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. Induce fit model
- B. Lock and key
- C. Both models
- D. None
Explanation: The lock and key model is the correct explanation for the working of sucrase and maltase.
Correct answer: Lock and key- A. Enzymes are unbiased for substrate
- B. Enzymes can modify their active sites
- C. Enzymes are restricted to one reaction type
- D. Enzymes can catalyze variety of reactions
Explanation: According to lock and key model, every enzyme is specific due to its active site for its substrate.
Correct answer: Enzymes are restricted to one reaction type- A. Oxidation of amino acid
- B. Atomization of amino acids
- C. Reduction of amino acid
- D. Ionization of amino acids
Explanation: Change in pH causes the imbalance of H'/OH ions, which causes the ionization of amino acids at the active sites and substrate as well.
Correct answer: Ionization of amino acids- A. Enzymes concentration
- B. Substrate concentration
- C. Light intensity
- D. Temperature
Explanation: Rate of reaction effects by substrate concentration, temperature, pH and enzyme concentration.
Correct answer: Light intensity- A. 7.60
- B. 9.00
- C. 8.00
- D. 9.70
Explanation: Optimum pH values for the catalytic activity of catalase, chymotrypsin, pancreatic lipase and Arginase are 7.60, 7.00-8.00, 9.00 and 9.70…
Correct answer: 9.00- A. Fixed temperature
- B. Controlled temperature
- C. Optimum temperature
- D. Active temperature
Explanation: All enzymes can work at their maximum rate at a specific temperature called as optimum temperature.
Correct answer: Optimum temperature- A. All enzymes in human body work at same temperature but different pH
- B. All enzymes in human body work at different temperature but same pH
- C. All enzymes in human body work at same temperature and same pH
- D. All enzymes in human body work at different temperature and different pH
Explanation: All enzymes in human body work at optimum temperature of 37°C with exception of testes.
Correct answer: All enzymes in human body work at same temperature but different pH- A. Active site
- B. Binding site
- C. Substrate
- D. Coenzyme
Explanation: Non-competitive reversible inhibitors block the allosteric site of enzyme, while competitive reversible inhibitors have structural…
Correct answer: Substrate489. Which of the following type of inhibitor can be neutralize by adding more substrate into reaction?
- A. Irreversible inhibitor
- B. Reversible inhibitor
- C. Irreversible non-competitive
- D. Irreversible competitive
Explanation: Reversible inhibitors can form weak linkages with the enzyme. Their effect can be neutralized completely or partly by an increase in the…
Correct answer: Reversible inhibitor- A. Non-competitive reversible
- B. Irreversible
- C. Competitive reversible
- D. None of these
Explanation: Competitive inhibitors are substances that compete with the substrate for binding to the active site of the enzyme.
Correct answer: Competitive reversible- A. Irreversible inhibitors
- B. Competitive inhibitors
- C. Non-competitive inhibitors
- D. Reversible inhibitors
Explanation: Penicillin is a competitive inhibitor. Other competitive inhibitors include antibodies, antimetabolites, iodoacetate, malonate and CoA…
Correct answer: Competitive inhibitors- A. Transferases
- B. Lyases
- C. Oxidoreductases
- D. Hydrolases
Explanation: Oxidoreductases catalyze oxidation/reduction of their substrate and act by removing or adding electron or H* ions from or to substrate.
Correct answer: Oxidoreductases- A. Active sites
- B. Binding site
- C. Catalytic groups
- D. Allosteric sites
Explanation: The allosteric site is a site that allows molecules to either activate or inhibit (or turn off) enzyme activity.
Correct answer: Allosteric sites- A. Formation of the product
- B. pH of optimum value
- C. Km value
- D. Molecular size of the enzyme.
Explanation: Km value or Michaelis constant is defined as the substrate concentration at which half of the enzyme molecules are forming (ES) complex or…
Correct answer: Km value- A. Carbonic anhydrase
- B. Tryptophanase
- C. Lactic dehydrogenase
- D. Tyrosinase
Explanation: Among the given options, the enzyme in which copper is necessarily associated as an activator is lactic dehydrogenase (option C).
Correct answer: Tyrosinase496. Enzymes that have slightly different molecular structure but perform identical activity are called :
- A. Holoenzymes
- B. Isoenzymes
- C. Apoenzymes
- D. Coenzymes
Explanation: The correct term for enzymes that have slightly different molecular structures but perform identical activities is isoenzymes.
Correct answer: Isoenzymes- A. 7.60
- B. 8 -9
- C. 9
- D. 9.7
Explanation: 9 is the correct answer. In vitro, pancreatic lipase exhibits the maximum activity at pH 7.5-8.5.
Correct answer: 8 -9- A. Tertiary structure
- B. Primary structure
- C. Secondary structure
- D. Net charge
Explanation: The primary structure is the simple level of protein structure. Primary structure is a basic amino acids sequences in a protein.
Correct answer: Net charge- A. 32F
- B. 46C
- C. 313K
- D. 37C
Explanation: All enzymes can work at their maximum rate at a specific temperature called as optimum temperature.
Correct answer: 37C- A. Completely
- B. Incompletely
- C. Changed
- D. Unchanged
Explanation: Enzymes are used in biochemical reactions as a biocatalyst. After catalysis enzyme structure remains unchanged and it can be used again…
Correct answer: Unchanged