GCSE Biology Practice Exam 2025 – Comprehensive Study Resource

After the blood has circulated through the organs and delivered oxygen and nutrients, it returns to the heart through the veins. This is a crucial part of the circulatory system, which operates in a closed loop.

Once the blood has delivered its oxygen to the tissues, it picks up carbon dioxide and other metabolic wastes. This deoxygenated blood is then collected by small veins, which gradually merge into larger veins, eventually leading back to the right atrium of the heart. From there, the heart can pump the blood to the lungs for re-oxygenation.

The other options do not accurately reflect the processes in the circulatory system. While the blood does ultimately go to the lungs for oxygenation, that process happens after it returns to the heart, and blood does not remain indefinitely in the organs nor is it stored there without being processed further. The return to the heart is essential for maintaining the continuous flow of blood throughout the body.