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

What is the primary function of heart valves?

1. To allow blood to flow in both directions

2. To ensure blood flows in one direction

3. To prevent blood clots

4. To increase blood flow to the lungs

The correct answer is: To ensure blood flows in one direction

The primary function of heart valves is to ensure that blood flows in one direction through the heart and into the major arteries. This unidirectional flow is crucial for efficient circulation, as it prevents backflow and maintains the pressure needed to propel blood to various parts of the body. Heart valves achieve this by opening and closing at appropriate times during the cardiac cycle. There are four main valves in the heart: the tricuspid valve, the pulmonary valve, the mitral valve, and the aortic valve. Each of these valves plays a role in regulating blood flow: the tricuspid and mitral valves separate the atria from the ventricles, while the pulmonary and aortic valves control blood flow from the ventricles into the pulmonary artery and aorta, respectively. The other options do not accurately capture the primary role of heart valves. Allowing blood to flow in both directions contradicts the function of valves; they are specifically designed to prevent this. Preventing blood clots is more associated with the function of blood components and the overall circulatory health rather than the inherent function of heart valves themselves. Lastly, heart valves do not serve to increase blood flow to the lungs; rather, they control the flow of blood as the heart pumps it through