Which of these is a nonsteroid hormone?

• A. Insulin
• B. Aldosterone
• C. Testosterone
• D. Cortisol

Answer: (A)

Verified step by step guidance

1. Understand the difference between steroid and nonsteroid hormones. Steroid hormones are derived from cholesterol and are lipid-soluble, allowing them to pass through cell membranes. Nonsteroid hormones, on the other hand, are not lipid-soluble and cannot pass through cell membranes directly.
2. Identify the chemical nature of each hormone listed. Steroid hormones include aldosterone, testosterone, and cortisol, which are all derived from cholesterol.
3. Recognize that insulin is a peptide hormone, which is a type of nonsteroid hormone. Peptide hormones are composed of amino acids and are water-soluble, meaning they cannot pass through the lipid bilayer of cell membranes.
4. Recall that nonsteroid hormones, like insulin, typically bind to receptors on the surface of target cells, triggering a cascade of intracellular events through second messengers.
5. Conclude that among the options provided, insulin is the nonsteroid hormone, as it is a peptide hormone, unlike the others which are steroid hormones.