Download Unit 1. Classical Genetics Exam. Advanced Version

“The person who makes a success of living is the one who sees his goal steadily and aims for it unswervingly. That is
dedication.” - Cecil B. DeMille
DO NOT WRITE ON ME!!
Unit 1. Classical Genetics Exam
Instructions: This is an individual assignment designed to test your understanding of Classical Genetics. Please
take your time and do your own work. Mark your answers to the selected response questions on your answer
sheet, and make sure to answer free response questions fully and in complete sentences. You can do this!
Selected Response (mark answers on answer sheet)
Use the following data table to answer questions # 1 - 2.
1. A group of students wanted to determine how the ability to taste PTC, a nontoxic chemical, is passed from
one generation to the next. The students decided to test families in their community for this ability. The
students gave each family member a paper strip coated with a small amount of PTC. Those who experienced
the bitter taste of PTC when they touched the paper strips to their tongues were called “tasters”; those who
could not taste the PTC were called “nontasters.”
Based on the data the students collected, the allele for tasting PTC is most likely
a. Dominant
b. Heterozygous
c. Recessive
d. Sex-Linked
2. Which of these explains how two taster parents could produce a nontaster child?
a. Both parents are heterozygous and produce a homozygous recessive child.
b. Both parents are homozygous recessive and produce a homozygous dominant child.
c. Both parents are heterozygous and produce a heterozygous child.
d.Both parents are homozygous dominant and produce a homozygous recessive child.
3. How many different genotypes are possible from the cross shown below?
AaBb x AaBb
a. 2
b. 4
c. 7
d. 9
“The person who makes a success of living is the one who sees his goal steadily and aims for it unswervingly. That is
dedication.” - Cecil B. DeMille
DO NOT WRITE ON ME!!
4. In humans, the allele for unattached earlobes (E) is dominant. The allele for attached earlobes (e) is recessive.
A woman who is heterozygous for this trait marries a man who has attached earlobes. What is the probability
that the couple’s child will have unattached earlobes?
a. 25%
b. 50%
c. 75%
d.100%
5. In humans, red-green color blindness is a sex-linked recessive trait. If a man and a woman produce a colorblind son, which of the following MUST be true?
a. The father is color-blind.
b. Both parents carry the allele for color blindness.
c. The father carries the allele for color blindness.
d. The mother carries the allele for color blindness.
6. A couple has 5 children, all sons. If the woman gives birth to a sixth child, what is the probability that the
sixth child will be a son?
a. 5/6
b. 1/2
c. 1/5
d. 1/6
7. Which of these combinations results in the expression of a recessive trait?
a. two dominant alleles
b. a dominant sex-linked allele and a Y chromosome
c. two recessive alleles
d. dominant allele and a recessive allele
8. As male children get older, some begin to closely resemble their fathers and have no resemblance to their
mothers. Which statement best explains this observation?
a. Several sperm fertilized the egg, so the fertilized egg contained more genes from their father.
b. More genes are inherited from the sperm cell of their father than from the egg cell of their mother, so
most traits will be like those of their father.
c. More genes from their father are expressed in traits that can be seen, and more genes from their
mother are expressed in traits that cannot be seen, such as blood type.
d. Genes from their father are stronger than genes from their mother, so the genes from their mother are
not expressed.
Use the following data table to answer questions # 9 - 10.
“The person who makes a success of living is the one who sees his goal steadily and aims for it unswervingly. That is
dedication.” - Cecil B. DeMille
DO NOT WRITE ON ME!!
9. In a species of fly, the allele for red eyes (R) is dominant to the allele for brown eyes (r). Red eye color in the
flies is not sex-linked. Students crossed male and female flies that had red eyes and recorded the eye color of
their offspring. Their data are shown below.
What are the most likely genotypes of the parent flies?
a. RR and rr
b. Rr and Rr
c. rr and rr
d. RR and Rr
10. Using the data in the table, what is the approximate ratio of red eyed offspring to brown eyed offspring?
a. 1:1
b. 2:1
c. 3:1
d. 4:1
Use the following information to help you answer questions # 11 - 12.
Galactosemia is an autosomal recessive trait. A normal couple has a child affected with galactosemia. For each of
the following situations, select the appropriate probability.
