SAT Biology Subject Test Practice Questions

Answer: E, I, II, and III. A person with AB blood type is often called the “universal recipient”, as he or she can accept blood from individuals with any blood type.

Key Takeaway: Blood type is characterized by the presence or absence of two types of antigens, or an agent that can cause an immune response. These two types of antigens are called I^A and I^B. Individuals with only I^A have the A blood type, and those with I^B have the B blood type. Individuals with both antigens have AB blood type, and those with neither have O blood type. If the antigen of the donor’s blood is not already present in the recipient’s blood, an immune response will take place. Since O blood does not have any antigens, that blood will not cause an immune response in any recipient. Thus, individuals with O type blood are called “universal donors”.