Chapter 15—Genetics and Populations
MULTIPLE CHOICE
1. What approach did Nancy Wexler take to identify a DNA marker associated with Huntington disease?
a.
population-based pedigree and DNA analysis
b.
DNA analysis of people from all over the world
c.
gathering DNA from members of her family
d.
DNA analysis of the entire population of Venezuela
e.
concordance analysis between monozygotic and dizygotic twins
2. What is a major reason the population studied by Nancy Wexler has such a high frequency of
Huntington disease?
a.
The population was genetically very diverse.
b.
Huntington disease originated in this population.
c.
People in the population all ate the same foods.
d.
People in the population all shared the same water supply.
e.
The population was reproductively isolated.
3. In order to construct her pedigree analysis for Huntington disease, Nancy Wexler used which of the
following populations?
a.
20,000 people from the database of the National Institutes of Health in the U.S.
b.
Close to 19,000 Venezuelans who lived in an isolated area.
c.
The entire population of Venezuela.
d.
Everybody with Huntington disease.
e.
Only families with no history of Huntington disease.
4. How did the frequency of Huntington disease (HD) in the population that Nancy Wexler studied
compare to the frequency in the general population?
a.
The frequency of the studied population was lower than the frequency of the general
population.
b.
The frequency of the studied population was higher than the frequency of the general
population.
c.
All of the people in the studied population had HD.
d.
The frequencies of the studied population and the general population were about the same.
e.
None of the people in the studied population had HD.
5. The founder effect refers to
a.
a population that frequently migrates to other parts of the world.
b.
a newly discovered population of organism.
c.
a group whose genetic origins can be traced to a small number of people.
d.
a group whose genetic origins can be traced to a large number of people.
e.
a group whose individuals are often marrying outside of the group.
6. Which of the following is true about Huntington disease (HD)?
a.
HD is caused by an increase in the number of copies of a repeated DNA sequence.
b.
HD is caused by a decrease in the number of copies of a repeated DNA sequence.
c.
HD is inherited in a recessive manner.
d.
HD affects only males.
e.
The HD gene does not cause disease when the number of repeats is 40 or more.
7. Which of the following persons is virtually certain to develop Huntington disease (HD)?
a.
a person who has 27−35 copies of the repeated sequence
b.
a person who has 36−40 copies of the repeated sequence
c.
a person who has over 40 copies of the repeated sequence
d.
a person who has 10−26 copies of the HD gene
e.
someone exposed to the infectious bacteria causing Huntington disease
8. Which of the following statements about Huntington disease (HD) is true ?
a.
The disease is caused by a high number of repeated DNA triplets.
b.
The gene responsible for the disease has not been located yet.
c.
As the number of repeated triplets decreases, the severity of the symptoms increases.
d.
People living around Lake Maracaibo in Venezuela show a very low frequency of HD.
e.
Normal copies of the HD gene only have one copy of the DNA triplet.
9. What is the advantage that heterozygotes of the sickle cell gene have over people who are not carriers?
a.
Carriers of the sickle cell allele are resistant to developing Huntington disease.
b.
Carriers of the sickle cell allele are resistant to malaria.
c.
Carriers of the sickle cell allele are resistant to Tay-Sachs.
d.
Carriers are more likely to live longer than non-carriers.
e.
Carriers of the sickle cell allele are resistant to cystic fibrosis.
10. Which of the following statements describes the relationship between malaria and sickle cell anemia?
a.
People infected with the malaria parasite are more likely to develop sickle cell anemia.
b.
The same parasite is responsible for both diseases.
c.
There is almost complete overlap in the geographic distributions of the two diseases.
d.
People suffering from sickle cell anemia are more likely to contract malaria.
e.
There is no overlap between the geographic distributions of the two diseases.
11. All of the following are examples of autosomal recessive disorders EXCEPT
a.
Huntington disease.
b.
sickle cell anemia.
c.
cystic fibrosis.
d.
PKU.
e.
Tay-Sachs.
12. Certain populations have a much higher frequency of carriers of recessive traits than others. These
populations have a higher
a.
carrier frequency.
b.
Wexler effect.
c.
founder effect.
d.
genetic drift.
e.
artificial selection.
13. On which chromosome is the gene for Huntington disease found?
a.
1
b.
4
c.
21
d.
X
e.
Y
14. The Y chromosome is passed from
a.
mothers to all of her sons.
b.
fathers to all of his daughters.
c.
fathers to all of his sons.
d.
mothers to all of her daughters.
e.
fathers to all of his children.
15. Which of the following is true about the Y chromosome?
a.
All humans have a copy of the Y chromosome.
b.
It passes from fathers to all of his children.
c.
It is constantly changing from generation to generation.
d.
It can be used to trace maternal ancestry.
e.
It can be used to trace paternal ancestry.
16. The genetic analysis of molecular markers on the Y chromosome supports which of the following
statements?
a.
The Lemba do have a history of migration from the Middle East.
b.
One in ten Lemba females carried the Cohen model haplotype.
c.
The Y chromosome haplotypes of the Israeli men were different from those of the men
from the Middle East.
d.
There was no relationship between the Jewish priests and the Lemba leaders.
e.
The genetic tests were inconclusive.
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17. How can we use the Hardy-Weinberg equation?
a.
