OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What does homeostasis primarily refer to?

1. The aggregation of cells

2. The maintenance of a stable internal environment

3. The processes of cell division

4. The growth of organisms

The correct answer is: The maintenance of a stable internal environment

Homeostasis primarily refers to the maintenance of a stable internal environment in an organism, despite changes in external conditions. This concept is crucial for the survival of living organisms, as it allows them to regulate factors such as temperature, pH, and electrolyte balance, which are vital for cellular functions and overall health. For example, humans maintain a core body temperature around 37 degrees Celsius, and if this temperature deviates, mechanisms such as sweating or shivering are triggered to restore balance. This process involves various feedback systems, primarily negative feedback loops, which detect changes and initiate responses to counteract those changes, ensuring that internal conditions remain within optimal ranges. While the aggregation of cells, processes of cell division, and growth of organisms are all important biological concepts, they do not specifically capture the essence of homeostasis, which is fundamentally about stability and regulation within an organism rather than cellular organization or growth dynamics.