Đề 14 – Bài tập, đề thi trắc nghiệm online Hóa sinh enzyme

1. In industrial applications, enzymes are widely used in:

A. Nuclear power generation

B. Manufacturing of synthetic polymers only

C. Food processing, detergents, and pharmaceuticals

D. Mining and mineral extraction exclusively

2. Which of the following factors does NOT typically affect the rate of an enzyme-catalyzed reaction?

A. Substrate concentration

B. Enzyme concentration

C. Presence of inhibitors

D. The color of the reaction solution

3. Compared to non-competitive inhibition, competitive inhibition typically affects:

A. Only the Vmax of the enzyme

B. Only the Km of the enzyme

C. Both Vmax and Km of the enzyme

D. Neither Vmax nor Km of the enzyme

4. Non-competitive inhibitors reduce enzyme activity by:

A. Binding directly to the active site

B. Altering the enzyme`s conformation when binding at a different site

C. Increasing the concentration of the substrate

D. Increasing the temperature of the reaction

5. A higher Km value of an enzyme indicates:

A. A higher affinity for the substrate

B. A lower affinity for the substrate

C. A faster maximum reaction rate (Vmax)

D. A more efficient enzyme

6. Competitive inhibitors of enzymes work by:

A. Binding to the enzyme at a site other than the active site

B. Destroying the enzyme`s tertiary structure

C. Binding reversibly to the active site, preventing substrate binding

D. Increasing the enzyme`s affinity for the substrate

7. The specificity of an enzyme for its substrate is primarily determined by:

A. The enzyme`s molecular weight

B. The enzyme`s concentration in the cell

C. The three-dimensional shape of the active site

D. The temperature of the reaction environment

8. Oxidoreductases catalyze reactions involving:

A. Rearrangement of atoms within a molecule

B. Joining of two molecules

C. Transfer of functional groups

D. Electron transfer (oxidation and reduction)

9. Enzymes primarily function as:

A. Structural components of cells

B. Catalysts in biochemical reactions

C. Energy storage molecules

D. Genetic information carriers

10. Why are enzymes considered highly specific catalysts?

A. Because they are very large molecules

B. Due to the presence of cofactors

C. Because of the precise three-dimensional structure of their active site

D. Because they are produced in very small quantities in cells

11. If you increase the substrate concentration in a reaction inhibited by a competitive inhibitor, what is the expected outcome on the reaction rate?

A. The reaction rate will decrease further

B. The reaction rate will remain unchanged

C. The reaction rate will eventually approach Vmax

D. The Vmax will decrease

12. Allosteric enzymes are characterized by:

A. Having only one substrate binding site

B. Strictly following Michaelis-Menten kinetics

C. Binding of regulatory molecules at sites other than the active site

D. Being active only at very high temperatures

13. The `induced-fit` model of enzyme action differs from the `lock-and-key` model by suggesting that:

A. Enzymes are consumed in the reaction

B. The active site of the enzyme is flexible and changes shape upon substrate binding

C. Substrates are always larger than enzymes

D. Enzymes only work at specific temperatures

14. Cofactors are best described as:

A. Protein components of enzymes

B. Organic substrates of enzymes

C. Non-protein chemical compounds required for enzyme activity

D. Products of enzyme-catalyzed reactions

15. Which of the following is an example of enzyme classification based on the type of reaction they catalyze?

A. Lyases

B. Trypsin

C. Catalase

D. Amylase

16. Enzyme deficiencies in humans often lead to:

A. Increased physical strength

B. Metabolic disorders

C. Enhanced cognitive functions

D. Resistance to infectious diseases

17. Which statement about enzymes is NOT true?

A. Enzymes are proteins (with some exceptions of catalytic RNA).

B. Enzymes are highly specific for their substrates.

C. Enzymes are consumed during the reaction process.

D. Enzymes lower the activation energy of reactions.

18. Feedback inhibition is a regulatory mechanism where:

A. The substrate of an enzyme inhibits its own production

B. The product of a metabolic pathway inhibits an earlier step in the pathway

C. Enzymes activate each other in a cascade

D. Inhibitors compete with substrates for the active site

19. What is the key difference between an apoenzyme and a holoenzyme?

A. Apoenzymes are active, while holoenzymes are inactive

B. Apoenzymes require a cofactor to be active, while holoenzymes are complete and active

C. Holoenzymes are protein-based, while apoenzymes are RNA-based

D. There is no significant difference between apoenzymes and holoenzymes

20. If you increase the substrate concentration in a reaction inhibited by a non-competitive inhibitor, what is the expected outcome on the reaction rate?

A. The reaction rate will eventually approach Vmax

B. The reaction rate will remain unchanged

C. The Vmax of the reaction will be reduced, and the rate will plateau at a lower maximum

D. The Km of the enzyme will decrease

21. What would be the most direct consequence if the active site of an enzyme were denatured?

A. The enzyme`s specificity would increase

B. The enzyme`s activity would be lost or significantly reduced

C. The enzyme would start catalyzing a different reaction

D. The enzyme would become a competitive inhibitor

22. In enzyme kinetics, Vmax represents:

A. The substrate concentration at half-maximal velocity

B. The initial velocity of the reaction

C. The maximum velocity of the enzyme-catalyzed reaction

D. The enzyme concentration

23. Coenzymes are a type of cofactor that are:

A. Inorganic ions

B. Always tightly bound to the enzyme

C. Organic molecules

D. Lipid-based molecules

24. The `lock-and-key` model of enzyme action describes:

A. Enzyme denaturation by high temperatures

B. The flexible nature of the enzyme active site

C. The rigid, precise fit of substrate into the active site

D. The competitive inhibition of enzymes

25. The Michaelis constant (Km) is defined as:

A. The maximum velocity of the reaction

B. The substrate concentration at which the reaction rate is half of Vmax

C. The enzyme concentration at which the reaction rate is Vmax

D. The equilibrium constant of the enzyme-substrate complex

26. Hydrolases are enzymes that catalyze:

A. Oxidation-reduction reactions

B. Transfer of functional groups

C. Hydrolysis reactions

D. Isomerization reactions

27. Enzymes are utilized in medical diagnostics for:

A. Replacing damaged organs

B. Measuring levels of specific substances in body fluids

C. Gene therapy

D. Radiation therapy

28. The optimal pH for enzyme activity is best described as:

A. Always neutral (pH 7)

B. The pH at which the enzyme exhibits maximum activity

C. The pH that denatures the enzyme

D. Irrelevant to enzyme activity

29. Enzymes lower the activation energy of a reaction by:

A. Increasing the temperature of the reaction

B. Providing an alternative reaction pathway with a lower energy barrier

C. Increasing the concentration of reactants

D. Changing the equilibrium constant of the reaction

30. Proteases are a class of enzymes commonly used in laundry detergents to:

A. Whiten fabrics

B. Break down protein-based stains

C. Add fragrance to clothes

D. Prevent color fading