Key Stage 3 (KS3) Science – Cells Practice Test

The heart is the organ responsible for pumping blood throughout the body. It functions as a muscular pump that contracts and relaxes rhythmically to maintain blood circulation. This circulation is crucial because it delivers oxygen and nutrients to tissues and organs and helps remove waste products like carbon dioxide. The heart has four chambers (two atria and two ventricles) that work together to ensure efficient blood flow: oxygen-rich blood is pumped from the left side to the body, while oxygen-poor blood is sent to the lungs for reoxygenation from the right side. This vital role makes the heart essential for the overall functioning of the circulatory system and the body as a whole.