Đề 12 – Bài tập, đề thi trắc nghiệm online Hóa sinh enzyme

A A. The Michaelis-Menten constant (Km). B B. The substrate concentration. C C. The enzyme concentration. D D. The activation energy of the reaction.

A A. Catalytic site. B B. Substrate-binding site. C C. Allosteric site. D D. Competitive site.

A A. Water. B B. ATP or another nucleoside triphosphate. C C. An oxidizing agent. D D. A reducing agent.

A A. To provide structural support to the enzyme molecule. B B. To bind cofactors necessary for enzyme activity. C C. To provide a specific environment for substrate binding and catalysis. D D. To regulate the overall rate of enzyme production in the cell.

A A. Carbon-carbon bonds. B B. Peptide bonds. C C. Hydrogen bonds. D D. Ionic bonds.

A A. Feedback inhibition by the end product. B B. Allosteric activation by a substrate. C C. Phosphorylation of an enzyme by a kinase. D D. Competitive inhibition by a structural analog of the substrate.

A A. Their activity increases indefinitely. B B. They become more stable and efficient. C C. They undergo denaturation and lose activity. D D. Their substrate specificity increases.

A A. It always decreases enzyme activity. B B. It initially increases enzyme activity but then decreases it beyond an optimal temperature. C C. It has no significant effect on enzyme activity. D D. It only increases enzyme activity indefinitely.

A A. The substrate of the enzyme. B B. The product of the metabolic pathway. C C. ATP. D D. Water.

A A. To increase the overall reaction rate in a cell. B B. To allow for tissue-specific or developmental stage-specific regulation of enzyme activity. C C. To prevent enzyme denaturation at high temperatures. D D. To reduce the specificity of enzymes for their substrates.

A A. An inactive precursor of an enzyme. B B. A type of enzyme that catalyzes reversible reactions. C C. An enzyme that requires very high substrate concentrations to function. D D. A non-protein enzyme.

A A. pH only affects the substrate concentration, not the enzyme itself. B B. pH alters the ionic state of amino acid residues in the enzyme, affecting its structure and active site. C C. pH changes the temperature of the reaction environment. D D. pH directly changes the activation energy of the reaction.

A A. Allosteric regulation. B B. Covalent modification. C C. Transcriptional regulation of enzyme synthesis. D D. Increasing the atmospheric pressure.

A A. The Lock-and-Key model only. B B. The Induced-Fit model only. C C. Both the Lock-and-Key and Induced-Fit models. D D. Neither the Lock-and-Key nor Induced-Fit models are relevant to enzyme specificity.

A A. The final product of the reaction. B B. The enzyme-substrate complex. C C. A high-energy, unstable intermediate in the reaction pathway. D D. The initial substrate before the reaction begins.

A A. To measure the reaction rate of an enzyme. B B. To classify and name enzymes based on the type of reaction they catalyze. C C. To determine the optimal pH for enzyme activity. D D. To calculate the molecular weight of an enzyme.

A A. Metal ions are always competitive inhibitors. B B. Metal ions can act as cofactors, participating in substrate binding, redox reactions, or stabilizing enzyme structure. C C. Metal ions only play a structural role and do not directly participate in catalysis. D D. Metal ions always decrease enzyme activity.

A A. Coenzymes are proteins, while prosthetic groups are not. B B. Coenzymes are tightly bound to the enzyme, while prosthetic groups are loosely bound. C C. Coenzymes are loosely bound and dissociable from the enzyme, often carrying chemical groups from one reaction to another, while prosthetic groups are tightly bound and permanently associated with the enzyme. D D. Prosthetic groups are organic molecules, while coenzymes are inorganic ions.

A A. Water molecules. B B. Phosphate groups. C C. Carbon dioxide molecules. D D. Nitrogen gas.

A A. It always decreases the reaction rate. B B. It initially increases the reaction rate, but the rate eventually plateaus at Vmax. C C. It has no effect on the reaction rate. D D. It increases the reaction rate indefinitely.

A A. They always require ATP. B B. They often form or remove double bonds. C C. They only operate in anabolic pathways. D D. They always involve water as a reactant.

A A. Hydrolases. B B. Isomerases. C C. Oxidoreductases. D D. Transferases.

A A. It decreases Vmax and increases Km. B B. It increases Vmax and decreases Km. C C. It increases Km but does not affect Vmax. D D. It decreases Vmax but does not affect Km.

A A. Their ability to function at extremely high temperatures. B B. Their high specificity and catalytic efficiency. C C. Their ability to be easily synthesized chemically. D D. Their lack of sensitivity to pH changes.

A A. Enzymes do not regulate metabolic flux; it is solely determined by substrate availability. B B. Enzymes accelerate specific reactions, and their activity can be regulated to control pathway flux. C C. Enzymes only determine the direction of metabolic pathways, not the flux. D D. Enzymes are only involved in catabolic pathways, not anabolic ones.

A A. The maximum rate of reaction at saturating substrate concentrations. B B. The substrate concentration at which the reaction rate is half of Vmax. C C. The rate constant for the breakdown of the enzyme-substrate complex. D D. The equilibrium constant for substrate binding to the enzyme.

A A. Rearrangement of atoms within a molecule. B B. Joining of two molecules. C C. Breakdown of a large molecule into smaller ones. D D. Transfer of a functional group between molecules.

A A. Enzymes increase the temperature of the reaction environment. B B. Enzymes lower the activation energy of the reaction. C C. Enzymes increase the concentration of reactants. D D. Enzymes are consumed in the reaction and need to be replenished.

A A. To provide additional functional groups for catalysis. B B. To stabilize the enzyme's tertiary structure. C C. To participate directly in the catalytic reaction. D D. To determine the substrate specificity of the enzyme.

A A. They increase Km but do not affect Vmax. B B. They decrease Km but do not affect Vmax. C C. They decrease Vmax but do not affect Km. D D. They increase both Vmax and Km.