A. Human immune systems are able to detect and combat viruses and bacteria that are harmful to the body. When a person has a peanut allergy, the immune system erroneously recognizes the proteins in peanuts as dangerous to the body. Because of this, the body triggers an allergic reaction.
B. The specific molecules that trigger peanut allergy are Ara h 1 and Ara h 3 whcih are members of the cupin superfamily of proteins, and Ara h 2 and Ara h 6 that are members of the prolamin superfamily.
C. It is because peanuts are different from tree nuts to which the walnut belongs. They have different compositions of proteins.
D. Allergic reaction is sort of similar to the rejection of a transplanted organ because the recipient's immune system identifies the tissue of the donor as foreign which triggers an immune response.