Chapter 11—Inheritance of Complex Traits
MULTIPLE CHOICE
1. Traits that are controlled by two or more genes are
a.
polygenic.
b.
dominant.
c.
recessive.
d.
multifactorial.
e.
none of these.
2. Which of the following statements about polygenic traits is FALSE?
a.
Skin color is a polygenic trait.
b.
One example of a polygenic trait is obesity in humans.
c.
Polygenic traits typically have a bell-shaped distribution pattern.
d.
Cleft palate is not a polygenic trait because an individual is either affected or unaffected.
e.
The genes controlling some polygenic traits are affected by the environment.
3. Traits that are controlled by two or more genes and environmental factors are
a.
multifactorial.
b.
polygenic.
c.
multifaceted.
d.
recessive.
e.
dominant.
4. Which of the following statements about multifactorial traits is FALSE?
a.
The phenotypic distribution of multifactorial traits is often a bell-shaped curve.
b.
A multifactorial trait involves interactions of genes with the environment.
c.
A wide range of phenotypes results from multifactorial traits.
d.
Environmental factors such as nutrition can affect height, which is a multifactorial trait.
e.
The inheritance of multifactorial traits exhibits simple dominance and recessiveness.
5. Which of the following diseases are multifactorial?
a.
cystic fibrosis
b.
spina bifida
c.
albinism
d.
severe combined immunodeficiency disorder (SCID)
e.
All of these diseases are multifactorial.
6. In the case of multifactorial traits,
a.
the phenotypic distribution follows no particular pattern.
b.
traits are inherited in a simple dominant or recessive manner.
c.
only one gene determines the phenotype.
d.
environmental factors play a role in determining the phenotype.
e.
All of these are characteristics of multifactorial traits.
7. Polygenic traits exhibit ____ phenotypes within a population.
a.
only one
b.
many
c.
two
d.
three
e.
None of these answers are correct.
8. Spina bifida is a birth defect involving the ____ system and appears in the ____ month of embryonic
development.
a.
nervous, first
b.
circulatory, second
c.
circulatory, third
d.
nervous, second
e.
skeletal, first
9. The central nervous system includes the
a.
spinal cord.
b.
brain.
c.
meninges surrounding the brain.
d.
meninges protecting the spinal cord.
e.
All of these answers are correct.
10. Which of the following statements about spina bifida is true?
a.
Spina bifida (SB) is not influenced by the environment.
b.
Spina bifida does not show any family clustering.
c.
A gene associated with the neural tube defects has been identified in mice but no such
gene exists in humans.
d.
The human X chromosome contains the gene associated with neural tube defects.
e.
A couple that has a child with spina bifida has an increased risk of having another child
with spina bifida.
108
11. Fingerprints are
a.
not formed until the last three weeks of embryonic development.
b.
unaffected by the nutrition of the mother.
c.
determined entirely by genetics.
d.
identical in identical twins.
e.
influenced by the prenatal environment.
12. In humans, obesity is
a.
a multifactorial trait.
b.
always easily treated with leptin.
c.
a simple dominant trait.
d.
entirely controlled by genetics.
e.
determined by at most two genes.
13. The numerical calculation of the same trait in both members of a pair of twins is called
a.
concordance.
b.
recombination.
c.
monozygosity.
d.
multifactorial.
e.
polygenic.
14. Which of the following statements about obesity is true?
a.
Obesity is a complex disorder involving the interaction of many genes and the
environment.
b.
All humans suffering from obesity respond to leptin treatment.
c.
The gene for the weight-controlling hormone is called LEP.
d.
The ob mice lack receptors on their brain cells.
e.
All of the genes associated with obesity are found on the same chromosome.
15. Intelligence
a.
is a multifactorial trait.
b.
is easily measured.
c.
shows a very low concordance in MZ twins.
d.
is currently determined by the size of one’s head.
e.
is not influenced by environmental factors.
16. Scientists studying the genes controlling intelligence have
a.
studied humans.
b.
used animal models.
c.
used recombinant DNA techniques.
d.
found that Drosophila has biochemical pathways that are also found in humans.
e.
All of these are true.
Chapter 11 – Inheritance of Complex Traits
17. All of the following are considered components to cognitive ability EXCEPT
a.
size of the skull
b.
spatial abilities
c.
memory
d.
reasoning
e.
