Question

I have a genetics question. Say that two strains of an organism are observed. Pure-Bred strain A produces 90% of wild-type phenotype and 10% mutant phenotype. In Pure-Bred strain produces 70% wild-type and 30% mutant phenotype (both mutant phenotypes are the same) When you cross strain A and B, you get 90% wild-type and 10% mutant phenotype? What could cause this variation in phenotype ratios? Incomplete dominance?

Answer 1

No, the type of variation shown in the above question is not incomplete dominance. It is complete dominance. Complete dominance is a form of dominance in heterozygous condition where the dominant allele completely mask the effect of recessive allele. This type of variation is observed in the above question where strain A produces 90% wild type and 10% mutant type and cross between strains A and B also produces 90% wild type and 10% mutant type. Incomplete dominance is intermediate dominance in which one allele for specific trait is not completely dominant over other allele. As a result, a third phenotype is expressed where combination of traits from both dominant and recessive is produced.