The equation is useful for the analysis of multifactorial traits.
b.
It is a test that can tell the difference between carriers of mutant alleles and those who do
not have the allele at all.
c.
The Hardy-Weinberg can be used to calculate how many identical twins there are in a
population.
d.
The Hardy-Weinberg equation can be used to estimate the carrier frequencies in
populations.
e.
It gives a clue to the function of a gene.
18. Cystic fibrosis affects all of the following EXCEPT
a.
the glands that produce mucus.
b.
the glands producing digestive enzymes.
c.
lung health.
d.
sweat glands.
e.
cholesterol levels.
19. When considering sickle cell anemia and malaria,
a.
both diseases are determined entirely by genetics.
b.
the geographic distributions of the two are very similar.
c.
there is no overlap in their geographic distributions.
d.
both disease are caused by the same parasite.
e.
the two diseases show no know relationship.
20. A person heterozygous for the cystic fibrosis allele may be more resistant to contracting
a.
typhoid fever.
b.
malaria.
c.
an HIV infection.
d.
Huntington disease.
e.
Tay-Sachs.
21. The discovery rule includes
a.
genetic testing evidence that must be disclosed to the defendant.
b.
close matches in the CODIS DNA database.
c.
DNA test results of the prosecuting attorneys.
d.
DNA evidence that is only circumstantial.
e.
the discovery of DNA evidence from past crimes.
22. Nancy Wexler was awarded a Lasker award for her work on
a.
Tay-Sachs.
b.
sickle cell anemia.
c.
malaria.
d.
Huntington disease.
e.
breast cancer.
Chapter 15—Genetics and Populations
23. Which of the following has not yet occurred with Huntington disease?
a.
The gene has been isolated and identified.
b.
The gene has been mapped.
c.
Pedigree analysis of the gene has been done.
d.
Population genetics analysis has determined the mode of inheritance.
e.
A cure has been developed.
24. Malaria is transmitted from person to person via
a.
mosquitoes.
b.
direct contact with an infected individual.
c.
food.
d.
bacteria.
e.
contact with bodily fluids of an infected individual.
25. All of the following are uses for the Hardy-Weinberg equation EXCEPT
a.
it can be used to measure the frequency in DNA markers used in DNA profiles.
b.
it can estimate the frequency of an allele in a population.
c.
that knowing the frequency of the alleles, one can calculate the frequency of carriers.
d.
it can be used to calculate how common the alleles are in a populations.
e.
it provides information on how effective drugs will be for treating certain diseases.
26. In a genetic disorder caused by a recessive allele, scientists cannot directly count those who carry the
allele in a population. Why is this the case?
a.
There is usually no discernible difference between carriers and non-carriers.
b.
Recessive disease alleles are usually lost from the population.
c.
The genes are most likely X-linked.
d.
The alleles are recessive and therefore are very rare.
e.
Environmental factors will mask the disease symptoms.
27. Today’s dog breeds are the result of
a.
natural selection.
b.
genetic drift.
c.
the founder effect.
d.
artificial selection.
e.
migration effects.
Chapter 15—Genetics and Populations
TRUE/FALSE
1. The carrier frequency can be estimated mathematically.
2. All populations of a species are genetically identical.
3. People infected with malaria experience recurring episodes of illness throughout life, and often die at a
young age.
4. Huntington disease is an example of a genetic condition that is inherited in a dominant fashion.
5. Huntington disease is caused by an expanding triplet repeat within the HD gene.
6. There is some evidence that people who are homozygous for the gene responsible for cystic fibrosis
are more resistant to typhoid fever.
7. Certain human populations show lower frequencies of carriers of recessive traits than others.
8. Areas with high frequencies of malaria infections usually have high frequencies of sickle cell carriers.
9. Both sickle cell anemia and cystic fibrosis are inherited recessively.
10. The frequency of a trait may vary from population to population.
11. The Hardy-Weinberg formula allows geneticists to determine the number of individuals with particular
genotypes in a population without performing DNA testing on the entire population.
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12. People who are heterozygous for the gene responsible for sickle-cell anemia have greater resistance to
malaria than the rest of the population.
13. Pedigrees can be helpful in tracking a condition through a large population.
MATCHING
Match the associated terms.
a.
Used to estimate carrier frequency
b.
Lung health problems
c.
Percentage of heterozygotes
d.
Often provides resistance to some infectious disease
e.
Triplet repeats
f.
Transmitted by mosquitoes
g.
Red blood cells are altered
h.
Artificial selection
i.
Disclosure of evidence
1. Huntington disease
2. Cystic fibrosis
3. Sickle Cell
4. Malaria
5. Dog breeds
6. Hardy-Weinberg equation
7. Heterozygote advantage
8. Carrier frequency
9. Discovery rule
ESSAY
1. Some genetic diseases occur at much higher frequencies in particular populations, especially
populations that are geographically isolated. Why does this happen? What is the advantage to studying
these isolated groups?
Chapter 15—Genetics and Populations
2. What are the ethical concerns for collecting genetic information on an entire population? Should
everyone be required to submit a sample, or should it be more selective?
SHORT ANSWER
1. What is population genetics? Why do geneticists sometimes study particular populations?
2. How might it be an advantage for a population to have a large number of carriers of a gene that causes
a genetic disorder such as sickle cell anemia or cystic fibrosis?