What is homeostasis?

• A. Process by which organisms mutate rapidly to adapt
• B. Process by which organisms maintain a relatively stable internal environment
• C. The spread of disease within a population
• D. The breakdown of bodily regulation under stress

Answer: (B)

Homeostasis is the ability of living systems to keep internal conditions stable even when the outside world changes. It means maintaining key factors like body temperature, fluid balance, pH, and blood glucose at relatively constant levels so cells can function properly. The body senses when things drift away from their normal range, uses a control center (often in the brain) to compare what is happening to the desired value, and then activates effectors (muscles or glands) to bring the variable back toward its set point. This is usually accomplished through negative feedback: the response counteracts the initial change, restoring balance. For example, if you get cold, your body conserves heat by narrowing blood vessels and generating warmth through shivering; if you’re hot, you sweat and vasodilate to cool down. Glucose levels are kept steady by insulin and glucagon working as needed after meals or during fasting.

The other ideas describe different concepts: rapid mutation relates to evolution, disease spread to epidemiology, and breakdown of regulation under stress describes a failure rather than the normal process of maintaining balance.