Question 1

Which of the graphs below would likely represent the distribution of a complex trait?

Accepted Answer

A) graph A 
B) graph B 
C) graph C 
D) graph D 
A) graph A 
B) graph B 
C) graph C 
D) graph D A

Question 2

Twin studies have been used to assess the relative importance of "nature" versus "nurture" in determining variation among individuals for complex traits. Which of the following statements is TRUE?

Accepted Answer

A) Identical twins differ because of genotype and environment. 
B) Fraternal twins differ only because of environment. 
C) Twin studies show that autism and clinical depression are significantly influenced by genotype. 
D) The concordance of fraternal twins is greater than that of identical twins for most complex traits. 
E) Studies of fraternal twins compensate for environmental influences that may be stronger for identical twins compared to fraternal twins. 
A) Identical twins differ because of genotype and environment. 
B) Fraternal twins differ only because of environment. 
C) Twin studies show that autism and clinical depression are significantly influenced by genotype. 
D) The concordance of fraternal twins is greater than that of identical twins for most complex traits. 
E) Studies of fraternal twins compensate for environmental influences that may be stronger for identical twins compared to fraternal twins. C

Question 3

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

Accepted Answer

A) The offspring have a worse environment than the parents had. 
B) The offspring have a better environment than the parents had. 
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 other answer options is correct. 
A) The offspring have a worse environment than the parents had. 
B) The offspring have a better environment than the parents had. 
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 other answer options is correct. A

Question 4

If all of the variation in a trait in the population is due to differences in the environment, then the mean phenotype of the offspring would be independent of parental phenotype and would be identical to the mean phenotype of the population.

Accepted Answer

A) True 
 B)False

Question 5

Consider a trait determined entirely by three independently assorting genes with two alleles in which one allele is dominant over the other. As in the wheat seed color example illustrated in Figure 18.4, imagine that each dominant allele contributes one unit to the phenotype of the trait. Individuals with a phenotype of F1F1F1S1F1F1F10 4 are affected and all other phenotypes are not affected. What is the concordance between same-sex fraternal twins?

Accepted Answer

A) 11% 
B) 21% 
C) 34% 
D) 45% 
E) 57% 
A) 11% 
B) 21% 
C) 34% 
D) 45% 
E) 57%

Question 6

A key difference between single gene traits such as those Mendel studied and complex traits such as human height is that:

Accepted Answer

A) complex traits are generally not significantly influenced by the environment, whereas single gene traits have a significant environmental component. 
B) single gene traits are generally not significantly influenced by the environment, whereas complex traits have a significant environmental component. 
C) complex traits show incomplete dominance, whereas single gene traits show complete dominance. 
D) single gene traits show both complete and incomplete dominance, whereas complex traits show only complete dominance. 
E) None of the answer options is correct. 
A) complex traits are generally not significantly influenced by the environment, whereas single gene traits have a significant environmental component. 
B) single gene traits are generally not significantly influenced by the environment, whereas complex traits have a significant environmental component. 
C) complex traits show incomplete dominance, whereas single gene traits show complete dominance. 
D) single gene traits show both complete and incomplete dominance, whereas complex traits show only complete dominance. 
E) None of the answer options is correct.

Question 7

Which of the following statements is TRUE regarding height in humans?

Accepted Answer

A) The majority of genes affecting human height have already been identified. 
B) Genes implicated in human height have no other roles in the body. 
C) Additional gene studies will not likely identify any height-related genes in humans. 
D) Only about 15 genes are involved in determining the height of an individual. 
E) None of the answer options is correct. 
A) The majority of genes affecting human height have already been identified. 
B) Genes implicated in human height have no other roles in the body. 
C) Additional gene studies will not likely identify any height-related genes in humans. 
D) Only about 15 genes are involved in determining the height of an individual. 
E) None of the answer options is correct.

Question 8

After reviewing the graph below, one could state that:

Accepted Answer

A) grain yield of strain 1 is less dependent than strain 2 on the nitrogen enrichment of the soil. 
B) at a nitrogen enrichment of 40 kg/hectare, strain 2 provides a higher yield of grain. 
C) nitrogen enrichment has little effect on grain yield of strain 2. 
D) strain 1 is the superior choice for grain yield. 
E) no interaction effect is observed between nitrogen enrichment and grain yield for either strain. 
A) grain yield of strain 1 is less dependent than strain 2 on the nitrogen enrichment of the soil. 
B) at a nitrogen enrichment of 40 kg/hectare, strain 2 provides a higher yield of grain. 
C) nitrogen enrichment has little effect on grain yield of strain 2. 
D) strain 1 is the superior choice for grain yield. 
E) no interaction effect is observed between nitrogen enrichment and grain yield for either strain.

