Question

Blood groups A and B are _______ and _______ character.

• A. Dominant, inborn
• B. Recessive, sex linked
• C. Dominant, sex linked
• D. Recessive, accquired

Answer 1

Answer: (A)

Dominant, inborn

Human blood group inheritance is the example of co-dominance and multiple alleles. It is governed by three alleles namely I${}^A$, I${}^B$ and I${}^O$. The alleles I${}^A$ and I${}^B$ express phenotype of both A and B blood group and hence are codominant to each other. The genotypes "I${}^A$I${}^O$" and "I${}^B$I${}^O$" express "A" and "B" blood group respectively; hence A and B blood group are dominant over "O" blood group. The alleles I${}^A$, I${}^B$ and I${}^O$ are not present on sex chromosomes and their inheritance is independent of the sex of the individual; hence they are not sex linked. The blood group of parents determine the blood group of offspring; hence it is genetic trait and is determined since birth. Correct option is A.