Deck 20: Genetic Analysis of Quantitative Traits

Question 1

If an X- linked recessive trait has a frequency of 5% in males, what percentage of females are carriers? (Assume that the population is in Hardy- Weinberg equilibrium.)

A) 9.5%
B) 4.2%
C) 5%
D) 10%
E) 95%

Answer 1

A

Question 2

Mexican hairless dogs are heterozygous (Hh), carrying a single copy of the lethal allele. In a given population, the Hh genotypic frequency is 60% and the frequency of each homozygote is 20%. Assuming w = 1 for the Hh and hh dogs, what is the estimated genotypic frequency of the lethal HH genotype after reproduction?

A) 46%
B) 10%
C) 14%
D) 39%
E) 20%

Answer 2

C

Question 3

Given the following genetic profile, what is the mean fitness of the population? $$\begin{array} { l l l l } \text { Genotype } & A 1 A 1 & A 1 A 2 & A 2 A 2 \\\text { Frequency } & 0.55 & 0.20 & 0.25 \\\text { Number } & 2750 & 1000 & 1250 \\\text { Relative fitness } ( w ) & 1.0 & 0.75 & 0.50\end{array}$$

A) 1
B) 0.3025
C) 0.825
D) 0.75
E) 0.55

Answer 3

0.825

Question 4

You are studying ABO blood groups, and know that 6.25% of the population has genotype IAIA and 42.25% of the population has Type O blood. What is the expected frequency of blood type B?

A) 14%
B) 6.5%
C) 51.5%
D) 13%
E) 1%

Question 5

You want to calculate the frequency of the allele causing sickle cell disease in your patients, and you know the genotypes of every individual. Assuming the population is not in Hardy- Weinberg equilibrium due to population substructure, which method can be used to calculate allele frequency?

A) genotype proportion method
B) binomial expansion
C) chi- square test
D) allele- counting method
E) square root method

Question 6

During a University of Nevada, Reno blood donation campaign, the frequencies of alleles determining the ABO blood groups were 0.70 for i, 0.2 for IA and 0.1 for IB. Assuming random mating, what is the expected frequency of blood type B?

A) 0.49
B) 0.18
C) 0.04
D) 0.32
E) 0.15

Question 7

Which aspect of population genetics can lead to changes in allele frequencies in a new mixed population following migration?

A) founder effect
B) mutation
C) gene flow
D) natural selection
E) bottleneck effect

Question 8

The incidence of phenylketonuria (PKU), an autosomal recessive genetic disorder, is approximately 1 in 4,500 in Ireland. Assuming Hardy- Weinberg equilibrium, what is the probability that a phenotypically normal Irish female, with no family history, and a phenotypically normal Irish male, with an affected sister, will have a child with PKU?

A) 0.028%
B) 0.49%
C) 1.96%
D) 0.55%
E) 2.2%

Question 9

Jeffrey Pines from Mt. Rose were genotyped at a resistance gene for a type of fungi that affects pines. Genotypes of 1000 of these Jeffrey Pines were: 300 R1R1, 500 R1R2, and 200 R2R2. Use a chi- square (ç2) test to determine if this population is in Hardy- Weinberg equilibrium? The critical chi- square value at P=.05 for 1 degree of freedom is 3.84.

A) 0.10; fail to reject
B) 10; fail to reject
C) 0.10; reject
D) 10; reject
E) 37.5; reject

Question 10

Data for an autosomal recessive trait shows that heterozygous individuals have the highest relative fitness. Those who are unaffected and homozygous for the dominant A allele have a relative fitness of 84% compared to heterozygous individuals, but only about 30% of those who are affected survived to reproduce. What is the estimated equilibrium frequency for allele A in this population?

A) 0.700
B) 0.160
C) 0.186
D) 0.814
E) 0.357

Question 11

The incidence of Tay Sachs, an autosomal recessive genetic disorder, is approximately 1 in 3,500 in a certain population of Ashkenazi Jews. Assuming Hardy- Weinberg equilibrium, what is the frequency of carriers for the Tay Sachs allele in this population?

A) 3.3%
B) 98.5%
C) 1.5%
D) 2.9%
E) 1.7%

Question 12

All Old Order Amish families from Lancaster County with Ellis- van Creveld syndrome can trace their genealogies to Mr. and Mrs. Samuel King, who immigrated to Lancaster County in 1744. This is an example of .

A) Hardy- Weinberg equilibrium
B) founder effect
C) mutation
D) gene flow
E) bottleneck effect

Question 13

Phenylketonuria (PKU) is extremely common in Ireland, affecting approximately 1 in 4500 live births. Assuming that the population is in Hardy- Weinberg equilibrium, what is the frequency of PKU carriers?

