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18th August 2014, 03:44 PM
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Join Date: Apr 2013
Re: CSIR Univetsity Grants Commission NET Answer Key of Life Sciences

As you want to get the CSIR Univetsity Grants Commission NET Answer Key of Life Sciences so here it is for you:

Some content of the file has been given here:

1. a) Draw a graph that will represent the following equation:

dA = kA
dt (5)
b) Describe a method to determine surface area of a leaf without using any
instrument.
(5)

c) Water is often contaminated by a variety of ionic impurities. What is the
best method to determine purity of a sample of water?
(5)

d) You have to test if ponds A, B and C differ significantly in their primary
productivity. What statistical test should be applied to your data? Justify your
choice of the test.
(5)
2. The extensive sequences (Gly-X-Pro)n or (Gly-X-Hpro)n stabilize the collagen
triple-helix, in which X is any amino acid.

(i) Why must Gly be present in every third residue?

(5)
(ii) What are the principal bonds, which are responsible for holding three
helical strands together in the superhelix?
(4)

(iii) How does each strand of the collagen helix differ from an α-helix in terms
of structural characteristics?
(3)

3. (a) An experiment was done to determine the effect of compound Y on the
biochemical reaction A + B → C. It was found that in the presence of Y,
very little, if any, product C was formed. However, on increasing the
concentration of A, C could be detected. Explain the effect of Y on the
reaction.
(2)
(b) Describe an approach by which secondary structure of RNA molecules
can be verified.
(5)
(c) How would you determine the aggregation state and shape of a biomacro-
molecule in solution?

4. a) What are the two tautomeric forms of cytosine? Show with the help of a
diagram.
(6)

b) How could one determine the degree of polymerization of a sample of
amylose?
(6)
5. a) Draw diagrams to illustrate sequence-dependent variation between two
adjacent base pairs, known as tilt, roll and twist.

(6)

b) What is the major difference between normal DNA double helix and RNA
double helix? How does this influence the biological function of these two
molecular forms?
(6)
6. A liver cell has been pulse-labeled with [3
H] uridine and a thin section of it is
obtained. The overall appearance of the autoradiograph (examined through
electron microscope) shows regions of white patches interspersed with black dots (silver
grains).

1) What are these sites?

(2)
2) Which site is functionally more active and why?
(4)

3) One of these sites is thought to contain DNA that is never transcribed in
any cell. Name the site and its physiological significance, if any.

(6)

7. (a) The basic function of the cell cycle is to duplicate the DNA accurately and
then distribute the copies precisely to daughter cells. So, why are there
gaps between S phase and M phase?
(4)

(b) What are DNA damage checkpoints which block the cell cycle
progression in G1 and G2 phases?
(8)

8. (a) What is the role of cross-linking glycans, in plant cell wall synthesis?
Name three cross-linking glycans, their structure and composition.
(6)
(b) “Cytoskeletal polymers have an intrinsic polarity”. Comment on the
statement.
(6)
9. a) What are the four major phospholipids present in the plasma membrane of
mammalian cells?
(4)
b) What is the distribution of these phospholipids in the outer and inner
monolayer in human red cell membrane?
(4)
c) The plasma membrane contains various phospholipases that are activated
by extracellular signal to cleave specific phospholipids. What is the
function of phospholipase C in response to extracellular signals?
(4)
10. (a) Draw a diagram of a DNA molecule undergoing replication. Indicate the
newly synthesized strands and identify the following:
(5)
i. Polarity of newly synthesized strands
ii. Leading and lagging strands
iii. Okazaki fragments
iv. RNA primers

(b) Cycloheximide and chloramphenicol both inhibit protein synthesis by
blocking peptidyl transferase. How are these two inhibitors different?
(4)

(c) Name the three enzymes involved in the formation of 5′-cap in
eukaryotic mRNA.
(3)

11. (a) (i) What are the three components, which arise from the 45S rRNA
precursor molecule?
(ii) If 3
H labeled uridine is fed to a cell transcribing rRNA genes, in
which rRNA gene product would the label appear first?
(iii) What is the major advantage of getting the three rRNA genes
transcribed together?
(6)
(b) Show pictorially the organization of the lac operon of E. coli.
(3)

(c) Design an experiment to show that induction of host protein synthesis
stops after T4-phage infection.
(3)
12. (a) Mention two approaches used for deciphering the genetic code.
(6)
(b) Insertion of a base in a coding sequence leads to a shift in the
reading frame, which in most cases produces a nonfunctional
protein. What kind of mutation in a tRNA might suppress frame
shifting?
(2)
(c) Bacteriophage T4 rapidly injects the total genome inside the host cell
while T7 injects the genome slowly. Explain the reason.
(4)
13. White blood cells (WBCs) lead a nomadic life, moving between the blood-stream and the
tissues, necessitating the presence of special adhesive properties to bind to the
endothelium in collaboration with integrin.

(a) Name the various molecules responsible for these adhesive properties.
(3)

(b) With the help of some appropriate experiments prove the localization of
these molecules on the cell surface and their carbohydrate-binding
properties.
(5)
(c) What is the nature of collaboration of these molecules with “integrin”?
Why is it crucial for WBC’s life?
(4)
14. (a) Giving one example each, describe the characteristics of autocrine and
paracrine signaling.
(4)

(b) Explain how a single epinephrine molecule can generate numerous Ca+2
ions as second messenger.
(4)
(c) Describe how a cAMP mediated signal can be terminated?
(4)
15. (a) What is the function of an adjuvant in immune response?
(2)

(b) When a virus is taken up by a dendritic cell, how is it processed and
presented to the T cell?
(5)
(c) What are transgenic and knockout mice and how are they developed?








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