Question

Five Mark Questions :
(a) Differentiate between dominance and codominance.
(b) explain codominance taking an example of human blood groups in the population

Answer 1

Law of dominance states that in a pair of alleles one is a dominant character and other is a recessive character. Only the dominant character will show itself in the heterozygous trait. The recessive character can show itself when it is present in a homozygotic condition.

Codominance is when both the allele express themselves in the hybrid. 1:2: 1 ratio is present in both genotype as well as the phenotype. There is no mixing of characters of the two alleles.

In human blood grouping system there are three alleles a, b, o.

The 3 alleles of human blood group are said to be codominant because both are expressed in the phenotype A and B.