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

What physiological response occurs primarily to maintain body temperature in cold environments?

1. Increased perspiration

2. Vasodilation of blood vessels

3. Shivering

4. Increased heart rate

The correct answer is: Shivering

When the body is exposed to cold environments, a key physiological response is shivering. Shivering is an involuntary action that involves rapid muscle contractions, which produce heat as a byproduct of the increased metabolic activity in the muscles. This heat generation helps to raise the body's core temperature, counteracting the effects of cold exposure. In cold conditions, the body prioritizes maintaining its temperature to protect essential physiological functions. Shivering can significantly increase heat production and is a rapid response mechanism to combat hypothermia. This response is controlled by the hypothalamus, which acts as the body's thermostat and triggers shivering when it detects a drop in body temperature. Other responses, such as increased perspiration or vasodilation of blood vessels, are not appropriate in cold temperatures since they would lead to greater heat loss from the body. Increased heart rate can occur in various situations, but it does not directly target the maintenance of body temperature in a cold environment as effectively as shivering does. Therefore, shivering is the primary physiological mechanism to maintain body temperature in cold conditions.