NET Life Science Model Question Paper 2015: Biology MCQ-8: Biochemistry: Amino Acids: Part 4

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(Sample/Model/Practice Questions for JRF/NET Life Science Examination, ICMR JRF, DBT JRF, GATE, ICAR NET, PG Entrance)

MCQ Biochemistry: Amino Acids Part 4 (MCQ 008)

1). Which group of a fully protonated glycine (NH3+ – CH2 – COOH) first release a ‘proton’ when it is titrated against – OH- ions?

a.       Carboxyl group
b.      Amino group
c.       Both at the same time
d.      It cannot be predicted

2). pKa is the measure of a group to __________ proton.

a.       Take up
b.      Release
c.       Combine
d.      Consume

3). Which of the following amino acid bears a guanidine group in the side chain?

a.       Lysine
b.      Arginine
c.       Histidine
d.      Proline

4). The precursor of glycine synthesis in microbes and plants is_______.

a.       Serine
b.      Leucine
c.       Valine
d.      None of these

5). Single letter code of selenocysteine is _____.

a.       B
b.      J
c.       U
d.      O

6). Which of the following amino acid have an imino group in the side chain?

a.       Proline
b.      Asparagine
c.       Glutamate
d.      Histidine

7). 4-hydroxy proline (a derivative of proline) is abundantly present in _______.

a.       Keratin
b.      Myoglobin
c.       Hemoglobin
d.      Collagen

Biology MCQ-8: Biology/Life Science Multiple Choice Questions (MCQ) / Model Questions with answers and explanations in Biochemistry: Amino Acids Part 4 for preparing CSIR JRF NET Life Science Examination and also for other competitive examinations in Life Science / Biological Science such as ICMR JRF Entrance, DBT JRF, GATE Life Science, GATE Biotechnology, ICAR, University PG Entrance Exam, JAM, GRE, Medical Entrance Examination etc. This set of practice questions for JRF/NET Life Science will help to build your confidence to face the real examination. A large quantum of questions in our practice MCQ is taken from previous year NET life science question papers. Please take advantage of our NET Lecture Notes, PPTs, Previous Year Questions and Mock Tests for you preparation. You can download these NET study material for free from our Slideshare account (link given below).

8). Desmosine is a complex derivative of five ____________ residues.

a.       Lysine
b.      Arginine
c.       Histidine
d.      Methionine

9). Isoelectric pH is designated as______.

a.      pKa
b.      pI
c.       Pi
d.      None of these

10). Which of the following amino acid is biosynthesized from Ribose 5-phposphate?

a.       Histidine
b.      Serine
c.       Glycine
d.      All of these

11). Amino acid biosynthesized from Pyruvate of glycolysis is _____.

a.       Alanine
b.      Valine
c.       Leucine
d.      All of these

12).  Aromatic amino acids (Phenylalaine, Tyrosine, and Tryptophan) are derived from Phosphoenol pyruvate and __________.

a.       Ribose 5-phosphate
b.      Erythrose 4-phosphate
c.       Oxaloacetate
d.      α-ketoglutarate

13).  Isoleucine is derived from ___________.

a.       Methionine
b.      Threonine
c.       Lysine
d.      Leucine

14).  Blood clotting protein thrombin usually contain which of the following modified amino acid?

a.       4-hydroxy proline
b.      5-hydroxy lysine
c.       6-N-methyl lysine
d.      γ-carboxy glutamate

15).  Cysteine is not an essential amino acid in human, since we have the machinery to synthesize cysteine from other two amino acids namely _______ and serine.

a.      Methionine
b.      Selenocysteine
c.       Citrulline
d.      Hydroxyproline

16). Which of the following contain a disulfide bridge?

a.       Cysteine
b.      Cystine
c.       Methionine
d.      None of these
e.       All of these

17). Which of the following protein contain a modified amino acid – desmosine?

a.       Keratin
b.      Gelatin
c.       Elastin
d.      Collagen

180.  During biosynthesis, Methionine and Threonine are derived from a common intermediate:

a.       Chorismate
b.      Citrulline
c.       Homoserine
d.      Cystathione

19).  6-N-methyl lysine is a derivative of lysine, present in__________.

a.       Keratin
b.      Collagen
c.       Myosin
d.      Myoglobin

20).  A common intermediate branch point in the synthesis of all aromatic amino acids such as Tryptophan, Phenylalanine and Tyrosine is _____.

a.       Homoserine
b.      Chorismate
c.       Cystathione
d.      None of these

21). Sarcosine, a ubiquitous non protenacius amino acid in animals and plants is ____.

a.       N-methylglycine
b.      N-methylvaline
c.       N-methylserine
d.      N-methylmethionine

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Answers and Explanations:

1. Ans. (a). Carboxyl group

First COOH group will release H+ ions and it will combine with OH- ions to form water. Only after complete ionization of all the COOH groups, the NH3+ release H+ ions.

2. Ans. (b). Release

pKa is the negative logarithm of Ka. Ka is the dissociation constant of an ionization reaction such as the ionization of acetic acid. Ka is similar to equilibrium constant of any chemical reaction and it is calculated by dividing the concentration of products divided by concentration of its reactants.  Ka denotes the strength of an acid. Strong acids will have a higher value of Ka where as a weaker acid will have a lesser values of Ka. The stronger the tendency to dissociate a proton, the stronger is the acid and the lower its pKa (Since pKa is negative logarithm of Ka i.e., reciprocal of ka).

3. Ans. (b). Arginine

4. Ans. (a). Serine

5. Ans. (c). U

6. Ans. (a). Proline

7. Ans. (d). Collagen

8. Ans. (a). Lysine

9. Ans. (b). pI

10. Ans. (a). Histidine

11. Ans. (d). All of these

12. Ans. (b). Erythrose 4-phosphate

13. Ans. (b). Threonine

14. Ans. (d) γ-carboxy glutamate

15. Ans. (a). Methionine

Methionine provide sulfur

Serine provide the backbone of cysteine

16. Ans. (b). Cystine

17. Ans. (c). Elastin

18. Ans. (c). Homoserine

19. Ans. (c). Myosin

20. Ans. (b). Chorismate

21. Ans. (a). N-methylglycine


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