Optometry Admission Test (OAT) Practice

What is defined as the ability to maintain a stable internal environment?

1. Metabolism

2. Homeostasis

3. Equilibrium

4. Adaptation

The correct answer is: Homeostasis

The ability to maintain a stable internal environment is referred to as homeostasis. Homeostasis is a vital concept in biology that describes how organisms regulate their internal conditions, such as temperature, pH, hydration, and electrolyte balance, despite external changes. This regulation is crucial for maintaining optimal functioning of biological processes and overall health. For example, when the external temperature rises, mechanisms such as sweat production in humans help to cool the body down, thus maintaining a stable internal temperature. This dynamic equilibrium enables cells and organs to function efficiently within their optimal range. In contrast, while metabolism involves all biochemical reactions occurring within an organism, including those for energy production and utilization, it does not specifically address the maintenance of internal stability. Equilibrium generally refers to a state where opposing forces or influences are balanced, but it lacks the dynamic aspect of active regulation seen in homeostasis. Adaptation refers to long-term changes in response to environmental challenges that might help an organism survive but does not pertain directly to the moment-to-moment regulation of internal conditions. Thus, homeostasis is clearly the most accurate definition pertaining to the question asked.