AP Psychology Practice Test 2025 - Free AP Psychology Practice Questions and Study Guide

Biological rhythms refer to the periodic fluctuations in physiological processes that occur in living organisms. These rhythms can take various forms, such as circadian rhythms, which follow a roughly 24-hour cycle, influencing sleep-wake patterns, hormone release, and body temperature, among other functions. The definition encompasses a wide range of cycles, including daily (diurnal), monthly (lunar), and seasonal rhythms, reflecting the intricate relationship between biological processes and time.

The other options provided do not capture the full scope of biological rhythms. Involuntary muscle contractions refer to muscle actions that occur without conscious control and do not represent a periodic pattern. Rapid eye movement during sleep is a specific aspect of sleep stages rather than a broader category of cyclic physiological changes. Patterns of eating and drinking can be influenced by biological rhythms but do not themselves represent the concept of biological rhythms as a whole.