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

What happens to the valves when the ventricles contract?

1. The atrial valves open and the arterial valves close

2. The valves to the atria close and valves to blood vessels open

3. All valves close completely

4. Valves do not have any movement

The correct answer is: The valves to the atria close and valves to blood vessels open

When the ventricles contract, they create a significant increase in pressure within the chambers of the heart. This pressure change causes the valves between the ventricles and the major blood vessels to open, allowing blood to be ejected into the arteries. Specifically, the atrioventricular (AV) valves, which connect the atria to the ventricles, close during ventricular contraction to prevent backflow of blood into the atria. Meanwhile, the semilunar valves at the bases of the pulmonary artery and aorta open to allow blood to flow out from the ventricles into these vessels. Thus, the correct description of this process is that the valves between the atria and ventricles close, while the valves leading to the blood vessels open, facilitating the forward movement of blood. This action ensures that the flow of blood is managed correctly during the heart's contraction phase.