Practice Questions

Many antibiotics selectively inhibit bacterial enzymes required for vital metabolic pathways. They do not work by activating enzymes or universally destroying DNA. Concept tested: Medical application of enzyme inhibitors.

Competitive inhibitors closely resemble the substrate, allowing them to occupy the enzyme's active site. Similarity to products or coenzymes is not responsible for competitive inhibition. Concept tested: Structure-function relationship.

Enzyme inhibitors regulate metabolic pathways, preventing excessive or unnecessary reactions and maintaining homeostasis. The other options have no physiological basis. Concept tested: Metabolic regulation.

A non-competitive inhibitor lowers the maximum reaction rate regardless of substrate concentration because it alters enzyme structure. Competitive inhibition can be overcome by excess substrate. Concept tested: Interpretation of enzyme kinetics.

Irreversible inhibitors permanently inactivate enzyme molecules. Cells regain activity only by producing new enzymes. Extra substrate cannot restore function. Concept tested: Consequences of irreversible inhibition.

Reversible inhibitors regulate metabolic pathways according to cellular needs. Permanent inactivation is characteristic of irreversible inhibitors rather than reversible regulation. Concept tested: Physiological regulation.

Increasing substrate concentration increases the likelihood of substrate binding instead of inhibitor binding, restoring enzyme activity. The remaining options are biologically incorrect. Concept tested: Reversibility of competitive inhibition.

Heavy metals such as lead commonly inhibit enzymes by binding strongly to functional groups, causing irreversible loss of activity. They neither serve as coenzymes nor enhance enzyme synthesis. Concept tested: Heavy metal inhibition.

Non-competitive inhibitors bind at an allosteric site and alter the enzyme's three-dimensional shape, reducing catalytic efficiency. They do not necessarily destroy the substrate or all proteins. Concept tested: Mechanism of non-competitive inhibition.

Competitive inhibitors resemble the substrate and compete for the enzyme's active site. Allosteric sites are involved in non-competitive inhibition, while coenzymes and products are not the primary binding sites for competitive inhibitors. Concept tested: Active site specificity.