What type of protein acts as a biological catalyst to speed up chemical reactions?

• A. Hormone
• B. Antibody
• C. Enzyme
• D. Transport protein

Answer: (C)

Enzymes are specialized proteins that function as biological catalysts, which means they significantly increase the rate of chemical reactions without being consumed in the process. They do this by lowering the activation energy required for reactions to occur, allowing biochemical processes to proceed at rates necessary for life. Enzymes are highly specific, often acting on a particular substrate to facilitate a specific reaction, and they play vital roles in various metabolic pathways, including digestion, energy production, and DNA replication.

The other types of proteins mentioned serve different functions. Hormones are signaling molecules that help regulate physiological processes in the body. Antibodies are proteins produced by the immune system to identify and neutralize foreign objects like bacteria and viruses. Transport proteins are involved in the movement of substances across cell membranes or within the body, but they do not catalyze chemical reactions. Thus, the role of enzymes as biological catalysts distinctly qualifies them as the correct answer in this context.