Advanced Placement (AP) Biology Practice Exam

What role does epinephrine play in the body?

1. Mediates long-term stress responses

2. Regulates blood sugar levels

3. Facilitates "fight-or-flight" responses

4. Transports nutrients across cell membranes

The correct answer is: Facilitates "fight-or-flight" responses

Epinephrine, also known as adrenaline, plays a crucial role in the "fight-or-flight" response, which is the body’s acute reaction to stress or danger. When an individual encounters a stressful situation, the adrenal glands release epinephrine into the bloodstream. This hormone prepares the body to react quickly by increasing heart rate, enhancing blood flow to muscles, and releasing energy stores. These physiological changes enable a rapid response to perceived threats, allowing an organism to either confront or flee from danger. The other options involve functions that do not primarily relate to epinephrine's role. For example, while blood sugar regulation is influenced by hormones like insulin and glucagon, it is not the main function of epinephrine. Although epinephrine does have some impact on blood sugar by promoting glucose release during stress, this is not its primary role. Similarly, epinephrine does not mediate long-term stress responses; that function is more associated with cortisol. Lastly, the transportation of nutrients across cell membranes is largely handled by various transport proteins and membranes but not directly by epinephrine. Hence, the correct understanding of epinephrine's pivotal role aligns with its function in facilitating the "fight-or-flight" response.