Question

AB blood group was discovered by
A. Decastello and Sturli
B. Karl Landsteiner
C. William Harvey
D. Wallace Alfred

Answer 1

Hint: He is associated with the discovery of different types of blood cells, that is, different blood groups. The discovery resulted in blood transfusions amongst individuals with compatible blood types.

Complete answer:
Blood consists of red blood cells, white blood cells and platelets in a liquid substance called plasma. The blood group is defined by blood antibodies and antigens. Antibodies are proteins found in plasma. They are part of the body's normal defenses. They detect foreign materials, such as germs, and warn the immune system to destroy them. Antigens are protein molecules found on the surface of the red blood cells.
The presence or absence of two antigens (A and B) on the surface of the red blood cells gives rise to four main blood types. Besides the A and B antigens, a protein called the Rh factor, that may be either present or absent. Thus, there are eight most common forms of blood groups (A+, A-, B+, B-, O+, O-, AB+, AB-).

The ABO blood group was first described by Karl Landsteiner. Through a series of studies, Landsteiner categorized blood into four well-known groups: A, B, AB and O. William Harvey was the first person to discover the circulation of blood and how the heart was involved in the pumping of blood.

Thus, the correct answer is option B. i.e., Karl Landsteiner.

Note: The human body normally creates antibodies that target certain kinds of red blood cell antigens. For instance, individuals with blood type A have A antigens on their red blood cells and make antibodies to attack B antigens; similarly, blood type B individuals have B antigens on their red blood cells and make antibodies to attack A antigens. So, people of type A cannot give their blood to people of type B, and vice versa.