A) 2.9%
B) 1.49%
C) 2.2%
D) 98.5%
E) 0.022%

Question 14

In an insect species, survival in agricultural fields regularly sprayed with insecticide is determined by the genotype for a detoxification enzyme encoded by a gene with two alleles, A and D. Which of the following statements is consistent with the data? $$\begin{array} { | l | l | } \hline \text { Genotype } & \text { Relative Fitness } \\\hline \mathrm { AA } & 1.00 \\\hline \mathrm { AD } & 0.70 \\\hline \mathrm { OD } & 0.05 \\\hline\end{array}$$

A) Directional selection will increase the frequency of the A allele at a pace determined by the intensity of natural selection.
B) The D allele frequency will change faster as it gets less frequent.
C) Eventually, natural selection should lead to a balanced polymorphism.
D) This will likely lead to the frequency of the A allele being eliminated (f=0.0) and the D allele being fixed (f=1.0).
E) Both the A and D alleles should reach stable equilibrium frequencies that are maintained in a steady state.

Question 15

Researchers collect data on an island population of frogs and find a mutation rate of the recessive allele, d, is 1 × 10- 6. The relative fitness of the individuals homozygous from this allele is 0.7. What is the allele frequency of this recessive allele at equilibrium?

A) 3.0 × 10- 7
B) 1.4 × 10- 6
C) 7.0 × 10- 7
D) 1.2 × 10- 3
E) 1.8 × 10- 3

Question 16

In a theoretical population where f (A1) = 0.95 and f (A2) = 0.05, µ = 1 × 10- 6, and v = 1 × 10- 7, what is Oq?

A) 5.26 × 10- 3
B) 9.55 × 10- 7
C) 9.45 × 10- 7
D) 5.00 × 10- 9
E) 9.50 × 10- 7

Question 17

A researcher is studying a newly discovered gene that causes increased body weight in domesticated chickens. In a mainland population, the frequency of the A1 allele is 0.2, for this gene with two alleles. If 100 of these mainland chicken are transported on a ship to an isolated island with a population of 200 A1A1 chickens, 400 A1A2 chickens, and 400 A2A2 chickens, what would the frequency of the A1 allele in the admixed population?

A) 0.764
B) 0.618
C) 0.745
D) 0.236
E) 0.382

Question 18

The incidence of Tay- Sachs, an autosomal recessive genetic disorder, is approximately 1 in 3,500 in a certain population of Ashkenazi Jews. Assuming that this population is in Hardy- Weinberg equilibrium, what is the probability that a phenotypically normal female, with no family history, and a phenotypically normal male, who had an affected sister, will have a child with Tay- Sachs?

A) 1.96%
B) 0.028%
C) 0.55%
D) 2.2%
E) 0.49%

Question 19

In a group of 500 people, the frequency of genotype NN is 40%. Assuming both autosomal inheritance and that the population is in Hardy- Weinberg equilibrium, how many individuals would you expect to have the MN genotype?

A) 68
B) 300
C) 200
D) 258
E) 232

Question 20

In the same population of patients you examined for sickle cell allele frequencies, you now want to test whether the disease symptoms are related to blood type. Since blood type is a codominant trait and the alleles are easily identifiable by the phenotype (blood type) of the individuals, which method is most helpful for identifying blood type allele frequency?

A) square root method
B) chi- square test
C) genotype proportion method
D) allele- counting method
E) binomial expansion

Question 21

Physical separation of a segment of a large population by a physical barrier that prevents gene flow can lead to .

A) hybrid sterility
B) gene flow
C) temporal isolation
D) sympatric speciation
E) allopatric speciation

Question 22

Both the founder effect and the bottleneck effect are mechanisms that produce large allele frequency sampling errors in a small population due to .

A) genetic drift
B) gene flow
C) random mating
D) random mutation
E) lethal alleles

Question 23

What is the consequence of natural selection favoring the heterozygous genotype (as exhibited by the sickle cell allele in malaria- prone regions), in which alleles reach stable equilibrium frequencies that are maintained by the ongoing action of selection against the homozygous genotypes?

Question 24

When looking at the MN blood group with two alleles, how many degrees of freedom will be used to compare observed versus expected results?

Question 25

Which mechanism maintains the biological ability of populations to interbreed and can thus prevent evolutionary divergence of populations?

Question 26

What is the ultimate source of genetic variation in populations?

Question 27

The coefficient of inbreeding (F) can be used to estimate the proportion of loci that are .

A) fixed in a population
B) lethal alleles
C) recessive
D) homozygous identical by descent
E) heterozygous by descent

Question 28

When populations share a single habitat but are isolated by genetic or postzygotic mechanisms that prevent gene flow, what process can cause populations to diverge?

A) random mating
B) gene duplication
C) allopatric speciation
D) sympatric speciation
E) random mutation

Question 29

The process by which an original species is transformed into a new species over an extended period of time that spans many generations is known as .

