what are the phenotypes possible when a negro marries a white
Skin colour in humans is an example of polygenic inheritance. It depends on the number of dominant alleles. More the number of dominant alleles more will be the production of melanin and so darker will be the skin colour. Dominant phenotype contains three pairs of dominant alleles (AABBCC) .While recessive phenotype, i.e. white, contains all six recessive alleles (aabbcc). So, when a dark skinned person marries a white, there are seven phenotypes possible in the offsprings. They are AABBCC (dark skinned same as the dominant parent), AaBBCC (less dark), AaBbCC (brown), AaBbCc (mulatto), aaBbCc (fair), aabbCc (very fair) and aabbcc (albino or white same as the recessive parent).