DBT BET Previous Year Question Paper: 2012-2013 with Answer Key: Part 3 (Questions 51-100)


Alu sequence in Human Chromosomes (green fluorescence) Source Wikipedia

Biotechnology Eligibility Test (BET) for DBT JRF Award (2012-13)
Previous Year Question Papers with Answer Key, Explanations & References
Government of India, Ministry of Science & Technology
Department of Biotechnology, New Delhi

 PART: B Set 3 (Questions 51 – 100)

51. Suppressor tRNA mutations are those in which

a.       Transcription of tRNA genes is suppressed
b.      Translation form mRNA is suppressed due to absence of tRNA
c.       Amino acid is incorporated in place of a stop codon due to mutation in anticodon region of tRNA
d.      Charging of tRNA with cognate amino acids is suppressed due to mutation in amino acyl tRNA synthase enzyme

Ans. (c)

Suppressor tRNA: also called as nonsense suppressor, due to the suppressor tRNA mutations, an amino acid is incorporated into the stop codon due to mutation in the anticodons of tRNA so that the releasing factors of translation cannot binds to the complex and the translocation process continues.

52. Which of the following media is best suited for the selective growth of E. coli with genotype: Str+ His- leu- lys-?

a.       Minimal medium with thiamine, histidine, leucine and lysine
b.      Luria agar
c.       Minimal medium with thiamine and streptomycin
d.      Minimal medium with thiamine, histidine, leucine, lysine and streptomycin

Ans. (d)

Minimal medium: media that contains minimum nutrients possible for bacterial growth, usually without the presence of amino acids. They used by microbiologists and geneticists to grow “wild type” microorganisms and to select microbes against recombinants.

In the question, the given bacterium is mutated for Histidine, Leucine, and lysine and it has got an antibiotic resistant gene Str+.

53. Which of the following amino acid is coded by maximum number of codons?

a.       Leucine
b.      Tryptophan
c.       Valine
d.      Alanine

Ans. (a)

Leucine can be coded by 6 codons
Methionine and Tryptophan are coded by least codons, only one codon
For details of amino acids and MCQ on amino acids: click here

54. In cell cycle, paternal and maternal chromosomes exhibit a ‘bouquet stage’ during

a.       Leptotene
b.      Zygotene
c.       Pachytene
d.      Diplotene

Ans. (b)

A stage of Meiosis I where pairing of homologous chromosomes take place.

55. Which of the following cytokines is secreted by both Th1 and Th2 type of cells?

a.       IL-2
b.      IL-3
c.       IL-4
d.      IFN-γ

Ans. (b)

56. Processing of transfer RNA involves

a.       Cleavage of extra bases from both 3’and 5’ ends
b.      Nucleotide sequence specific methylation of bases
c.       Addition of sequences CCA by a nucleotidyl transferase
d.      Addition of methylated guanosine at 5’ end

Ans. (c)

57. Somatic mutation of Immunoglobulin gene accounts for

a.       Allelic exclusion
b.      Class switching from IgM to IgG
c.       Affinity maturation
d.      V(D)J recombination

Ans. (c)

58. Which of the following enzyme NOT used in pyrosequencing?

a.       DNA polymerase
b.      Pyrophosphatase
c.       Luciferase
d.      ATP sulfurylase

Ans. (b)

59. Which of the following statements is not true for HFr strains of E. coli?

a.       F factor is integrated in the genome
b.      Chromosomal markers are transferred from donor to recipient
c.       They act as donors in the cross
d.      Progeny of the cross always becomes F+

Ans. (d)

60. Which of the following organisms contain a 11 bp specific DNA sequence that acts as self-recognition sequence in natural transformation?

a.       Streptococcus pneumonia
b.       Bacillus subtilis
c.       E. coli
d.       Hemophilus influenza

Ans. (d)

61. The amino acid sequence of a novel membrane protein contains four immunoglobulin-like domains and six fibronectin-like repeats. This protein is most likely a:

a.       Hormone responsive ion channel
b.      Cell adhesion molecule
c.       G-protein
d.      Transcription factor

Ans. (b)

62. Which one of the following viruses is not transmitted by the fecal-oral route?

a.       Hepatitis A virus
b.      Hepatitis E virus
c.       Hepatitis D virus
d.      Enterovirus

Ans. (c)

63. The earliest markers of the B-cell lineage which first appears during maturation of the precursor B cells and remains throughout the life span of the B cell is

a.       B7
b.      CR1
c.       Class II MHC
d.      B220 (or CD45)

Ans. (d)

