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

Which of the following helps maintain homeostasis?

1. Increased blood flow to extremities

2. Response to internal and external changes

3. Restricting metabolic processes

4. Enhancing hormone levels

The correct answer is: Response to internal and external changes

The option that helps maintain homeostasis is the response to internal and external changes. Homeostasis refers to the body’s ability to maintain a stable internal environment despite fluctuations in external conditions. This involves various physiological processes and feedback mechanisms that detect changes in the internal state of the body, such as temperature, pH, and nutrient levels, and initiate appropriate responses to restore balance. For example, if the temperature increases, the body responds by activating sweat glands to cool down through evaporation. Conversely, if an internal parameter deviates from its optimal range, the body has systems in place to correct it, such as increasing respiration rate to improve oxygen levels or regulating fluid balance through thirst mechanisms. This responsive adaptability is crucial for the overall functioning and health of living organisms.