Apentix/AP Biology/Unit 1: Chemistry of Life/Question
AP Biologyeasymcq1 pt

A small amount of catalase destroys millions of hydrogen peroxide molecules and is still intact afterward. Why can enzymes act repeatedly without being used up?

A.They lower the activation barrier through a cycle that regenerates them after every product release
B.They are consumed slowly, so a little enzyme lasts through many reactions
C.They supply activation energy from their own reserve of stored chemical bonds
D.They replicate quickly enough to replace whatever portion the reaction destroys

Explanation

Core Concept

An enzyme binds substrate, converts it to product, and releases the product, which restores the active site to its starting state. Because nothing permanent happens to the enzyme's structure during the cycle, one enzyme molecule repeats the process enormous numbers of times. Catalysis changes only the route and speed of the reaction, never the catalyst itself, which is what distinguishes enzymes from stoichiometric reactants that are genuinely consumed.

Correct Answer

AThey lower the activation barrier through a cycle that regenerates them after every product release

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