Exam 4 Book Questions Flashcards
Briefly explain how the number of genes influencing a polygenic trait can be determined.
Cross two individuals that are each homozygous for different genes affecting the traits and then intercross the resulting F1progeny to produce the F2. Determine what proportion of the F2progeny resemble one of the original homozygotes in the P generation. This proportion should be(1/4)^n, wherenequals the number of loci with segregating pairs of alleles that affect the characteristic.
A geneticist is interested in whether asthma is caused by a mutation in the DS112 gene. The geneticist collects DNA from 120 people with asthma and 100 people without asthma, and she sequences the DNA. She finds that 35 of the people with asthma and none of those without it have a mutation in the DS112 gene. What is the population in this study?
A) The 120 people with asthma
B) The 100 people without asthma
C) The 35 people with a mutation in the DS112 gene
D) All people with asthma
D) All people with asthma
The measurements of a distribution with a higher ____________ will be more spread out.
A) mean
B) variance
C) standard deviation
D) variance and standard deviation
D) variance and standard deviation
In Lubbock, Texas, rainfall and temperature exhibit a significant correlation of −0.7. Which conclusion is correct?
A) There is usually more rainfall when the temperature is high.
B) There is usually more rainfall when the temperature is low.
C) Rainfall is equally likely when the temperature is high or low.
B) There is usually more rainfall when the temperature is low.
If the environmental variance (VE) increases and all other variance components remain the same, what will the effect be?
A) Broad-sense heritability will decrease.
B) Broad-sense heritability will increase.
C) Narrow-sense heritability will increase.
D) Broad-sense heritability will increase, but narrow-sense heritability will decrease.
A) Broad-sense heritability will decrease.
Suppose that you just learned that the narrow-sense heritability of blood pressure measured among a group of African Americans in Detroit, Michigan, is 0.4. What does this heritability tell you about genetic and environmental contributions to blood pressure?
It indicates that about 40% of the differences in blood pressure among African Americans in Detroit are due to additive genetic differences. It neither provides information about the heritability of blood pressure in other groups of people nor indicates anything about the nature of differences in blood pressure between African Americans in Detroit and people in other groups.
The narrow-sense heritability for a trait is 0.4 and the selection differential is 0.5. What is the predicted response to selection?
0.2
In a herd of dairy cattle, milk yield and the percentage of butterfat exhibit a genetic correlation of −0.38. If greater milk yield is selected in this herd, what will be the effect on the percentage of butterfat?
The percentage of butterfat will decrease.
What are some advantages of using allelic frequencies to describe the gene pool of a population over using genotypic frequencies?
There are fewer alleles than genotypes, so the gene pool can be described by fewer parameters when allelic frequencies are used. Additionally, the genotypes are temporary assemblages of alleles that break down each generation; the alleles are passed from generation to generation in sexually reproducing organisms.
Which of the following statements is not an assumption of the Hardy–Weinberg law?
A) The allelic frequencies (pandq) are equal.
B) The population is randomly mating.
C) The population is large.
D) Natural selection has no effect.
A) The allelic frequencies (pandq) are equal.
What is the expected frequency of heterozygotes in a population with allelic frequencies x and y that is in Hardy–Weinberg equilibrium?
A) x+y
B) xy
C) 2xy
D) (x−y)^2
C) 2xy
In cats, all-white color is dominant over colors other than all-white. In a population of 100 cats, 19 are all-white. Assuming that the population is in Hardy–Weinberg equilibrium, what is the frequency of the all-white allele in this population?
0.10
What is the effect of outcrossing on a population?
A) Allelic frequencies change.
B) There will be more heterozygotes than predicted by the Hardy–Weinberg law.
C) There will be fewer heterozygotes than predicted by the Hardy–Weinberg law.
D) Genotypic frequencies will equal those predicted by the Hardy–Weinberg law.
B) There will be more heterozygotes than predicted by the Hardy–Weinberg law.
When a population is in mutational equilibrium, which of the following is true?
A) The number of forward mutations is greater than the number of reverse mutations.
B) No forward or reverse mutations occur.
C) The number of forward mutations is equal to the number of reverse mutations.
D) The population is in Hardy–Weinberg equilibrium.
C) The number of forward mutations is equal to the number of reverse mutations.
In each generation, 10 random individuals migrate from population A to population B. What will happen to allelic frequency q as a result of migration when q is equal in populations A and B?
A) q in A will decrease.
B) q in B will increase.
C) q will not change in either A or B.
D) q in B will become q^2
C) q will not change in either A or B.
