Genetics
1. Duchenne muscular dystrophy (MD) is inherited as a sex-linked dominant characteristic. If a normal man marries a heterozygous woman. What percentage of their children will have MD?
a. All sons
b. All daughters
c. Half sons and half daughters
d. All sons, no daughters
e. All daughters, no sons
2. In humans, the allele for chronic simple glaucoma is dominant over the allele for normal eyes. Suppose a normal woman married a man with glaucoma whose father was normal. What proportion of their children would you predict will have glaucoma?
a. All
b. One-half
c. One-third
d. One-fourth
e. None
3. In a family of six children, two are blood type O; two are type AB; one is type B and another, type A. What are the blood types of the parents?
a. Type AB and type O
b. Type A and type B
c. Type A and type O
d. Type B and type O
e. Can't tell
4. Male pattern baldness is dominant in human males and recessive in females. Assume a heterozygous male and a homozygous normal female have many children. What would be the expected phenotypes of their children?
a. All bald
b. All sons bald, no bald daughters
c. No bald sons, all daughters bald
d. One-half sons bald, no bald daughters
e. One-half sons bald, all bald daughters
5. Adrenoleukodystrophy (ALD) is a sex-linked recessive trait in humans. ALD causes mental deterioration and death at about 2 years of age. Suppose a couple's first son died from ALD, the probability their next child will have ALD is:
a. 1
b. 1:4
c. 1:2
d. 3:4
e. 1
6. X-linked lymphoproliferative (XLP) disease is inherited as a sex-linked recessive trait; XLP is fatal in childhood. There are 272 people in the world known to have XLP. What is the gender of these 272 people?
a. All female
b. 1 female: 1 male
c. 1 female: 3 males
d. 3 females: 1 male
e. All male
7. In humans, perfect pitch is inherited as an autosomal dominant trait. If two heterozygous people have children, what percentage of children will have perfect pitch?
a. 100%
b. 75%
c. 50%
d. 25%
e. 0%
8. In humans, tune deafness is inherited as an autosomal domiant trait. (Tune-deaf people can't tell when over half the notes in a familiar tune like "Happy Birthday" are wrong.) A tune-deaf man and a normal woman have two normal children. What is the genotype of the man?
a. Homozygous dominant
b. Heterozygous
c. Homozygous recessive
d. Hemizygous
e. Can't tell
9. Cystic fibrosis is inherited as an autosomal recessive. Suppose a woman who carries the trait marries a normal man who does not carry it. What percent of their children would be expected to have the disease?
a. 0%
b. 25%
c. 50%
d. 75%
e. 100%
10. In humans, there are several abnormal genes for hemoglobin. In the homozygous condition, one such gene causes thalassemia major, an anemia that is fatal in childhood. The heterozygous genotype results in thalassemia minor. What is the probability that two people with thalassemia minor will have a normal child?
a. 1
b. 3 out of 4
c. 1 out of 2
d. 1 out of 4
e. 0
11. In tigers, albinism is inherited as an autosomal recessive trait. Assuming the gene for albinism is present in both parents, what is the probability that two normal tigers will have an albino offspring?
a. 1
b. 3 out of 4
c. 1 out of 2
d. 1 out of 4
e. 0
12. In humans, Hunter's syndrome is inherited as a sex-linked recessive trait. Hunter's syndrome is characterized by excretion of chondroitin-sulfate and severely deformed bones. Suppose a man with Hunter's marries a woman who is heterozygous for the trait. If they have a son, what is the probability that he will have the disease?
a. 1
b. 3 out of 4
c. 1 out of 2
d. 1 out of 4
e. 0
13. In humans, Hunter's syndrome is inherited as a sex-linked recessive trait. Hunter's syndrome is characterized by excretion of chondroitin-sulfate and severely deformed bones. Suppose a man with Hunter's marries a woman who is fully normal for the trait. If they have a daughter, what is the probability that she will have the disease?
a. 1
b. 3 out of 4
c. 1 out of 2
d. 1 out of 4
e. 0
14. In humans, the allele for freckles is inherited as an autosomal dominant trait. If a homozygous recessive man marries a homozygous dominant woman, you would expect the phenotypes of their children to be:
a. All the children will have freckles
b. Half the children will have freckles
c. Only the sons with have freckles
d. Only the daughters will have freckles
e. One-fourth of the children will have freckles
15. Suppose a human male died of Huntington's chorea, the same disease that killed his father. Huntington's chorea causes a progressive mental deterioration beginning in the third or fourth decade of life. Persons afflicted with this disease always have a parent who was similarly afflicted, and they always transmit the disorder to half of their children. Genetically, this disease is inherited as:
a. An autosomal recessive trait
b. An autosomal dominant trait
c. A sex-linked recessive trait
d. A sex-linked dominant trait
e. A Y-linked trait