BIOL 334 MIDTERM 1 EXAM QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026
1. Which of the following statements about the nature of enzyme catalysis is correct?
a) An enzyme alters the equilibrium position of the reaction it catalyses by influencing the energy of
activation
of that reaction.
b) An enzyme can shift the reaction's equilibrium position to favor product formation by increasing
molecular
collisions between the reacting molecules.
c) An enzyme lowers the free energy difference between substrate(s) and product(s) but it cannot
change the
equilibrium position of the reaction it catalyses.
d) An enzyme greatly accelerates reaction rates by lowering the activation energy of a chemical
reaction.
e) Most enzymes are usually saturated with their substrate in vivo. - Answers D
2. Which of the following statements about Michaelis-Menten enzyme kinetics is correct?
a) Km, the Michaelis constant, is the concentration of substrate required to attain Vmax.
b) Km, the Michaelis constant, is the dissociation constant of the enzyme-substrate complex.
c) Km, the Michaelis constant, is expressed in terms of the reaction's velocity.
d) Km, the Michaelis constant, reflects the (apparent) affinity the enzyme has for its substrate.
e) An enzyme that displays Michaelis-Menten kinetics can never show a sigmoidal plot of Vo vs [S]. -
Answers D
3. Which of the following statements about competitive inhibition of an enzyme-catalyzed reaction is
correct?
a) A competitive inhibitor and substrate can bind simultaneously to the enzyme.
b) The enzyme's Vmax and Km values are unchanged in the presence of a competitive inhibitor.
c) The enzyme's Vmax remains unchanged in the presence of a competitive inhibitor.
d) The enzyme's Km value for its substrate is reduced in the presence of a competitive inhibitor.
e) A competitive inhibitor is covalently attached to an amino acid in the enzyme's active site. -
Answers C
4. Which of the following statements about allosteric enzymes is correct?
a) Allosteric enzymes are often monomeric (single-subunit) enzymes.
b) The only ways to significantly change the in vivo activity of an allosteric enzyme is either by altering
rates of
its synthesis or degradation, or by changing the concentration of its substrate(s).
c) Allosteric enzymes always show 'Michaelis-Menten' (i.e. hyperbolic) substrate saturation kinetics.
d) The 'native form' of an allosteric enzyme can contain non-catalytic subunits.
e) An allosteric enzyme cannot be both homotropic and heterotropic. - Answers D
5. Which of the following statements about competitive inhibition of an enzyme-catalyzed reaction is
correct?
a) The addition of high concentrations of the substrate cannot overcome the effect of a competitive
inhibitor.
b) A competitive inhibitor can bind to the enzyme-substrate complex.
c) Competitive inhibition can be overcome by the addition of large amounts of substrate to a reaction.
d) Vmax decreases in the presence of a competitive inhibitor.
e) A high Ki value means its an effective inhibitor. - Answers C
6. Which of the following statements about Michaelis-Menten kinetics are correct?
a) A high Km value indicates a high affinity of an enzyme for its substrate.
b) A low Km values indicates a high affinity of an enzyme for its substrate.
c) The Km of an enzyme increases when the enzyme's concentration is increased.
d) The Km of an enzyme is unchanged when the enzyme's concentration is increased.
e) B and D are correct. - Answers E
7. Which of the statements regarding enzymes is false?
a) Enzymes are proteins.
b) An enzyme is usually very specific for the substrate(s) it binds and the chemical reaction that it
performs
with it.
, c) Enzymes shift the equilibrium position of a chemical reaction in favor of the product(s).
d) Enzyme activity can be dramatically altered without changing its substrate concentration.
e) Some enzymes have turnover numbers (kcat) in excess of 1,000,000 sec-1. - Answers C
8. When [S] = KM, the velocity of an enzyme catalyzed reaction is:
a) 0.1 x Vmax.
b) 0.2 x Vmax.
c) 0.3 x Vmax.
d) 0.5 x Vmax.
e) 0.9 x Vmax. - Answers D
9. β-galactosidase catalyzes the hydrolysis of the disaccharide lactose to yield glucose and galactose.
