Enzymes MCQs (Quiz 1)By guishaqasif / April 27, 2026 This quiz is automatically created to help you get started. It will be created only once. 1. Which statement best describes an enzyme? An inorganic catalyst that increases activation energy A biological catalyst, usually protein, that lowers activation energy A carbohydrate that is consumed during reactions A lipid molecule that binds substrates non-specifically 2. An enzyme that acts only on a single substrate (e.g., urease on urea) shows __________ Stereospecificity Bond specificity Absolute specificity Group specificity 3. Which option correctly classifies the molecule according to its role as a cofactor? Mg²⁺ – organic coenzyme NAD⁺ – inorganic metal ion Zn²⁺ – inorganic metal ion cofactor FAD – protein (apoenzyme component) 4. The catalytically active enzyme formed by apoenzyme plus cofactor is _____________ Holoenzyme Substrate complex Prosthetic group Coenzyme 5. The region of an enzyme responsible for substrate binding and catalysis is called the _________ Active site Binding groove unrelated to catalysis Allosteric site Regulatory domain 6. An enzyme that acts only on the L-form of an amino acid demonstrates ______________ Absolute specificity Group specificity Linkage specificity Stereospecificity 7. The inactive protein component of an enzyme lacking its cofactor is called ____________ Holoenzyme Apoenzyme Zymogen Prosthetic group 8. The enzyme–substrate (ES) complex is ________ A transient intermediate essential for catalysis Formed only in irreversible reactions Irrelevant to enzyme kinetics A permanent structure that inactivates the enzyme 9. An enzyme that catalyzes reactions of structurally related substrates exhibits ____________ Group specificity Stereospecificity Absolute specificity No specificity 10. Ribozymes are best described as _____________ DNA molecules with catalytic activity Protein enzymes with RNA cofactors Lipid-based catalysts RNA molecules with catalytic activity Loading … Question 1 of 10
