- What is the primary function of enzymes in biological reactions? a) To provide energy
b) To catalyze chemical reactions
c) To increase temperature
d) To provide structural supportAnswer: b) To catalyze chemical reactions - Enzymes are primarily made up of which type of molecules? a) Carbohydrates
b) Nucleic acids
c) Proteins
d) LipidsAnswer: c) Proteins - What is the name of the molecule that an enzyme acts upon? a) Coenzyme
b) Substrate
c) Catalyst
d) ProductAnswer: b) Substrate - What part of the enzyme binds to the substrate? a) Active site
b) Allosteric site
c) Reaction site
d) Inhibitory siteAnswer: a) Active site - Which of the following factors does NOT affect enzyme activity? a) Temperature
b) pH level
c) Substrate concentration
d) Enzyme sizeAnswer: d) Enzyme size - What happens to an enzyme if the temperature is too high? a) It becomes more active
b) It is denatured and loses its activity
c) It increases its affinity for the substrate
d) It catalyzes reactions fasterAnswer: b) It is denatured and loses its activity - Which of the following is true about enzyme-substrate specificity? a) Each enzyme can bind to any substrate
b) Enzymes are non-specific in their action
c) Enzymes are specific to a particular substrate
d) Substrates have the ability to change the enzyme’s structureAnswer: c) Enzymes are specific to a particular substrate - What is the role of a coenzyme in enzymatic reactions? a) To inhibit the enzyme’s activity
b) To change the substrate
c) To bind to the enzyme and assist in catalysis
d) To break down the enzymeAnswer: c) To bind to the enzyme and assist in catalysis - At high substrate concentration, what is the effect on enzyme activity? a) Enzyme activity decreases
b) Enzyme activity remains constant
c) Enzyme activity increases indefinitely
d) Enzyme activity reaches a maximum level and plateausAnswer: d) Enzyme activity reaches a maximum level and plateaus - What is the term used for the energy required to start a chemical reaction? a) Activation energy
b) Activation potential
c) Free energy
d) Threshold energyAnswer: a) Activation energy - How does an enzyme reduce the activation energy of a reaction? a) By raising the temperature
b) By forming an enzyme-substrate complex
c) By increasing the concentration of reactants
d) By increasing the volume of the solutionAnswer: b) By forming an enzyme-substrate complex - What is enzyme inhibition? a) The increase in enzyme activity
b) The decrease in enzyme activity
c) The reversible binding of a coenzyme
d) The formation of an enzyme-product complexAnswer: b) The decrease in enzyme activity - What is the effect of increasing temperature on enzyme activity up to an optimal point? a) It decreases the enzyme’s activity
b) It increases the enzyme’s activity
c) It has no effect on enzyme activity
d) It denatures the enzymeAnswer: b) It increases the enzyme’s activity - Which of the following is a characteristic of allosteric enzymes? a) They are irreversible
b) They can be activated or inhibited by molecules binding to sites other than the active site
c) They only work in the presence of coenzymes
d) They cannot be inhibited by temperatureAnswer: b) They can be activated or inhibited by molecules binding to sites other than the active site - Which of the following can act as an enzyme inhibitor? a) Competitive inhibitors
b) Non-competitive inhibitors
c) Feedback inhibitors
d) All of the aboveAnswer: d) All of the above - What is a competitive inhibitor? a) A molecule that binds to the active site and blocks the substrate
b) A molecule that binds to a coenzyme
c) A molecule that enhances enzyme activity
d) A molecule that binds to a site other than the active siteAnswer: a) A molecule that binds to the active site and blocks the substrate - Which statement about enzymes and pH is correct? a) Each enzyme has an optimal pH at which it works best
b) Enzyme activity increases at higher pH levels
c) Enzyme activity is not affected by pH
d) All enzymes work best in strongly acidic conditionsAnswer: a) Each enzyme has an optimal pH at which it works best - What is the role of an enzyme in a biochemical pathway? a) To transport molecules across membranes
b) To catalyze the conversion of substrates into products
c) To provide energy for the pathway
d) To form cellular structuresAnswer: b) To catalyze the conversion of substrates into products - Which of the following is true regarding enzyme denaturation? a) Denaturation causes a permanent loss of enzyme activity
b) Denaturation can be reversed in all cases
c) Denaturation increases enzyme efficiency
d) Denaturation has no effect on enzyme activityAnswer: a) Denaturation causes a permanent loss of enzyme activity - What is the function of a prosthetic group in an enzyme? a) To enhance enzyme-substrate binding
b) To permanently attach to the enzyme and help catalysis
c) To act as a competitive inhibitor
d) To deactivate the enzymeAnswer: b) To permanently attach to the enzyme and help catalysis - What happens to the enzyme activity if the enzyme concentration is increased? a) Enzyme activity decreases
b) Enzyme activity increases, but only to a point
c) Enzyme activity remains the same
d) Enzyme activity becomes constantAnswer: b) Enzyme activity increases, but only to a point - Which of the following is NOT a factor that affects enzyme activity? a) Temperature
b) Substrate concentration
c) Enzyme concentration
d) DNA sequenceAnswer: d) DNA sequence - What is the effect of a non-competitive inhibitor on enzyme activity? a) It binds to the active site, preventing the substrate from binding
b) It increases the enzyme activity
c) It binds to a site other than the active site, changing the enzyme’s shape
d) It has no effect on enzyme activityAnswer: c) It binds to a site other than the active site, changing the enzyme’s shape - What is the term used to describe the process where the end product of a metabolic pathway inhibits an enzyme involved earlier in the pathway? a) Competitive inhibition
b) Non-competitive inhibition
c) Feedback inhibition
d) Irreversible inhibitionAnswer: c) Feedback inhibition - Which of the following conditions would most likely result in enzyme denaturation? a) A slight increase in temperature
b) A drastic increase in temperature
c) A slight change in pH
d) A slight increase in substrate concentrationAnswer: b) A drastic increase in temperature - Which of the following is NOT a cofactor for enzyme activity? a) Metal ions
b) Coenzymes
c) ATP
d) Water moleculesAnswer: d) Water molecules - What type of enzyme catalyzes the breakdown of protein molecules? a) Lipase
b) Protease
c) Amylase
d) LactaseAnswer: b) Protease - Which statement about enzymes is false? a) Enzymes increase the rate of chemical reactions
b) Enzymes are consumed in the reaction
c) Enzymes work by lowering the activation energy
d) Enzymes are specific to their substratesAnswer: b) Enzymes are consumed in the reaction - What is the effect of substrate concentration on enzyme activity? a) It decreases enzyme activity
b) It increases enzyme activity up to a saturation point
c) It has no effect on enzyme activity
d) It inactivates enzymesAnswer: b) It increases enzyme activity up to a saturation point - Which of the following is an example of an enzyme that requires a coenzyme for activity? a) Lipase
b) DNA polymerase
c) Amylase
d) LactaseAnswer: b) DNA polymerase
Home Biology Topics with MCQs Biochemistry MCQs on “Enzymes: Catalysis and Factors Affecting Activity”