Question 9

When heritability is 100%, the environment plays:

Accepted Answer

A) no role in the expression of the trait. 
B) a role in the expression of a trait, but it is a small one. 
C) a role in the expression of a trait, but it cannot be measured. 
D) no role in variation in the trait among individuals. 
E) a role in variation in the trait among individuals, but it cannot be measured. 
A) no role in the expression of the trait. 
B) a role in the expression of a trait, but it is a small one. 
C) a role in the expression of a trait, but it cannot be measured. 
D) no role in variation in the trait among individuals. 
E) a role in variation in the trait among individuals, but it cannot be measured.

Question 10

A small difference between the concordance rates seen in fraternal and identical suggests that:

Accepted Answer

A) variation due to genotype is far more important than variation due to environment. 
B) variation due to genotype is far less important than variation due to environment. 
C) variation due to genotype is about equally as important as that due to environment. 
D) the trait is probably due to a single gene that shows Mendelian inheritance patterns. 
E) the genes affecting the trait interact strongly with the environment. 
A) variation due to genotype is far more important than variation due to environment. 
B) variation due to genotype is far less important than variation due to environment. 
C) variation due to genotype is about equally as important as that due to environment. 
D) the trait is probably due to a single gene that shows Mendelian inheritance patterns. 
E) the genes affecting the trait interact strongly with the environment.

Question 11

In a study of concordance, a sample of identical twins was evaluated for adult-onset diabetes. The data below were collected for this trait:
1. In 36 identical twin pairs, both showed adult-onset diabetes.
2. In 40 identical twin pairs, only one showed adult-onset diabetes.
3. In 336 identical twin pairs, neither showed adult-onset diabetes.
The data above imply that the environment is not an important component of adult-onset diabetes.

Accepted Answer

A) True 
 B)False

Question 12

_____ of a trait in a population is the proportion of the total variation in the trait (phenotypic variation) that is due to genetic differences among individuals.

Accepted Answer

A) Heritability 
B) Regression 
C) Complexity 
D) Similarity 
E) Genetics 
A) Heritability 
B) Regression 
C) Complexity 
D) Similarity 
E) Genetics

Question 13

If genetically identical strains of corn are grown in different environments, then differences in height would be due to the environment and the heritability measure would:

Accepted Answer

A) be 100%. 
B) be 0%. 
C) indicate that the environment has no effect on inheritance of the trait. 
D) indicate that the genotypic differences have no effect on the inheritance of the trait. 
E) None of the answer options is correct. 
A) be 100%. 
B) be 0%. 
C) indicate that the environment has no effect on inheritance of the trait. 
D) indicate that the genotypic differences have no effect on the inheritance of the trait. 
E) None of the answer options is correct.

Question 14

In a study of concordance, a sample of identical twins was evaluated for adult-onset diabetes. The data below were collected for this trait:
1. In 36 identical twin pairs, both showed adult-onset diabetes.
2. In 40 identical twin pairs, only one showed adult-onset diabetes.
3. In 336 identical twin pairs, neither showed adult-onset diabetes.
The concordance for adult-onset diabetes among fraternal twins is 10%. Thus, this trait is not likely to have a strong genetic component.

Accepted Answer

A) True 
 B)False

Question 15

Pleiotropy refers to:

Accepted Answer

A) the interaction of two genes affecting a single trait. 
B) the interaction of multiple genes affecting multiple traits. 
C) the interaction of multiple genes affecting a single trait. 
D) a single gene having multiple effects. 
E) two different norms of reaction for a single trait. 
A) the interaction of two genes affecting a single trait. 
B) the interaction of multiple genes affecting multiple traits. 
C) the interaction of multiple genes affecting a single trait. 
D) a single gene having multiple effects. 
E) two different norms of reaction for a single trait.

Question 16

Comparisons of traits in identical and fraternal twins are useful because they:

Accepted Answer

A) allow estimates of the number of genes affecting a complex trait. 
B) reveal the extent of genotype-by-environment interaction in causing phenotypic variation. 
C) reveal the relative importance of genes and environment in causing phenotypic variation. 
D) None of the answer options is correct. 
A) allow estimates of the number of genes affecting a complex trait. 
B) reveal the extent of genotype-by-environment interaction in causing phenotypic variation. 
C) reveal the relative importance of genes and environment in causing phenotypic variation. 
D) None of the answer options is correct.

Question 17

Heritability in nonscientific terms means "the capability of being inherited or being passed on by inheritance"; this is an accurate description of the inheritance of a complex trait.

Accepted Answer

A) True 
 B)False

Question 18

Of the students in your class, 95% are between 140 cm and 180 cm tall. Assuming that these data are normally distributed, what is the mean height of the students?

Accepted Answer

A) 140 cm 
B) 150 cm 
C) 160 cm 
D) 170 cm 
E) 180 cm 
A) 140 cm 
B) 150 cm 
C) 160 cm 
D) 170 cm 
E) 180 cm

Question 19

If the concordance rate between identical twins is less than 100 %, what does this imply?

