Part C-Dec 2016

CSIR-UGC National Eligibility Test (NET) for Junior Research Fellowship and Lecturer-ship

Some Important Questions Collected from the Memory of Students and Probable Questions and Answers

Previous Year Questions & Answers – Part C Dec. 2016

1. From the following statements,
A.For a reaction to occur spontaneously the free energy change must be negative
B.The interaction between two nitrogen molecules in the gaseous state is predominantly electrostatic
C.By knowing bond energies, it is possible to deduce whether the bond is covalent bond or hydrogen bond
D.Hydrophobic interactions are not important in a folded globular protein.
Pick the combination with ALL WRONG statements.

1. A and B           2. B and C
3. C and D          4. B and D
Ans:- 4
Expln:- Since nitrogen is apolar, no there is no electrostatic interaction. Hydrophobic interactions are responsible for proper folding.
2. A researcher investigated a set of conditions for a protein with an isoelectric point of 6.5 and also binds to calcium. This protein was subjected to four independent treatments : (i) pH 6.4 (ii) 10% glycerol, (iii) 10 mM CaCl2, (iv) 40% ammonium sulphate. This was followed by centrifugation and estimation of the protein in the supernatant. The results are depicted in the graph below :

Which of the following treatments best represents the results shown in the graph ?
1.a = ammonium sulphate, b = glycerol, c = pH 6.4, d = CaCl2
2.a = CaCl2, b = glycerol, c = ammonium sulphate, d = pH 6.4
3.a = pH 6.4, b = CaCl2, c = ammonium sulphate, d = glycerol
4.a = CaCl2, b = pH 6.4, c = glycerol, d = ammonium sulphate

Ans:- 4
Expln:- Protein near their isoelectric point (Pi) value gets precipitated, as pH 6.4 is very near to its PI value so we will get minimum protein in the supernatant, which is either b or d. Ammonium sulphate also precipitates the proteins, so minimum protein in the supernatant. CaCl2 and glycerol will help in the solubilization they max protein will be present in the supernatant.
3. In the biosynthesis of purine :

1.All N atoms, C4 and C5 are from aspartic acid
2.NI is from Aspartic acid; N3 from N9 are from Glutamine side-chain; N7, C4 and C5 are from Glycine.
3.NI is from Aspartic acid; N3 from Glutamine side-chain; N9 from N attached to Cα of Glutamine ; N7, C4 and C5 are from Glycine
4. NI is from Glutamine; N3 from Glutamine side-chain; N9 from N attached to Cα of Glutamine; N7, C4 and C5 are from Glycine

Ans:- 2
Expln:- Nitrogen N1 from aspartic acid, N3 and N9 from glutamine and N7, C4 and C5 comes from glycine.


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