Receptors for nonsteroid hormones are located in _____.

• A. the plasma membrane
• B. the cytoplasm
• C. the nucleus
• D. the mitochondria

Answer: (A)

Verified step by step guidance

1. Understand the difference between steroid and nonsteroid hormones. Steroid hormones are lipid-soluble and can pass through the plasma membrane, while nonsteroid hormones are not lipid-soluble and cannot pass through the plasma membrane.
2. Recall that nonsteroid hormones, such as peptide or protein hormones, require a receptor on the cell surface because they cannot diffuse through the lipid bilayer of the plasma membrane.
3. Identify the location of receptors for nonsteroid hormones. Since these hormones cannot enter the cell, their receptors must be located on the plasma membrane, where they can bind to the hormone outside the cell.
4. Understand the mechanism of action: When a nonsteroid hormone binds to its receptor on the plasma membrane, it triggers a signal transduction pathway inside the cell, often involving secondary messengers like cyclic AMP (cAMP).
5. Eliminate incorrect options: The cytoplasm, nucleus, and mitochondria are incorrect because nonsteroid hormones cannot directly enter the cell to interact with receptors in these locations.