Cross Breeds

3.In certain breeds of dogs, black fur (B) is dominant to the brown fur (b) trait. Following a test cross, 1 ?

3.In certain breeds of dogs, black fur (B) is dominant to the brown fur (b) trait. Following a test cross, 1 black female gives rise to both black and brown puppies. A second black female is test crossed several times and produces 5 black puppies in the first litter, 5 in another, and 4 in a third. Give the most probable genotypes of female 1 and her offspring and of female 2 and all her offspring.

Public Comments

1. (case 1) Female: Bb Offspring: Bb, bb (case 2) Female: BB Offspring: Bb "test cross" mean breed the subject (here, female dog) with male dog with recessive trait (bb). If the offsprings show both phenotypes (black and brown), the subject is heterozygous (case 1) If the offsprings show dominant phenotypes (black ONLY), the subject is homozygous (case 2)