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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Read the Enzymes notesFree MDCAT chapter notes with key terms633 questions · page 11 of 32
- A. Turnover number
- B. Substrate number
- C. Reaction number
- D. None of these options is correct.
Explanation: The turnover number (kcat) is defined as the number of substrate molecules converted into product by one molecule of enzyme active site…
Correct answer: Turnover number- A. Denaturation
- B. Saturation
- C. Composition
- D. Inhibition
Explanation: If adding more substrate to an already occurring enzymatic reaction has no effect on the rate of the reaction, the process is called…
Correct answer: Saturation- A. 2
- B. 3
- C. 4
- D. 5
Explanation: Pepsin is a protease enzyme, released in the stomach, alongside HCI. Because of HCI, the pH drops to significantly low levels however…
Correct answer: 2- A. Reactants
- B. Enzymes
- C. Products
- D. All of these
Explanation: In enzymatic mechanisms, when the substrate binds to the enzyme's active site, it forms an enzyme-substrate complex.
Correct answer: Products- A. Competitive inhibitors
- B. Allosteric inhibition
- C. Non-competitive inhibitors
- D. Irreversible inhibition
Explanation: Non-competitive inhibitors are molecules that bind to an enzyme at a location other than the active site, leading to a conformational…
Correct answer: Non-competitive inhibitors- A. Additional factor
- B. Cofactor
- C. Efficient cofactor
- D. Extra factor
Explanation: A non-protein part that is essential for the proper functioning of an enzyme is called a "cofactor." Cofactors are often inorganic ions or…
Correct answer: Cofactor- A. Low concentration of substrate
- B. High concentration of inhibitor
- C. Moderate concentration of inhibitor
- D. High concentration of substrate
Explanation: Competitive inhibition can be alleviated by increasing substrate concentration.
Correct answer: High concentration of substrate- A. Covalently bonded non-protein part of an enzyme.
- B. Cofactor consists of metal ions.
- C. Loosely bonded non-protein part of an enzyme.
- D. Both A and B.
Explanation: A coenzyme is a non-protein organic compound that associates with an enzyme to facilitate the enzyme's activity.
Correct answer: Loosely bonded non-protein part of an enzyme.- A. Specific enzyme can transform only a specific substrate.
- B. Active site of an enzyme is a non-flexible structure.
- C. Active site does not change before during or even after the reaction.
- D. It explains the mechanism of every chemical reaction.
Explanation: The lock-and-key model describes enzyme-substrate interactions, suggesting that enzymes and substrates have specific complementary shapes…
Correct answer: It explains the mechanism of every chemical reaction.- A. The contact between the substrate and the enzyme causes a change in the shape of the active site.
- B. The shape of the substrate and the shape of the active site are complementary to each other
- C. The substrate fits into the active site and forms bonds with the amino acids at the active site
- D. All of the above
Explanation: The enzyme substrate complex is a temporary molecule formed when an enzyme comes into perfect contact with its substrate.The substrate…
Correct answer: The contact between the substrate and the enzyme causes a change in the shape of the active site.- A. Reaction site
- B. Active site
- C. Binding site
- D. None of these
Explanation: The active site of an enzyme is a specific region where the substrate, or substrates, bind and undergo a chemical reaction.
Correct answer: Active site- A. Enzyme
- B. Substrate
- C. E-S complex
- D. All of these options are correct
Explanation: c) ES-complex:This option is correct. Uncompetitive inhibition is characterized by the binding of the inhibitor to the enzyme-substrate…
Correct answer: E-S complex- A. 1
- B. 2
- C. 3
- D. 4
Explanation: There are two main models that represent the enzyme-substrate interaction:Lock-and-Key ModelInduced Fit Model
Correct answer: 2- A. 5
- B. 7.5
- C. 9
- D. 3
Explanation: pH 7.5 is closest to neutral and most enzymes would denature in other values of pH.
Correct answer: 7.5- A. Activation Energy
- B. Catalysis
- C. Enzyme Specificity
- D. Denaturation
Explanation: The mechanism of enzyme activation is referred to as "enzyme catalysis" or simply "catalysis." Enzymes are biological catalysts that…
Correct answer: Catalysis- A. Diastase
- B. Maltase
- C. Zymase
- D. All of above options are correct
Explanation: Zymase is a complex mixture of enzymes found in yeast cells. It plays a crucial role in the process of fermentation.
Correct answer: Zymase- A. Malonic acid
- B. Malic acid
- C. Fumaric acid
- D. Acetic acid
Explanation: The competitive inhibitor of succinic dehydrogenase is malonate. Malonate closely resembles the substrate succinate and binds to the…
Correct answer: Malonic acid- A. Allosteric regulation
- B. Negative regulation
- C. Metabolic pathway loop
- D. Feedback inhibition
Explanation: Correct option is D.The type of enzymatic regulation where the end product of an enzymatic reaction inhibits formation of product in an…
Correct answer: Feedback inhibition- A. Substrate concentration
- B. Product concentration
- C. Both of these
- D. None of these
Explanation: Enzymes are biological catalysts that facilitate and accelerate chemical reactions in living organisms.
Correct answer: Both of these- A. Vitamin B
- B. Vitamin B12
- C. Vitamin C
- D. Vitamin B1
Explanation: Coenzymes are organic molecules that help in the catalysis of chemical reactions by binding to the active sites.
Correct answer: Vitamin C