Question 1

Inbred lines of animals, such as laboratory mice, are useful for studying complex traits because:

Accepted Answer

A)  individuals are genetically identical, so differences in traits must be due to environmental differences.
B)  although individuals differ both genetically and environmentally, the genetic differences are known, so differences in traits can be understood.
C)  animals are kept in identical environments, so any differences in traits are due to differences in their genes.
D)  both genetic and environmental differences between individuals are known, making differences in their traits easy to understand.
E)  None of the answer options is correct.F) A) and E)
G) D) and E)

Question 2

A new mutation arises that affects a complex trait. In most cases, its effect is likely to be:

Accepted Answer

A)  small.
B)  medium.
C)  large.D) All of the above
E) B) and C)

Question 3

One hope of personalized medicine is that:

Accepted Answer

A)  physicians will be able to use an individual's genotype to avoid harmful side-effects of some medications.
B)  physicians will be able to use an individual's lifestyle factors to moderate harmful side-effects of medication.
C)  it will lead to medications with fewer side-effects.
D)  physicians will be able to use an individual's lifestyle factors to identify preventative medicines that have minimal side-effects.
E)  individuals will receive preventative medications for diseases they have not yet contracted.F) None of the above
G) B) and C)

Question 4

Consider a trait determined by a rare mutation in the Y chromosome. What is the concordance between male twins? Between fraternal twins that are both male?

Accepted Answer

A)  identical concordance = 1; fraternal concordance = 0
B)  identical concordance = 1; fraternal concordance = 1/4
C)  identical concordance = 1; fraternal concordance = 1/2
D)  identical concordance = 1; fraternal concordance = 3/4
E)  identical concordance = 1; fraternal concordance = 1F) A) and E)
G) B) and C)

Question 5

In a parent-offspring regression experiment, suggest a hypothesis that could explain the solid line in the following graph.

Accepted Answer

A)  The offspring have a "worse" environment than the parents did.
B)  The offspring have a "better" environment than the parents did.
C)  The trait has a heritability that is less than 0.
D)  The trait has a heritability that is greater than 1.
E)  None of the answer options is correct.F) B) and E)
G) A) and D)

Question 6

Environmental effects have no impact on true-breeding, homozygous strains (inbred lines) of plants or animals.

Accepted Answer

A) True 
 B)False

Question 7

In regard to gaining weight, some human genotypes may tolerate a high-fat diet more than others.

Accepted Answer

A) True 
 B)False

Question 8

Lack of exercise is an example of a(n)  _____ for/of obesity and diabetes.

Accepted Answer

A)  complex trait
B)  quantitative trait
C)  cause
D)  environmental risk factor
E)  genetic risk factorF) C) and D)
G) A) and B)

Question 9

Using identical twins to study heritability is complicated by the fact that:

Accepted Answer

A)  identical twins often experience identical uterine environments, whereas fraternal twins do not.
B)  identical twins are often treated more similarly to one another than are fraternal twins.
C)  fraternal twins often share the same uterine environment, whereas identical twins do not.
D)  identical twins often experience a more similar uterine environment and more similar treatment during childhood than do fraternal twins.
E)  even identical twins are sometimes genetically different from one another.F) B) and D)
G) A) and C)

Question 10

Current evidence BEST supports which statement about the relative number of genes and their effects in most complex traits?

Accepted Answer

A)  Few genes affecting a complex trait have a small effect, more have a middling effect, and most have a large effect.
B)  Few genes affecting a complex trait have a small effect, most have a middling effect, and some have a large effect.
C)  Some genes affecting a complex trait have a small effect, few have a middling effect, and most have a large effect.
D)  Some genes affecting a complex trait have a small effect, most have a middling effect, and few have a large effect.
E)  Most genes affecting a complex trait have a small effect, some have a middling effect, and few have a large effect.F) C) and D)
G) A) and E)

Question 11

In general, the phenotypes of a complex trait should exhibit a(n)  _____ distribution.

Accepted Answer

A)  complex
B)  normal
C)  skewed
D)  inverted
E)  bimodalF) None of the above
G) A) and D)

Question 12

Which of the traits depicted here has the GREATEST heritability?

