What role do enzymes play in the body?

Enzymes play a critical role in the body primarily by acting as catalysts. This means they facilitate and speed up biochemical reactions without being consumed in the process. Enzymes lower the activation energy required for reactions to occur, which is vital for many bodily functions, including digestion and metabolism. Without enzymes, many of the biochemical processes that sustain life would occur too slowly to be effective.

While other options mention essential functions, they do not accurately describe the primary role of enzymes. For instance, providing energy is primarily the role of macronutrients like carbohydrates, fats, and proteins rather than enzymes themselves. Similarly, storing nutrients pertains to molecules like glycogen and fats, while transporting oxygen is primarily the function of hemoglobin found in red blood cells. Therefore, the defining characteristic of enzymes is their catalytic ability, which is fundamental to all living organisms.