CSIR Life sciences Paper 1 Part B

LIFE SCIENCES

PAPER I(PART ‘B’)

41. During protein synthesis, L-amino acid binds to t-RNA through
1. α-amino group.
2. hydrophobic side chain.
3. α–carboxyl group.
4. carboxyl group of the side chain.

42. The peptide bond is planar
1. due to restriction caused by rotation around cα–N bond
2. due to restriction around cα–c′ bond
3. due to delocalization of the lone pair of electrons of the nitrogen onto
carbonyl oxygen
4. because amide protons and carbonyl oxygen are involved in hydrogen
bonding.

43. Hydrogen bond length will NOT be
1. independent of the nature of donor and acceptor atoms.
2. dependent on donor and acceptor atoms.
3. dependent on the solvent in which the molecule is dissolved.
4. dependent on the other atoms bonded with the donor and acceptor atom.

44. Why a DNA duplex melts at a specific temperature (Tm) on heating?
1. Loss of base stacking energy
2. The double helix is intrinsically unstable
3. The single helix is more stable as compared to the double helix
4. The DNA double helix is a co-operative structure stabilized by hydrogen
bonds and base pairing

45. Lipid bilayers can be formed by phospholipids which have variable head groups
and fatty acyl chains. The fluidity of the membrane will depend on
1. only the nature of head groups.
2. only the length of the fatty acid chains irrespective of the extent of
unsaturation.
3. only unsaturation irrespective of the length of the fatty acid chains.
4. length and degree of unsaturation of fatty acid chains.
46. Which one of the following RNA molecules is involved in regulation of gene
expression?
1. miRNA
2. rRNA
3. 5S RNA
4. tRNA

47. In which organelle is NADP+ the final electron acceptor?
1. Only chloroplast
2. Only mitochondrion
3. Both chloroplast and mitochondrion
4. Lysosome

48. When the K'q = 1, ΔG° is equal to
1. –1.
2. 0.
3. +1.
4. 10.

49. Which one of the following human pathogen is a flagellated protozoan?
1. Trypanosoma
2. Plasmodium
3. Paramecium
4. Entamoeba

50. Which of the following mammalian cells usually does NOT divide in adult life?
1. Epithelial cells in lung
2. Nerve cells in brain
3. Liver cells
4. Osteoblast cells

51. What happens to the Cdk-cyclin A complex at metaphase?
1. Both cyclin A and Cdk remain undegraded
2. Only Cdk is degraded
3. Only cyclin A is degraded
4. Both cyclin A and Cdk are degraded

52. The average human genome has approximately 3×109 base pairs coding for
various proteins. If an “average” protein contains 400 amino acids, what is the
maximum number of proteins that can be encoded by the human genome?
1. 2.5 × 106.
2. 2.5 × 107 .
3. 3.0 × 106 .
4. 3.5 × 107 .

53. In eukaryotes, the interaction of enhancer and promoter elements is brought
closer by
1. zinc finger.
2. DNA looping.
3. helix turn helix.
4. palindrome.

54. Which of the following cytoskeleton elements guides the movement of vesicles
containing cell wall precursors from their site of formation in Golgi to the site of
new wall formation in a growing pollen tube?
1. Myosin
2. Actin
3. Kinesin
4. Dynein

55. Ionophores are small hydrophobic molecules that can partition into the lipid
bilayer and increase their permeability to specific inorganic ions. Which of the
following is a channel forming ionophore?
1. Valinomycin.
2. Actinomycin.
3. Gramicidin A.
4. Nicin.

56. Which GTPases regulate intracellular transport in mammalian cells through
vesicle fusion?
1. Rab
2. Ran
3. Ras
4. Rho

57. The region where RNA polymerase binds to promoter in prokaryotes is called
1. Pribnow box.
2. Hogness box.
3. Homeo box.
4. Shine-Dalgarno box.

58. Which of the following features highlights the difference between Z-DNA and BDNA?
1. Double helical nature
2. Orientation of phosphate backbone
3. Pairing of G – C
4. Antiparallel nature of two polynucleotide strands of double helix

59. Ribosomal subunits are assembled in
1. cytoplasm.
2. nucleolus.
3. nucleus.
4. endoplasmic reticulum.

60. The absence of sigma factor in RNA polymerase
1. affects elongation only.
2. blocks initiation only.
3. affects both initiation and elongation.
4. does not affect transcription.

61. Which of the following features is not required in the initiation step of protein
synthesis?
1. Amino acid activation
2. Binding of mRNA to the ribosomes
3. Transfer of activated amino acid to tRNA
4. Joining together of two amino acids by peptide bond formation

62. By which of the following mechanisms does cycloheximide inhibit protein
synthesis?
1. Blocking the peptidyl transferase of 80S euokaryotic ribosomes
2. Blocking the peptidyl transferase of 70S prokaryotic ribosomes
3. By binding to DNA dependent RNA polymerase
4. By binding to sigma factor

63. Which of the following is a natural inducer of the lac operon in E. coli?
1. Lactose
2. Galactose
3. Allolactose
4. IPTG

64. Antitermination of RNA synthesis is a major mechanism of regulation in
1. lytic phase of λ phage.
2. lysogenic phase of λ phage.
3. lac operon.
4. trp operon.

