You are studying coat color and number of toes in mice. You perform the following crosses:

Cross 1: Black, five-toed x white, six-toed gives: All black, six-toed progeny

Cross 2: White, five-toed x black, six-toed gives: All black, six-toed progeny

A. For each trait (coat color and number of toes), state which is the dominant phenotype and which is the recessive phenotype.

Answer: Dominant allele

Coat color = black

Number of toes = six

Recessive allele

White color

Five toes

Explanation:

Based on Mendelian law of independent assortment of genes

The genes for black coat and five toes are hetero zygote for the coat color and toes number. Likewise the gene for white coat and six toes

. The black coat color is a dominant / phenotype over the recessive white color, while the five toes is recessive phenotype to the dominant six toes.

This is evident from the F1 and F2 generations where all the offspring were all black and six - toed.

If the white coat and five - toed were the dominant allele, then some of the offspring should have appeared either as homo zygote or hetero zygote allele as white with five - toes!, in the F1 - F2 generation assuming they were masked in F1 in the presence of black coat and six toes, so far they can segregated independently of one another.