Final answer:
Blood type O- is known as the 'universal donor' due to the absence of A and B antigens on its red blood cells, preventing immune reactions when given to recipients of any blood type.
Step-by-step explanation:
Blood type O- is called the 'universal donor' because it has no antigens on its surface, making it compatible with any other blood type. Since it lacks A and B antigens, a transfusion of O- blood does not elicit an immune response in the recipient, regardless of the recipient's blood type. People with type O blood have both anti-A and anti-B antibodies in their plasma,
meaning they can only receive type O blood themselves. On the other hand, type AB blood is known as the 'universal recipient' because these individuals have both A and B antigens on their red blood cells and do not produce anti-A or anti-B antibodies, allowing them to receive blood from any ABO blood type.