OK, now we know that there were four types of offspring. A female with normal spots, a female with dark spots, a male with normal spots, and a male with dark spots. You should be able to determine the genotypes of each offspring. For instance, the female with normal spots must have one X chromosome from each parent. She can only get the Xⁿ allele from her father. However, because she has normal spots, she must have gotten one X^N allele from her mother. What does this tell us about the mother?

We also know that there is a female cub with dark spots. In order for a female to have dark spots, she must have what genotype?

Again one of the X chromosomes came from her mother and one from her father. With this information and that obtained from the discussion of the first female cub, you should be able to determine the genotype of the mother. You could also use the same sort of comparison with the male cubs or you could perform a series of all possible crosses of females with genotypes resulting in normal spots to males with dark spots using the punnett square below to see which results in the particular pattern of spotted offspring observed.

Now return to the question page and select the correct answers.

You already know that the female cub with normal spots has a heterozygous genotype (X^NXⁿ). The male with which she is being paired has normal spots. What does that make his genotype?

Now perform a punnett square, placing the gametes of one parent across the top and the gametes of the other parent down the side. You will not be able to use superscripts on this table so use XN, Xn, and Y in your notation.

Your punnett square should look similar to the one below. If it does not, review the material on gamete formation and how to set up the punnett square and try again.

Now count up how many of each genotype and phenotype you have in the male offspring and in the female offspring.

Now return to the question page and select the genotypes requested.