If a homozygous black bull is mated with a homozygous white cow and the calf is gray, this could be an example of . However, if the calf has black and white spots this could be an example of.

Incomplete dominance

Co-dominance

Explanation:

Gregor Mendel discovered the principles that governs heredity, in which one of them is that an allele called DOMINANT allele, is capable of masking the expression of its variant allele called RECESSIVE allele in a heterozygous state. However, there has been genetic scenarios contrary to this his LAW OF DOMINANCE.

One of those Non-mendelian pattern of inheritance is a phenomenon called INCOMPLETE DOMINANCE, where an allele does not mask the expression of another completely, instead their combined state produces a third intermediate phenotype that is different from both parents. This is the case of the homozygous black bull mated with a homozygous white cow to produce a grey calf. The grey phenotype is an intermediate phenotype of both the black and white colours that forms due to incomplete dominance.

Another genetic scenario is called CO-DOMINANCE, where one allele is neither dominant nor recessive to the other allele, but instead both phenotypes becomes simultaneously expressed in the heterozygous offspring. In this case, the black bull and white cow were mated to form a heterozygous calf with both black and white spots.