OCR GCSE Biology 2025 – 400 Free Practice Questions to Pass the Exam

Heart valves play a crucial role in maintaining the proper flow of blood through the heart and ensuring that it moves in the right direction. Their primary function is to prevent the backflow of blood. This is important because it ensures that blood flows from the heart to the lungs and body in a single direction, allowing for efficient circulation and preventing any mixing of oxygenated and deoxygenated blood.

When the heart contracts, the valves open to allow blood to be ejected from the heart chambers. Once the heart relaxes, the valves close, effectively blocking any return flow of blood into the chambers. This mechanism is vital for the heart's functionality, as it maintains the pressure needed for effective circulation while preventing any inefficiencies that could arise from blood regurgitating or flowing backward.

The other choices do not accurately describe the function of heart valves. They are designed specifically to control flow direction rather than increase blood pressure, allow backflow, or assist in oxygen absorption. The valves ensure a one-way flow, which is key to the overall efficiency and effectiveness of the cardiovascular system.