All of these are considered components of cognitive ability.
18. Which of the following statements about treatment rights is true in the U.S.?
a.
The patient can be forced to undergo treatment even if he or she does not want it.
b.
A pregnant woman cannot consent to or refuse medical treatment for her fetus.
c.
A parent can decide to donate his/her child’s organ under the law.
d.
Typically, if the person is younger (the age varies by state), his or her parents have to
provide consent for them.
e.
All of these are true.
19. The premise of an IQ test is that intelligence
a.
is an inherited trait that is influenced by environmental factors.
b.
is determined by a single gene.
c.
is determined entirely by the environment.
d.
cannot be expressed in a numerical form.
e.
None of these are correct.
20. In the case of complex traits,
a.
all of the genes involved are present on the same chromosome.
b.
at least three genes are involved.
c.
the phenotype is determined strictly by environmental factors.
d.
there can be a wide range of phenotypes.
e.
the trait is never influenced by environmental factors.
21. The threshold model has been proposed to explain situations in which
a.
a small number of genotypes can produce a wide range of phenotypes.
b.
a wide range of genotypes can produce a limited number of phenotypes.
c.
environmental factors only affect individuals.
d.
a simple trait can produce a wide range of phenotypes.
e.
environmental factors do not have an influence on phenotype.
TRUE/FALSE
1. Mutations in the VANGL1 gene have been associated with spina bifida.
2. There are four basic types of spina bifida.
3. Height is an example of a multifactorial trait.
4. Height does not follow a bell-shaped curve population distribution.
5. Spina bifida is a birth defect involving the nervous system.
6. Patients with spina bifida have been cured using gene therapy.
7. The percentage of adults in the United States who are overweight has increased rapidly in the last 30-
40 years.
8. Eye color and fingerprints are each determined by a single gene.
9. For pregnant females, diets deficient in folic acid have been shown to be a risk factor for spina bifida.
10. A gene associated with neural tube defects has been identified in mice, but not in humans.
11. Within a population, the typical distribution of a polygenic trait is a bell-shaped curve.
12. All humans suffering from obesity should respond to leptin treatment.
13. All complex traits exhibit a wide range of phenotypes.
Chapter 11 – Inheritance of Complex Traits
MATCHING
Match the appropriate terms with the descriptions. You may choose the same answer for more than
one question.
a.
multifactorial trait
b.
intelligence quotient
c.
concordance
d.
bell curve
e.
monozygotic twins
f.
developmental dyslexia
g.
spina bifida
h.
folic acid
1. Traits that involve interactions between genes and environmental factors
2. Problems with formation of the neural tube
3. The presence of the same trait in both members of a pair of twins
4. Often useful to study complex traits in humans
5. Human fingerprints
6. Associated with mutations in genes affecting intelligence
7. Numerical value derived after testing
8. Obesity in humans
9. Decreases risk factor for neural tube defects
ESSAY
1. If monozygotic twins demonstrate very high concordance for a trait whether they are raised together or
apart, what does this suggest about the heritability of this trait? Explain your answer.
2. Suppose a friend of yours referred to eye color, height, and intelligence as simple traits. How would
you explain the error to your friend? Why are these considered complex traits?
3. Explain why animal models are useful for investigating complex human traits. Provide examples
where research in animal models have led to subsequent findings in humans. What are some of the
issues with using animal models?
SHORT ANSWER
1. What is the difference between simple traits and complex traits? What are polygenic and multifactorial
traits?
2. MZ (monozygotic) twins are genetically identical; DZ (dizygotic) twins share about 50% of their
genes with each other. A study of 2,685 twin pairs showed that female MZ twins are six times more
likely than DZ twins to have a high concordance for alcoholism. All of the twin pairs were raised
together. What does this finding suggest about genetic and environmental components for alcoholism?
Explain your answer.
3. A particular trait shows a high concordance in MZ twins raised together but a lower concordance in
MZ twins raised apart. What do these results indicate about genetic and environmental components
controlling this trait?
4. Even though there are only two phenotypes for cleft palate (affected or unaffected), scientists know
that cleft palate is a multifactorial trait. Explain how this can be.