1 In cockerspaniels2 genes are responsible for color of coat

1) In cocker-spaniels,2 genes are responsible for color of coats.

A_B   Black

A-bb Red

aaB_ Liver

aabb Lemon

Two black dogs produce a litter of 5 puppies. 2 black, 1 red, 1 liver, and 1 lemon. What are the genotypes of the black parents? If you cross a homozygous red dog with a homozygous liver-colored dog what colors would you expect in the puppies??

2) In humans, free ear lobes are dominant over attached lobes. The presence of mid-digital hair is dominant over the absence of hair. A man whose genotype is AAHh marries a woman who has attached ear lobes and no mid-digital hair. What is the genotype of the woman? Could this couple have a child with free ear lobes and mid-digital hair? Could they have a child with attached ear lobes and no mid-digital hair?

Solve the following dihybrid cross problems please.

Solution

1: Since the cross between two black dog (A-B-) gives one lemon puppy out of total progeny phenotypes. To have a puppy with aabb(lemon) genotype, both parent should have atleast one copy of a and b alleles each. This makes the genotype of black parents to be \"AaBb\".
The cross between homozygous red (AAbb) and homozygous liver (aaBB) would give all progenies with AaBb genotype which would exhibit black coat color.