. |
Telomeres are usually rich in which nucleotide? |
| A. | Adenine |
| B. | Guanine |
| C. | Thymine |
| D. | Cytosine |
| Answer» C. Thymine | |
| 40. |
Which is the largest among the followings? |
| A. | Nucleotide |
| B. | Nitrogenous base |
| C. | Phosphate |
| D. | Carbon |
| Answer» B. Nitrogenous base | |
| 41. |
The chromosomal DNA complexes with |
| A. | three types of histone as H1, H2A and H4 |
| B. | five types of histone as H1, H2A, H2B, H3 and H4 |
| C. | four types of histone as H1, H2A, H3 and H4 |
| D. | two types of histone as H1 and H4 |
| Answer» C. four types of histone as H1, H2A, H3 and H4 | |
| 42. |
Which of the following would not contain DNA? |
| A. | Yeast |
| B. | Bacteria |
| C. | Glass crystals |
| D. | Mold |
| Answer» D. Mold | |
| 43. |
What bands will be observed in a cesium chloride gradient after two rounds of replication? |
| A. | One light, one medium and one heavy band |
| B. | One light and one medium band |
| C. | One medium band |
| D. | One medium and one heavy band |
| Answer» C. One medium band | |
| 44. |
Replication in E. coli is initiated by the generation of short RNA primers using |
| A. | RNA polymerase |
| B. | primase |
| C. | reverse transcriptase |
| D. | both (a) and (b) |
| Answer» E. | |
| 45. |
What is the range of melting point temperatures (Tm) for most DNA molecules? |
| A. | 50 to 60 C |
| B. | 60 to 80 C |
| C. | 70 to 90 C |
| D. | 80 to l00 C |
| Answer» E. | |
| 46. |
30 nm wide helix with five or six nucleosomes per helix is known as |
| A. | solenoid |
| B. | halonoid |
| C. | kinoplast |
| D. | none of these |
| Answer» B. halonoid | |
| 47. |
In DNA, guanine pairs with |
| A. | Adenine |
| B. | Cytosine |
| C. | Thymine |
| D. | Uracil |
| Answer» C. Thymine | |
| 48. |
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 | |
| 49. |
DNA helicase is used to |
| A. | unwind the double helix |
| B. | interact the double helix closely |
| C. | break a phosphodiester bond in DNA strand |
| D. | none of the above |
| Answer» B. interact the double helix closely | |
| 50. |
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 | |