IGCSE Biology – Coordination and Response Practice Test 2026 - Free Biology Practice Questions and Study Guide

Insulin lowers blood glucose levels. After you eat, the pancreas releases insulin, which tells liver, muscle, and fat cells to take up glucose from the bloodstream. In muscle and fat, insulin promotes the movement of GLUT4 transporters to the cell surface, increasing glucose uptake. In the liver, insulin stimulates glycogen synthesis (glycogenesis) and glycolysis and reduces glucose production, so circulating glucose falls toward normal. Glucagon, in contrast, raises blood glucose by triggering glycogen breakdown and gluconeogenesis in the liver during fasting. Estrogen and testosterone aren’t primary regulators of blood glucose in the same way insulin is.