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

When blood glucose levels are too high, what hormone helps to reduce those levels?

1. Adrenaline

2. Cortisol

3. Insulin

4. Glucagon

The correct answer is: Insulin

Insulin is the hormone responsible for reducing blood glucose levels when they are too high. It is produced by the pancreas and plays a crucial role in glucose metabolism. When blood glucose levels rise, such as after eating, the pancreas secretes insulin into the bloodstream. This hormone facilitates the uptake of glucose by cells, particularly in the liver, muscle, and fat tissues, allowing them to utilize glucose for energy or store it as glycogen for later use. Additionally, insulin promotes the conversion of excess glucose into fat. In contrast, other hormones mentioned work differently in managing blood glucose levels. Adrenaline and cortisol are hormones that typically increase blood sugar levels, particularly during stress or fasting, while glucagon stimulates the release of glucose into the bloodstream by promoting the conversion of glycogen to glucose in the liver. Thus, insulin is essential for lowering high blood glucose levels effectively.