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CSRI JRF NET Life Sciences June 2017 Model Question Paper Set- 4

biological significance of hydrogen bonds in water

CSIR JRF/NET Life Science Exam June 2017 (I)
Model Question Paper 4/4
(CSIR MCQ011: Practice Questions with Answer Key)

1.  Penicillin-resistant bacteria produce β-lactamase which inactivates penicillin by:

a.       Esterifying the carboxyl group
b.      Oxidizing S atom
c.       Hydrolyzing the side chain
d.      Hydrolyzing the C-N bond

Ans. (d)

β-lactamases or penicillinase are a class of enzymes produced by some bacteria which degrade penicillin antibiotic and thereby impart resistance against penicillin. All penicillin antibiotics contain a β-lactum ring structure which is essential for the antibiotic activity. The β-lactamase enzyme will degrade the β-lactum ring and thus inhibit the antibiotic properties.

2. Pseudo-murein is present in cell wall of:

a.       Streptococci
b.      Staphylococci
c.       Methanococci
d.      Micrococci

Ans. (c). Methanococci

Methanococci is an Archaebacteria.

Pseudo-murein or pseudo-peptidoglycan is a major cell wall component of some Archaebacteria. It is structurally different from the peptidoglycan of the true bacteria. However, it is functionally similar to the peptidoglycan wall of bacteria. Pseudo-murein is a hetero-polysaccharide of N-acetylglucosamine and N-acetyltalosaminuronic acid connected by β-1,3-glycosidic bonds. Lysozyme enzyme is unable to degrade the pseudo-murein cell wall.

Learn more: Difference between Murein and Pseudo-murein

Learn more: Comparison table of Bacteria, Archaea and Eukarya

3. Bacteria that can penetrate intact corneal epithelium is:

a.      Pseudomonas aeruginosa
b.      Staphylococus aureus
c.       Listeria monocytogenes
d.      Yersinia pestis

Ans. (b). Staphylococus aureus

4. Which of the following bacterial toxins does not have ADP-ribosyl transferase activity:

a.       Cholera toxin
b.      Diphtheria toxin
c.       Exotoxin A
d.      S aureus α toxin

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Life Sciences JRF NET Model Question Paper for June 2017 Examination (Set 3/4)

NAM and NAG Structure

CSIR JRF/NET Life Science Exam
June 2017 (I) Model Question Paper 3/4
(Practice Questions with Answer Key)

(1). During glycogen metabolism, the glycogen in the cell is first breakdown to glucose-1-phosphate by the enzyme glycogen phosphorylase. This reaction is a______

a.       Glycolysis reaction
b.      Hydrolysis reaction
c.       Phosphorolysis reaction
d.      Glucolysis reaction

Learn more: MCQ on Carbohydrates (3 sets)

(2). Which of the following genes is activated as ‘oncogenes’ in some human tumors?

a.       K-ras
b.      BRCA1
c.       RB-1
d.      APC

(3). If the frequency of males affected with an X- linked recessive condition in a human population is 0.10 (one in ten) what will be the expected frequency of affected females?

a.       0.0001
b.      0.001
c.       O.02
d.      0.01

(4). What are the assumptions of Hardy-Weinberg equilibrium?

a.       Small population size, random mating no selection, no migration, no mutation
b.      Large population size, random mating, no selection, no migration, no mutation
c.       Large population size, random mating, heterozygotes survive the best, no migration, no mutation
d.      Large population size, random mating, no selection, migrants enter form other populations, no mutation

Learn more: Hardy-Weinberg Equilibrium and Population Genetics (Notes)

(5). The receptor for which of the following hormone is a transcription factor?

a.       Insulin
b.      Glucagon
c.       Estrogen
d.      Adrenalin

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NET Life Sciences Model Question Paper for June 2017 Exam (Set 2/4)

two chiral centre in amino acids

CSIR JRF/NET Life Science Exam
June 2017 (I) Model Question Paper 2/4
(Practice Questions with Answer Key)

(1). The quaternary structure of human hemoglobin is best described as:

a.       Dimer of two myoglobin dimers
b.      Tetramer of identical subunits
c.       Tetramer of four different subunits
d.      Tetramer of two different subunits

(2). Which of the following statements is NOT true for Fluorescence Resonance Energy Transfer (FRET)?

a.       Donor and acceptor molecules mush be in close proximity
b.      Absorption spectrum of the acceptor must overlap fluorescence emission spectrum of the donor
c.       Donor and acceptor transition dipole orientation must be approximately parallel
d.      Energy transfer is directly proportional to the size of the proteins.

(3). Which of the amino acid pairs have two chiral centres?

a.       Proline and Arginine
b.      Leucine and Isoleucine
c.       Isoleucine and Threonine
d.      Methionine and Cysteine

Learn more: MCQ on Amino Acids (4 sets)

(4). The H – C – H angle in methane is:

a.       109.5⁰
b.      90⁰
c.       120⁰
d.      180⁰

(5). Difference between the R- and T- states of hemoglobin is:

a.       Dimeric and tetrameric structures
b.      Oxy- and deoxy- states
c.       Binding to ferrous and ferric ions
d.      Folded and unfolded states

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CSIR JRF NET Life Sciences Model Question Paper for June 2017 Exam (Set 1/4)

Biosynthesis of purine & pyrimidine

CSIR JRF/NET Life Science Exam
June 2017 (I)
Model Question Paper 1/5
(Practice Questions with Answer Key)

(1). Action of topoisomerase leads to changes in

a.       Linking number of single-stranded linear DNA
b.      Lining number of double stranded linear DNA
c.       Linking number of closed circular single stranded DNA
d.      Linking number of closed circular double stranded DNA

(2). Sarcomas are cancers originating from:

a.       Spleen
b.      Lymph node
c.       Skin
d.      Connective tissue

(3). Receptor mediated endocytosis from plasma membrane requires which one of the following coat proteins

a.       Clathri
b.      Adaptin
c.       Arrestin
d.      Glycophorin

(4). Which of the following compound does not acts as ‘second messenger’ during signaling process?

a.       cAMP
b.      Calcium ions
c.       Inositol 3.4.5 triphosphate
d.      Triacylglycerol

(5). Which of the following peptide is not synthesized on ribosome?

a.       Cyclosporin
b.      Somatotropin
c.       Vasopressin
d.      Oxytocin

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