A) morphogenesis
B) founder effect
C) anagenesis
D) neogenesis
E) cladogenesis

Question 30

Given the following pedigree, what is the coefficient of inbreeding for individual G?
Use Key Analytic Tool pedigree in Chapter 20, page 402 from SGSM

A) 1/32
B) 1/8
C) 1/4
D) 1/16
E) 1/64

Question 31

Of the five aspects of Hardy- Weinberg equilibrium, which one directly affects phenotypic frequencies rather than genotypic frequencies?

Question 32

If the relative fitness value is w = 0.6, what is the selection coefficient used to identify the differences between the fitnesses of organisms with different traits?

Question 33

What type of statistical analysis is used to compare observed and expected results in order to evaluate the validity of an estimate based on the Hardy- Weinberg equilibrium?

Question 34

When examining the effects of forward and reverse mutation rates, what equation is used to calculate the change in the frequency of A2, or Oq?

Question 35

Which of the following is an example of a postzygotic mechanism for reproductive isolation?

A) behavioral isolation
B) hybrid sterility
C) habitat separation
D) gametic isolation
E) mechanical isolation

Question 36

Cheetahs exhibit significant inbreeding and loss of heterozygosity due to overhunting and loss of habitat experienced at some point in their evolutionary history. Which genetic mechanism occurs when a large population is substantially reduced at random, acting independently of natural selection?

A) founder effect
B) Hardy- Weinberg equilibrium
C) gene flow
D) mutation
E) bottleneck effect

Question 37

A difference in allelic frequencies that is produced when a new population is established by a few individuals is known as what type of genetic drift?

Question 38

What is a common type of nonrandom mating?

Question 39

If the frequency of PKU, an autosomal recessive disease, is 1% in males, what is the frequency of females with PKU? (You may assume that the population is in
Hardy- Weinberg equilibrium.)

Question 40

How would you calculate the coefficient of inbreeding for individual IV- 1 in the pedigree below?

A) F= 2(1/2)3
B) F= 4(1/2)2
C) F= 2(1/2)2
D) F= 2(1/2)4
E) F= 4(1/2)3

Question 41

The coefficient of inbreeding quantifies the probability that two alleles in a homozygous individual are _ _, having descended from the same copy of the allele carried by a common ancestor of the inbred individual.

Question 42

is an evolutionary mechanism that favors the reproductive success of certain members of a population over others as a result of differences in anatomical, physiological, or behavioral traits they possess.

Question 43

Draw a pedigree for an inbreeding coefficient of F= 2(1/2)4.

Question 44

In an island population, the frequencies of the three MN blood types are given here:
M: 550
MN: 725
N: 225
a. Calculate the allele frequency of M and N.
b. Assuming random mating, what are the expected frequencies for each blood type?
c. Use chi- square analysis to test your hypothesis that mating is random for this population.

Question 45

What type of geographic separation resulted in diversification of an ancestral species of ground squirrel into two species, Ammospermophilus leucurus, found on the north rim of the Grand Canyon, and members of the Ammospermophilus harrisii on the south rim of the canyon?

Question 46

What are the three key elements for determining F, a measure that a particular allele is IBD, using pedigree analysis?

Question 47

Explain why rare recessive alleles are more likely to produce a recessive phenotype as a result of inbreeding.

Question 48

In the pattern of natural selection called the favored phenotype has a homozygous genotype, while the consequence of natural selection favoring the heterozygote is a balanced polymorphism.

Question 49

Inbreeding depression, the reduction in fitness of inbred organisms, often results from the reduced level of what (within the gene pool)?

Question 50

Burkitt's lymphoma is a cancer of the lymphatic system that is more common in individuals who are homozygous þAþA that succumb more easily to malaria. þSþS individuals suffer from anemia. þAþS have the highest relative fitness. Resistance to malaria and Burkitt's lymphoma are both an example of advantage.

Question 51

In the general population, 1 in 300 individuals is a carrier for Tay- Sachs disease, while 1 in 30 individuals of Ashkenazi Jew descent are carriers. Tay- Sachs also affects 1 in 30 individuals with French- Canadian ancestry, although two completely unique mutations are responsible for the Ashkenazi and French- Canadian mutations.
What are the chances of two individuals who are carriers having a child with Tay- Sachs if
a. both individuals are not of Ashkenazi or French- Canadian descent?
b. one individual is of Ashkenazi descent and the other is from the general population?
c. both individuals are of Ashkenazi descent?

Question 52

Using the allele frequencies in the table below, what is the probability that a random person would be heterozygous 12/14 for VAW?

Question 53

The pattern of species evolution known as is one of branching in which an ancestral species gives rise to two or more new species.

Question 54

Using the allele frequencies in the table below, what is the probability that a random person is heterozygous 12/14 for VAW and homozygous 18/18 for FAG? (Assume that the two loci are unlinked.)