1. A polygenic trait is regulated by more than one gene. The phenotype of the organism is regulated by sum total of all the dominant alleles of these genes. Therefore, these traits exhibit continuous variations and are called quantitative traits. Skin color in humans is an example as it is regulated by more than one genes and the phenotype is determined by total dominant alleles of these genes.
2. If allele R gives red phenotype and the W gives white phenotype, a cross between RR (red) and WW (white) would produce all the cows with RW genotype. The parent cow with RR genotype would form all the gametes with R allele while all the gametes from WW parent would have one copy of the W allele. The random fusion of gametes with R and W alleles would produce progeny with RW genotype.
