10. The pH of an aqueous solution of a 1 mM NaCl is (a 6 (b) 7 8 (d)9(e)None of

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10. The pH of an aqueous solution of a 1 mM NaCl is (a 6 (b) 7 8 (d)9(e)None of the above 11. An enzyme that converts NADH to NAD at the expense of ATP is a (a) Ligase (b) Reducing enzyme (c) Transferase (d) Lyase (e) None of the above 12. Cyclic forms of sugars predominate over open chain structures, both in solution and in the solid state. For example alcohols may react with aldehydes to form (a) stable compounds called acetals (b) unstable compounds called acetals (c) stable compounds called hemiacetals (d) unstable compounds called acetals (e unstable compounds called hemiacetals 13. Proline, tyrosine and threonine are some of the sulfur containing amino acids found in cells (a) True (b) False 14. Which of the following co-amino acids is (b) Throenine (c) Glycine acidic? (a) Leucine (d) Glutamine (e) None of the above. 15. The specific activity of an enzyme is (a) The amount of enzyme that produces one mole of product per second under standard conditions (b) The activity of an enzyme in relation to a standard preparation of the enzyme (c) The number of enzyme units per milligram of enzyme protein (d) The amount of enzyme causing transformation of one micromole of substrate per minute under standard conditions (e) The activity of an enzyme in the presence of its preferred substrate. 16. Mutarotation is the case where (a) Gamma and beta sugars slowly change into an equilibrium mixture of both (b) Alpha and Beta sugars slowly change into an equilibrium mixture of both (c) Gamma sugars slowly change into an equilibrium mixture of both (d) Gamma and beta sugars slowly change into an equilibrium mixture of both (e) None of the above 17. By convention, peptide structures are written from right to left, starting with the free o-carboxyl group amino acid residue (the C-terminal), and ending with the having a having a free ino group (the so-called N-terminal amino acid) (a) True (b) False 18. The amphoteric properties of proteins are not only important in terms of protein structure and function but are also useful in a number (a) Analytical procedures only for the purification of proteins (b) Analytical procedures only for the identification of proteins (c) Analytical procedures for the purification and identification of proteins (d None of the above

Explanation / Answer

10) NaCl is a salt of strong acid HCl and strong base NaOH, and it fully dissociates in aqueous solution into Na+ and Cl- ions.So,no hydrolysis of salt occurs to produce any hydronium ion,H3O+ as it is with salts of weak acids and bases.

NaCl ---->Na+ +Cl-    neutral

H2O--->H+ +OH-,

So, [OH-]=[H+]=10^-7 ,pH=7 (option b)

11)NAD+ +H+ +2e- <---->NaDH (redox reaction) catalysed by reducing enzymes

This redox reaction takes place in conjugation with several biochemical reactions in the cells,with the expense of ATP.

example-glycolysis-breakdown of glucose

2NAD+ +glucose +2ADP----->2pyruvate+2NADH +2ATP (exergoic reaction)

ligase-repairs DNA double strand,though ATP dependent mechanism

transferase-transfers functional groups from molecule to molecule

lyase-catalyses breaking of old bonds by oxidation ,hydrolysis or substitution in biomolecules with the expense of ATP

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