Deck 22: Population Genetics and Evolution

Question 1

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

Answer 1

E

Question 2

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

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

Answer 2

B

Question 3

In a group of 500 people,the frequency of genotype NN is 40%.How many individuals would you expect to have the MN genotype?

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

Answer 3

B

Question 4

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

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

Question 5

Which aspect of population genetics refers to chance fluctuations of allele frequencies resulting from sampling error and is more prominent in small,isolated populations?

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

Question 6

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

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

Question 7

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

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

Question 8

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

Question 9

If an X-linked recessive trait has a frequency of 5% in males,what percentage of females are carriers?

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

Question 10

Recessive mutations are subject to natural selection only when they are in the homozygous recessive genotype.What does this mean in terms of allele frequency?

A)Recessive mutations persist in a population at a frequency somewhat greater than mutation frequency.
B)Recessive mutations persist in a population at a frequency far less than the mutation frequency.
C)Recessive mutations persist in a population at a frequency equal to the mutation frequency.
D)The frequency of the mutant allele will ultimately approach 0 if there is no heterozygote advantage.
E)The frequency of the mutant allele will be unchanged because recessive mutations are in Hardy-Weinberg equilibrium.

Question 11

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

Question 12

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)allopatric speciation
C)sympatric speciation
D)random mutation
E)gene duplication

Question 13

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

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

Question 14

Phenylketonuria (PKU)is extremely common in Ireland,affecting approximately 1 in 4500 live births.What is the frequency of PKU carriers?

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

Question 15

Mexican hairless dogs are heterozygous (Hh),carrying a single copy of the dominant 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)20%
B)14%
C)10%
D)39%
E)46%

Question 16

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

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

Question 17

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

Question 18

In CODIS,what type of genetic marker is used to predict population genotype frequencies?

A)dsRNAs
B)PCR products
C)CpG islands
D)STRPs
E)FISH chromosome patterns

Question 19

Given the following genetic profile,how many individuals would remain after natural selection? Genotype A₁A₁ A₁A₂ A₂A₂
Frequency 0.55 0.20 0.25
Number 2750 1000 1250
Relative fitness (w) 1.0 0.75 0.50

A)5000
B)2750
C)4125
D)1250
E)2250

Question 20

Given the following pedigree,what is the coefficient of inbreeding for individual V-1?

A)1/2
B)1/4
C)1/8
D)1/16
E)1/64

Question 21

Which two molecular techniques are used in DNA profiling to generate data included in the FBI's CODIS database?

Question 22

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

Question 23

If the genotype frequency in an admixed population is f(A₁)= 0.75,what is the genotypic frequency of heterozygotes in the admixed population?

Question 24

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

Question 25

If the frequency of hemophilia,an X-linked recessive disorder,is 10% in males,what is the frequency of carriers in the population (both males and females)?

Question 26

A relative fitness value of w = 1 means an organism exhibits what trait?

Question 27

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

Question 28

If the frequency of PKU (an autosomal recessive disease)is 1%,what percentage of the population are completely unaffected (homozygous dominant)?

Question 29

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 Δq?

Question 30

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

Question 31

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 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

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

Question 34

If the frequency of hemophilia,an X-linked recessive disease,is 10% in males,what is the frequency of females with hemophilia?

Question 35

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

Question 36

Using the allele frequencies in the table below,what is the probability that a random person who was heterozygous 12/14 for VWA would also be homozygous 18/18 for FGA?

Question 37

If the frequency of PKU,an autosomal recessive disease,is 1% in males,what is the frequency of females with PKU?

Question 38

What is the ultimate source of genetic variation in populations?

Question 39

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 40

What are the two most common types of nonrandom mating?

Question 41

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 42

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

Question 43

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

Question 44

If the heterozygous genotype is favored (as exhibited by the sickle cell allele in malaria-prone regions),selection results in a ________ in which alleles reach stable equilibrium frequencies that are maintained by the ongoing action of selection against the homozygous genotypes.

Question 45

Achrondroplasia is an autosomal dominant genetic disorder,while red-green color blindness is an X-linked recessive disorder.For a given population,the frequency of achondroplasia is 1 in 25,000.If red-green color blindness affects 9% of males,what percentage of the population would you expect to be
a. colorblind males of normal height?
b. colorblind females of normal height?
c. males with normal vision and achondroplasia?
d. females with normal vision and achondroplasia?
e. males with both colorblindness and achondroplasia?
f. females with both colorblindness and achondroplasia?

Question 46

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 47

Forward and reverse mutation can create a ________,given a sufficient number of generations and the absence of other evolutionary processes.

Question 48

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 49

________ 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 50

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 one is not?
c. both individuals are of Ashkenazi descent?

Question 51

If an Ashkenazi carrier and a French-Canadian carrier had a child,what are the chances that they would have a child who is a carrier for both types of the mutation?