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LTIPLE CHOICE QUESTIONS FOR M.SC. MICROBIOLOGY ENTRANCE EXAM PREPARATION, TU, 2012 (SUBJECT: MOLECULAR BIOLOGY/GENETICS)

a. b. c. d. a. b. c. d.

a. b. c. d. a. b. c. d. a. b. c. d.

a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d.

1. The scientists who proposed 3D model of DNA Rosaline Frankline James Watson Francis crick Frederick Sanger 2. Who first discovered Nucleic acid? Friedrich Miescher P. A. Levene Erwin Chargaff Tatum 3. One complete turn of DNA molecules have ………………..base pairing with …………………diameter. 10 base pairing and 10 nm 12 base pairing and 6 nm 10 base pairing and 34 nm One base pairing and 3.4 nm 4. Which of the following forces stabilize the DNA double helix structure? Hydrogen bonds between complementary bases Stacking interactions between bases Super-coiling structure All 5. Which of the following best describes the arrangement of the sides of the DNA molecule? twisted antiparallel super coiling alternating 6. If a DNA molecule is found to be composed of 40% thymine, what percentage of guanine would be expected. 10% 20% 40% 80% 7. The enzymes that break hydrogen bonds and unwind DNA are: primers forks helicases polymerases 8. Okasaki fragments occur during……………… on ………………………strand. Transformation and ss RNA Replication and lagging polymerase reaction and amplifying DNA Synthesis and leading 9. Which of the following must happen first in order for DNA replication to occur? DNA polymerase binds to the leading strand DNA is unwound Hydrogen bonds form between bases chromosomes condense 10. Which of the following is required for DNA replication to occur?

a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d.

DNA helicase DNA ligase DNA polymerase all of these 11. DNA replication results in: 2 completely new DNA molecules 2 DNA molecules that each contain a strand of the original 1 new DNA molecule, 1 old molecule is conserved 1 new molecule of RNA 12. During replication, what enzyme adds complimentary bases? helicase synthesase replicase polymerase 13. Which one polymerase synthesize DNA molecule in Replication? Polymerase I Polymerase II Polymerase III All 14. Which one of the following choices best completes about the histones: Are basic proteins rich in lysine and or arginine Are bound covalently attached to DNA Are found in high concentration in ribosomes Are identical to protamines 15. One class of RNA characteristically contains unusual purines and pyridines is tRNA mRNA rRNA 16S RNA 16. Which of the following statements about mRNA is, are correct? mRNA exists as single stranded molecule. mRNA has a 7’-methylguanosine “cap” at its 5’ end. mRNA has a 3’-poly-A sequence. All of the above 17. Which one of the following choices best completes about tRNA? Is the largest of the RNA species Has little or no secondary structure Must exist in at least 20 different forms, one for each amino acid Exists in cytosol associated with histones 18. Which one of the following molecule is not a component of the 30S initiation complex? GTP Initiation factor 2 (IF2) mRNA ATP 19. The genetic code Is degenerate in that many triplets code for more than one amino acid Is read in the direction 3’-5’ Triplet CCA is found at the beginning of nearly all mRNA coding Is generally referred to as universal 20. Which one of the following plasmid codes for the production of bacteriocins ? F plasmid R plasmid Col-plasmid Virulence plasmid 21. The plaque forming lamda virus is

a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d.

a. b. c. d.

