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

Which hormone is responsible for regulating metabolic processes in the body?

1. Insulin

2. Thyroxine

3. Adrenaline

4. Testosterone

The correct answer is: Thyroxine

Thyroxine is a key hormone produced by the thyroid gland that plays a significant role in regulating metabolic processes in the body. It influences how the body uses energy, controls the metabolic rate, and regulates the development and function of many organs. By increasing the rate at which cells convert oxygen and calories into energy, thyroxine directly impacts metabolism, affecting everything from weight management to temperature regulation. While insulin is crucial for glucose metabolism, particularly in controlling blood sugar levels, it primarily aids in the storage of energy rather than broadly regulating metabolic processes. Adrenaline, produced by the adrenal glands, is involved in the body's 'fight or flight' response and temporarily increases metabolic rate during stressful situations but does not serve as a regulator of overall metabolism. Testosterone is responsible for male sexual characteristics and muscle mass development but has a more limited role in metabolic regulation compared to thyroxine. Thus, thyroxine is the hormone that best illustrates the regulation of metabolic processes throughout the body.