Multiple Choice Questions (MCQ) and Answers on Enzymes and Kinetics
Question.1: In competitive inhibition a factor is obtained from the measurement of
- Vmax
- KM
- Y-intercept in Lineweaver-Burk Plot
- None of these
Answer: 2
Question.2: Which of these proteases is not a cysteine active site protease?
- Calpain
- Cathepsin D
- Papain
- None of the above
Answer: 2
Question.3: Given an enzyme with a Km = 10m M and Vmax = 100 m mol/min. If [S] = 100 m M, which of the following will be true?
- A 10 fold increase in Vmax would increase velocity 10 fold y
- A 10 fold decrease in Km would increase velocity
- Both (a) and (b)
- A 10 fold increase in Vmax would decrease velocity 20 fold
Answer: 1
Question.4: Which of the following statements is true for enzymatically catalyzed reaction?
- The activation energy of the reaction is lowered so that a larger proportion of the substrate qualifies to overcome it
- Additional substrate molecules are energized to overcome the activation energy of the reaction
- The activation energy of the reaction is increased, thus decreasing the likelihood that any substrate molecules will overcome it
- The activation energy of the reaction is lowered so that a fewer substrate molecules can overcome it
Answer: 1
Question.5: The reciprocal equation for non competitive inhibition can be arranged to the equation for the
- Dixon plot
- Woolf-Augusteinsson-Hofstee plot
- Eadie-Scatchard plot
- Hanes-Woolf plot
Answer: 1
Question.6: The relationship between Keq, Km and Vmax is known as
- Haldane equation
- Michaelis Menten equation
- Numerical solution approach
- Gibbs-Helmholtz equation
Answer: 1
Question.7: A competitive inhibitor of an enzyme is usually
- a highly reactive compound
- a metal ion such as Hg2+ or Pb2+
- structurally similar to the substrate.
- water insoluble
Answer: 3
Question.8: Linear inhibition is sometimes called as
- complete inhibition
- incomplete inhibtion
- partial inhibition
- mixed inhibition
Answer: 1
Question.9: The types of inhibition pattern based on Michaelis Menten equation are
- competitive
- non-competitive
- uncompetitive
- all of the above
Answer: 4
Question.10: The rate-determining step of Michaelis Menten kinetics is
- the complex formation step
- the complex dissociation step to produce product
- the product formation step
- Both (a)and(c)
Answer: 2
Question.11: The effect of non-competitive inhibition on a Lineweaver-Burk Plot is that
- it can move the entire curve to the right
- it can change the y-intercept
- it can change the x-intercept
- all of these
Answer: 2
Question.12: The active site of an enzyme remains
- at the center of globular proteins
- rigid and does not change shape
- complementary to the rest of the molecule
- none of the above
Answer: 4
Question.13: The conformational change in an enzyme after the substrate is bound that allows the chemical reaction to proceed, can be explained by
- induced fit
- transition
- fit and fine
- Pasteur
Answer: 1
Question.14: The Woolf-Augusteinsson-Hofstee plot of ν versus ν/[S] and the Eadie-Scatchard plot of ν/[S] versus ν do not involve reciprocals of ν therefore are considered to be more reliable when the error in v is
- non-significant
- significant
- nothing to do with the reliability
- non significant in selected cases
Answer: 2
Question.15: Which category of enzymes belongs to class two in the international classification?
- Hydrolases
- Ligases
- Transferases
- Isomerase
Answer: 3
Question.16: Non-competitive inhibitor of an enzyme catalyzed reaction
- decreases Vmax
- binds to Michaelis complex (ES)
- both (a) and (b)
- can actually increase reaction velocity in rare cases
Answer: 3
Question.17: Which of the following statements is not true?
- Enzymes are proteins that bind to specific substrates and increase the velocity of reactions involving those substrates
- Enzymes function by overcoming the activation energy barrier of a reaction
- Enzymes make thermodynamically favorable reactions to proceed; they cannot make unfavorable reactions to occur
- Enzymes only function when they are in intact cells
Answer: 4
Question.18: Which of the following common drugs is not a specific enzyme inhibitor?
- Iodine
- Methotrexate
- Sulfbnilamide
- Penicillin
Answer: 1
Question.19: The enzyme inhibition can occur by
- reversible inhibitors
- irreversible inhibitors
- Both (a) and (b)
- None of these
Answer: 3
Question.20: In a Lineweaver-Burk Plot, competitive inhibitor shows which of the following effect?
- It moves the entire curve to right
- It moves the entire curve to left
- It changes the x-intercept
- It has no effect on the slope
Answer: 3
Question.21: Which of these enzymes contains a Zinc (Zn) ion?
- Carboxypeptidase A
- Phosphorylase B kinase
- Tyrosine hydroxylase
- Phosphodiesterase
Answer: 1
Question.22: Quasi steady state is also known as
- Michaelis Menten approach
- Briggs-Haldane approach
- Pseudo steady state
- all of the above
Answer: 3
Question.23: An enzyme and a reactant molecule maintain relationship as
- a temporary association
- an association stabilized by a covalent bond
- one in which the enzyme is changed permanently
- non complementary binding
Answer: 1
Question.24: An enzyme is assayed at an initial substrate concentration of 2 x 10-5M. In 6 minute, half of the substrate is used. The Km for the substrate is 2 x 10-3M. The value of k in minute is
- 0.115
- 0.42
- 0.093
- 6.693
Answer: 1
Question.25: The plot commonly used for determining the value of Vmax is
- Lineweaver Burk plot
- Langmuir plot
- Eadie Hofstee plot
- all of these
Answer: 4
Question.26: Which graphical method is used to determine an enzyme degree of cooperativity?
- Hill plot
- Koshland curve
- Michaelis-Menten hyperbola
- Can not be determined
Answer: 1
Question.27: A classical uncompetitive inhibitor is a compound that binds
- reversibly to the enzyme substrate complex yielding an inactive ESI complex
- irreversibly to the enzyme substrate complex yielding an inactive ESI complex
- reversibly to the enzyme substrate complex yielding an active ESI complex
- irreversibly to the enzyme substrate complex yielding an active ESI complex
Answer: 1
Question.28: A noncompetitive inhibitor of an enzyme-catalyzed reaction
- increases KM and increases Vmax
- increases KM and reduces Vmax
- reduces KM and increases Vmax
- reduces KM and reduces Vmax
Answer: 2
Question.29: An allosteric inhibitor of an enzyme usually
- participates in feedback regulation
- denatures the enzyme
- is a hydrophobic compound
- causes the enzyme to work faster
Answer: 1
Question.30: Which of the following activity is possible by transferases?
- Transfer of methyl groups
- Transfer of glycosyl group
- Both (a) and (b)
- None of these
Answer: 3