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

What role does glucagon play in blood sugar regulation?

1. It lowers blood glucose levels

2. It raises blood glucose levels when they're low

3. It prevents diabetes

4. It converts glucose to fat

The correct answer is: It raises blood glucose levels when they're low

Glucagon plays a crucial role in blood sugar regulation, particularly in raising blood glucose levels when they are low. It is a hormone produced by the alpha cells in the pancreas. When blood sugar levels drop, such as during fasting or prolonged physical activity, glucagon is released into the bloodstream. The primary action of glucagon is to signal the liver to break down glycogen into glucose, a process called glycogenolysis. This glucose is then released into the bloodstream, effectively increasing blood glucose concentrations. Additionally, glucagon also promotes gluconeogenesis, the production of glucose from non-carbohydrate sources in the liver. This action is essential for maintaining normal blood sugar levels, especially during times when the body requires energy but food intake is not immediate. Therefore, the correct answer underscores glucagon's vital function in ensuring that the body's cells have enough fuel to operate efficiently.