Advanced Placement (AP) Biology Practice Exam

Which of the following options describes the action of a hormone?

1. It inhibits the action of local signals.

2. It is secreted from exocrine glands.

3. It stimulates specific cells or tissues into action.

4. It is destroyed immediately upon secretion.

The correct answer is: It stimulates specific cells or tissues into action.

The chosen answer accurately describes the action of a hormone because hormones are chemical messengers that are secreted into the bloodstream and travel to specific target cells or tissues, where they exert their effects. This action is often involved in regulating physiological processes, such as metabolism, growth, and mood. Hormones bind to specific receptors on the target cells, triggering a response that can influence various functions within those cells, creating specific biological effects. In contrast, other options do not correctly represent the primary function of hormones. Some hormones are not produced by exocrine glands; instead, they are typically secreted by endocrine glands, which release hormones directly into the bloodstream. Furthermore, hormones do not inhibit local signals; rather, they can work alongside local signaling molecules to coordinate responses throughout the body. Lastly, hormones are not destroyed immediately after secretion; instead, they remain in circulation for a defined period to interact with target cells before being broken down or excreted. This stability allows hormones to carry out their regulatory functions effectively.