64. Which of the following repair mechanisms is absent in a cell arrested in cell cycle?

a.       Transcriptional coupled repair mechanism
b.      Excision repair mechanism
c.       DNA synthesis annealing repair mechanism
d.      Recombination repair mechanism

Ans. (C)

65. Intracellular transport in mammalian cells through vesicular fusion is regulated by which among the following GTPase?

a.       Rho
b.      Ran
c.       Rab
d.      Ras

Ans. (c)

66. HSP70 chaperons are not present in which among the following organelles?

a.       Endoplasmic reticulum
b.      Golgi bodies
c.       Nucleus
d.      Mitochondria

Ans. (b)

67. Major gluconeogenesis occurs in

a.       Liver and kidney
b.      Liver and heart
c.       Liver and skeletal muscles
d.      Liver and adrenal gland

Ans. (a)

68. A change in which of the following genes is responsible for Fragile X syndrome?

a.       FMR1
b.      RELB
c.       FXR1
d.      FAD2

Ans. (a)

69. Molecular basis of Chediak-Higashi syndrome is

a.       Mutation in a protein involved in regulation of intracellular trafficking
b.      Due to deficiency of adenosine deaminase
c.       Error in antigen processing
d.      Reversal of anergy in self-reactive clones

Ans. (a)

70. Type III hypersensitivity is mediated by

a.       Immune complex deposition
b.      Antigen specific T cells
c.       Complement cascade
d.      Perforin and granzyme

Ans. (a)

71. Junctional diversity affects primarily the amino acid sequence in:

a.       All CDR equally
b.      CDR1
c.       CDR2
d.      CDR3

Ans. (d)

72. A child stung by a bee experiences respiratory distress within minutes and lapses into unconsciousness. This reaction is probably mediated by

a.       IgE antibody
b.      IgG antibody
c.       Sensitized T cells
d.      Complement

Ans. (a)

73. Neutrophils are attracted to an infected area by:

a.       IgM
b.      Vascular permeability
c.       Phagocytosis of IgE coated bacteria
d.      Aggregation of C4 and C2

Ans. (c)

74. In the immune response to a hapten-protein conjugate, in order to get anti-hapten antibodies it is essential that

a.       The hapten be recognized by helper T cells
b.      The protein be recognized by helper T cells
c.       The protein be recognized by B cells
d.      The hapten be recognized by suppressor T cells

Ans. (b)

75. Chromatin loops are formed by periodic attachment of the following onto the nuclear skeleton

a.       Histones
b.      MARs
c.       Promoters
d.      Introns

Ans. (b)

76. Telomeric DNA does not contain

a.       G-rich sequences
b.      Quadruplex
c.       T and D loops
d.      AT rich sequences

Ans. (d)

77. The ATP required for ligation during base excision repair is generated from

a.       NAD
b.      Poly (ADP-ribose)
c.       DNA
d.      AMP

Ans. (b)

78. The covalent modification of histones that is not known to play a role in regulation of gene expression is

a.       Poly (ADP-ribosyl)ation
b.      Acetylation
c.       Methylation
d.      Glycosylation

Ans. (d)

79. Okazaki fragments are

a.       RNA primers for DNA synthesis
b.      Short DNA fragments after nuclease digestion
c.       Newly synthesized DNA fragments
d.      Short stretches of DNA attached to RNA primers on lagging strand

Ans. (d)

80. The changes in the electrical potential of a neron constitute the action potential occur in the following order

a.       Depolarization > resting potential > hyperpolarization > resting potential
b.      Resting potential > depolarization > hyperpolarization > resting potential
c.       Resting potential > hyperpolarization > resting potential > resting potential
d.      Resting potential > hyperpolarization > resting potential > depolarization

Ans. (b)

81.  Suppose you were to treat a normal mammalian cell with a substance that inhibits the Na-K ATPase, what would be the most immediate effect upon the cell?

a.       There would be no change at all
b.      The cell’s osmotic balance would be disrupted and the cell would begins to swell
c.       The cell membrane potential would immediately drop to zero
d.      The cell would very quickly run out of ATP

Ans. (c)

82. In a population that is in equilibrium, the proportion of individuals showing the dominant trait at a given locus having two alleles is 84%. The frequency of the recessive allele in the population is:

a.       0.4
b.      0.3
c.       0.2
d.      0.16

Ans. (a)

83. Developing T cell that react strongly with self-peptides bound to self- MHC molecules are:

a.       Eliminated in the thymus
b.      Eliminated in the bone marrow
c.       Suppressed in peripheral blood circulation
d.      Allowed to function normally

Ans. (a)

