Which protein increases the rate of a chemical reaction without being consumed in the process?

The correct answer is a protein that increases the rate of a chemical reaction without being consumed in the process is known as an enzyme. Enzymes are biological catalysts that facilitate and speed up chemical reactions in living organisms by lowering the activation energy required for the reaction to occur. They achieve this by binding to substrates and converting them into products while remaining unchanged after the reaction.

Enzymes play a crucial role in various metabolic processes, making them essential for life. Their ability to be reused multiple times in reactions distinguishes them from other molecules that may participate in reactions but do not significantly alter the rate at which they occur. In contrast, while catalysts can refer to both biological and non-biological entities, the specific context of protein function points toward the role that enzymes play in biological systems.

Inhibitors and hormones have different functions; inhibitors decrease the rate of reactions or metabolic processes, while hormones are messengers that regulate physiological activities but do not act as catalysts for chemical reactions. Thus, the role and characteristics of enzymes clearly align with the definition given in the question.