NET Life Sciences Model Question Paper for June 2017 Exam (Set 2/5)

two chiral centre in amino acids

CSIR JRF/NET Life Science Exam
June 2017 (I) Model Question Paper 2/5
(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

(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

(6). A genetic unit that codes for amino acid sequence of a complete functional polypeptide could be termed as:

a.       Recon
b.      Intron
c.       Exon
d.      Cistron

(7). Transcription termination of mRNA genes in eukaryotes occurs:

a.       At polyadenylation sites by the action of a termination factor
b.      By the formation of a strong hairpin structure in the vicinity of polyadenylation site
c.       Termination factor bound to the termination site in the vicinity of polyadenylation site
d.      At pause sites following the polyadenylation sites

(8). Assume that thymine constitutes 15% of bases in double helical DNA. The percentage of cytosine is:

a.       35%
b.      15%
c.       85%
d.      30%

(9). Codon-anticodon interaction is through:

a.       Hydrogen bonds
b.      Covalent bonds
c.       Phosphodiester linkages
d.      Disulphide linkages

(10).  Eukaryotic DNA synthesis is inhibited by:

a.       Aphidicolin
b.      Cyclohexamide
c.       Chloramphenicol
d.      Ampicillin

(11).  A reporter gene:

a.       Acts as repressor
b.      Allows gene expression to be readily measured
c.       Enhances mRNA stability
d.      Interacts with RNA polymerase

(12).  What will be the molecular weight of poly(A) chain consisting of 100 residues where the molecular weight of AMP is 300

a.       30000
b.      29700
c.       28218
d.      29982

(13).  Zinc fingers are important in cellular regulation because they are:

a.       At the catalytic site of many kinases
b.      A structural motif in many DNA binding proteins
c.       Characteristic of palindromic stretches of unique DNA sequences
d.      Restricted to the cytoplasmic domain of growth factors receptors

(14).  Which of the following combination is correct?   

a.       Amylase – peptide bond
b.      Protease – Phosphodiester bond
c.       Lipase – ester bond
d.      Nuclease – Glycosidic bond

(15).  The amino acid with pKa closest to the physiological pH is:

a.       Serine
b.      Histidine
c.       Threonine
d.      Proline

(16).  A positively controlled operon can be identified by mutation in the regulatory gene leading to:

a.       Constitutive expression
b.      Very high level of expression
c.       Inducibility of the operon
d.      Repression of the operon

(17).  Zygotic induction occurs under the following condition:

a.       By exposure of a non-lysogenic F’ cell to an antibiotic
b.      In a cross between a lysogenic donor Hfr strain and recipient F’ strain
c.       When to F plasmids recombine in conjugation
d.      In a cross between lysogenic donor F+ strain and recipient F- strain

(18).  Two strains of mouse are said to be congenic if they are:

a.       Identical in all genetic loci
b.      Identical in all genetic loci except one locus
c.       Non-identical in all genetic loci
d.      Identical in 50% of genetic loci

(19).  A village has 400 normal residents. Transferrin is an iron carrier protein found in blood. And its electrophoretic variation is determined by an autosomal co-dominant system. The residents of this village were typed for their transferrin alleles. Their distribution was 100 CC, 100 CD and 200DD. What is the frequency of the C allele?

a.       8/5
b.      ½
c.       3/8
d.      ¼

(20).  People with Klinefelter syndrome have 47 chromosomes, including three sex chromosomes (XXY). What is the term used to describe the aberration that occurs during meiosis that results in this abnormal chromosome number?

a.       Crossing over
b.      Non-disjunction
c.       Independent assortment
d.      Disjunction

CSIR JRF NET June 2017 Model Question Papers

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Answer Key with Explanations

1. Ans. (d). Tetramer of two different subunits

2. Ans. (d). Energy transfer is directly proportional to the size of the proteins.

3. Ans. (c). Isoleucine and Threonine

4. Ans. (a). 109.5⁰

5. Ans. (b). Oxy and Deoxy- states

6. Ans. (d). Cistron

7. Ans. (c). Termination factor bound to the termination site in the vicinity of polyadenylation site

8. Ans. (a). 35%

9. Ans. (a). Hydrogen bonds

10. Ans. (a). Aphidicolin

Aphidicolin: an antibiotic obtained from Cerphalosporium aphidicola. It is a specific inhibitor of eukaryotic DNA replication by inhibiting DNA polymerase enzyme A and D. Aphidicolin block the cell cycle at S phase and hence have anticancer properties.

Cycloheximide: an antibiotic obtained from Streptomyces griseus. It is protein synthesis inhibitor in eukaryotes; inhibit protein synthesis by interfering with the translocation step of translation.

11.  Ans. (b). Allow gene expression to be readily measured

12.  Ans. (c). 28218

13.  Ans. (b). A structural motif in many DNA binding proteins

14.  Ans. (c). Lipase –ester bond

15.  Ans. (b). Histidine

16.  Ans. (d). Repression of the operon

17.  Ans. (b). In a cross between a lysogenic donor Hfr  strain and a recipient F’ strain

18.  Ans. (b). Identical in all genetic loci except one locus

19.  Ans. (c). 3/8

20.  Ans. (b). Non-disjunction

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