If someone with auburn hair has children with someone with red hair (but whose mother had black hair ) what are the genotype and phenotype probabilities for their children ?

The phenotype is - 75 % red and 25 %brown.

The genotype is hRhR - 25%

hBkhR - 50%

hBrhBk - 25%.

The cross given here is a simple dominant - recessive relationship between the three types of alleles of hair colour. The genes of this characteristics are present in autosomes, so will be segregated equally among all the sexes of the offsprings.

Now the genotype of auburn and red with black mother is given. So during gametogenesis, the gametes from the parents will be

Father - hBr and hR

Mother - hBk and hR

So, the probable combinations are hBrhBk, hBrhR and hBkhR.

The frequency of the combinations are 25%, 25% and 50% respectively.

The phenotypic ratio will be red : brown as 3:1.