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ENZYMES- Part 16
See all quizzes of ENZYMES- Part 16 here:
1 An increase in LDH-5 enzyme is seen in
the following except
(A) Acute hepatitis (B) Muscular distrophies
(C) Breast carcinoma (D) Pulmonary embolism
2. Diastase can be used for the hydrolysis
can be used for the hydrolysis of
(A) Sucrose (B) Starch
(C) Cellulose (D) Maltose
3. Which of the following statements is true?
(A) Enzymes have names ending ase
(B) Enzymes are highly specific in their action
(C) Enzymes are living organisms
(D) Enzymes get activated on heating
4. Enzymes activity is controlled by
(A) pH of the solution
(B) Temperature
(C) Concentration of the enzyme
(D) Concentration of the substrate
(E) All of these
5. Which of the following is not true regarding
enzymes?
(A) They catalyze only a particular type of reaction
(B) They remain active even after separation from
the source
(C) They are destroyed after the completion of
the reaction they catalyse
(D) They are irreversibly destroyed at high
temperature
(E) Their activity depends on the pH of the solution
6 The number of enzymes known is about
(A) 10,000 (B) 100
(C) 50 (D) 26
487. Nicotine present in tobacco is a/an
(A) Alkaloid (B) Terpene
(C) Steroid (D) Protein
8. The poisonous alkaloid present in the oil
of hemlock is
(A) Cocaine (B) Nicotine
(C) Quinine (D) Morphine
9. Alkaloids are usually purified by extraction
with
(A) Ether (B) Dil HCl
(C) NaOH (D) Chloroform
170 MCQs IN BIOCHEMISTRY
10. The number of N-MC groups in alkaloids
is best estimate with the help of
(A) HI (B) H2SO4
(C) (CH3CO)2 CO (D) CH3 Mg I
11. A competitive inhibitor of an enzyme
(A) Increases Km without affecting Vmax
(B) Decreases Km without affecting Vmax
(C) Increases Vmax without affecting Km
(D) Decreases both Vmax and Km
12. The Michaelis constant, Km is
(A) Numerically equal to ½ Vmax
(B) Dependent on the enzyme concentration
(C) Independent of pH
(D) Numerically equal to the substrate concentration
that gives half maximal velocity
13. The rate of an enzyme catalyzed reaction
was measured using several substrate
concentrations that were much lower
than Km, the dependence of reaction
velocity on substrate concentration can
best be described as
(A) Independent of enzyme concentration
(B) A constant fraction of Vmax
(C) Equal to Km
(D) Proportional to the substrate concentration
14. The presence of a non competitive inhibitor
(A) Leads to both an increase in the Vmax of a
reaction and an increase in Km
(B) Leads to a decrease in the observed Vmax
(C) Leads to a decrease in Km and Vmax
(D) Leads to an increase in Km without affecting
Vmax
15. Which one of the following statements is
not characteristic of allosteric enzymes?
(A) They frequently catalyze a committed step
early in a metabolic pathway
(B) They are often composed of subunits
(C) They follow Michaelis-Menten kinetics
(D) They frequently show cooperativity for
substrate binding
16. The abnormal isoenzyme need not
(A) Be an oxidoreductase
(B) Have any coenzyme
(C) Require ATP
(D) Be localized intracellularly
(E) Be a catalyst
17. LDH assays are most useful in diagnosing
diseases of the
(A) Heart (B) Pancreas
(C) Brain (D) Kidney
18. The chemical forces that bind most
coenzymes and substrates to enzymes
such as LDH are
(A) Hydrogen bonds (B) Peptide bonds
(C) Coordinate bonds (D) Covalent bonds
19. How many different proteins may be
present in normal LDH?
(A) One (B) Two
(C) Three (D) Four
20. All the isoenzymes function with the
coenzyme:
(A) NADP+ (B) FAD
(C) Lipoate (D) NAD+
21. ‘Lock’ and ‘Key’ theory was proposed by
(A) Sorenson (B) Fischer
(C) Mehler (D) Sanger
22. Which of the following forms part of a
coenzyme?
(A) Zn2+ (B) Lipase
(C) Vitamin B2 (D) Lysine
23. The shape of an enzyme and consequently
its activity can be reversibly
altered from moment to moment by
(A) Heat (B) Amino acid substrate
(C) Allosteric subunits (D) Sulfur substitutions
24. Which one of the following regulatory
actions involves a reversible covalent
modification of the enzyme?
(A) Phosphorylation of ser-OH on the enzyme
(B) Allosteric modulation
(C) Competitive inhibition
(D) Non-competitive inhibition
25. An enzyme is a
(A) Carbohydrate (B) Lipid
(C) Protein (D) Nucleic acid
26. An enzyme promotes a chemical reaction
by
(A) Lowering the energy of activation
(B) Causing the release of heat which acts as a
primer
(C) Increasing molecular motion
(D) Changing the free energy difference between
substrate and product
27. In most metabolic pathways, all needed
enzymes are arranged together in a
multienzyme complex within a
(A) Solution of ATP
(B) Membrane
(C) Quanternary protein
(D) Coenzyme
28. An enzyme catalyzes the conversion of an
aldose sugar to a ketose sugar would be
classified as one of the
(A) Transferases (B) Isomerases
(C) Oxido reductases (D) Hydrolases
29. The function of an enzyme is to
(A) Cause chemical reactions that would not
otherwise take place
(B) Change the rates of chemical reactions
(C) Control the equilibrium points of reactions
(D) Change the directions of reactions
30. In which of the following types of
enzymes, water may be added to a C—C
double bond without breaking the bond?
(A) Hydrolase (B) Hydratase
(C) Hydroxylase (D) Oxygenase
