Final answer:
The ability of RBCs to generate ATP through anaerobic mechanisms without consuming transported oxygen makes them efficient oxygen carriers. This, combined with their biconcave shape providing a high surface area for gas exchange, and a lack of a nucleus creating space for more hemoglobin, contributes to their efficiency.
Step-by-step explanation:
The factor that has the greatest effect on making red blood cells (RBCs) very efficient oxygen transporters is that they generate ATP by anaerobic mechanisms and do not consume any of the oxygen they carry. The absence of a nucleus in mammalian RBCs means that there is more room for the iron-containing protein hemoglobin, which can bind to oxygen. Hemoglobin molecules are critical to oxygen transport; with about 250 million hemoglobin molecules in each RBC, each cell can carry one billion molecules of oxygen. Furthermore, the lack of mitochondria in RBCs prevents these cells from using oxygen for their own metabolic processes. Instead, they metabolize anaerobically and do not deplete the oxygen intended for delivery to the body's tissues.
The biconcave shape of erythrocytes offers a larger surface area-to-volume ratio facilitating efficient gas exchange. Additionally, the flexibility of erythrocytes allows them to navigate through the narrow capillary beds, ensuring extended opportunities for the exchange of oxygen and carbon dioxide. Overall, these structural and functional adaptations enable RBCs to transport oxygen throughout the body effectively.