Accepted Answer

A) Concordance rates are difficult for researchers to calculate; a lack of 100% concordance reflects experimental error. 
B) Concordance rates are estimates and can be only measured if one of the twins shows the trait. 
C) Concordance rates less than 100% reflect environmental effects on the trait. 
D) Concordance rates are estimates of genetic influence only. 
A) Concordance rates are difficult for researchers to calculate; a lack of 100% concordance reflects experimental error. 
B) Concordance rates are estimates and can be only measured if one of the twins shows the trait. 
C) Concordance rates less than 100% reflect environmental effects on the trait. 
D) Concordance rates are estimates of genetic influence only.

Question 20

One hope of personalized medicine is that:

Accepted Answer

A) physicians will be able to use an individual's genotype to identify the most effective medication for that patient. 
B) physicians will be able to use an individual's lifestyle factors to identify the most effective medication for that patient. 
C) it will lead to treatments that are more widely useful across genotypes. 
D) it will lead to medications with fewer side-effects. 
E) it will lead to preventative treatments for diseases for which each individual is uniquely at risk. 
A) physicians will be able to use an individual's genotype to identify the most effective medication for that patient. 
B) physicians will be able to use an individual's lifestyle factors to identify the most effective medication for that patient. 
C) it will lead to treatments that are more widely useful across genotypes. 
D) it will lead to medications with fewer side-effects. 
E) it will lead to preventative treatments for diseases for which each individual is uniquely at risk.

Exam 18: The Genetic and Environmental Basis of Complex Traits

Which of the graphs below would likely represent the distribution of a complex trait?

Twin studies have been used to assess the relative importance of "nature" versus "nurture" in determining variation among individuals for complex traits. Which of the following statements is TRUE?

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

If all of the variation in a trait in the population is due to differences in the environment, then the mean phenotype of the offspring would be independent of parental phenotype and would be identical to the mean phenotype of the population.

A key difference between single gene traits such as those Mendel studied and complex traits such as human height is that:

Which of the following statements is TRUE regarding height in humans?

After reviewing the graph below, one could state that:

When heritability is 100%, the environment plays:

A small difference between the concordance rates seen in fraternal and identical suggests that:

_____ of a trait in a population is the proportion of the total variation in the trait (phenotypic variation) that is due to genetic differences among individuals.

If genetically identical strains of corn are grown in different environments, then differences in height would be due to the environment and the heritability measure would:

Pleiotropy refers to:

Comparisons of traits in identical and fraternal twins are useful because they:

Heritability in nonscientific terms means "the capability of being inherited or being passed on by inheritance"; this is an accurate description of the inheritance of a complex trait.

Of the students in your class, 95% are between 140 cm and 180 cm tall. Assuming that these data are normally distributed, what is the mean height of the students?

If the concordance rate between identical twins is less than 100 %, what does this imply?

One hope of personalized medicine is that:

Life: Chemical, Cellular, and Evolutionary Foundations

The Molecules of Life

Nucleic Acids and Transcription

Translation and Protein Structure

Organizing Principles: Lipids, Membranes, and Cell Compartments

Making Life Work: Capturing and Using Energy

Cellular Respiration: Harvesting Energy From Carbohydrates and Other Fuel Molecules

Photosynthesis: Using Sunlight to Build Carbohydrates

Cell Signaling

Cell and Tissue Architecture: Cytoskeleton, Cell Junctions, and Extracellular Matrix

Cell Division: Variations, Regulation, and Cancer

Dna Replication and Manipulation

Genomes

Mutation and Dna Repair

Genetic Variation

Mendelian Inheritance

Inheritance of Sex Chromosomes, Linked Genes, and Organelles

Genetic and Epigenetic Regulation

Genes and Development

Evolution: How Genotypes and Phenotypes Change Over Time

Species and Speciation

Evolutionary Patterns: Phylogeny and Fossils

Human Origins and Evolution

Cycling Carbon

Bacteria and Archaea

Eukaryotic Cells: Origins and Diversity

Being Multicellular

Plant Structure and Function: Moving Photosynthesis Onto Land

Plant Reproduction: Finding Mates and Dispersing Young

Plant Growth and Development

Plant Defense: Keeping the World Green

Plant Diversity

Fungi: Structure, Function, and Diversity

Animal Nervous Systems

Animal Sensory Systems and Brain Function

Animal Movement: Muscles and Skeletons

Animal Endocrine Systems

Animal Cardiovascular and Respiratory Systems

Animal Metabolism, Nutrition, and Digestion

Animal Renal Systems: Water and Waste

Animal Reproduction and Development

Animal Immune Systems

Animal Diversity

Animal Behavior

Population Ecology

Species Interactions, Communities, and Ecosystems

Biomes and Global Ecology

The Anthropocene: Humans As a Planetary Force

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