A lytic virus A lysogenic virus A template virus None 22. The mechanism of tetracycline is to inhibit translation process by Blocking the binding of aminoacyl tRNA to A-site of ribosome Blocking initiation of RNA chains by binding to RNA polymerase Binding DNA to block the movement of RNA polymerase Preventing the transition from initiation complex to chain elongating ribosome/miscoding 23. One of the following statement best describes about the Hfr positive cell in conjugation. It is a recipient cell It is a fertile as a chromosomal segment of it is transferred to F- cell It has high frequency of recombination All 24. Short RNA primers required for DNA replication is synthesized by DNA primase DNA ligase DNA helicase DNA gyrase 25. Transcription results in: an amino acid chain messenger RNA complementary DNA okazaki fragments 26. A stretch of chromosome that codes for a trait can be called a(n): chromatid replication fork gene base-pair 27. In RNA, _____ codon(s) translate to ______ amino acid(s) 1, 1 3, 1 3, 3 1, 20 28. Translation begins: a. at the replication fork b. on the lagging strand c. at the start codon d. in the nucleus 29. A nucleotide consists of: a phosphate and a base a phosphate, and a sugar a base and an amino acid a phosphate, a sugar, and a base 30. The sugar in RNA is _____, the sugar in DNA is _______. a. deoxyribose, ribose b. ribose, deoxyribose c. ribose, phosphate d. ribose, uracil

31. The diploid cells of an animal have 44 chromosomes. How many chromosomes would you expect to find in the animal’s sperm cells?

a. b. c. d.

22 44 88 2 32. Down’s Syndome occurs when an invidual has: a. an extra chromosome 21 b. a missing chromosome c. an extra set of homologs d. haploid cells 33. After examining a karyotype of an animal, a researcher counts 50 individual chromosomes of varying sizes. How many homologs are in the karyotype? a. 25 b. 50 c. 100 d. 200 34. Chromosomes are paired together based on their: a. size b. banding pattern c. centromere location d. all of these 35. Chromosomes line up on the equator during: a. anaphase b. telophase c. metaphase d. interphase 36. The purpose of mitosis is to: a. create new cells b. copy DNA c. cellular repair d. reproduction 37. What did Frederick Griffith’s discover? a. DNA carried genetic information b. bacteria could transform c. mice died when exposed to viruses d. viruses were encapsulated 38. What was the overall conclusion of the hershey-chase experiment? 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 39. The 5′ and 3′ numbers are related to the: a. length of the DNA strand b. carbon rings in sugar c. the number of phosphates d. the base pair rule 40. A nucleoside consists of: a. a nitrogen base b. a nitrogen base and a sugar c. a nitrogen base, sugar, and phosphate d. two nitrogen bases, a sugar, and a phosphate 41. The element that transformed the bacteria in Griffith’s experiments was: a. protein b. capsules c. DNA d. Heat

42. The “rungs” of the DNA ladder are made of: phosphates & bases sugars sugars & phosphates bases 43. In order to transform to a virulent form of bacteria, non encapsulated bacteria must: a. Divide b. be exposed to killed capsulated bacteria c. be exposed to radioactive phosphorous d. infect a host 44. A DNA strand has the following bases: A A G C C A. What are the bases on its complimentary strand? a. AAGCCA b. A C C G A A c. TTCGGT d. C C A T T C 45. RNA is synthesized on a DNA template in a process called ______, which utilizes the enzyme _______. a. translation, RNA polymerase b. transcription, DNA polymerase c. transcription, RNA polymerase d. replication, DNA polymerase 47. Which of the following is NOT a necessary component of translation? a. Anticodon b. mRNA c. Ligase d. amino acid 48. Given the following DNA strand, which of the following is its complementary mRNA? GGACTGATT a. CCTGACTAA b. C C U G A C U A A c. GGACTGATT d. T T A G T C A G G 50. Proteins contain ____ different amino acids, whereas DNA and RNA are composed of ___ different nucleotides. a. 20, 64 b. 3, 20 c. 4, 20 d. 20, 4 51. The base pair rules states that: a. Replication is semiconservative b. A pairs with T, G pairs with C c. DNA is a double helix held together by hydrogen bonds d. A pairs with G, T pairs with C 52. Once transcription has been completed, which of the following is NOT necessary for protein synthesis to occur? a. tRNA b. ribosomes c. mRNA d. DNA 53. Which site of the tRNA molecule binds to the mRNA molecule? a. Anticodon b. Codon c. amino acid d. 5 prime end a. b. c. d.

a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d.

a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d. a. b. c. d. a.

