Enzymes are biological catalysts that speed up chemical reactions in living cells without being used up. They play a vital role in digestion, respiration, metabolism, and many other life processes. This quiz is designed to test your understanding of enzymes, their properties, and their functions. Read each question carefully and choose the most appropriate answer.
Enzymes and Their Functions Quiz
1. Enzymes are best described as
A. Carbohydrates
B. Lipids
C. Proteins
D. Vitamins
2. The main function of enzymes in living organisms is to
A. Produce energy
B. Speed up chemical reactions
C. Store food
D. Transport oxygen
3. The substance on which an enzyme acts is called the
A. Product
B. Catalyst
C. Substrate
D. Inhibitor
4. Which of the following is an example of a digestive enzyme?
A. Haemoglobin
B. Amylase
C. Insulin
D. Chlorophyll
5. Enzymes are usually specific in their action because
A. They dissolve easily
B. They have active sites
C. They are large molecules
D. They are acidic
Enzymes and Their Functions Quiz
6. The region of an enzyme where the substrate binds is called the
A. Bonding site
B. Reaction site
C. Active site
D. Control site
7. Which model explains enzyme action?
A. Key and lock model
B. Fluid mosaic model
C. Chain reaction model
D. Cycle model
8. The optimum temperature for most human enzymes is about
A. 25°C
B. 30°C
C. 37°C
D. 45°C
9. When enzymes are exposed to very high temperatures, they become
A. Activated
B. Denatured
C. Multiplied
D. Preserved
10. The optimum pH for the enzyme pepsin is
A. Acidic
B. Neutral
C. Alkaline
D. Basic
Enzymes and Their Functions Quiz
11. Which enzyme digests proteins in the stomach?
A. Amylase
B. Lipase
C. Pepsin
D. Maltase
12. Salivary amylase acts mainly on
A. Proteins
B. Fats
C. Starch
D. Vitamins
13. Enzymes can be reused after a reaction because they are
A. Changed permanently
B. Destroyed
C. Unaffected
D. Reduced
14. A substance that slows down enzyme action is called a(n)
A. Activator
B. Substrate
C. Inhibitor
D. Co-enzyme
15. Which of the following affects enzyme activity?
A. Temperature
B. pH
C. Substrate concentration
D. All of the above
16. Enzymes that work inside cells are called
A. Extracellular enzymes
B. Digestive enzymes
C. Intracellular enzymes
D. External enzymes
17. The breakdown of hydrogen peroxide by catalase produces
A. Oxygen and water
B. Carbon dioxide and water
C. Nitrogen and water
D. Hydrogen and oxygen
18. Co-enzymes are usually made up of
A. Proteins
B. Vitamins
C. Lipids
D. Minerals
19. Which enzyme converts maltose to glucose?
A. Amylase
B. Sucrase
C. Maltase
D. Lactase
20. The shape of an enzyme is important because it
A. Determines its colour
B. Controls its movement
C. Determines its specificity
D. Affects its size
Enzymes and Their Functions Quiz
21. An enzyme that breaks down fats is called
A. Protease
B. Amylase
C. Lipase
D. Peptidase
22. Which condition may stop enzyme activity completely?
A. Low temperature
B. High temperature
C. Low substrate level
D. Neutral pH
23. Enzymes involved in respiration are found mainly in the
A. Ribosome
B. Mitochondrion
C. Vacuole
D. Lysosome
24. The end products of enzyme reactions are known as
A. Substrates
B. Catalysts
C. Products
D. Inhibitors
25. Which statement about enzymes is correct?
A. They are used up in reactions
B. They work at any temperature
C. They are highly specific
D. They are not affected by pH
Enzymes and Their Functions Quiz Answers and Explanations
1. C — Proteins
Most enzymes are proteins that act as biological catalysts.
2. B — Speed up chemical reactions
Enzymes increase the rate of chemical reactions in living cells.
3. C — Substrate
The substrate is the substance that an enzyme acts upon.
4. B — Amylase
Amylase helps in the digestion of starch.
5. B — They have active sites
Active sites allow enzymes to bind only specific substrates.
6. C — Active site
The active site is the part of the enzyme where reactions occur.
7. A — Key and lock model
This model explains how enzymes fit their substrates.
8. C — 37°C
Human enzymes work best at normal body temperature.
9. B — Denatured
High temperatures destroy enzyme structure.
10. A — Acidic
Pepsin works best in acidic conditions of the stomach.
11. C — Pepsin
Pepsin digests proteins in the stomach.
12. C — Starch
Salivary amylase converts starch to maltose.
13. C — Unaffected
Enzymes remain unchanged after reactions.
14. C — Inhibitor
Inhibitors reduce or stop enzyme action.
15. D — All of the above
Temperature, pH, and substrate concentration affect enzymes.
16. C — Intracellular enzymes
These enzymes function inside cells.
17. A — Oxygen and water
Catalase breaks hydrogen peroxide into water and oxygen.
18. B — Vitamins
Many co-enzymes are derived from vitamins.
19. C — Maltase
Maltase converts maltose into glucose.
20. C — Determines its specificity
Enzyme shape decides which substrate it acts on.
21. C — Lipase
Lipase breaks down fats into fatty acids and glycerol.
22. B — High temperature
High heat can permanently destroy enzymes.
23. B — Mitochondrion
Respiration enzymes are found in mitochondria.
24. C — Products
Products are substances formed after reactions.
25. C — They are highly specific
Each enzyme works on a particular substrate only.
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