Question

The similarity shared by all the three types of dominances; complete dominance, incomplete dominance and co-dominance : 1) Absence of blending of alleles 2) Presence of blending of alleles 3) Expression of alleles of gene 4) Both 2 and 3

Answer 1

The similarity shared by all the three types of dominances; complete dominance, incomplete dominance, and co-dominance : Expression of alleles of gene (Option 3)

• Complete dominance - The expression of the dominant allele is present in homozygous as well as heterozygous form. It does not allow recessive allele to express unless in case of homozygous recessive. Blending is not seen in complete dominance.
• Co-dominance - The dominant allele and recessive allele express themselves in only homozygous conditions. In heterozygous condition, we can observe a blending of dominant and recessive leading to a third phenotype.
• Incomplete dominance - Like co-dominance the dominant and recessive alleles express themselves completely in homozygous condition. However, in heterozygous, we can observe characteristics of dominant as well as recessive in the same organism.  
• Hence the allele whether recessive or dominant shows expression in either homozygous or heterozygous form.