54. Okazaki fragments occur on the ___ and are bonded together by ______. leading strand, polymerase mRNA, anticodons lagging strand, ligase tRNA, polymerase 55. How many different codons are possible? 3 20 64 an infinite number 56. The prokaryotic ribosome is of 70S type which is composed of subunits: 50S and 30S 40S and 60S 5S, 23S, and 33 polypeptides, 16S and 21 polypeptides All 57. The role of RNA polymerase I is to transcribe genes of: 5.8S, 18S and 28S rRNA genes All protein-coding genes plu s coRNA genes and some snRNA genes tRNA genes, 5S rRNA genes, some snRNA genes and genes for other small RNAs none of the above 58. Recognition and attachment of correct amino acids in tRNA during translation depends on the enzyme: Reverse transcriptase Aminoacyl tRNA synthetases RNA polymerase Spliceosome 59. The RNA message is decoded on Ribosomes tRNAs mRNAs small RNAs 60. The chain termination codons in translation is/are AUG UAA UAG UGA 61. AUG, an intiation codon in translation codes for an amino acid Methionine Arginine Tyrosine Glycine 62. The mutation caused due to long time exposure on UV light is Spontaneous mutation Induced mutation Both None 62. Which scientists established that EcoRI could generate staggered or “sticky” ends? Berg and Jackson b. c. d.

Mertz and Davis Cohen and Boyer Helling and Chang

63. pBR322 is a plasmid vector commoly used in molecular cloning capable of conjugal transfer with tet gene all of the above 64. pUC18 plasmid has marker gene a. b. c. d.

ampicillin resistant gene tetracycline resistant gene F factor All of the above 65. T4 DNA ligase used in molecular cloning is a. b. c. d.

Encoded by gene 30 of bacteriophage T4 A monomeric protein of 487 amino acids For joining inserted DNA into vector DNA All 66. Fertility plasmid (F plasmid) is a circular DNA molecule of a. b. c. d.

100 Kb 200 Kb 300 Kb 400 Kb 67. The lamda virus has genomic DNA of molecular size a. b. c. d.

48.5 Kb 60 Kb 80 Kb 100 Kb 68. The following compound is used to precipitate DNA a. b. c. d.

SDS Salt Proteinase K Ethanol 69. Competent cells for transformation are prepared by treating cells with a. b. c. d.

High concentrations of Lysozyme High concentration of calcium chloride High concentration of SDS High concentration of sodium hydroxide 70. Mutagenic agent hydroxylamine reacts with a. b. c. d.

Adenine Guanine Cytocine Thymine 71. Mutation resulting from replacement of purine from one strand of DNA with the other purine and vice versa (Pyrimidine) is………………………mutation. a. b. c. d.

a. b.

Transversion M Transition M

Frameshift M Deletion M 72. Which one of the following is/are point mutation? c. d.

Transversion M Transition M Frameshift M All 73. RNA polymerase is composed of two  subunits, one  subunit, one  subunit and one sigma  subunit. Which one subunit (factor) is involved in initiation of transcription? a. b. c. d.

 subunit  subunit  subunit  subunit 74. The termination factor of transcription is a. b. c. d.

Rho factor G:C riched region followed by six or more A:T base pairs Sigma factor All of the above 75. The excision of introns sequences from primary transcripts is required before translation. It is done by a. b. c. d.

Restriction endonucleases DNA gyrase RNA polymerase RNA splicing 76. Gene expression in prokaryotes is regulated at …………levels. a. b. c. d.

Transcription mRNA processing mRNA turnover/translation/post-translation All of the above 77. The operon model, a negative control mechanism was developed in 1961 by a. b. c. d.

Griffith Jacob and Monod Zinder and Lederberg Lederberg and Tatum 78. The three structural genes in lac operon, lacZ, lacy and lacA encoding the enzymes a. b. c. d.

 galactoside permease,  galactosidase and  galactoside tranacetylase  galactoside tranacetylase,  galactoside permease and galactosidase  galactosidase,  galactoside permease and  galactoside tranacetylase Only  galactosidase 79. Which one of the following is /are catalytic ribozymes? a. b. c. d.

