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

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
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In competitive enzyme activity inhibition (A) The structure of inhibitor generally resembles that of the substrate (B) Inhibitor decreases apparent Km (C) Km remains unaffective (E) Inhibitor decreases Vmax without affecting Km

Description : In competitive enzyme activity inhibition (A) The structure of inhibitor generally resembles that of the substrate (B) Inhibitor decreases apparent Km (C) Km remains unaffective (E) Inhibitor decreases Vmax without affecting Km

Last Answer : Answer : A

Kinetics of an allosteric enzyme are explained by (A) Michaelis-Menten equation (B) Lineweaver-Burk plot (C) Hill plot (D) All of these

Description : Kinetics of an allosteric enzyme are explained by (A) Michaelis-Menten equation (B) Lineweaver-Burk plot (C) Hill plot (D) All of these

Last Answer : Answer : C

In enzyme kinetics Km implies (A) The substrate concentration that gives one half Vmax (B) The dissocation constant for the enzyme substrate comples (C) Concentration of enzyme (D) Half of the substrate concentration required to achieve Vmax

Description : In enzyme kinetics Km implies (A) The substrate concentration that gives one half Vmax (B) The dissocation constant for the enzyme substrate comples (C) Concentration of enzyme (D) Half of the substrate concentration required to achieve Vmax

Last Answer : Answer : A

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

Description : 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

Last Answer : Answer : B

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

Description : 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

Last Answer : Answer : C

In competitive enzyme activity inhibition (A) Apparent Km is decreased (B) Apparent Km is increased (C) Vmax is increased (D) Vmax is decreased

Description : In competitive enzyme activity inhibition (A) Apparent Km is decreased (B) Apparent Km is increased (C) Vmax is increased (D) Vmax is decreased

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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

Description : 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

Last Answer : Answer : A

The kinetic effect of purely 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 Vmax without affecting Km

Description : The kinetic effect of purely 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 Vmax without affecting Km

Last Answer : Answer : A

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

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Last Answer : Answer : B

The following abnormality in PRPP synthetase can cause primary gout: (A) High Vmax (B) Low Km (C) Resistance to allosteric inihbition. (D) All of these

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In enzyme kinetics Vmax reflects (A) The amount of an active enzyme (B) Substrate concentration (C) Half the substrate concentration (D) Enzyme substrate complex

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A sigmoidal plot of substrate concentration ([S]) verses reaction velocity (V) may indicate (A) Michaelis-Menten kinetics (B) Co-operative binding (C) Competitive inhibition (D) Non-competitive inhibition

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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

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In Lineweaver-Burk plot, the y-intercept represents (A) Vmax (B) Km (C) Km (D) 1/Km

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Last Answer : Answer : B

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

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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

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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

Description : 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

Last Answer : Answer : C

Which inactivates an enzyme by occupying its active site? (A) Competitive inhibitor (B) Allosteric inhibitor (C) Non-competitive inhibitor (D) All of these

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Last Answer : Answer : A

‘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

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From the L ineweaver-Burk p lot of Michaelis-Menten equation, Km and Vmax can be determined when V is the reaction velocity at substrate concentration S, the X-axis experimental data are expressed as (A) 1/V (B) V (C) 1/S (D) S

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Last Answer : Answer : C

Km value of enzyme is substrate concentration at (A) ½ Vmax (B) 2 Vmax (C) ½ Vmax (D) 4 Vmax

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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

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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

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If the substrate concentration is much below the km of the enzyme, the velocity of the reaction is (A) Directly proportional to substrate concentration (B) Not affected by enzyme concentration (C) Nearly equal to Vmax (D) Inversely proportional to substrate concentration

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In reversible non-competitive enzyme activity inhibition (A) Vmax is increased (B) Km is increased (C) Km is decreased (D) Concentration of active enzyme is reduced

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A substance unrelated to substrate but capable of reversibly changing activity of enzyme by binding to a site other than active site is called (a) Competitive inhibitor (b) Non-competitive inhibitor (c) Catalytic inhibitor (d) Allosteric modulator/inhibitor

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Competitive inhibitors (A) Decrease the Km (B) Decrease the Vmax (C) Increase the Km (D) Increase the Vmax

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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

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Which one of the following statements is incorrect? (a) The competitive inhibitor does not affect the rate of breakdown of the enzyme-substrate complex. (b) The presence of the competitive inhibitor decreases the Km of the enzyme for the substrate. (c) A competitive inhibitor reacts reversibly with the enzyme to form an enzyme-inhibitor complex. (d) In competitive inhibition, the inhibitor molecule is not chemically changed by the enzyme.

