Which of the following best describes the primary difference between an enzyme and a hormone?

• A. Enzymes are only found in animals, whereas hormones are found in both plants and animals.
• B. Enzymes are composed of nucleic acids, while hormones are always proteins.
• C. Enzymes are secreted into the bloodstream, while hormones function only within cells.
• D. Enzymes act as biological catalysts to speed up chemical reactions, while hormones serve as chemical messengers that regulate physiological processes.

Answer: (D)

Verified step by step guidance

1. Step 1: Begin by understanding the definitions of enzymes and hormones. Enzymes are biological molecules, typically proteins, that act as catalysts to speed up chemical reactions without being consumed in the process. Hormones, on the other hand, are chemical messengers that regulate physiological processes and are secreted by glands in the body.
2. Step 2: Compare the functions of enzymes and hormones. Enzymes facilitate biochemical reactions by lowering the activation energy required for the reaction to occur. Hormones, however, are involved in signaling and communication between cells or organs to maintain homeostasis.
3. Step 3: Analyze the structural differences. Enzymes are primarily proteins, although some RNA molecules (ribozymes) can also act as enzymes. Hormones can be proteins, peptides, steroids, or other types of molecules, depending on their specific function and origin.
4. Step 4: Examine the location and mechanism of action. Enzymes typically function within cells or in extracellular spaces to catalyze reactions. Hormones are secreted into the bloodstream (in animals) or transported within plants to reach target cells or tissues where they exert their effects.
5. Step 5: Conclude by summarizing the primary difference: Enzymes act as biological catalysts to speed up chemical reactions, while hormones serve as chemical messengers that regulate physiological processes.