𝓕𝓞𝓡 𝘚𝘵𝘶𝘥𝘦𝘯𝘵𝘴: post #778 — TG.ME

Biology UEE format Questions from Enzymes 1. What is the primary role of enzymes in biological systems? A. Decrease activation energy B. Increase activation energy C. Provide energy for reactions D. Become part of the product Explanation: Enzymes act as biological catalysts that speed up reactions by lowering activation energy. They are not consumed or permanently changed in the reaction. 2. Which of the following correctly defines the active site of an enzyme? A. The region where products are stored B. The region where inhibitors bind only C. The specific region where substrate binds and reaction occurs D. The part that determines enzyme solubility Explanation: The active site is a specific region of the enzyme with a unique shape where the substrate binds and the chemical reaction takes place. 3. Which enzyme is responsible for breaking down fats into fatty acids? A. Amylase B. Protease C. Lactase D. Lipase Explanation: Lipase specifically catalyzes the breakdown of lipids (fats) into fatty acids and glycerol. 4. Which property of enzymes explains their inability to pass through semipermeable membranes? A. Solubility B. Colloidal nature C. Specificity D. Reversibility Explanation: Due to their large molecular size, enzymes behave as colloids and cannot pass through semipermeable membranes. 5. Which of the following correctly matches enzyme structure levels with their features? A. Primary – hydrogen bonding between chains B. Secondary – peptide bond sequence C. Tertiary – three-dimensional folding due to side chain interactions D. Quaternary – single polypeptide chain Explanation: Tertiary structure represents the 3D folding of a protein due to interactions between side chains (R groups). 6. Which statement best describes competitive inhibition? A. Inhibitor binds only to enzyme-substrate complex B. Inhibitor binds permanently to enzyme C. Inhibitor increases enzyme activity D. Inhibitor competes with substrate for active site Explanation: Competitive inhibitors resemble substrates and compete for the active site, preventing substrate binding. 7. Which class of enzymes catalyzes the conversion of a molecule into its isomer? A. Ligases B. Hydrolases C. Isomerases D. Transferases Explanation: Isomerases rearrange atoms within a molecule, forming different isomers of the same compound. 8. Which of the following best explains enzyme denaturation? A. Loss of three-dimensional structure B. Loss of primary structure C. Increase in enzyme concentration D. Increase in substrate concentration Explanation: Denaturation involves loss of the tertiary (3D) structure, which destroys the active site and enzyme function. 9. Which of the following statements about enzymes is CORRECT? A. Enzymes are consumed during reactions B. Enzymes increase activation energy C. Enzymes can catalyze reversible reactions D. Enzymes work equally at all pH values Explanation: Enzymes are not consumed and lower activation energy. However, many enzymes can catalyze both forward and reverse reactions, depending on conditions. 10. Which combination correctly forms an active enzyme or holoenzyme? A. Apoenzyme + substrate B. Apoenzyme + cofactor C. Cofactor + substrate D. Enzyme + inhibitor Explanation: An apoenzyme is inactive alone. When it binds with a cofactor, it becomes an active holoenzyme. ✅ Final Answers 1. A, 2. C, 3. D, 4. B, 5. C, 6. D, 7. C, 8. A, 9. C, 10. B