+20 Questions on Enzymes
20 multiple choice questions on Enzymes, ideal for high school or introductory college biology students. The correct answers are listed at the end.
Multiple Choice Questions: Enzymes
1. What is an enzyme?
A) A type of sugar
B) A protein that speeds up reactions
C) A lipid used for energy storage
D) A nucleic acid
2. The substance that an enzyme acts upon is called:
A) Product
B) Reactant
C) Substrate
D) Cofactor
3. What is the region on the enzyme where the substrate binds?
A) Catalyst site
B) Reaction zone
C) Active site
D) Binding shell
4. Enzymes speed up chemical reactions by:
A) Increasing the temperature
B) Increasing activation energy
C) Decreasing activation energy
D) Changing the substrate into water
5. After an enzyme catalyzes a reaction, it:
A) Becomes part of the product
B) Is destroyed
C) Remains unchanged
D) Turns into a sugar
6. Enzymes are made of:
A) Carbohydrates
B) Lipids
C) Proteins
D) Nucleic acids
7. Which of the following affects enzyme activity?
A) pH
B) Temperature
C) Substrate concentration
D) All of the above
8. What happens when an enzyme is denatured?
A) It becomes more efficient
B) It changes shape and loses function
C) It doubles its speed
D) It binds to any substrate
9. Enzymes are said to be specific. What does this mean?
A) They only work at high temperatures
B) Each enzyme works on one specific substrate
C) They can catalyze any type of reaction
D) They are made of specific DNA sequences
10. What is the name of the model that explains how enzymes work?
A) Fluid mosaic model
B) Induced fit model
C) DNA replication model
D) Photosynthesis model
11. Which type of biomolecule is most enzymes classified as?
A) Nucleic acids
B) Proteins
C) Carbohydrates
D) Lipids
12. What does a catalyst do in a chemical reaction?
A) Slows the reaction
B) Changes the product
C) Speeds up the reaction
D) Adds water
13. What is the result of an enzyme binding with a substrate?
A) New enzymes
B) A product is formed
C) Temperature increases
D) pH decreases
14. Enzymes work best under:
A) Extreme pH levels
B) High salinity
C) Optimal conditions (correct pH and temperature)
D) Light exposure
15. Which enzyme helps digest proteins in the stomach?
A) Amylase
B) Lactase
C) Pepsin
D) Lipase
16. What kind of macromolecule does lipase break down?
A) Proteins
B) Nucleic acids
C) Lipids
D) Carbohydrates
17. What would likely happen to enzyme activity at very high temperatures?
A) Increase forever
B) Stay the same
C) Stop due to denaturation
D) Enzyme multiplies
18. Which of these is an example of an enzyme found in saliva?
A) Lactase
B) Pepsin
C) Amylase
D) Trypsin
19. Which term describes the enzyme’s ability to bind to only one type of substrate?
A) Selectivity
B) Specificity
C) Simplicity
D) Symmetry
20. Which term refers to the molecule that helps an enzyme function but is not a protein?
A) Inhibitor
B) Substrate
C) Cofactor
D) Hormone
Answer Key
1. B) A protein that speeds up reactions
2. C) Substrate
3. C) Active site
4. C) Decreasing activation energy
5. C) Remains unchanged
6. C) Proteins
7. D) All of the above
8. B) It changes shape and loses function
9. B) Each enzyme works on one specific substrate
10. B) Induced fit model
11. B) Proteins
12. C) Speeds up the reaction
13. B) A product is formed
14. C) Optimal conditions (correct pH and temperature)
15. C) Pepsin
16. C) Lipids
17. C) Stop due to denaturation
18. C) Amylase
19. B) Specificity
20. C) Cofactor
Dive into the groundbreaking science of neurotransmitters—your brain’s invisible architects—in Chemical Harmony: How Neurotransmitters Shape Our Lives (2025). This meticulously researched book reveals how serotonin, dopamine, GABA, and other brain chemicals silently orchestrate every aspect of your existence, from decision-making and relationships to mental health and emotional resilience.Click here to buy
👉 +3000 Biology Questions with Answers Key.
Share Online!
