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ENZYMES- Part 15
See all quizzes of ENZYMES- Part 15 here:
1 Multiple forms of the same enzymes are
known as
(A) Zymogens (B) Isoenzymes
(C) Proenzymes (D) Pre-enzymes
2. In non-competitive enzyme action
(A) Vmax is increased
(B) Apparent km is increased
(C) Apparent km is decreased
(D) Concentration of active enzyme molecule is
reduced
3. An allosteric enzyme influences the
enzyme activity by
(A) Competiting for the catalytic site with the
substrate
(B) Changing the specificity of the enzyme for
the substrate
(C) Changing the conformation of the enzyme by
binding to a site other than catalytic site
(D) Changing the nature of the products formed
4. Which of the following regulatory
reactions involves a reversible covalent
modification of an enzyme?
(A) Phosphorylation of serine OH on the enzyme
(B) Allosteric modulation
(C) Competitive inhibition
(D) Non-competitive inhibition
5. A competitive inhibitor of an enzyme has
which of the following properties?
(A) It is frequently a feedback inhibitor
(B) It becomes covalently attached to an enzyme
(C) It decreases the Vmax
(D) It interferes with substrate binding to the
enzyme
6. When [s] is equal to Km, which of the
following conditions exist?
(A) Half the enzyme molecules are bound to
substrate
(B) The velocity of the reaction is equal to Vmax
(C) The velocity of the reaction is independent of
substrate concentration
(D) Enzyme is completely saturated with substrate
7. Which of the following statements about
an enzyme exhibiting allosteric kinetics
with cooperative interaction is false?
(A) A plot of V-Vk [s] has a sigmaidal shape
(B) An inhibitor may increase the apparent Km
(C) Line weaver Bnrk plot is useful for determining
Km and Vmax
(D) Removal of allosteric inhibitor may result in
hyperbolic V-S [s] plot
8. Pantothenic acid acts on
(A) NADP (B) NADPH
(C) FAD (D) CoA
9. Vitamin deficiency that causes fatty liver
includes all except
(A) Vitamin E (B) Pyridoxine
(C) Retionic acid (D) Pantothenic acid
10. In which of the following types of
enzymes an inducer is not required?
(A) Inhibited enzyme (B) Cooperative enzyme
(C) Allosteric enzyme (D) Constitutive enzyme
11. In which of the following types of enzyme
water may be added to a C—C double
bond without breaking the bond?
(A) Hydrolase (B) Hydratase
(C) Hydroxylase (D) Esterase
12. ‘Lock’ and ‘Key’ model of enzyme action
proposed by Fisher implies that
(A) The active site is flexible and adjusts to
substrate
(B) The active site requires removal of PO4 group
(C) The active site is complementary in shape to
that of the substrate
(D) Substrates change conformation prior to active
site interaction
13. In competitive inhibition of enzyme action
(A) The apparent Km is decreased
(B) The apparent Km is increased
(C) Vmax is decreased
(D) Apparent concentration of enzyme molecules
decreased
14. In competitive inhibition which of the
following kinetic effect is true ?
(A) Decreases both Km and Vmax
(B) Increases both Km and Vmax
(C) Decreases Km without affecting Vmax
(D) Increases Km without affecting Vmax
15. Enzymes increase the rates of reactions
by
(A) Increasing the free energy of activation
(B) Decreasing the energy of activation
(C) Changing the equilibrium constant of the
reaction
(D) Increasing the free energy change of the
reaction
16. The most useful test for the diagnosis of
acute hemorrhagic pancreatitis during
the first few days is
(A) Urinary lipase test (B) Serum calcium
(C) Urinary amylase (D) Serum amylase
17. The best test for acute pancreatitis in the
presence of mumps is
(A) A serological test for mumps
(B) Serum amylase
(C) Urinary amylase
(D) Serum lipase
18. The slow moving fraction of LDH is
typically increased in pancreas with
(A) Cerebrovascular accidents
(B) Acute myocardial infarction
(C) Acute pancreatitis
(D) Acute viral hepatits
19. Which of the following enzyme typically
elevated in alcoholism?
(A) Serum ALP
(B) Serum GOT
(C) Serum γ-GT
(D) Serum acid phosphatase
20. Patients with hepatocellular jaundice, as
compared to those with purely obstructive
jaundice tend to have
(A) Lower serum ALP, LDH and AST activity
(B) Lower serum ALP, Higher LDH and AST activity
(C) Higher serum ALP, LDH and AST activity
(D) Higher serum ALP, Lower LDH and AST activity
21. If results of the serum bilirubin, serum ALP,
LDH and AST determinations suggest
obstructive jaundice, the best confirmatory
test would be the estimation of
(A) Serum ALT
(B) Serum 5’ nucleotidase
(C) Serum Pseudo cholinesterase
(D) None of these
22. Which enzyme estimation will be helpful
in differentiating the elevated serum ALP
found in obstructive jaundice as well as
bone disorders?
(A) Serum AST (B) Serum ALT
(C) Serum LDH (D) Serum γ-GT
23. Cardiac muscle contains which of the
following CK osoenzyme?
(A) BB only (B) MM and BB only
(C) MM, BB and MB (D) MM and MB only
ENZYMES 169
24. Liver and skeletol measle disorders are
characterized by on disk proportionate
increase in which of the LDH isoenzyme
fraction?
(A) LDH-1 (B) LDH-1 and LDH-2
(C) LDH-3 and LDH-4 (D) LDH-2 and LDH-3
(E) LDH-5
25. On the third day following onset of acute
myocardial infarction, which enzyme
estimation will have the best predictive
value?
(A) Serum AST (B) Serum CK
(C) Serum ALT (D) Serum LDH
26. Serum AST activity is not characteristically
elevated as the result of
(A) Myocardial infarction
(B) Passive congestion of liver
(C) Muscular dystrophies
(D) Peptic ulcer
27. On which day following acute myocardial
infarction the estimation of serum AST will
be of greatest significance?
(A) First day (B) Second day
(C) Third day (D) Fourth day
28. In which diseases of the following organs,
isoenzymes LDH-1 and LDH-2 will be
released in plasma?
(A) Kidney, R.B.C and Liver
(B) Heart, Kidney and R.B.C
(C) Heart, Kidney and Liver
(D) Heart, Lungs and Brain
29. Plasma non-functional enzymes are
(A) totally absent
(B) low concentration in plastic
(C) important for diagnosis of several disease
(D) All of these
30. Pyruvate dehydrogenase contains all
except
(A) Biotin (B) NAD
(C) FAD (D) CoA
