OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam 2025 - Free GCSE Biology Practice Questions and Study Guide

When blood glucose levels increase due to adrenaline, the liver releases more glucose into the blood. Adrenaline, also known as epinephrine, is a hormone produced by the adrenal glands during stressful situations. It prepares the body for a "fight or flight" response by ensuring that there is a quick supply of energy available.

In response to adrenaline, the liver activates glycogenolysis, the process of breaking down glycogen (a stored form of glucose) into glucose. This released glucose then enters the bloodstream, increasing blood glucose levels. This quick surge in energy is vital during emergencies, enabling the body to respond effectively by providing immediate energy for muscles and other tissues.

This physiological process showcases how the body maintains homeostasis and responds to stressors by mobilizing energy reserves. In contrast, the other options pertain to different functions and responses that do not apply when adrenaline raises glucose levels.