Download Genetics Problems

Biology
Name: ___________________________
Genetics Problems
1. Albinism is a condition in which a person does not make skin pigment. It is caused by a recessive
allele. Normal skin pigment is the dominant trait. Cross a homozygous pigmented person with
an albino. What are the phenotype and genotype probabilities of their children?
2. Cross two heterozygous pigmented parents. What are the phenotype and genotype probabilities
of their children?
3. Cross a heterozygous normally pigmented parent with an albino parent. What are the
phenotype and genotype probabilities of their children?
4. Brown eyes are dominant to blue eyes. A brown eyed man marries a blue eyed woman. The first
child is blue eyed. What is the man’s genotype? Show a punnett square to prove this.
5. Tall pea plants are dominant to short pea plants. Two heterozygous tall pea plants were crossed
and they produced 100 seeds. What types of pea plants are EXPECTED to grow from these 100
seeds? List the phenotype probabilities.
6. Mr. A has blue eyes, but both his parents have brown eyes. Mrs. A has brown eyes; her mother
has brown eyes but her father has blue eyes. Mrs. A has seven brothers and sisters, all of whom
have brown eyes. Indicate the genotype of the following”
Mr. A _______________
Mrs. A _________________
Mr. A’s father ___________
Mrs. A’s father ________________
Mr. A’s mother ___________
Mrs. A’s mother _______________
What proportion of Mr. and Mrs. A’s children will have brown eyes? _____________
Biology
Sex Linkage Problems
Name: _____________________________
1. In fruit flies, red eye color (R) is dominant over white eye color (r), and the trait is linked on
the X chromosome. What genotypes and phenotypes will result from a cross between a redeyed male and a heterozygous red-eyed female?
2. Hemophilia is sex linked to the X chromosome, and it is recessive genetic disorder. A carrier
woman mates with a man who has hemophilia. What are the odds of having a child with
hemophilia?
3. In humans, color blindness (c) is recessive to normal vision (C) and is sex-linked. Two parents
with normal vision have a color -blind son. What is the probability that their next child will
be a color blind daughter?
4. Why are males more afflicted with recessive sex linked traits than females?
5. Can a male transmit a sex linked trait on the X chromosome to his son? Explain.
Biology
Name: _______________________________
Blood type problems
1. Cross a homozygous Type A person with a heterozygous Type B person. Show all possible results
for their children.
2. Cross a Type AB person with a Type O person. Show all possible results for their children.
3. A woman with type AB blood marries a man with type A blood. His mother had type O blood.
What blood type is not likely to occur among the couple’s children. Explain by showing work.
4. A man has type A blood and his wife has Type B blood. A physician types the blood of their 4
children and is amazed to find one of each of the 4 blood types among them. Explain how this
can happen. Show work.
Biology
Incomplete Dominance
Name: ___________________________
1. When white chickens (W) are mated with black chickens (W’), the baby chicks are grey
(WW’). Cross two grey chickens and list the genotype and phenotype probabilities of their
offspring. Show the punnett square.
2. Cross a grey chicken with a white chicken and list the genotype and phenotype probabilities
of the baby chicks. Show the punnett square.
3. When yellow guinea pigs (Y) are crossed with white guinea pigs (y), cream colored offspring
are produced (Yy). Can a pet store owner mate a cream colored male and a white female to
obtain yellow guinea pigs? Show your work.
4. A cross between round radishes (R) and long radishes(r) produces oval radishes (Rr). In a
radish breeding experiment, the following radishes were obtained:
25 long radishes: 52 oval radishes:26 round radishes
Determine the probable genotypes and phenotypes of the parent radish plants. Show work.