Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

Which term describes the maintenance of stable internal conditions in an organism?

1. Osmoregulation

2. Allostasis

3. Homeostasis

4. Metabolism

The correct answer is: Homeostasis

The term that describes the maintenance of stable internal conditions in an organism is homeostasis. Homeostasis refers to the processes that living organisms use to maintain a constant internal environment despite changing external conditions. It encompasses various physiological processes, including the regulation of temperature, pH, hydration, and electrolyte balance. For example, when the body gets too hot, mechanisms like sweating and increased blood flow to the skin help to cool it down, thus maintaining the necessary conditions for optimal cell function. Similarly, if blood sugar levels rise after eating, the body releases insulin to lower these levels back to a stable range. Other terms listed may relate to specific aspects of physiological balance but do not encompass the broader concept of maintaining internal stability. Osmoregulation specifically refers to the control of water and solute concentrations, and while important, it is a subset of homeostasis. Allostasis involves the process of achieving stability through change, adapting to stressors, but it is more about the dynamic aspect rather than the steady state. Metabolism refers to the total chemical processes occurring in a living organism, which includes both the breaking down and building up of substances, rather than specifically addressing the stability of internal conditions.