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Bio Enzymes MDCAT MCQs with Answers

Bio Enzymes MDCAT MCQs

Welcome to the Bio Enzymes MDCAT MCQs with Answers. In this post, we have shared Bio Enzymes Multiple Choice Questions and Answers for PMC MDCAT 2024. Each question in MDCAT Biology offers a chance to enhance your knowledge regarding Enzymes MCQs in this MDCAT Online Test.

Enzymes are primarily composed of:
a) Carbohydrates
b) Nucleic acids
c) Proteins
d) Lipids

Answer
c) Proteins

Which of the following is not a function of enzymes?
a) Catalyzing biochemical reactions
b) Acting as a structural component
c) Lowering activation energy
d) Increasing reaction rate

Answer
b) Acting as a structural component

The substance upon which an enzyme acts is called the:
a) Coenzyme
b) Inhibitor
c) Substrate
d) Product

Answer
c) Substrate

The region on an enzyme where the substrate binds is known as the:
a) Active site
b) Allosteric site
c) Enzyme-substrate complex
d) Catalytic center

Answer
a) Active site

Enzymes that require a non-protein molecule for activity are called:
a) Apoenzymes
b) Holoenzymes
c) Coenzymes
d) Proenzymes

Answer
b) Holoenzymes

Which of the following is a common characteristic of all enzymes?
a) They increase the energy of activation
b) They are consumed in the reaction
c) They speed up the rate of biochemical reactions
d) They are irreversible

Answer
c) They speed up the rate of biochemical reactions

Enzymes that catalyze the addition of water to substrates are known as:
a) Hydrolases
b) Oxidoreductases
c) Ligases
d) Transferases

Answer
a) Hydrolases

Enzymes that catalyze redox reactions are classified as:
a) Hydrolases
b) Oxidoreductases
c) Transferases
d) Lyases

Answer
b) Oxidoreductases

The model that describes enzyme activity where the enzyme changes shape to fit the substrate is known as:
a) Lock and key model
b) Induced fit model
c) Transition state model
d) Enzyme-substrate complex model

Answer
b) Induced fit model

The effect of temperature on enzyme activity is described by the:
a) Michaelis-Menten equation
b) Arrhenius equation
c) Temperature coefficient
d) Bell curve

Answer
c) Temperature coefficient

Enzymes that catalyze the transfer of functional groups are known as:
a) Hydrolases
b) Transferases
c) Isomerases
d) Ligases

Answer
b) Transferases

The term used to describe the optimum pH for an enzyme’s activity is:
a) Enzyme specificity
b) Enzyme denaturation
c) Optimal pH
d) Isozyme

Answer
c) Optimal pH

Enzymes that join two molecules together are known as:
a) Lyases
b) Ligases
c) Hydrolases
d) Isomerases

Answer
b) Ligases

The effect of increasing substrate concentration on the rate of an enzyme-catalyzed reaction is described by the:
a) Lock and key model
b) Michaelis-Menten kinetics
c) Lineweaver-Burk plot
d) Eadie-Hofstee equation

Answer
b) Michaelis-Menten kinetics

Which factor can denature an enzyme?
a) Optimal temperature
b) Optimal pH
c) High temperature
d) Proper substrate concentration

Answer
c) High temperature

Enzyme inhibitors that bind irreversibly to an enzyme are known as:
a) Competitive inhibitors
b) Non-competitive inhibitors
c) Irreversible inhibitors
d) Reversible inhibitors

Answer
c) Irreversible inhibitors

The region on the enzyme where an allosteric effector binds is called the:
a) Active site
b) Allosteric site
c) Substrate binding site
d) Enzyme-substrate complex

Answer
b) Allosteric site

In the presence of a competitive inhibitor, the Km of an enzyme-catalyzed reaction:
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero

Answer
a) Increases

The maximum rate of an enzyme-catalyzed reaction when the enzyme is saturated with substrate is known as:
a) Km
b) Vmax
c) Michaelis constant
d) Turnover number

Answer
b) Vmax

Enzymes that catalyze the interconversion of isomers are called:
a) Hydrolases
b) Ligases
c) Isomerases
d) Transferases

Answer
c) Isomerases

The enzyme responsible for the conversion of hydrogen peroxide to water and oxygen is:
a) Catalase
b) Amylase
c) Lipase
d) Protease

