Why are enzymes essential to organisms in the context of catalysis?

• A. Enzymes increase the $E$_a required for reactions.
• B. Enzymes decrease the overall $\mathrm{Delta}G$ of reactions.
• C. Enzymes provide an alternative reaction pathway with a lower $E$_a.
• D. Enzymes are consumed in the reactions they catalyze.

Answer: (C)

Verified step by step guidance

1. Understand the role of enzymes: Enzymes are biological catalysts that speed up chemical reactions in living organisms without being consumed in the process.
2. Recognize the concept of activation energy: Activation energy is the minimum energy required for a chemical reaction to occur. Enzymes work by lowering this energy barrier.
3. Identify the correct statement: Enzymes provide an alternative reaction pathway with a lower activation energy, which allows reactions to proceed more quickly and efficiently.
4. Clarify misconceptions: Enzymes do not increase the activation energy or decrease the overall energy change of reactions. They also are not consumed in the reactions they catalyze.
5. Conclude with the importance of enzymes: By lowering the activation energy, enzymes enable essential biochemical reactions to occur under the mild conditions of temperature and pressure found in living organisms.