Accepted Answer

A)  trait M
B)  trait H
C)  trait K
D)  trait LE) All of the above
F) None of the above

Question 13

One day, scientists will be able to cure obesity by targeting a single gene.

Accepted Answer

A) True 
 B)False

Question 14

The data in the graph below show the concordance between identical twins and same-sex fraternal twins for five complex traits. Based on these data, which of the traits shows the GREATEST effect of heredity relative to environment?

Accepted Answer

A)  trait M
B)  trait H
C)  trait K
D)  trait L
E)  trait QF) A) and E)
G) C) and D)

Question 15

If all variation among individuals in a population is due to differing genotypes alone, heritability is _____, and the slope of the line used to measure it is _____.

Accepted Answer

A)  100%; 0.5
B)  100%; 1
C)  50%; 0.5
D)  50%; 1
E)  0%; 0F) C) and E)
G) A) and C)

Question 16

Although more than 50 genes contribute to the level of HDL (high-density lipoproteins) , LDL (low-density lipoproteins) , or triglycerides, it has also been shown that a single gene within this population of genes can affect two or three of these types of molecules. This single gene with its multiple effects is said to show:

Accepted Answer

A)  pleiotropy.
B)  unitropy.
C)  trisomy.
D)  zygotropy.
E)  epidomy.F) All of the above
G) D) and E)

Question 17

When considering complex traits in health and disease, which of the following statements is NOT correct?

Accepted Answer

A)  Diabetes, high blood pressure, asthma, epilepsy, schizophrenia, and clinical depression are all complex traits.
B)  Cystic fibrosis, sickle-cell anemia, and phenylketonuria are simple Mendelian disorders.
C)  The majority of birth anomalies result only from genetic risk factors.
D)  Many genes that contribute to complex traits are clustered on the same chromosome.
E)  Many genes that contribute to complex traits arose through the process of duplication of a single gene followed by divergence over time, generating a family of genes near one another with related functions.F) A) and B)
G) A) and C)

Question 18

Consider a trait determined entirely by environmental risk factors for which the chance that a random individual is affected is 20%. What is the concordance between identical twins? What is the concordance between same-sex fraternal twins?

Accepted Answer

A)  identical concordance = 1.0; fraternal concordance = 0.125
B)  identical concordance = 0.125; fraternal concordance = 0.125
C)  identical concordance = 0.125; fraternal concordance = 0.111
D)  identical concordance = 0.111; fraternal concordance = 0.111
E)  None of the answer options is correct.F) A) and E)
G) C) and D)

Question 19

When identical twins differ in phenotype of a complex trait, it is almost always due to:

Accepted Answer

A)  mutation.
B)  segregation.
C)  epistasis.
D)  genotype-by-environment interaction.
E)  the environment.F) A) and B)
G) None of the above

Question 20

In twin studies, scientists measure concordance, which is defined as the:

Accepted Answer

A)  extent to which variation in phenotype in a population is due to variation in genotype.
B)  percentage of cases in which both members of a pair of twins show the trait when at least one member shows it.
C)  percentage of cases in which both members of a pair of identical twins, but not fraternal twins, show the trait when at least one member shows it.
D)  percentage of cases in which both members of a pair of fraternal twins, but not identical twins, show the trait when at least one member shows it.
E)  extent to which differences in the environment influences differences in phenotype.F) A) and B)
G) B) and E)

Exam 18: The Genetic and Environmental Basis of Complex Traits

Consider a trait determined by a rare mutation in the Y chromosome. What is the concordance between male twins? Between fraternal twins that are both male?

Correct Answer
verified

In general, the phenotypes of a complex trait should exhibit a(n) _____ distribution.

Correct Answer
verified

One hope of personalized medicine is that:

Correct Answer
verified

When identical twins differ in phenotype of a complex trait, it is almost always due to:

Correct Answer
verified

Which of the traits depicted here has the GREATEST heritability?

Correct Answer
verified

Lack of exercise is an example of a(n) _____ for/of obesity and diabetes.

Correct Answer
verified

Environmental effects have no impact on true-breeding, homozygous strains (inbred lines) of plants or animals.

