Assessment And Qualifications Alliance (AQA) GCSE Biology Paper 1 Practice Exam

When blood reaches body cells, oxygen is released from the red blood cells. This process is a key part of cellular respiration, where body tissues utilize oxygen to produce energy. Red blood cells are equipped with hemoglobin, a protein that binds oxygen in the lungs and carries it through the bloodstream to various cells throughout the body. As blood flows into capillaries surrounding the body cells, the higher concentration of oxygen in the red blood cells drives diffusion, allowing oxygen to exit the red blood cells and enter the body cells where it is needed. Understanding the role of red blood cells in transporting oxygen is fundamental to grasping how the body functions in supplying energy for cellular activities. While carbon dioxide is indeed a byproduct of cellular respiration and does diffuse into red blood cells for transport back to the lungs, the primary function occurring as blood reaches body cells is the release of oxygen. Blood filtering by the lungs pertains to gas exchange in the respiratory system, and oxygen absorption by red blood cells occurs in the lungs, not at the level of body cells.