The male fruit fly has an XY profile of the sex chromosomes, and the female has an XX profile of the sex chromosomes.
If a male is white-eyed, then it must have a white recessive allele on his only X chromosome and the red eyed female can be homozygous (having two dominant red eye alleles) or heterozygous (having both a dominant and a recessive allele).
If the female is homozygous then all of the offspring will be red-eyed, and if she's heterozygous then half of the offspring will be white eyed. (see the table provided below)
If a male is white-eyed, then it must have a white recessive allele on his only X chromosome and the red eyed female can be homozygous (having two dominant red eye alleles) or heterozygous (having both a dominant and a recessive allele).
If the female is homozygous then all of the offspring will be red-eyed, and if she's heterozygous then half of the offspring will be white eyed. (see the table provided below)