Enzyme Classification & Nomenclature MCQ Quiz | Enzymology

Welcome to the Enzymology quiz focused on Enzyme Classification and Nomenclature. This quiz is specifically designed for MBBS students to test and reinforce their understanding of the IUBMB classification system. You will encounter 25 multiple-choice questions covering the six major enzyme classes, EC numbers, and the distinction between systematic and trivial names. A strong grasp of this topic is fundamental for understanding metabolic pathways and pharmacology. After completing the quiz, you can submit your answers to see your score and review the correct responses. For your convenience, an option to download all questions with their correct answers in a PDF format is also available for offline study and revision. Good luck!

1. The IUBMB classifies enzymes into how many major classes?

2. Which class of enzymes catalyzes oxidation-reduction reactions?

3. In the EC nomenclature system (e.g., EC 2.7.1.1), what does the first number represent?

4. Hexokinase, which transfers a phosphate group from ATP to glucose, belongs to which enzyme class?

5. Enzymes that catalyze the hydrolysis of ester, ether, peptide, or glycosyl bonds are classified as:

6. The enzyme Lactate Dehydrogenase (LDH) which interconverts lactate and pyruvate is an example of:

7. Which enzyme class catalyzes the cleavage of C-C, C-O, C-N, and other bonds by elimination, leaving double bonds or rings?

8. What is the EC number class for Isomerases?

9. DNA Ligase, which joins two fragments of DNA by forming a phosphodiester bond, is an example of which class of enzyme?

10. The systematic name of an enzyme provides:

11. Which of the following is an example of a Lyase?

12. The enzyme urease catalyzes the hydrolysis of urea to ammonia and carbon dioxide. It belongs to which class?

13. What is the key characteristic of reactions catalyzed by Ligases (EC 6)?

14. In the EC number 2.7.1.1 (Hexokinase), what does the second number (7) represent?

15. Phosphoglucose isomerase, which converts glucose-6-phosphate to fructose-6-phosphate, is a member of which enzyme class?

16. Enzymes ending with the suffix “-ase” attached to the substrate name (e.g., lactase, sucrase) often belong to which class?

17. Which class of enzyme is responsible for the formation of C-C, C-S, C-O, and C-N bonds by condensation reactions?

18. Fumarase, which catalyzes the hydration of fumarate to malate, is an example of a(n):

19. What does the EC stand for in the enzyme classification system?

20. Aconitase, which catalyzes the isomerization of citrate to isocitrate in the Krebs cycle, belongs to which class?

21. Kinases are a sub-subclass of which major enzyme class?

22. Which of the following reactions would be catalyzed by an enzyme from class EC 1?

24. An enzyme that catalyzes the rearrangement of atoms within a single molecule is a(n):

25. The enzyme pyruvate carboxylase, which adds CO2 to pyruvate to form oxaloacetate using ATP, belongs to which class?