Question

A blood precipitation test was proposed by
(a)Wallace
(b)Nuttal
(c)Bateson
(d)Needham

Answer 1

Hint: The blood precipitation theory was proposed by a scientist who also helped Darwin to give the theory of natural selection which was then published in Darwin’s book The Origin of species. He based the blood precipitation test on the antigen-antibody interaction.

Complete answer:
Antigens are substances found in the blood that are not recognized by the receptors of blood and thus induce an immune response against themselves. Antigens can include bacteria, viruses, and other microorganisms. Antibodies are chemicals that are produced by the immune system in response to the antigens that were detected in the blood. The function of antibodies is to destroy the antigens. When an antigen reacts with its antibody, there are clumps of dead RBC formed which will precipitate out from the blood.

Additional Information: A very good example of antigen-antibody interaction is the ABO blood group system
The reason why we need to match blood groups during transfusion is because of the ABO antigens which will interact with their antibodies and form clumps.
If someone with the blood group A is present, he will have antigen A present in his body naturally. But antigen B will not be present, hence if antigen B containing blood group is introduced in such a person, antibodies will destroy those RBC.
The same applies to all the blood groups.
So, the correct answer is ‘Wallace’.

Note: -Antibodies are large Y shaped particles that are produced by the B-lymphocytes of the immune system.
-Another example of antigen-antibody interaction is the case of erythroblastosis fetalis.
-In this case, the Rh antigen of RBC of the baby is not recognized by the mother and thus RBC is killed by the mother’s antibodies leading to the death of the baby.