A Level Biology Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

The primary function of the vena cava is to carry deoxygenated blood into the heart. The vena cava consists of two major veins: the superior vena cava, which brings blood from the upper body, and the inferior vena cava, which brings blood from the lower body. Both of these veins empty into the right atrium of the heart. This is a critical role in the circulatory system because it ensures that blood returning from the body, which has delivered oxygen to tissues and collected carbon dioxide and other waste products, is directed back to the heart for reoxygenation in the lungs.

The other options involve different physiological processes unrelated to the direct function of the vena cava. While oxygenated blood transport pertains to the pulmonary veins, blood pressure regulation primarily involves arteries and the heart's pumping action, and nutrient absorption is a function linked to the digestive system rather than the vena cava's role in circulation.