Exam 18: The Genetic and Environmental Basis of Complex Traits

The graph here shows the results of growing one strain of a crop plant in soils with different nitrogen contents. If a different strain of the same plant were grown in the same soils, you would predict that:

Name one drawback of personalized medicine, though the science behind it is sound.

In the graph of Galton's height data below, which line on the graph represents the average height of the parents in a mating?

Sometimes a fertilized egg, after a few of rounds of division, separates into two embryos that results in identical, or _____, twins.

Genetic mapping of inherited risk factors that code for metabolic components of complex traits, such as genes affecting sugar metabolism in the case of type 2I diabetes, sometimes implicates different genes affecting two or more of the traits that are close together in a chromosome. This finding can be explained by:

Consider a trait determined by a rare, simple Mendelian, autosomal dominant allele. What is the concordance between identical twins? Between same-sex fraternal twins?

The plots shown here depict several possible outcomes of an experiment comparing the mean phenotype of a behavioral trait in two strains of mice in three environments. Strain 1 is represented by filled circles and Strain 2 is represented by open circles. Environment 1 (E₁) is deficient in stimulation for the behavior, environment 2 (E₂) has an average level of stimulation, and environment 3 (E₃) is enriched in stimulation. Which of the possible results indicates the presence of genotype-by-environment interaction for one or both of the strains?

Down syndrome, the most common type of birth anomaly due to an extra chromosome, is also known as _____ 21.

Francis Galton, a contemporary of Charles Darwin, studied variation in complex traits such as human height. Use the bar graphs shown below to answer the following question: Which of the following statements BEST describes graph (a), which depicts Galton's data showing distribution of offspring height from the tallest parents he studied?

As many as two-thirds of the American population suffers from disorders determined by multiple genes and environmental factors.

The data in the table 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? Trait Identical twin concordance (\%) Same-sex fraternal twin concordance (\%) M 100 50 H 100 75 K 100 15 L 100 100 Q 100 25

Traits that are influenced by multiple genes and the environment are called _____ traits.

Which of the following birth anomalies are complex traits?

Traits such as human height, blood pressure, and blood sugar levels can be measured along a continuum and are often called _____ traits.

Which of the traits in the accompanying table has the GREATEST heritability? Trait Population mean Parental mean Offspring mean 100 120 100 100 120 105 100 120 110 100 120 115 100 120 120

According to the graph from Figure 18.10, shown below, which complex trait shows very little influence from a genetic component?

When heritability is 100%, the variation among individuals in the population is due to:

If genetically different strains of corn are grown in a greenhouse and subject to identical environmental conditions, then differences in height would be due to genetic differences and the heritability measure would:

Most human variation is due to _____ traits.

Francis Galton, a contemporary of Charles Darwin, studied variation in complex traits such as human height. Use the bar graphs shown below to answer the following question: Which of the following statements best describes Figure 18.7 graph (b), which depicts Galton's data showing distribution of offspring height from the shortest parents he studied?