Do not write on paper
Follow these steps A, B, and C before asking Mrs. Gaylord for help with numbers 1 - 5. She will rotate around to each
group.
A. Tape a piece of paper to the wall and write the words “Sex-Linked Traits” on the top of the paper.
B. Create 7 Punnett squares (with a little space for writing above and to the sides of the grid) on the paper.
C. Write your group names at the very bottom of the paper.
Answer questions 1 – 7 using the Punnett squares and your collective brain power …
1. Colorblindness is a recessive allele carried on the X chromosome. A man that is colorblind copulates with a woman
that is not colorblind. What is the percentage that their son will be colorblind? What is the percentage that their
daughter will be colorblind?
2. Hemophilia is a recessive allele carried on the X chromosome. If a normal man conceives a child with a woman that is
a carrier for hemophilia, what percentage of their daughters will have hemophilia? What percentage of their sons will
have hemophilia?
3. A hemophilic boy has one non-hemophilic brother and two non-hemophilic sisters. What are the genotypes and
phenotypes of his parents?
4. Rett Syndrome is a dominant sex-linked trait carried on the X chromosome. A girl with Rett Syndrome has no sisters
but she does have two brothers that do not have the disease. What are the genotypes and phenotypes of the parents?
5. Baldness is transmitted in the same way that colorblindness is transmitted. A woman that carries the trait for baldness
conceives a child with a man that is not bald. What is the probability that their child is a bald male?