MCQs on Enzyme Chemistry.(Dr. Sidhu)2024

ENZYME CHEMISTRY

1. MCQs on Enzyme Chemistry
1. What are enzymes primarily made of?
a) Lipids
b) Carbohydrates
c) Proteins
d) Nucleic acids
Answer: c) Proteins
2. Which of the following is an example of a coenzyme?
a) ATP
b) NAD+
c) Hemoglobin
d) Chlorophyll
Answer: b) NAD+
3. What is the region of the enzyme where substrate molecules bind called?
a) Active site
b) Binding pocket
c) Reaction zone
d) Allosteric site
Answer: a) Active site
4. Which factor does not affect enzyme activity?
a) Temperature
b) pH
c) Substrate concentration
d) Gravity
Answer: d) Gravity
5. Which enzyme is responsible for the breakdown of hydrogen peroxide into water
and oxygen?
a) Amylase
b) Lipase
c) Catalase
d) Peroxidase
Answer: c) Catalase
6. What is the term for a non-protein molecule that aids enzyme activity?
a) Cofactor
b) Substrate
c) Inhibitor
d) Isomerase
Answer: a) Cofactor
7. What does an enzyme’s specificity refer to?
a) Its ability to be reused
b) Its ability to bind to a specific substrate
c) Its ability to generate ATP

2. d) Its molecular size
Answer: b) Its ability to bind to a specific substrate
8. Which type of inhibition occurs when an inhibitor binds to the active site of an
enzyme?
a) Competitive inhibition
b) Non-competitive inhibition
c) Uncompetitive inhibition
d) Allosteric inhibition
Answer: a) Competitive inhibition
9. What is the Michaelis constant (Km)?
a) The pH at which an enzyme works best
b) The temperature at which an enzyme is denatured
c) The substrate concentration at which the reaction rate is half of Vmax
d) The concentration of enzyme in a reaction
Answer: c) The substrate concentration at which the reaction rate is half of Vmax
10. What type of enzyme catalyzes the transfer of functional groups between
molecules?
a) Hydrolases
b) Lyases
c) Transferases
d) Ligases
Answer: c) Transferases
11. What is the primary role of enzymes in biological systems?
a) To provide energy for reactions
b) To increase the rate of biochemical reactions
c) To change the equilibrium of a reaction
d) To break down nutrients only
Answer: b) To increase the rate of biochemical reactions
12. Which type of bond is most commonly involved in enzyme-substrate
interactions?
a) Covalent bonds
b) Ionic bonds
c) Hydrogen bonds
d) Metallic bonds
Answer: c) Hydrogen bonds
13. Which enzyme catalyzes the hydrolysis of starch into maltose?
a) Maltase
b) Amylase
c) Lactase
d) Lipase
Answer: b) Amylase
14. What happens to an enzyme when it is exposed to extreme pH or temperature?
a) It becomes more active

3. b) It undergoes denaturation
c) It binds permanently to the substrate
d) It produces energy
Answer: b) It undergoes denaturation
15. What is the enzyme classification system based on?
a) Their size
b) Their molecular weight
c) The type of reaction they catalyze
d) Their origin in the body
Answer: c) The type of reaction they catalyze
16. Which of the following enzymes is involved in DNA replication?
a) DNA ligase
b) DNA polymerase
c) Helicase
d) All of the above
Answer: d) All of the above
17. What is the optimum temperature range for most human enzymes?
a) 25–30°C
b) 35–40°C
c) 55–60°C
d) 70–80°C
Answer: b) 35–40°C
18. What is an allosteric site on an enzyme?
a) The site where substrates bind
b) A secondary site that regulates enzyme activity
c) A site that denatures the enzyme
d) A site where inhibitors always bind
Answer: b) A secondary site that regulates enzyme activity
19. What is the role of the enzyme carbonic anhydrase?
a) Hydrolyzing proteins
b) Catalyzing the conversion of carbon dioxide and water to bicarbonate
c) Synthesizing carbohydrates
d) Breaking down lipids
Answer: b) Catalyzing the conversion of carbon dioxide and water to bicarbonate
20. Which of the following is an irreversible enzyme inhibitor?
a) Competitive inhibitor
b) Non-competitive inhibitor
c) Suicide inhibitor
d) Uncompetitive inhibitor
Answer: c) Suicide inhibitor
21. Enzymes belong to which class of biomolecules?
a) Lipids
b) Carbohydrates

4. c) Proteins
d) Vitamins
Answer: c) Proteins
22. Which enzyme is used in the clotting of milk during cheese production?
a) Pepsin
b) Rennin
c) Trypsin
d) Amylase
Answer: b) Rennin
23. Which enzyme catalyzes the breakdown of fats into glycerol and fatty acids?
a) Amylase
b) Lipase
c) Peptidase
d) Sucrase
Answer: b) Lipase
24. What is feedback inhibition in enzyme activity?
a) The substrate enhances enzyme activity
b) The product of a reaction inhibits enzyme activity
c) The enzyme denatures at high substrate concentration
d) None of the above
Answer: b) The product of a reaction inhibits enzyme activity
25. What is the function of lysozyme?
a) Hydrolyzing bacterial cell walls
b) Breaking down lipids
c) Hydrolyzing starch
d) Synthesizing DNA
Answer: a) Hydrolyzing bacterial cell walls