A Level Biology Practice Exam

What effect does an enzyme inhibitor have on a metabolic pathway?

1. It accelerates the reactions

2. It intensifies substrate binding

3. It slows down the metabolic reactions

4. It stops all enzyme activity

The correct answer is: It slows down the metabolic reactions

An enzyme inhibitor plays a crucial role in regulating metabolic pathways, often resulting in a slowdown of the reactions in that pathway. Enzyme inhibitors can bind to enzymes and either decrease their activity or prevent them from catalyzing reactions effectively. When an inhibitor is present, it may compete with substrates for binding to the active site or bind to another site on the enzyme, inducing a conformational change that reduces its catalytic efficiency. As a result, the overall rate of the metabolic reactions is reduced, leading to a decrease in the production of the end product. This regulatory mechanism is vital for maintaining homeostasis within cells, allowing them to respond to changes in their environment by modulating metabolic rates as needed. While there are different types of enzyme inhibitors and their effects can vary, the fundamental outcome of introducing an inhibitor is that it slows down enzyme-mediated reactions in the metabolic pathway, which is why the chosen answer is accurate.