Enzymes MCQs (Quiz 6)By guishaqasif / April 28, 2026 1. Cardiac troponin remains elevated for an extended period after myocardial injury primarily due to _______ Low tissue specificity High rate of new synthesis after injury Rapid clearance from circulation Strong binding to contractile proteins with slow release during myofibril degradation 2. Transition state analog inhibitors are typically _______ Weak inhibitors with low binding affinity Products that accumulate during reactions Strong inhibitors due to tight binding to the active site Substrates that are converted into products 3. In a repressible operon, accumulation of the end product results in _______ Increased enzyme synthesis Inactivation of the repressor protein Activation of transcription of structural genes Formation of an active repressor–corepressor complex that binds the operator 4. For an enzyme following Michaelis–Menten kinetics, when [S] = Km, the fraction of enzyme in ES form is approximately _______ 100% 50% 75% 25% 5. Enzyme catalysis typically involves _______ No defined mechanism Multiple catalytic strategies acting simultaneously A random, non-specific mechanism A single catalytic mechanism operating in isolation 6. A Hill coefficient greater than 1 indicates _______ Competitive inhibition at the active site Positive cooperativity among binding sites Negative cooperativity among binding sites No cooperativity in substrate binding 7. Ligases (synthetases) catalyze the formation of covalent bonds and typically require _______ Water for hydrolysis reactions NADH as a reducing agent FAD as an electron carrier ATP to provide energy for bond formation 8. In a Lineweaver–Burk (double reciprocal) plot, a set of parallel lines is characteristic of _______ Non-competitive inhibition (same Km, different Vmax) Competitive inhibition (same Vmax, different Km) Mixed inhibition (both Km and Vmax change unequally) Uncompetitive inhibition (both Km and Vmax decrease proportionally) 9. A ping–pong (double-displacement) enzyme mechanism involves _______ No substrate binding during the reaction Simultaneous binding of both substrates to the enzyme Sequential substrate binding with formation of a transient enzyme intermediate An irreversible reaction with no intermediate formation 10. The Michaelis–Menten (curve) plot of reaction velocity versus substrate concentration is typically _______ Exponential Hyperbolic Sigmoidal Linear Loading … Question 1 of 10
