Which statement best describes the function of enzymes in living systems?

Which statement best describes the function of enzymes in living systems?

• A. They store energy
• B. They catalyze reactions by lowering activation energy
• C. They increase activation energy
• D. They are always consumed

Answer: (C)

Enzymes act as biological catalysts that speed up chemical reactions by offering an alternative pathway with a lower activation energy. They do this by binding the substrate at the active site to form an enzyme–substrate complex, which orients the reactants and stabilizes the transition state, reducing the energy barrier needed to convert substrates into products. Because of this lowered energy hurdle, the reaction proceeds faster under the influence of the enzyme. Enzymes do not store energy themselves; energy storage is handled by molecules like ATP. They are not consumed in the reaction and can catalyze many reaction cycles. They do not increase activation energy; their role is to lower it. Enzyme activity also depends on conditions such as temperature and pH, and can be modulated by cofactors and inhibitors.

Enzymes act as biological catalysts that speed up chemical reactions by offering an alternative pathway with a lower activation energy. They do this by binding the substrate at the active site to form an enzyme–substrate complex, which orients the reactants and stabilizes the transition state, reducing the energy barrier needed to convert substrates into products. Because of this lowered energy hurdle, the reaction proceeds faster under the influence of the enzyme. Enzymes do not store energy themselves; energy storage is handled by molecules like ATP. They are not consumed in the reaction and can catalyze many reaction cycles. They do not increase activation energy; their role is to lower it. Enzyme activity also depends on conditions such as temperature and pH, and can be modulated by cofactors and inhibitors.