SQA National 5 Biology Practice Exam

The upper chambers of the heart that receive blood from the veins are called atria. The heart consists of four chambers: two upper atria and two lower ventricles. The atria function as receiving chambers for blood returning to the heart. The right atrium receives deoxygenated blood from the body via the superior and inferior vena cavae, while the left atrium receives oxygenated blood from the lungs through the pulmonary veins.

This distinction is crucial in understanding the heart's anatomy and its role in the circulatory system, as the atria prepare blood for the next step in the circulation process by passing it into the ventricles, which then pump the blood out of the heart. The other choices refer to different parts of the circulatory system: ventricles are the pumping chambers, the aorta is the major artery carrying oxygenated blood away from the heart, and arteries are blood vessels that carry blood away from the heart.