Enzymes – Online MCQs Test – Biology MCAT

1. Enzyme, Glycosidases is included in class:

Ligases

Lyases

Hydrolases

Transferases

2. Enzymes are classified into _________classes:

Six

Four

Five

Three

3. If the non-protein part is covalently bonded to enzyme, it is known as a:

Prosthetic group

Holoenzyme

Co-factor

Coenzyme

4. Competitive Inhibitor is one which:

Normally binds to active site of an enzyme

Binds close to the active site of an enzyme

Binds away from the active site of an enzyme

Competes for the active site of an enzyme

5. Magnesium (Mg⁺²) is an inorganic activators for the enzyme:

Carbonic Anhydrase

Esterase

Amylase

Phosphatase

6. In non-competitive inhibition, the binding site other than the active site is called:

Prosteric site

Prosthetic site

Allosteric site

Allo-enzyme site

7. Coenzyme can function

In association with an Apo-enzyme

In association with a vitamin

Independently of the Apo-enzyme

In association with a protein

8. Concerning temperature affecting enzyme activity, which of the following statement is correct?

Most enzymes are highly active at 50°C

Enzymes are completely destroyed at 50°C

Enzymes are temperature-resistant

Most enzymes are highly active at 37°C

9. A co-enzyme constitutes:

1% portion of entire enzyme molecule

1% portion of half enzyme molecule

5% portion of half enzyme molecule

90% portion of entire enzyme molecule

10. Koshland in 1959 proposed:

Catalyst Fit Theory

Enzyme Lock Theory

Induce Fit Theory

Key-Lock Theory

11. Non-competitive inhibitor is one which:

Competes to the active site of enzyme

Binds away from the active site of an enzyme

Normally binds to active site of an enzyme

Binds close the active site of an enzyme

12. Molecule of ribonucleic acid which function as enzymes are called:

Ribosomes

Ribozymes

Ribozames

Ribozomes

13. Enzymes can:

React with acidic and alkaline substances both.

React with alkaline substances only as they are proteins.

No react with acidic and alkaline substances as they are proteins.

React with acidic substances only as they are proteins.

14. The conversion of complex food into simpler and soluble substances by the action of enzymes is

Assimilation

Ingestion

Translocation

Digestion

15. The inorganic ions which act as a prosthetic group in holoenzymes are called:

Co-factors

Co-activators

Co-enzymes

Ho a-group

16. An enzyme acts by

Reducing the energy of activation

Increasing the pH

Increasing the energy of activation

Decreasing the pH

17. Fischer in 1898 proposed:

Key-Lock Theory

Induce Fit Theory

Enzyme Lock Theory

Catalyst Fit Theory

18. Which one of the following statements regarding enzyme inhibition is correct?

Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme.

Non-competitive inhibitors often bind to the enzyme irreversibly.

Non-competitive inhibition of an enzyme can be overcome by adding large amount of substrate

Competitive inhibition is seen when a substrate competes with an enzyme for binding to an inhibitor protein.

19. Molecule binds to the active site of an enzyme is:

Competitive Inhibitor

Non-competitive Inhibitor

Allosteric Inhibitor

Allosteric Activator

20. At low concentration of substrate the reaction rate is directly proportional to the available.

Coenzyme

Cofactor

Enzyme

Substrate

Enzymes-Medical College Admission Test Preparation Notes