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

Where does blood flow to upon entering the heart?

1. Into the left ventricle and right ventricle

2. Into the lungs for oxygenation

3. Into the two atria from the vena cava and pulmonary vein

4. Directly to the aorta

The correct answer is: Into the two atria from the vena cava and pulmonary vein

Upon entering the heart, blood first flows into the two atria, specifically the right atrium and the left atrium. The right atrium receives deoxygenated blood from the body through the vena cava, while the left atrium receives oxygenated blood from the lungs via the pulmonary vein. This initial entry point is crucial for the heart's function, as it allows the heart to manage and direct blood flow effectively: deoxygenated blood from the body is sent to the lungs for oxygenation, and oxygenated blood from the lungs is prepared to be pumped out to the rest of the body. The other options do not accurately reflect the flow of blood upon entering the heart. Blood does not enter into the ventricles directly; rather, it must first fill the atria. Additionally, while blood does travel to the lungs for oxygenation, this occurs after it has been collected in the right atrium and subsequently pumped into the right ventricle, which sends the blood to the lungs. Finally, blood does not enter the aorta directly; the aorta is the vessel that blood moves into after being pumped from the left ventricle. Thus, the correct answer accurately describes the initial point of blood entry into the heart structure.