What
other substrate does β-galactosidase require (apart from galactose)?
a) NADPH
b) ATP
c) H2O
d) AMP
e) PPi - Answers C
10. Lactate dehydrogenase from human skeletal muscle and heart provides a good example of:
a) isozymes
b) isomerases
c) proenzymes
d) apoenzymes
e) holoenzymes - Answers A
11. The 'thermal kinetic window' corresponds to the temperature range over which an enzyme
displays:
a) the minimal Km value for its substrate(s)
b) the maximal Vmax
c) a conformation which causes it to remain stable and active
d) the minimal Q10 value
e) allosteric activation - Answers A
12. Any non-protein component that is absolutely required by an enzyme for it to have catalytic
activity is
referred to as a:
a) co-enzyme
b) prosthetic group
c) regulatory subunit
d) co-factor
e) allosteric activator - Answers D
13. In mixed inhibition of enzyme activity...
a) Binding of the inhibitor cannot occur when the enzyme has substrate bound in its active site.
b) The inhibitor can bind to the free enzyme or the enzyme-substrate complex.
c) Amount of inhibitor bound to the enzyme is independent of inhibitor concentration.
d) Binding of the inhibitor cannot be affected in the presence of an allosteric activator.
e) Inhibitor binding has no effect on the enzyme's Km value for its substrate - Answers B
14. Which of the following statements about allosteric enzymes is false?
a) Allosteric enzymes may or may not exhibit sigmoidal substrate saturation kinetics.
b) Activators usually bind to an allosteric site.
c) Allosteric effectors compete with the substrate for binding sites.
d) Binding of the effector alters the conformation of the enzyme molecule.
e) Allosteric enzymes usually have quaternary structure. - Answers C
15. Q10 values for most enzymes from homeothermic (warm blooded) animal species are approx. 2.0,
whereas
Q10 values for enzymes of many poikilothermic (cold blooded) species are often much less than 2.0
(and
sometimes close to 1.0). How might this help a poikilothermic animal adapt to its environment?
a) Metabolic processes are not as severely influenced by changes in environmental temperature.
b) It helps keep proteins from denaturing at high temperatures.
1. Which of the following statements about the nature of enzyme catalysis is correct?
a) An enzyme alters the equilibrium position of the reaction it catalyses by influencing the energy of
activation
of that reaction.
b) An enzyme can shift the reaction's equilibrium position to favor product formation by increasing
molecular
collisions between the reacting molecules.
c) An enzyme lowers the free energy difference between substrate(s) and product(s) but it cannot
change the
equilibrium position of the reaction it catalyses.
d) An enzyme greatly accelerates reaction rates by lowering the activation energy of a chemical
reaction.
e) Most enzymes are usually saturated with their substrate in vivo. - Answers D
2. Which of the following statements about Michaelis-Menten enzyme kinetics is correct?
a) Km, the Michaelis constant, is the concentration of substrate required to attain Vmax.
b) Km, the Michaelis constant, is the dissociation constant of the enzyme-substrate complex.
c) Km, the Michaelis constant, is expressed in terms of the reaction's velocity.
d) Km, the Michaelis constant, reflects the (apparent) affinity the enzyme has for its substrate.
e) An enzyme that displays Michaelis-Menten kinetics can never show a sigmoidal plot of Vo vs [S]. -
Answers D
3. Which of the following statements about competitive inhibition of an enzyme-catalyzed reaction is
correct?
a) A competitive inhibitor and substrate can bind simultaneously to the enzyme.
b) The enzyme's Vmax and Km values are unchanged in the presence of a competitive inhibitor.
c) The enzyme's Vmax remains unchanged in the presence of a competitive inhibitor.
d) The enzyme's Km value for its substrate is reduced in the presence of a competitive inhibitor.
e) A competitive inhibitor is covalently attached to an amino acid in the enzyme's active site. -
Answers C
4. Which of the following statements about allosteric enzymes is correct?
a) Allosteric enzymes are often monomeric (single-subunit) enzymes.
b) The only ways to significantly change the in vivo activity of an allosteric enzyme is either by altering
rates of
its synthesis or degradation, or by changing the concentration of its substrate(s).
