Which component of blood is responsible for transporting oxygen?

The transportation of oxygen in the bloodstream is primarily the function of hemoglobin, which is a protein found within red blood cells. Hemoglobin has a unique ability to bind to oxygen in the lungs, where oxygen concentration is high, allowing it to pick up oxygen molecules efficiently. Once the red blood cells circulate to the tissues, hemoglobin releases the oxygen where it is needed most for cellular metabolism.

In contrast, other components of blood play different roles. Platelets are primarily involved in clotting and preventing bleeding, while plasma serves as the liquid medium for carrying nutrients, waste products, and hormones. White blood cells are crucial for the immune response, fighting off infections and disease, but they do not play a direct role in oxygen transport. Thus, hemoglobin in red blood cells is unequivocally responsible for the primary function of oxygen transportation in the circulatory system.