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

What role does insulin play in the body?

1. It converts glycogen back to glucose

2. It tells the body to convert glucose into glycogen

3. It regulates salt balance in the blood

4. It aids in digestion of carbohydrates

The correct answer is: It tells the body to convert glucose into glycogen

Insulin plays a crucial role in regulating blood sugar levels within the body. Its primary function is to signal cells, particularly liver, muscle, and fat cells, to uptake glucose from the bloodstream. When you consume carbohydrates, they are broken down into glucose, which enters the bloodstream and raises blood sugar levels. Insulin is then released by the pancreas in response to this increase in glucose. The primary action of insulin is to instruct the body to convert excess glucose into glycogen, a storage form of glucose that is primarily stored in the liver and muscles. This process helps to lower blood sugar levels back to a normal range and ensures that energy is stored for future use. The effectiveness of insulin in promoting the conversion of glucose to glycogen is critical for maintaining metabolic balance and energy homeostasis. In contrast, the other options describe processes unrelated to insulin's main functions. While converting glycogen back to glucose is a role of another hormone called glucagon, regulating salt balance involves hormones like aldosterone, and aiding in digestion of carbohydrates is primarily the job of digestive enzymes rather than insulin. Thus, the correct answer reflects the direct impact of insulin on glucose metabolism.