Questions:

Question 1: Jeff and Emily are married and expecting their first child. Jeff has normal vision and so does Emily, but she is a carrier for colorblindness. (MUST USE XX and XY.)

1. What is the probability that their child will be colorblind?

2. They find out that they will be having twins (one boy and one girl).

3. What is the probability that their son will be colorblind?

4. What is the probability their daughter will be colorblind? Carrier? Normal?

Question 2: Sofia, whose blood clots normally, has a hemophilic father. Her husband’s (Tommy) blood clots normally. Their first child was a girl and their second child was a boy.

1. What is Sofia’s genotype and phenotype?

2. What is Tommy’s genotype and phenotype?

3. What are the possible genotypes for their daughter?

4. What are the possible genotypes for their son?

5. What are the chances their 3rd child will be a girl that is also a carrier for hemophilia?

Question 3: Elizabeth and Sam have an 18 month old son named Scotty. He was late to walk, stumbles easily, and has difficulty getting up and moving around. After many tests, it was determined that Scotty inherited Duchene’s Muscular Dystrophy (DMD), which is an X-linked trait. Both parents are unaffected.

1. What is Elizabeth’s genotype and phenotype?

2. What is Sam’s genotype and phenotype?

3. What is the genotype for their son, Scotty?

4. What is the probability that they will have a girl with DMD?

5. Elizabeth is expecting another child. What is the probability she will have another child with DMD?

6. She finds out that the child will be a girl. What is the probability that she will be normal and NOT carry the gene for DMD?