Question

All the offspring of a cross between a black-eyed mendelian and an orange-eyed mendelian have black eyes. What is the expected phenotypic ratio of a cross between two orange-eyed mendelians?

Answer 1

1:0 orange eyes:black eyes

Step-by-step explanation:

If black-eyed mendelian and an orange-eyed mendelian give all the offspring with black eyes, this means that the black eye allele is dominantt over orange eye. So, if we name the gene for the eye color with A, the genotypes of the parents would be AA (black eyes) and aa (orange eyes).

P: AA x aa

F1: Aa Aa Aa Aa (all heterozygous with black eyes).

Cross between two orange-eyed mendelians:

P: aa x aa

F1: aa aa aa aa all of them with orange eyes