Messenger RNA tRNA Ribosomes Spliceosomes 80. An example of a restriction enzyme that gives a blunt end cut is: a. b. c. d.

a. b. c. d.

SmaI BamHI TaqI EcoRI 81. Which active enzyme is present in bacteria that give blue colony in the presence of X-gal? a. Ampicillin resistance b. Tetracycline resistance c. Permease d. β-galactosidase 82. A multiple cloning site ortant for chromosomal DNA ns many restriction enzyme and recognition sites called alpha-complementation as a probe in Southern blots 83. Choramphenicol reisistant gene of bacterial plasmid is responsible for a. inhibition of bacterial cell wall synthesis b. binding to 30S subunit of ribosome c. binding to 50S subunit of ribosome d. inhibition of glycolysis pathway 84. What is the function of tra genes in bacteria? a. production of bacteriocins b. resist to antibiotics c. helps in conjugation d. cause pathogenecity in bacteria 85. pUC19 plasmid vector contains one of the following selectable marker gene a. kanR b. ampR c. tetR d. tra genes 86. In the lysogenic pathway the bacteriophage genome a. Is not integrated into the host genome b. Is integrated into the host genome c. Results in bacterial lysis d. Contain cohesive termini 87. Arrange the following vectors in ascending order in terms of size of possible inserts: a. BACs, cosmids, plasmids, bacteriophage b. Cosmids, bacteriophage, plasmids, BACs c. Plasmids, bacteriophage, cosmids, BACs d. Bacteriophage, BACs, plasmids, cosmids 88. The first eukaryote-infecting virus used for cloning was: a. HIV b. SV40 c. Adenovirus d. Lambda phage 89. A cDNA library: a. Contains information related to gene regulation b. Is of the same size as genomic library c. Represents those genes expressed in a particular tissue at a particular time d. Represents the entire genome of the organism 90. A nylon membrane is used for Southern blots because a. Agarose gels are fragile b. Probes cannot be visualized in agarose c. DNA cannot be denatured in agarose d. Agarose gels do not efficiently separate DNA fragments

91. Dideoxyribonucleotides differ from deoxyribonucleotides because an additional hydroxyl group is missing from position a. 5’ b. 1’ c. 2’ d. 3’ 92. What is the annealing temperature for the following 21 mer primer? AAGCTTGTCCAGAATTTCGAT a. 58C b. 62C c. 54C d. 50C 93. Which one of following is the recognization site for HindIII enzyme a.

5'GGCC

b.

5'GAATTA

c.

5'GGATCC

d.

5'AAGCTT

3'CCGG 3'CTTAAT 3'CCTAGG 3'TTCGAA 94. Which one of following is the recognization site for EcoRI enzyme a.

5'GGCC

b.

5'GAATTC

c.

5'GGATCC

d.

5'AAGCTT

3'CCGG 3'CTTAAG 3'CCTAGG 3'TTCGAA 95. How many bands would you obtain when DNA is cut by EcoRI and HindIII ? a. 6 b. 8 c. 10 d. 12 96. Cancer, a type of genetic disorder is due to mutation in a. Single gene b. Multi gene c. Mitochondrial DNA d. Chromosome 97. The genetic disorder Huntington’s disease is caused due to defect in:a. Chromosome 16 b. Chromosome 20 c. Y chromosome d. Chromosome 98. Which one of the following statement about randomly amplification of polymorphic DNA is not true? a. RAPD sequences are used to detect Variability in the PCR priming site. b. Banding patterns of amplified product is not same for every individual in a pop c. RAPQ methods do not distinguish between homozygous & heterozygous allele states d. RAPD method is useful to distinguish between homozygous & heterozygous allele states. 99. Methodology for southern blot hybridization include:a. Gel electrophoresis of DNA fragments b. Restriction Digestion c. Hybridization

d.

all of the above 100. Which one of the following histones most strongly binds to DNA? a. H1 b. H5 c. H3B d. ALL