Question

In fruit flies, bar eye is inherited by an X-linked allele (B for bar). If a heterozygous bar-eyed female is mated to a non-bar-eyed male, what will be the expected ratio of phenotype given four offspring?

Answer 1

barred eye vs non -barred eye

`2:2\\1:1`

Step-by-step explanation:

Let the genotype of heterozygous bar-eyed female be
`X_BX_b`

where
`X_B` represents the allele for X -linked dominant bar trait

while
`X_b` represents the allele for X -linked recessive trait

So the cross is carried out between
`X_BX_b` and
`X_bY`

The offspring produced are -

`X_BX_b`

`X_BY`

`X_bX_b`

`X_bY`

Phenotypic ration is

barred eye vs non -barred eye

`2:2\\1:1`