11. What is the probability that the father of the galactosemic child is heterozygous for the recessive allele?
a. 1/4
b. 1/2
c. 1/16
d. 1
12. What is the probability that the couple’s next child will be affected with galactosemia?
a. 0
b. 1/4
c. 1/2
d. 1
13. Hemophilia is caused by a sex-linked recessive trait. What is the genotype of a male who has Hemophilia?
a. X H X H
b. X h X h
c. X H Y
d. X h Y
“The person who makes a success of living is the one who sees his goal steadily and aims for it unswervingly. That is
dedication.” - Cecil B. DeMille
DO NOT WRITE ON ME!!
The pedigree below shows the occurrence of red-green colorblindness in four generations of a family. Use the
information in the pedigree to answer questions # 14 - 16.
14.How many individuals are carriers for the red-green colorblindness in the four generations?
a. 3
b. 4
c. 7
d. 12
15.In generation IV, individual 5 married someone who is a carrier of red-green colorblindness.
If they have a female child, what is the chance that she will be born with red-green
colorblindness?
a. 0%
b. 25%
c. 50%
d. 100%
16.Hemophila A, a blood disorder, is inherited in a similar way to red-green colorblindness.
Therefore, hemophilia most often results when the affected gene is passed from
a. father to son
b. father to daughter
c. mother to son
d. mother to daughter
Use the information and Punnett square below to answer questions #17 - 18.
In guinea pigs, the allele for black fur (B) is dominant. The allele for brown fur (b) is recessive. Two guinea pigs
were crossed as shown in the Punnett square below. Numbers 1, 2, 3, and 4 represent the types of offspring
produced from the cross.
17.What is the probability that an offspring from this cross would have brown fur?
a. 0%
b. 25%
“The person who makes a success of living is the one who sees his goal steadily and aims for it unswervingly. That is
dedication.” - Cecil B. DeMille
DO NOT WRITE ON ME!!
c. 50%
d. 75%
18.Which of these describes the phenotypes of the parent guinea pigs?
a. Both parents have black fur.
b. Both parents have brown fur.
c. One parent has black fur, and the other has brown fur.
d. One parent has a mixture of black and brown fur, and the other has black fur.
Use the information and the pedigree below to answer the following item.
In humans, the allele for having feet with normal arches is dominant (A). The allele for flat feet is recessive (a).
The pedigree below shows the occurrence of normal arches and flat feet in four generations of a family. In the
pedigree, individuals are identified by the generation and individual numbers. For example, Individual 2 in
Generation I is identified as I-2.
19.Which of these individuals in the pedigree is a male with the genotype aa?
a. Individual I-1
b. Individual II-2
c. Individual III-2
d. Individual III-5
20. A represents the dominant allele and a represents the recessive allele of a pair. If, in 1000 offspring, 500 are
“The person who makes a success of living is the one who sees his goal steadily and aims for it unswervingly. That is
dedication.” - Cecil B. DeMille
DO NOT WRITE ON ME!!
aa and 500 are of some other genotype, which of the following are most probably the genotypes of the two
parents?
a. Aa and Aa
b. Aa and aa
c. AA and Aa
d. AA and aa
21. A form of vitamin D-resistant rickets, know as hypophosphatemia, is inherited as an X-linked (sex-linked)
dominant trait. If a male with hypophosphatemia marries a normal female, which of the following predictions
concerning their potential offspring would be true?
a. All of their sons would inherit the disease.
b. All of their daughters would inherit the disease.
c. About 50 % of their sons would inherit the disease.
d. About 50 % of their daughters would inherit the disease.
22. Barney and Betty are about to have their first child. They both have “normal” feet but Barney’s father has flat
feet and Betty has a child from a previous marriage that has flat feet. What is the probability that they will
have a child with flat feet?
a. 0 %
b. 25 %
c. 50 %
d. 75 %
1. In fruit flies, the gene for eye color is sex-linked. Red eyes (R) are dominant to white eyes (r). In a cross
between a carrier female fruit fly and a white-eyed male, what percent of the female offspring will have
white eyes?
a. 0 %
b. 25 %
c. 50 %
d. 100 %
24. In cats, the allele for coat color is controlled by codominance. Black coat color (B) is dominant to white coat
color (b). What is the phenotype of heterozygous cats?
a. gray cat
b. BB
c. black and white spotted
d. Bb
25. In sheep, eye color is controlled by a single gene with two alleles. When a homozygous brown-eyed sheep is
crossed with a homozygous green-eyed sheep, blue-eyed offspring are produced. If the blue-eyed sheep are
mated with each other, what percent of their offspring will most likely have brown eyes?
a. 0 %
b. 25 %
c. 50 %
d. 75 %