Enzymes as Catalysts

Steps:

• Recall that enzymes are biological catalysts that speed up chemical reactions without being consumed.
• Evaluate each option against the core function of enzymes: lowering activation energy to increase reaction rates.
• Check if the statement applies universally to all enzymes in all contexts.
• Identify the option that holds true based on the definition of catalysis.

Why B is correct:

• Enzymes are catalysts, which by definition lower the activation energy barrier, thereby increasing the rate of biochemical reactions without altering the equilibrium.

Why the others are wrong:

• A: Enzymes do not change end products; they only facilitate the existing reaction pathway.
• C: Enzymes catalyse reactions both inside and outside cells, like in saliva or stomach.
• D: While most function at body temperature, some enzymes from extremophiles work at higher or lower temperatures.

Final answer: B