What term describes maintaining relatively constant internal conditions despite changes in the external environment?

• A. Metabolism
• B. Homeostasis
• C. Osmosis
• D. Digestion

Answer: (B)

Maintaining relatively constant internal conditions despite changes in the external environment is homeostasis. The body uses sensors to monitor variables like temperature, pH, and ion levels, and it activates responses that push those values back toward a normal range when they stray. This typically works through negative feedback: a deviation triggers actions that oppose the change, stabilizing the system. For example, if the outside temperature drops, the body may conserve heat and generate warmth to keep core temperature steady; if blood glucose rises after a meal, insulin helps tissues take up glucose to return levels to normal. This idea is distinct from metabolism, which refers to all the chemical reactions in the body; osmosis, the diffusion of water across membranes; and digestion, the breakdown of food. Understanding homeostasis helps explain how organisms maintain critical conditions within narrow limits despite varying environments.