Download Genetics Problem Set #2 Blood Type, Sex-linked (X

Genetics Problem Set #2
Blood Type, Sex-linked (X-linked), and Other Funky-Type Problems
Directions: Do these on separate paper.
1. A man with type A blood marries a woman with type B blood. Their child has type O
blood.
A. What are the genotypes of each of these people?
B. Use a punnett square to show the probabilities of the phenotypes in the offspring
from this marriage.
C. Show the Punnett squares and circle how they differ if both parents are homozygous.
2. Blood typing has often been used as evidence in paternity cases, when the blood
type of the mother and child may indicate that a man alleged to be the father could not
possibly have fathered the child. For the following mother and child combinations,
indicate which blood groups of potential fathers would be exonerated.
Blood Group of Mother
Blood Group of Child
Man Exonerated if He
Belongs to Blood Group (s)
AB
A
O
B
A
AB
O
O
B
A
3. Imagine that a newly discovered, recessively inherited disease is expressed only in
individuals with type O blood, although the disease and blood group are independently
inherited. A normal man with type A blood and a normal woman with type B blood
have already had one child with the disease. The woman is now pregnant for a second
time. What is the probability that the second child will also have the disease? Assume
that both parents are heterozygous for the gene that causes the disease. Show at least
1 punnett square and use the multiplication rule. This is the same technique you’d use
to include Rh factors in you calculations.
4. Sex Linkage-Complete the following crosses using punnett squares. Show the
probabilities of the genotypes and the phenotypes in the offspring. Colorblindness and
Hemophilia are recessive, sex-linked diseases.
A. XHY x XhXh
C. XhY x XHXh
B. XbY x XBXb
D. XBY x XBXb
5. A man with hemophilia has a daughter of normal phenotype. She marries a man who
is normal for the trait. Show at least 1 punnett square when you respond:
A. What is the probability that a daughter of this mating will be a hemophiliac?
B. That a son will be a hemophiliac?
C. If the couple has four sons, what is the probability that all four will be born with
hemophilia? (Hint: Use multiplication rule)
6. A color-blind man marries a woman with normal vision whose father was color-blind.
Use at least one punnett square to address the following:
A. What is the probability that they will have a color-blind daughter?
B. What is the probability that their first son will be color-blind? (Hint: Take note of the
wording in these two problems)
Funky Problems (Google the organisms prior to starting these problems)
7. A. A female magpie moth, was discovered that had paler wings than normal. It was
a female and was crossed with a normal dark-winged male. All the offspring had dark
wings. Explain what this shows about the inheritance of wing color in this species.
B. The dark-colored offspring were crossed with each other to produce the F2
generation. Explain, using a Punnett grid, what the expected ratio of dark and light
offspring is in the F2 generation.
C. The actual F2 results were:
Males: all dark winged;
Females: 1:1 ratio of dark and pale winged.
Explain what these results show about the inheritance of wing color in this species.
D. Sex determination in the magpie moth is not the same as in humans. Deduce the sex
chromosomes of magpie moths from the results of the above experiment
E. Predict the result of crossing a dark female moth with a pale male moth. Show your
work with a punnett square.
8. BB or Bb = black Labrador Retriever
bb = brown Labrador Retriever
But the presence of any color is also controlled by the C gene. Presence of C means the
dog has color (black or brown) and cc= albino (yellow) dog.
Cross a BbCc (Black lab) with a bbcc (yellow lab). Use a punnett square and show the
probabilities of the phenotypes in the offspring. (Hint: See page 279 for an example)