1. Early in this century, geneticists performed this cross:
P red-eyed female x white-eyed male
F1 red-eyed female red-eyed male
a. From these results, which characteristic is dominant?
b. They went on to perform this cross:
F1 x F1 red-eyed female x red-eyed male
F2 red-eyed female 1:1 red- to white-eyed male
Are these results explainable if the allele for red/white eye color is on the Y chromosome but not on the X chromosome? On the X chromosome but not on the Y chromosome? Explain. How do these results support the hypothesis that genes are on the chromosomes?Answer
2. Considering Figure 24.11, you are a geneticist who has been hired to convince the British royal family that Queen Victoria was a carrier for hemophilia, an X-linked gene.
a. How does Figure 24.11 show that hemophilia is X-linked?
b. The present members of the royal family are descended from Edward VII, who did not inherit the allele for hemophilia. What were his chances of inheriting the allele?
c. In hemophiliacs, a clotting factor is defective. Would you expect this factor to be a carbohydrate, lipid, nucleic acid, or protein? Why?
d. Considering that it is sometimes possible today to test the DNA (taken from bone cells) of persons long dead, what would you expect to find if the DNA of Victoria were examined?