A Level Biology Practice Exam 2025 – All-in-One Study Guide to Excel in Your A Levels!

Insulin's primary role in the human body is to regulate blood glucose concentration. This hormone is produced by the pancreas and plays a crucial role in maintaining homeostasis by controlling the levels of glucose in the bloodstream. When blood sugar levels rise after eating, insulin is released to facilitate the uptake of glucose by cells, particularly in muscle and fat tissues. This process lowers blood glucose levels, preventing hyperglycemia (excess blood sugar levels).

While the function of transporting glucose into cells is a component of insulin's action, it is part of the broader regulatory role that insulin plays in blood glucose concentration. The functions related to digestion of proteins and the stimulation of red blood cell production do not directly pertain to insulin's main regulatory mechanism regarding glucose. Thus, focusing on the regulation of blood glucose concentration accurately captures the essence of insulin's vital role in human physiology.