84. Which of the following statements is correct?

a.       T lymphocytes are conditioned by the bone marrow
b.      B lymphocytes are conditioned by thymus
c.       B cells produce plasma and memory cells
d.      T cells do not produce cytokines

Ans. (c)

85. What is the force among the following that is primarily responsible for stabilizing the tertiary structure of globular proteins?

a.       Disulfide bonding
b.      The hydrophobic effect
c.       Hydrogen bonding
d.      Ionic interactions

Ans. (b)

86. Which of the following sequences describes the passage of an action potential in the neuron?

a.       Axon, cell body, dendrite, synaptic cleft
b.      Synaptic cleft, axon, dendrite, cells body
c.       Dendrite, synaptic cleft, cell body, axon
d.      Dendrite, cell body, axon, synaptic cleft

Ans. (d)

87. In the biological treatment of waste, bacteria such as species of Acinetobacter and Zoogloea are considered to play a key role in floc formation

a.       By the synthesis and secretion of polysaccharides
b.      Since they are acid producers
c.       As they are slow growing methanogens
d.      Since they break down acetic acid into methane and CO2

Ans. (a)

88. During primary sedimentation and biological treatment of waste water, vast quantities of sludge are generated which are assessed by sludge volume index (SVI), defined as the volume occupied by 1 g of sludge after settling for 30 min in a 1L Imoff cone which measures the

a.       Sludge thickening
b.      Sludge stabilization
c.       Sludge dewatering
d.      Rate of acid utilization

Ans. (a)

89. Some extremozmes are found to remain active and stable up to 140oC. The decreased flexibility and rigidity of the molecule is due to

a.       Highly nonpolar core
b.      Reduction in glycine content
c.       Presence of unsaturated fatty acids
d.      Ornithine content

Ans. (b)

90. Solid state fermentation (SSF) involve solid substrate at low moisture levels or water activities where

a.       The water content is > 95%
b.      The water content is between 40-80%
c.       The water content is between 4-8%
d.      The water content is 10%

Ans. (b)

91. The common type of duplication generates a second copy of the gene

a.       In close proximity of the first copy
b.      In a distant location on the same chromosome
c.       On a different chromosome
d.      In any chromosome at random probability

Ans. (a)

92. A silent substitution

a.       Creates a premature stop codon, thus silencing expression of the gene
b.      Substitutes  one amino acid for a different amino acid with similar properties so it does not affect protein function
c.       Change only one DNA base in a codon without changing the amino acid sequence
d.      Occurs outside the protein coding region in the 5’ or 3’ un-translated region and thus does not affect protein function

Ans. (c)

93. Satellite DNAs are not typically found within which of the following parts of a chromosome?

a.       Heterochromatin
b.      Euchromatin
c.       Telomeres
d.      Centromeres

Ans. (a)

94. What is the sugar-sugar linkage among the following is the 5’ cap on mRNA molecules?

a.       5’ – 3’
b.      3’ – 5’
c.       3’ – 3’
d.      5’ – 5’

Ans. (d)

95. Introduction of a non-sense mutation in a eukaryotic protein coding gene often leads to

a.       Retention of mRNA in a nucleus so it is not translated
b.      Increased degradation of the mRNA in the nucleus
c.       Increased degradation of the mRNA in the cytoplasm
d.      Decreased ribosome binding in the cytoplasm in mRNA due to its shorter size

Ans. (c)

96. What effect would ‘N’ nutation have on phage lambda infection?

a.       No effect, infection would proceed as normal to either lytic or lysogeny pathway
b.      Lytic pathway blocked only lysogeny possible
c.       Lysogeny pathway blocked only lytic pathway possible
d.      Complete abolishment of infection, neither lytic nor lysogeny pathway is possible

Ans. (d)

97. The bacterial ftsZ gene is required for

a.       Septum formation
b.      Perispetal annulus formation and localization
c.       DNA replication
d.      Transport of DNA

Ans. (a)

98. Two plasmids are of the same compatibility group if they

a.       Can co-exist in the same bacterial cell
b.      Cannot co-exist in the same bacterial cell
c.       Carry the same antibiotic gene
d.      Carry the same toxin gene

Ans. (b)

99. Replication defective retroviruses are most commonly generated by

a.       Recombination and rearrangement of sequences
b.      Mutation at critical sites in viral genes
c.       Deletion of a segment of the viral genome
d.      Insertion of the sequence in the viral gene

Ans. (a)

100. Alu elements are

a.       SINEs
b.      LINEs
c.       Retroposon
d.      DNA transposon

Ans. (a)

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