Question

Why is Mendel's law of dominance not always true?

Answer 1

Exceptions in Mendel's law of dominance:

1. According to Mendel's law of dominance, only one form of a trait will manifest in the offspring of two parents who have distinct, opposing qualities. The sole phenotypic characteristic that the hybrid offspring will display is the dominant trait.
2. Codominance and incomplete dominance make Mendel's law of dominance not always true.
3. Mendel's law of dominance is not always applicable because occasionally both alleles are codominant, as in the inheritance of the ABO blood group.
4. Occasionally the dominant allele exhibits incomplete dominance over the recessive allele and the heterozygote displays an intermediary phenotype, as in the inheritance of flower color in the snapdragon flower which is termed incomplete dominance