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Vmax of an enzyme may be affected by (A) pH (B) Temperature (C) Non-competitive inhibitors (D) All of these

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In non competitive enzyme activity inhibition, inhibitor (A) Increases Km (B) Decreases Km (C) Does not effect Km (D) Increases Km

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In reversible non-competitive enzyme activity inhibition (A) Inhibitor bears structural resemblance to substrate (B) Inhibitor lowers the maximum velocity attainable with a given amount of enzyme (C) Km is increased (D) Km is decreased

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AMP is an allosteric inhibitor of (A) PRPP synthetase (B) Adenylosucciante synthetase (C) Both (A) and (B) (D) None of these

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GMP is an allosteric inhibitor of all the following except (A) PRPP synthetase (B) PRPP glutamyl amido synthetase (C) IMP dehydrogenase (D) Adenylosuccinate synthetase

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An allosteric inhibitor of IMP dehydrogenase is (A) AMP (B) ADP (C) GMP (D) GDP

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An allosteric inhibitor of adenylosuccinate synthetase is (A) AMP (B) ADP (C) GMP (D) GDP

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An allosteric inhibitor of PRPP glutamyl amido transferase is (A) AMP (B) ADP (C) GMP (D) All of these

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ATP is a co-substrate as well as an allosteric inhibitor of (A) Phosphofructokinase (B) Hexokinase (C) Glucokinase (D) None of these

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Last Answer : Answer : A

Glucose-6-phosphate is an allosteric inhibitor of (A) Glucokinase (B) Hexokinase (C) Phosphohexose isomerase (D) None of these

Description : Glucose-6-phosphate is an allosteric inhibitor of (A) Glucokinase (B) Hexokinase (C) Phosphohexose isomerase (D) None of these

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An allosteric inhibitor of pyruvate dehydrogenase is (A) Acetyl CoA (B) ATP (C) NADH (D) Pyruvate

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Allosteric inhibitor of glutamate dehydrogenase is (A) ATP (B) ADP (C) AMP (D) GMP

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A point defect exhibiting an apparent gain in one direction will exhibit what, when measured in the opposite direction?

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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

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Last Answer : Answer : D

When the velocity of an enzymatic reaction equals Vmax, substrate concentration is (A) Half of Km (B) Equal to Km (C) Twice the Km (D) Far above the Km

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Fischer’s ‘lock and key’ model of the enzyme action implies that (A) The active site is complementary in shape to that of substance only after interaction. (B) The active site is complementary in shape to that of substance (C) Substrates change conformation prior to active site interaction (D) The active site is flexible and adjusts to substrate

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Which of the following is a specific inhibitor of the enzyme alcohol dehydrogenase and is useful in the treatment of methanol poisoning: A. Disulfiram B. Ethylene glycol C. Calcium leucovorin D. Fomepizole

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What are the salient features of enzyme kinetics?

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Which statement is correct regarding the relationship between internal auditing and the external auditor? a. Some judgments relating to the audit of the financial statements are those of the internal auditor. b. The external audit function's objectives vary according to management's requirements. c. Certain aspects of internal auditing may be useful in determining the nature, timing and extent of external audit procedures. d. The external auditor is responsible for the audit opinion expressed, however that responsibility may be reduced by any use made of internal auditing

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An enzyme of pyrimidine nucleotide biosynthesis sensitive to allosteric regulation is (A) Aspartate transcarbamoylase (B) Dihydroorotase (C) Dihydroorotate dehydrogenase (D) Orotidylic acid decarboxylase

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