A bull might be a carrier of osteopetrosis marble bone disea

A bull might be a carrier of osteopetrosis (marble bone disease, assume two alleles in this locus), a recessive lethal condition. Twenty percent of all cows in the same heard are thought to be carriers of the osteopetrosis allele. Artificial insemination matings to randomly chosen cows have already produced 100 normal calves, and no homozygous recessive calves.What is your level of confidence that the bull is not a carrier of the gene for osteopetrosis

Solution

Bull is not thhe carrier for the osteopetrosis. Since the homozygous recessive condition is lethal and mating with randomly chosen cows (which are possible carrier of the osteopetrosis) has produced no homozygous recessive calves. If the bull was also carrier, some of the calves would be homozygous recessive.