MMSC 436 EXAM 1 ENZYME & CARDIAC REVIEW
QUESTIONS WITH VERIFIED ANSWERS
An international unit (IU) of enzyme activity is the quantity of enzyme that:
a. Converts 1 umol of substrate to product per liter
b. Forms 1 mg of product per deciliter
c. Converts 1 umol of substrate to product per minute
d. Forms 1 umol of product per deciliter - Answers - c. Converts 1 umol of substrate to
product per minute
Which of the following measurement modes does not allow for continuous monitoring of
enzyme activity?
a. Initial absorbance is measured followed by a second reading after 5 minutes
b. Absorbance is measured at 10-second intervals for 100 seconds
c. Absorbance is monitored continuously for 1 minute using a chart recorder
d. Reflectance is measured from a xenon source lamp pulsing at 60 Hz - Answers - a.
Initial absorbance is measured followed by a second reading after 5 minutes
Which of the following statements regarding enzymatic reactions is true?
a. The enzyme shifts the equilibrium of the reaction to the right
b. The enzyme alters the equilibrium constant of the reaction
c. The enzyme increases the rate of the reaction
d. The enzyme alters the energy difference between reactants and products - Answers -
c. The enzyme increases the rate of the reaction
Which statement about enzymes is true?
a. An enzyme alters the Gibbs free energy of the reaction
b. Enzymes cause a reaction with a positive free energy to occur spontaneously
c. An enzyme's natural substrate has the highest Km
d. A competitive inhibitor will alter the apparent Km of the reaction - Answers - d. A
competitive inhibitor will alter the apparent Km of the reaction
Which substrate concentration is needed to achieve zero-order condition?
a. Greater than 99 x Km
b. [S] = Km
c. Less than 10 x Km
d. [S] = 0 - Answers - a. Greater than 99 x Km
Which of the following statements is true?
a. Apoenzyme + prosthetic group = holoenzyme
b. A coenzyme is an inorganic molecule required for activity
c. Cofactors are as tightly bound to the enzyme as prosthetic groups
, d. All enzymes have optimal activity at pH 7.00 - Answers - a. Apoenzyme + prosthetic
group = holoenzyme
Which of the following statements about enzymatic reactions is true?
a. NADH has absorbance maxima at 340 and 366 nm
b. Enzyme concentration must be in excess to achieve zero-order kinetics
c. Rate is proportional to substrate concentration in a zero-order reaction
d. Accumulation of the product increase the reaction rate - Answers - a. NADH has
absorbance maxima at 340 and 366 nm
The increase in the level of serum enzymes used to detect cholestatic liver disease is
caused mainly by:
a. Enzyme release from dead cells
b. Leakage from cells with altered membrane permeability
c. Decreased perfusion of the tissue
d. Increased production and secretion by cells - Answers - d. Increased production and
secretion by cells
Which of the following enzymes is considered most tissue specific?
a. CK
b. Amylase
c. ALP
d. ADH - Answers - d. ADH
Which of the following enzymes is activated by calcium ions?
a. CK
b. Amylase
c. ALP
d. LD - Answers - b. Amylase
Which of the following enzymes is a transferase?
a. ALP
b. CK
c. Amylase
d. LD - Answers - b. CK
Which statement about methods for measuring LD is true?
a. The formation of pyruvate from lactate (forward reaction) generates NAD+
b. The pyruvate-to-lactate reaction proceeds at about twice the rate as the forward
reaction
c. The lactate-to-pyruvate reaction is optimized at pH 7.4
d. The negative-rate reaction is preferred - Answers - b. The pyruvate-to-lactate reaction
proceeds at about twice the rate as the forward reaction
Which condition produces the highest elevation of serum lactate dehydrogenase (LD)?
a. Pernicious anemia
QUESTIONS WITH VERIFIED ANSWERS
An international unit (IU) of enzyme activity is the quantity of enzyme that:
a. Converts 1 umol of substrate to product per liter
b. Forms 1 mg of product per deciliter
c. Converts 1 umol of substrate to product per minute
d. Forms 1 umol of product per deciliter - Answers - c. Converts 1 umol of substrate to
product per minute
Which of the following measurement modes does not allow for continuous monitoring of
enzyme activity?
a. Initial absorbance is measured followed by a second reading after 5 minutes
b. Absorbance is measured at 10-second intervals for 100 seconds
c. Absorbance is monitored continuously for 1 minute using a chart recorder
d. Reflectance is measured from a xenon source lamp pulsing at 60 Hz - Answers - a.
Initial absorbance is measured followed by a second reading after 5 minutes
Which of the following statements regarding enzymatic reactions is true?
a. The enzyme shifts the equilibrium of the reaction to the right
b. The enzyme alters the equilibrium constant of the reaction
c. The enzyme increases the rate of the reaction
d. The enzyme alters the energy difference between reactants and products - Answers -
c. The enzyme increases the rate of the reaction
Which statement about enzymes is true?
a. An enzyme alters the Gibbs free energy of the reaction
b. Enzymes cause a reaction with a positive free energy to occur spontaneously
c. An enzyme's natural substrate has the highest Km
d. A competitive inhibitor will alter the apparent Km of the reaction - Answers - d. A
competitive inhibitor will alter the apparent Km of the reaction
Which substrate concentration is needed to achieve zero-order condition?
a. Greater than 99 x Km
b. [S] = Km
c. Less than 10 x Km
d. [S] = 0 - Answers - a. Greater than 99 x Km
Which of the following statements is true?
a. Apoenzyme + prosthetic group = holoenzyme
b. A coenzyme is an inorganic molecule required for activity
c. Cofactors are as tightly bound to the enzyme as prosthetic groups
, d. All enzymes have optimal activity at pH 7.00 - Answers - a. Apoenzyme + prosthetic
group = holoenzyme
Which of the following statements about enzymatic reactions is true?
a. NADH has absorbance maxima at 340 and 366 nm
b. Enzyme concentration must be in excess to achieve zero-order kinetics
c. Rate is proportional to substrate concentration in a zero-order reaction
d. Accumulation of the product increase the reaction rate - Answers - a. NADH has
absorbance maxima at 340 and 366 nm
The increase in the level of serum enzymes used to detect cholestatic liver disease is
caused mainly by:
a. Enzyme release from dead cells
b. Leakage from cells with altered membrane permeability
c. Decreased perfusion of the tissue
d. Increased production and secretion by cells - Answers - d. Increased production and
secretion by cells
Which of the following enzymes is considered most tissue specific?
a. CK
b. Amylase
c. ALP
d. ADH - Answers - d. ADH
Which of the following enzymes is activated by calcium ions?
a. CK
b. Amylase
c. ALP
d. LD - Answers - b. Amylase
Which of the following enzymes is a transferase?
a. ALP
b. CK
c. Amylase
d. LD - Answers - b. CK
Which statement about methods for measuring LD is true?
a. The formation of pyruvate from lactate (forward reaction) generates NAD+
b. The pyruvate-to-lactate reaction proceeds at about twice the rate as the forward
reaction
c. The lactate-to-pyruvate reaction is optimized at pH 7.4
d. The negative-rate reaction is preferred - Answers - b. The pyruvate-to-lactate reaction
proceeds at about twice the rate as the forward reaction
Which condition produces the highest elevation of serum lactate dehydrogenase (LD)?
a. Pernicious anemia
