Question

a krabby blind whale has married pearl who has normal vision. oneof their two sons is also colorblind. what arr the genotypes of the parents?​

Answer 1

Answer:

Heterozygous dominant (Bb) and homozygous recessive (bb)

Explanation:

This cross involves the gene that codes for color blindness in whales. The allele for no color blindness/normal vision (B) is dominant over the allele for color blindness (b). This means that B will mask the phenotypic expression of b in a heterozygous state (Bb).

According to the question, one of the parents is color blind meaning it possesses the homozygous recessive genotype (bb) while the other parent (pearl) has a normal vision which can either be homozygous dominant or heterozygous dominant since the normal vision allele (B) is dominant.

However, since one of the two offsprings (sons) is also color blind, this implies that the parent with normal vision is heterozygous i.e. contains both dominant and recessive alleles, for the trait. What happens is that, when a bb and Bb parent are crossed, they produce gametes with either a recessive or dominant allele.

The Bb produces gametes with B and b alleles while the bb produces gametes with b and b alleles. When this are crossed using a punnet square, four possible offsprings will be produced with two distinct genotypes: Bb and bb. Hence, this means that there is a 1/2 chance of producing an offspring with the recessive trait from this cross as the case is in the whales.