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IGCSEBiology

Homeostasis

Exam-ready definition

The maintenance of a constant internal environment in the body. For example, keeping core temperature and blood glucose concentration within narrow limits.

How this is marked

The paying phrase is 'constant internal environment'. Six-mark questions on temperature control want the negative feedback chain: receptor detects change → coordinator → effector responds → condition returns to set point.

In an exam answer

Defining it in a temperature question: 'Homeostasis is maintaining a constant internal environment, such as keeping body temperature at about 37 °C despite changes outside.'

Full topic guide: Coordination & response