Correct Answer
verified

In twin studies, scientists measure concordance, which is defined as the:

Correct Answer
verified

If all variation among individuals in a population is due to differing genotypes alone, heritability is _, and the slope of the line used to measure it is _.

Correct Answer
verified

Inbred lines of animals, such as laboratory mice, are useful for studying complex traits because:

Correct Answer
verified

Correct Answer
verified

In a parent-offspring regression experiment, suggest a hypothesis that could explain the solid line in the following graph.

Correct Answer
verified

One day, scientists will be able to cure obesity by targeting a single gene.

Correct Answer
verified

A new mutation arises that affects a complex trait. In most cases, its effect is likely to be:

Correct Answer
verified

Current evidence BEST supports which statement about the relative number of genes and their effects in most complex traits?

Correct Answer
verified

In regard to gaining weight, some human genotypes may tolerate a high-fat diet more than others.

Correct Answer
verified

Using identical twins to study heritability is complicated by the fact that:

Correct Answer
verified

The data in the graph below show the concordance between identical twins and same-sex fraternal twins for five complex traits. Based on these data, which of the traits shows the GREATEST effect of heredity relative to environment?

Correct Answer
verified

When considering complex traits in health and disease, which of the following statements is NOT correct?

Correct Answer
verified

Consider a trait determined entirely by environmental risk factors for which the chance that a random individual is affected is 20%. What is the concordance between identical twins? What is the concordance between same-sex fraternal twins?

Correct Answer
verified

Exam 18: The Genetic and Environmental Basis of Complex Traits

Consider a trait determined by a rare mutation in the Y chromosome. What is the concordance between male twins? Between fraternal twins that are both male?

Correct AnswerverifiedShow Answer

In general, the phenotypes of a complex trait should exhibit a(n) _____ distribution.

Correct AnswerverifiedShow Answer

One hope of personalized medicine is that:

Correct AnswerverifiedShow Answer

When identical twins differ in phenotype of a complex trait, it is almost always due to:

Correct AnswerverifiedShow Answer

Which of the traits depicted here has the GREATEST heritability?

Correct AnswerverifiedShow Answer

Lack of exercise is an example of a(n) _____ for/of obesity and diabetes.

Correct AnswerverifiedShow Answer

Environmental effects have no impact on true-breeding, homozygous strains (inbred lines) of plants or animals.

Correct AnswerverifiedShow Answer

In twin studies, scientists measure concordance, which is defined as the:

Correct AnswerverifiedShow Answer

If all variation among individuals in a population is due to differing genotypes alone, heritability is _____, and the slope of the line used to measure it is _____.

Correct AnswerverifiedShow Answer

Inbred lines of animals, such as laboratory mice, are useful for studying complex traits because:

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

In a parent-offspring regression experiment, suggest a hypothesis that could explain the solid line in the following graph.

Correct AnswerverifiedShow Answer

One day, scientists will be able to cure obesity by targeting a single gene.

Correct AnswerverifiedShow Answer

A new mutation arises that affects a complex trait. In most cases, its effect is likely to be:

Correct AnswerverifiedShow Answer

Current evidence BEST supports which statement about the relative number of genes and their effects in most complex traits?

Correct AnswerverifiedShow Answer

In regard to gaining weight, some human genotypes may tolerate a high-fat diet more than others.

Correct AnswerverifiedShow Answer

Using identical twins to study heritability is complicated by the fact that:

Correct AnswerverifiedShow Answer

The data in the graph below show the concordance between identical twins and same-sex fraternal twins for five complex traits. Based on these data, which of the traits shows the GREATEST effect of heredity relative to environment?

Correct AnswerverifiedShow Answer

When considering complex traits in health and disease, which of the following statements is NOT correct?

Correct AnswerverifiedShow Answer

Consider a trait determined entirely by environmental risk factors for which the chance that a random individual is affected is 20%. What is the concordance between identical twins? What is the concordance between same-sex fraternal twins?

Correct AnswerverifiedShow Answer

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If all variation among individuals in a population is due to differing genotypes alone, heritability is _, and the slope of the line used to measure it is _.

Correct Answer
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