A Level Biology Practice Exam

What is end-product inhibition?

1. A process that enhances enzyme activity

2. A reaction that occurs without enzymes

3. An inhibition of the enzyme by its own product

4. Formation of new substrates

The correct answer is: An inhibition of the enzyme by its own product

End-product inhibition is a regulatory mechanism in metabolic pathways where the final product of a biochemical reaction inhibits an enzyme involved in its production. This type of feedback inhibition is crucial for maintaining homeostasis within a cell, as it prevents the overproduction of substances that are no longer needed. When the concentration of the end product rises, it binds to the enzyme that catalyzes the reaction early in the pathway, effectively reducing the enzyme's activity. This allows the cell to conserve resources and maintain energy efficiency, ensuring that metabolic processes are tightly regulated according to the cell's needs. The other options do not accurately describe end-product inhibition. Enhancing enzyme activity suggests an increase in function rather than a regulatory decrease. A reaction occurring without enzymes implies a non-catalyzed process, which does not align with the concept of end-product inhibition. The formation of new substrates does not reflect the feedback control mechanism established by the end product. This makes the choice reflecting the inhibition of the enzyme by its own product the most accurate description of end-product inhibition.