Mating of a DDee male to a ddEE female results in an F1 offspring with normal speech and hearing. Intermarriage between normal speech hearing (DdEe) offspring in the F1 generation resulted in 9 normal speech hearing and 7 deaf offspring in the F2 generation.
here,
The genotype of the crowned male is DDee
Genotype ddEE of the crowned female
The first progeny is F1 and the second progeny is F2
Parents : ♂ × ♀
Phenotype: crowned male crowned female
Genotype : DDee ddEE
Gamete : (De) (dE)
F1 Lineage : DdEe (Speech Hearing)
Self fertilization : F1×F1
Parents : ♂ × ♀
Phenotype : speech hearing speech hearing
Genotype : DdEe DdEe
Gamete : (DE)(De)(dE)(de) (DE)(De)(dE)(de)
F2 progeny (checker board)
Comment: It can be seen from the checker board, out of 16 children, 9 are hearing and 7 are hearing impaired. In this case, if the recessive gene d or e is present in double form (dd/ee), the child will be born.
Phenotypic Ratio : Normal Speech Hearing : crowned = 9 : 7