B is dominant for black fur over b for white fur. Cross two rabbits, heterozygous for fur color.

Parental cross: Bb x Bb  

F1:

- Expected phenotypic ratio: 3/4 black fur (B_); 1/4 white fur (bb) >> 3:1

- Expected genotypic ratio: 1/4 BB; 1/2 Bb; 1/4 bb >> 1:2:1  

Explanation:

A gene variant or 'allele' is dominant when it completely masks the presence of the other allele called recessive in individuals that are heterozygous for that gene. In this case, the allele 'B' associated with the black fur phenotype exhibits complete dominance on the allele 'b' associated with the white fur phenotype. In consequence, the mating between two heterozygous (Bb) parents will produce an F1 generation with an expected phenotypic ratio for the fur trait of 3:1, i.e., 3 black fur individuals (B_ genotype) and 1 white fur individual (bb genotype), and an expected genotypic ratio of 1:2:1 among BB, Bb and bb genotypes.

not sure if this is what you'r looking for nnew= nold