Question

Three Mark Questions :
How are dominance, co-dominance and incomplete dominance patterns of inheritance different from each other?

Answer 1

• Dominance = One of the alleles is dominant over the other recessive one. For example, T allele is dominant over t allele.

• Codominance = In this case, both parental genes are expressed equally in the progeny. None the of parental gene is able to repress each other and so the resulting progeny resembles both to both of its parent at the same time.For example coat colour in cattle. If one with red coat (skin with red colour hair) is crossed with one having white coat then the F1 hybrid would have roan colour hair (.i.e. patches of both red and white colour hair on skin)

• Incomplete dominance = neither of the parental gene are able to express themselves independently in the progeny but a blend of both is expressed. So the resulting progeny resembles neither of its parents. For example in snapdragon flower ,if a pure (homozygous) red coloured flower is crossed with pure (homozygous) white coloured flower then the F1 generation includes pink coloured flower (heterozygous) .