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

The primary role of the valves in the heart is to ensure that blood flows in the right direction. The heart has four main valves—the mitral valve, tricuspid valve, aortic valve, and pulmonary valve—that open and close in a coordinated manner. This prevents the backflow of blood and maintains a unidirectional flow throughout the heart's chambers and into the arteries.

When the heart contracts, the valves close to prevent blood from flowing backward into the chambers. When the heart relaxes, the valves open to allow blood to fill the chambers. This precise action of the valves is crucial for efficient circulation, ensuring that oxygen-rich blood is delivered to the body and that deoxygenated blood is directed to the lungs for reoxygenation. The functioning of the valves is essential for maintaining the heart's rhythm and overall cardiovascular health.

The other options, while related to various aspects of heart function, do not accurately describe the primary role of the valves. Valves do not directly regulate blood pressure, assist in oxygenating the blood, or enhance the contraction of the heart. Instead, their primary focus is on directing blood flow properly through the heart's structure.