What is the process called by which organisms maintain a stable internal environment?

The process by which organisms maintain a stable internal environment is referred to as homeostasis. This term encompasses the various mechanisms that living organisms use to regulate their internal conditions, such as temperature, pH, hydration, and ion concentrations, despite changes in the external environment.

Homeostasis is crucial for maintaining optimal conditions for cellular processes, ensuring that biological functions can occur efficiently. For instance, in humans, mechanisms like sweating to cool down when overheated, or shivering to generate heat when cold, illustrate homeostasis in action.

The other options relate to different biological concepts. Metabolism refers to the chemical processes that occur within a living organism to maintain life, including the conversion of food to energy and the construction of cellular components. Regulation is more general and can refer to various processes of control in biological systems, but it does not specifically denote the internal stability aspect. Adaptation refers to the evolutionary changes that occur in populations over generations, allowing organisms to better survive in their environments but is not a process of internal stability management. Understanding homeostasis is foundational in biology, as it highlights how organisms interact with their environments while maintaining the conditions necessary for life.