Name ______Due Date ______

Probability WS

Answer questions 1-4 on your own paper…You must show your work . . . please highlight or circle your final answer.

1. A man of blood group B is being sued by a woman of blood group A for paternity. The woman’s child is blood group O.

a. If this man actually is the father of this child, specify the genotypes of both parents.

b. If it was impossible for this group B man to be the father of this child, specify the genotypes of both parents

2. In Labrador retriever dogs, the dominant gene B determines black coat color and bb produces brown. A separate gene, E, however,

shows dominant epistasis over the B and b alleles. If the dominant E is present, the dog will be a golden color. The homozygous

recessive form of this gene (ee) allows expression of B and b.

a. Determine the genotypes of the parent dogs if a golden female is crossed with a golden male dog and 16 puppies are

produced, 12 golden, 2 black, and 2 brown.

b. Determine the expected phenotype ratios in the following cross: EeBb X eeBb

3. In pea plants,

•  long stems are dominant to short stems

•  purple flowers are dominant to white, and

•  round seeds are dominant to wrinkled.

A plant that is heterozygous for all three loci self-pollinates and 2012 progeny are examined. How many of the resulting plants would

you expect to be long-stemmed with purple flowers, producing wrinkled seeds?

4. A sex-linked dominant trait found in humans is hypophosphatemia (low phosphate blood levels resulting in deformed bones,

bowleggedness). If a bowlegged man marries a normal-legged woman, . . .

a.  What is the probability of a normal-legged daughter?

b.  What is the probability of a normal-legged son?

5. Although the gene for pattern baldness is not located on the X-chromosome, it is influenced by the sex of the individual. The gene is

dominant in men and recessive in women. A heterozygous bald, color blind man marries a non-bald woman with normal vision whose

father was non-bald and color blind and whose mother was non-bald with normal vision.

a.  What is the probability of having a bald, colorblind female?

b.  What is the probability of having a bald, colorblind male?

c.  What is the probability of having a hairy, normal-vision female?

6. Examine the pedigree below. What is the path of inheritance for the trait shown? Identify the genotypes of each individual in the

pedigree.

I

1 2 3 4

II

1 2 3 4 5 6

III

1

7. Examine the pedigree for hemophilia, which is sex-linked recessive. Determine the genotype(s) for each of the following individuals:

1. ______5. ______

2. ______6. ______

3. ______7. ______

4. ______

8. Examine the pedigrees below. First, identify all possible paths of inheritance from the list below. Then, identify the most probable

path of inheritance: that is, the best fit.

a.  autosomal dominant

b.  autosomal recessive

c.  X-linked dominant

d.  X-linked recessive