Answer
a) Catalase

Enzyme activity is often regulated by:
a) Changes in pH
b) Temperature
c) Allosteric effectors
d) All of the above

Answer
d) All of the above

The process by which an enzyme becomes less active due to environmental changes is known as:
a) Activation
b) Denaturation
c) Inhibition
d) Induction

Answer
b) Denaturation

Which of the following describes the relationship between an enzyme and its substrate?
a) Lock and key model
b) Competitive model
c) Allosteric model
d) Induced fit model

Answer
a) Lock and key model

The turnover number of an enzyme refers to:
a) The maximum rate of reaction
b) The number of substrate molecules converted per enzyme molecule per second
c) The concentration of substrate at half-maximum velocity
d) The amount of enzyme required for complete substrate conversion

Answer
b) The number of substrate molecules converted per enzyme molecule per second

Enzyme cofactors can be:
a) Vitamins
b) Metal ions
c) Organic molecules
d) All of the above

Answer
d) All of the above

Enzyme specificity refers to:
a) The ability of an enzyme to act on a wide range of substrates
b) The ability of an enzyme to recognize and bind to a specific substrate
c) The ability of an enzyme to function in different pH ranges
d) The ability of an enzyme to catalyze multiple reactions

Answer
b) The ability of an enzyme to recognize and bind to a specific substrate

Which enzyme is responsible for breaking down starch into maltose?
a) Lactase
b) Amylase
c) Sucrase
d) Pepsin

Answer
b) Amylase

Which term describes an enzyme’s ability to lower the activation energy of a reaction?
a) Catalysis
b) Substrate specificity
c) Enzyme efficiency
d) Activation energy reduction

Answer
a) Catalysis

Inhibitors that bind to the enzyme-substrate complex are classified as:
a) Competitive inhibitors
b) Non-competitive inhibitors
c) Allosteric inhibitors
d) Irreversible inhibitors

Answer
b) Non-competitive inhibitors

The enzyme lactase is responsible for:
a) Breaking down proteins
b) Breaking down fats
c) Breaking down lactose into glucose and galactose
d) Synthesizing proteins

Answer
c) Breaking down lactose into glucose and galactose

Which of the following statements about enzyme inhibitors is true?
a) All enzyme inhibitors increase the enzyme’s activity
b) Non-competitive inhibitors can bind to both the enzyme and enzyme-substrate complex
c) Competitive inhibitors bind to the allosteric site of the enzyme
d) Irreversible inhibitors bind loosely to the enzyme

Answer
b) Non-competitive inhibitors can bind to both the enzyme and enzyme-substrate complex

Enzyme kinetics is often studied using which model?
a) Lock and key model
b) Michaelis-Menten model
c) Induced fit model
d) Allosteric model

Answer
b) Michaelis-Menten model

Enzymes that catalyze the breakdown of proteins are known as:
a) Amylases
b) Lipases
c) Proteases
d) Nucleases

Answer
c) Proteases

Enzymes that facilitate the transfer of a phosphate group are called:
a) Kinases
b) Phosphatases
c) Transferases
d) Hydrolases

Answer
a) Kinases

Enzyme activity can be regulated by:
a) Allosteric regulation
b) Covalent modification
c) Feedback inhibition
d) All of the above

Answer
d) All of the above

Enzymes that remove phosphate groups from proteins are known as:
a) Kinases
b) Phosphatases
c) Ligases
d) Isomerases

Answer
b) Phosphatases

Which type of enzyme regulation involves the binding of an effector molecule at a site other than the active site?
a) Competitive inhibition
b) Non-competitive inhibition
c) Allosteric regulation
d) Feedback inhibition

Answer
c) Allosteric regulation

The process of enzyme-catalyzed reactions involving substrate molecules is often depicted as:
a) A bell-shaped curve
b) A reaction coordinate diagram
c) A saturation curve
d) A rate equation

Answer
b) A reaction coordinate diagram

Enzyme turnover number is defined as:
a) The number of substrate molecules converted to product per unit time
b) The concentration of enzyme needed to convert the substrate
c) The rate at which an enzyme is denatured
d) The amount of enzyme required to reach Vmax

Answer
a) The number of substrate molecules converted to product per unit time

Enzymes that catalyze the breakdown of nucleic acids are called:
a) Nucleases
b) Lipases
c) Amylases
d) Proteases

Answer
a) Nucleases

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