Genetics Problems

1.) In guinea pigs, black (B) is dominant to brown (b), and dolid color (S) is dominant to spotted (s). A heterozygous black, solid-colored pig is mated with a brown, spotted pig. The total offspring for several litters are black solid=16, black spotted=5, brown solid=5, and brown spotted=14.

Are these genes linked or unlinked? If they are linked, how many map units are they apart?

2.) A woman is a carrier for a sex-linked lethal gene that causes an embryo with the gene to spontaneously abort. She has nine children. How many of these do you expect to be boys?

3.) A dominant sex-linked gene B produces white bars on black chickens, as seen in the Barred Plymouth Rock breed. A clutch of chicks has equal numbers of black and barred chicks. (Sex is determined by the Z-W system in birds: ZZ are males, ZW are females.)
a.) If only the females are found to be black, what were the genotypes of the parents?
b.) If males and females are evenly represented in the black and barred chicks, what were the genotypes of the parents?

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