65. Influenza virus binds to its host cells through which one of the following
carbohydrate moiety.
1. N-acetyl glucosamine
2. N-acetyl neuraminic acid
3. Fucose
4. Mellibiose

66. In mammals, G protein coupled receptors (GPCR) play a major role in mediating
effects of various hormones NOT through
1. activation of protein kinase A.
2. activation of adenylate cyclase.
3. inactivation of adenylate cyclase.
4. activation of tyrosine kinase activity.

67. Receptors for neurotransmitters are located on the
1. cell surface.
2. nucleus.
3. endosome.
4. Golgi apparatus.

68. One of the major transmembrane proteins in a “tight junction” is
1. lectin.
2. claudin.
3. adherin.
4. integrin.

69. Retroviruses are well known as cancer causing agents because it
1. causes mutations in host genes involved in growth.
2. integrates their proviral DNA next to protooncogenes.
3. generates defective viruses lacking some of the viral genes.
4. integrates their T antigens into the host genome.
70. Select the correct statement:
1. In vertebrate development, immune and nervous systems are
the prevalent sites for apoptosis.
2. Apoptosis is triggered by growth stimulus.
3. The tumor suppressor factor p53 inhibits apoptosis.
4. The soluble form of tumor necrosis factor cannot induce apoptosis.

71. ELISA assay
1. uses complement mediated cell lysis.
2. uses a radiolabeled second antibody.
3. involves addition of substrate which is converted to coloured end product.
4. requires specialized red blood cells.

72. In mosaic development, the prospective potency of cells
1. equals its prospective fate.
2. is greater than prospective fate.
3. is less than prospective fate.
4. and fate are unrelated.

73. Experiments with sea urchin demonstrated species specific sperm-egg
recognition through the protein
1. bindin.
2. avidin.
3. activin.
4. hyalin.

74. Exposing a regenerating limb to which of the following chemicals results in the
blastema proximalization?
1. Ascorbic acid
2. Thyroxine
3. Retinoic acid
4. Glutamic acid

75. Temperature-dependent sex determination is observed in
1. Drosophila.
2. amphibians.
3. reptiles.
4. sea urchins.
76. Some plants require vernalization (prolonged cold treatment) for transition to
flowering. For floral induction, vernalization signal is perceived primarily by
1. young leaves subtending the apical meristem.
2. mature leaves near the root-shoot junction.
3. all vegetative parts.
4. shoot apical meristem.

77. Which phase of embryogenesis in plants is characterized by the initiation of
deposition of storage reserves?
1. Globular stage
2. Heart stage
3. Torpedo stage
4. Cell enlargement stage

78. Which of the following statements is NOT true in relation to growth of animals?
1. When all body parts grow at the same rate, it is called isometric growth.
2. When different body parts grow at different rates, it is called allometric
growth.
3. Two-fold change in weight will cause a 1.26-fold expansion in length if
growth is allometric.
4. Isometric growth cannot create dramatic changes in the structure of
organisms.

79. Abnormalities during development caused by exogenous agents are called
disruptions and the agents are specifically called
1. morphogen.
2. teratogen.
3. allergen.
4. mutagen.

80. At which of the following steps does application of dichlorophenyl-dimethyl urea
(DCMU) inhibit electron flow during photosynthesis?
1. P680* → Pheophytin
2. QA → QB
3. QB → Cytb6f complex
4. Cytb6f complex → plastocyanin

81. A major functional difference between the succinyl CoA-synthetase of plant and
animal cell mitochondria is that it
1. does not produce ATP in plant cell.
2. does not produce GTP in plant cell.
3. produces ATP in plants and GTP in animals.
4. produces GTP in plants and ATP in animals.

82. A common symptom of molybdenum deficiency in plants is the accumulation of
nitrate in the cytosol, which results from
1. reduced nitrite reductase activity.
2. reduced nitrate reductase activity.
3. reduced transport of nitrate into the vacuoles.
4. reduced transport of nitrate into the chloroplasts.

83. The Rht mutations in wheat that were pivotal for 'Green Revolution' cause
reduction in plant height due to impairment in
1. gibberellic acid biosynthesis pathway.
2. gibberellic acid signaling pathway.
3. auxin biosynthetic pathway.
4. auxin response pathway.

84. Which of the following phytochrome controlled responses displays red/far-red
reversibility?
1. Very low-fluence responses
2. Low-fluence responses
3. High-irradiance responses
4. Very high-irradiance responses

85. At permanent wilting point, plants cannot regain turgor pressure even if
transpiration stops because
1. water potential of soil (ψw) is less than or equal to osmotic potential (ψS)
of the plant.
2. ψw is higher than ψS .
3. ψw and ψS are unaltered.
4. ψS remains unaltered.

86. Alkaloid production in plants is regulated by a change in the endogenous pool of
1. gibberellins.
2. jasmonates.
3. brassinosteroids.
4. abscisic acid.

87. Flooding and submergence of plants leads to anoxic conditions. Usually, floodtolerant
species alter their developmental programme, resulting in
1. increased activity at the apical meristem.
2. growth retardation of foliage.
3. elongation growth of their stems.
4. increased proliferation of root system.

88. An organism with the genotype AABbCcDD is selfed. The four genes are
independently assorting. What proportion of the progeny will show the genotype
AAbbccDD?
1. 1/4
2. 1/16
3. 1/64
4. 1/256

89. Two fruitflies with mutant eye color were crossed. All progenies obtained from
this cross had wild type eye colour as
1. the mutations are allelic.
2. one mutation is dominant over the other.
3. the mutations are co-dominant.
4. the mutations are in two different genes.