Question

In horses, some of the genes for hair color are incompletely dominant. Phenotypes are brown, white, and yellow-tannish called palomino. Brown hair is homozygous dominant, white hair is homozygous recessive, and palomino is heterozygous. What are the genotype and phenotype ratios for a palomino female and a palomino male?

Answer 1

A cross between two palomino horses results in a phenotypic ratio of 1 brown : 2 palomino : 1 white, reflecting incomplete dominance in their genetic makeup.

Step-by-step explanation:

In horses with incompletely dominant genes for hair color, the crossing of two heterozygous palominos (each with one brown allele and one white allele) would produce offspring with the following genotype and phenotype ratios:

• 1 brown (homozygous dominant, brown allele + brown allele)
• 2 palomino (heterozygous, brown allele + white allele)
• 1 white (homozygous recessive, white allele + white allele)

We use the Punnett square to determine these ratios, with the palomino genotype represented as Bw (brown allele + white allele). The potential offspring genotypes from a Bw x Bw cross would be:

• BB - brown horse
• Bw - palomino horse
• Bw - palomino horse
• ww - white horse

Therefore, the phenotypic ratio for their offspring would be 1 brown : 2 palomino : 1 white.