in horses, black coat color is caused by the dominant allele, b, and chestnut color is caused by the recessive allele, b. trotting gait is due to a dominant allele, t. the genotype tt is lethal and causes the horses to die before delivery. consider a cross between tt and tt horses. among the surviving progeny, what proportion are expected to be chestnut colored and heterozygous for trotting gait?
