Question

Short / Long answer type questions.
(a) Explain the phenomena of multiple allelism and co-dominance taking ABO blood group as an example. (b) What is the phenotype of the following: (i) A i, (ii) ii

Answer 1

(a) Multiple alleles mean three or more forms of a gene that can occupy the same locus but only two out of three can be present in an individual at the same time. For example, the ABO blood group system is controlled by three genes but only at a time is present in the individual.

Codominance is a form of dominance in which both the alleles express themselves equally in a heterozygous condition. This results in offspring which is neither dominant nor recessive. Example, in an individual with AB blood group, both the A and B alleles express themselves equally.

(b) Ai $\to$ A blood group

ii $\to$ O blood group