Question

figure 1: incomplete dominance using snapdragons. a different pattern is codominance, in which both alleles are expressed in the heterozygote rather than one or the other. a good example of codominance is the human phenotype for blood groups. at the gene for blood group, a person can carry one of three alleles: a, b, or o. these alleles code for a group of proteins known as antigens, which helps the body’s immune system recognize pathogens. allele a results in the production of a antigens, allele b results in the production of b antigens, and allele o results in the production of no antigens. if a person inherits the a allele from one parent and the b allele from the other parent, then that person produces both antigens. because the a and b alleles both cause the production of antigens, and they are considered codominant traits. part 2 — questions: after completing the reading, answer the following questions. any data, calculations, or models you use to support your thinking should be explained. 1. how does incomplete dominance contradict the idea of dominant and recessive alleles?

Explanation:

In incomplete dominance, the heterozygote shows an intermediate phenotype rather than the dominant - phenotype as in classic dominant - recessive allele relationships. For example, in snapdragons, a cross between red and white - flowered plants gives pink - flowered heterozygotes. This goes against the idea that the dominant allele completely masks the recessive one in the heterozygote.

Answer:

In incomplete dominance, the heterozygote has an intermediate phenotype instead of the dominant phenotype being fully expressed as in the case of classic dominant - recessive alleles.