Free Enzymes MCQs with Answers
633 Enzymes MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Enzymes are biological catalysts that lower activation energy without being consumed, and their specificity is explained by the lock and key and induced fit models. Work includes the effects of temperature, pH and substrate concentration on reaction rate, plus competitive and non-competitive inhibition and how these differ.
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- A. Active site
- B. Substrate
- C. Cofactor
- D. Enzyme
Explanation: The correct answer is 'Cofactor'. A cofactor is a non-protein chemical compound required for the biological activity of some proteins…
Correct answer: Cofactor- A. Activation
- B. Destabalization
- C. Kinetic
- D. Free
Explanation: The energy required to destabilize existing chemical bonds in order to initiate a chemical reaction is called "activation energy."…
Correct answer: Activation- A. Key
- B. Active site
- C. Hyperactive site
- D. None of these.
Explanation: The substrate binds to a specific region of an enzyme called the active site.
Correct answer: Active site- A. High
- B. Low
- C. Remains the same
- D. None of these options is correct.
Explanation: The higher the activation energy, the slower the chemical reaction will be.
Correct answer: Low- A. 1960
- B. 1961
- C. 1959
- D. 1966
Explanation: The induced-fit model was first proposed by Koshland in 1959 to explain the protein conformational changes in the binding process.
Correct answer: 1959- A. The Keq of a reaction remains unchanged in the presence of an enzyme.
- B. Enzymes speed up the rate of reaction in DNA synthesis.
- C. Harsh, acidic conditions can completely denature an enzyme.
- D. An enzyme is completely converted to product during metabolism.
Explanation: Enzymes are not consumed or completely converted to products during metabolism.
Correct answer: An enzyme is completely converted to product during metabolism.- A. Increases enzyme activity
- B. Doesn't change enzyme activity
- C. Decreases enzyme activity
- D. None of these options is correct
Explanation: A competitive inhibitor affects enzyme activity by directly competing with the substrate for binding to the active site of the enzyme.
Correct answer: Decreases enzyme activity- A. Remains same
- B. Denatures
- C. Adopts a geometric conformation
- D. Dissolves
Explanation: Upon increasing the temperature, the shape of an enzyme's active site may change.
Correct answer: Denatures- A. 9.0
- B. 9.3
- C. 9.7
- D. 10
Explanation: The correct answer is 9.7 because this is the optimum pH for the enzyme arginase, where it exhibits maximum catalytic activity.
Correct answer: 9.7- A. Louis Pasteur
- B. Emil Fischer
- C. Daniel Koshland
- D. Urey Miller
Explanation: Emil Fischer (1890) proposed a Lock and Key model to visualize substrate and enzyme interaction.
Correct answer: Emil Fischer- A. Lipase
- B. Protease
- C. Amylase
- D. Polymerase
Explanation: Antibodies, being proteins, can be digested or broken down by proteolytic enzymes.
Correct answer: Protease- A. Product
- B. Reactant
- C. Substrate
- D. All of these
Explanation: Enzymes bind with the chemical reactant, typically a substrate, at a specific region on the enzyme molecule known as the "active site."…
Correct answer: Substrate- A. Enzyme
- B. Reactant
- C. Product
- D. Substrate
Explanation: Reversible inhibitors attach to enzymes with non-covalent interactions such as hydrogen bonds, hydrophobic interactions and ionic bonds.
Correct answer: Enzyme- A. Light Energy
- B. Heat Energy
- C. Active Energy
- D. Activation Energy
Explanation: The type of energy reduced by enzymes to facilitate biological reactions is referred to as "activation energy." Enzymes play a crucial…
Correct answer: Activation Energy- A. Non competitive
- B. Irreversible
- C. Temperature sensitive
- D. Competitive reversible
Explanation: 'Compound A' caused a toxic effect by inhibiting the action of a certain enzyme.
Correct answer: Competitive reversible- A. Increasing the activation energy
- B. Reducing the activation energy
- C. Making exergonic reactions endergonic
- D. Making endergonic reactions exergonic
Explanation: Enzymes work by reducing the activation energy required for a chemical reaction to occur.
Correct answer: Reducing the activation energy- A. Holoenzymes
- B. Actinases
- C. Zymogens
- D. Mucopolysaccharides
Explanation: Inactive enzyme precursors like pepsinogen for pepsin are commonly referred to as "zymogens" or "proenzymes." Zymogens are inactive forms…
Correct answer: Zymogens- A. Unit membrane model
- B. Fluid mosaic model
- C. Reflective index model
- D. Induced fit model
Explanation: In 1959, Daniel E. Koshland, an American biochemist, proposed the "induced fit" model of enzyme-substrate interaction.
Correct answer: Induced fit model- A. Hydrogen bonds
- B. Ionic interactions
- C. Hydrophobic interactions
- D. Covalent linkages
Explanation: The correct answer is Covalent linkages because these bonds involve a strong and permanent connection between atoms, which is not typical…
Correct answer: Covalent linkages200. Urease present in:
- A. Banana
- B. Grapes
- C. Soya sauce
- D. Soya bean
Explanation: Urease is an enzyme that catalyzes the hydrolysis of urea to produce ammonia and carbon dioxide.
Correct answer: Soya bean