c) Allosteric enzymes always show 'Michaelis-Menten' (i.e. hyperbolic) substrate saturation kinetics.
d) The 'native form' of an allosteric enzyme can contain non-catalytic subunits.
e) An allosteric enzyme cannot be both homotropic and heterotropic. - Answers D
5. Which of the following statements about competitive inhibition of an enzyme-catalyzed reaction is
correct?
a) The addition of high concentrations of the substrate cannot overcome the effect of a competitive
inhibitor.
b) A competitive inhibitor can bind to the enzyme-substrate complex.
c) Competitive inhibition can be overcome by the addition of large amounts of substrate to a reaction.
d) Vmax decreases in the presence of a competitive inhibitor.
e) A high Ki value means its an effective inhibitor. - Answers C
6. Which of the following statements about Michaelis-Menten kinetics are correct?
a) A high Km value indicates a high affinity of an enzyme for its substrate.
b) A low Km values indicates a high affinity of an enzyme for its substrate.
c) The Km of an enzyme increases when the enzyme's concentration is increased.
d) The Km of an enzyme is unchanged when the enzyme's concentration is increased.
e) B and D are correct. - Answers E
7. Which of the statements regarding enzymes is false?
a) Enzymes are proteins.
b) An enzyme is usually very specific for the substrate(s) it binds and the chemical reaction that it
performs
with it.
, c) Enzymes shift the equilibrium position of a chemical reaction in favor of the product(s).
d) Enzyme activity can be dramatically altered without changing its substrate concentration.
e) Some enzymes have turnover numbers (kcat) in excess of 1,000,000 sec-1. - Answers C
8. When [S] = KM, the velocity of an enzyme catalyzed reaction is:
a) 0.1 x Vmax.
b) 0.2 x Vmax.
c) 0.3 x Vmax.
d) 0.5 x Vmax.
e) 0.9 x Vmax. - Answers D
9. β-galactosidase catalyzes the hydrolysis of the disaccharide lactose to yield glucose and galactose.
What
other substrate does β-galactosidase require (apart from galactose)?
a) NADPH
b) ATP
c) H2O
d) AMP
e) PPi - Answers C
10. Lactate dehydrogenase from human skeletal muscle and heart provides a good example of:
a) isozymes
b) isomerases
c) proenzymes
d) apoenzymes
e) holoenzymes - Answers A
11. The 'thermal kinetic window' corresponds to the temperature range over which an enzyme
displays:
a) the minimal Km value for its substrate(s)
b) the maximal Vmax
c) a conformation which causes it to remain stable and active
d) the minimal Q10 value
e) allosteric activation - Answers A
12. Any non-protein component that is absolutely required by an enzyme for it to have catalytic
activity is
referred to as a:
a) co-enzyme
b) prosthetic group
c) regulatory subunit
d) co-factor
e) allosteric activator - Answers D
13. In mixed inhibition of enzyme activity...
a) Binding of the inhibitor cannot occur when the enzyme has substrate bound in its active site.
b) The inhibitor can bind to the free enzyme or the enzyme-substrate complex.
c) Amount of inhibitor bound to the enzyme is independent of inhibitor concentration.
d) Binding of the inhibitor cannot be affected in the presence of an allosteric activator.
e) Inhibitor binding has no effect on the enzyme's Km value for its substrate - Answers B
14. Which of the following statements about allosteric enzymes is false?
a) Allosteric enzymes may or may not exhibit sigmoidal substrate saturation kinetics.
b) Activators usually bind to an allosteric site.
c) Allosteric effectors compete with the substrate for binding sites.
d) Binding of the effector alters the conformation of the enzyme molecule.
e) Allosteric enzymes usually have quaternary structure. - Answers C
15. Q10 values for most enzymes from homeothermic (warm blooded) animal species are approx. 2.0,
whereas
Q10 values for enzymes of many poikilothermic (cold blooded) species are often much less than 2.0
(and
sometimes close to 1.0). How might this help a poikilothermic animal adapt to its environment?
a) Metabolic processes are not as severely influenced by changes in environmental temperature.
b) It helps keep proteins from denaturing at high temperatures.
