Deck 26: Population and Evolutionary Genetics

Question 1

Which of the following does not change gene frequencies in populations?

A)selection
B)migration
C)mutation
D)diet

Answer 1

D

Question 2

What does the variable 2pq represent?

Answer 2

the expected frequency of heterozygotes in a population in Hardy-Weinberg equilibrium

Question 3

What term is given to the total genetic information carried by all members of a population?

A)gene pool
B)race
C)genome
D)breeding unit
E)chromosome complement

Answer 3

A

Question 4

What is meant by the equation p + q = 1.0?

Question 5

A number of mechanisms operate to maintain genetic diversity in a population.Why is such diversity favored?

A)Genetic diversity may better adapt a population to inevitable changes in the environment.
B)Genetic diversity helps populations avoid diploidy.
C)Homozygosity is an evolutionary advantage.
D)Diversity leads to inbreeding advantages.
E)Greater genetic diversity increases the chances of haploidy.

Question 6

Assume that in a Hardy- Weinberg population,9% of the individuals are of the homozygous recessive phenotype.What percentage are homozygous dominant?

A)91%
B)9%
C)51%
D)49%

Question 7

Give a brief definition of the term genetic equilibrium.

Question 8

Which assumption pertains to a population in a Hardy- Weinberg equilibrium?

A)a selectively mating population
B)no migration,mutation or,genetic drift
C)a selective advantage of one genotype
D)a small population

Question 9

Which method is often used to analyze proteins and nucleic acids by physical separation when estimating genetic variation in populations?

A)electrophoresis
B)centrifugation
C)absorption spectrophotometry
D)in situ hybridization
E)fluorometry

Question 10

Albinism is an autosomal recessive trait in humans.Assume that there are 100 albinos aa)in a population of 1 million.How many individuals would be expected to be homozygous normal AA under equilibrium conditions?

A)980,100
B)100
C)10,000
D)999,900
E)19,800

Question 11

In a population of 100 individuals,49% are of the NN blood type.What percentage is expected to be MN assuming Hardy- Weinberg equilibrium conditions?

A)51%
B)42%
C)9%
D)21%
E)There is insufficient information to answer this question.

Question 12

Assume that a trait is caused by the homozygous state of a gene that is recessive and autosomal.Nine percent of the individuals in a given population express the phenotype caused by this gene.What percentage of the individuals would be heterozygous for the gene? Assume that the population is in Hardy- Weinberg equilibrium.

A)91%
B)9%
C)42%
D)58%

Question 13

A certain form of albinism in humans is recessive and autosomal.Assume that 1% of the individuals in a given population are albino.Assuming that the population is in Hardy- Weinberg equilibrium,what percentage of the individuals in this population is expected to be heterozygous?

A)9%
B)82%
C)99%
D)18%

Question 14

In a population of cattle,the following color distribution was noted: 36% red RR ,48% roan Rr),and 16% white rr .This population is in a Hardy- Weinberg equilibrium.What will be the distribution of genotypes in the next generation if the Hardy- Weinberg assumptions are met?

A)36% red; 48% roan; 16% white
B)30% red; 60% roan; 10% white
C)30% red; 50% roan; 20% white
D)40% red; 40% roan; 20% white

Question 15

In a population of 10,000 individuals,where 3600 are MM,1600 are Mm,and 4800 are mm,what are the frequencies of the M alleles and the m alleles?

Question 16

In small isolated populations,gene frequencies can fluctuate considerably.The term that applies to this circumstance is___ .

A)genetic drift
B)allelic separation
C)natural selection
D)genetic isolation
E)stabilizing selection

Question 17

Assuming that p = 0.3 for a population in Hardy- Weinberg equilibrium,what would be the expected frequency of heterozygotes for the involved allelic pair?

Question 18

In a population that meets the Hardy- Weinberg equilibrium assumptions,81% of the individuals are homozygous for a recessive allele.What percentage of the individuals would be expected to be heterozygous for this locus in the next generation?

A)19%
B)18%
C)72%
D)81%

Question 19

Which general term is used to group various biological and behavioral properties of organisms that act to prevent or reduce interbreeding?

A)genetic divergence
B)inbreeding
C)allopatric speciation
D)reproductive isolating mechanisms
E)phyletic evolution

Question 20

What is the term given to a group of individuals belonging to the same species that live in a defined geographic area that actually or potentially interbreed?

A)genetics
B)cytogenetics
C)hybrid vigor
D)population
E)consanguinity

Question 21

Selection that favors the middle phenotype and selects against the extreme phenotypes is said to be_______ .

A)directional selection
B)disruptive selection
C)stabilizing selection
D)diselection

Question 22

In zoo animals,inbreeding often occurs because of a lack of a sufficient pool of breeding individuals.Under such conditions,what two characteristics are often exhibited among inbred organisms?

Question 23

Which factor contributes to the phenomenon of natural selection?

A)competition for survival
B)lack of competition in mating
C)genetic homogeneity in a population
D)underpopulation

Question 24

What are the genetic consequences of inbreeding?

Question 25

Provide a general definition for the term speciation.

Question 26

Present a rationale for using DNA sequence polymorphisms as an index of genetic diversity.

Question 27

Migration occurs when individuals move between populations.Considering a single pair of alleles,A and a,what formula is used to indicate the new frequency of A in one generation of migration?

Question 28

Suppose that a given gene undergoes a mutation to a dominant allele such that 2 out of 100,000 offspring exhibit the new mutant phenotype.Assuming that these offspring are heterozygous,what is the mutation rate for the gene?

Question 29

Which term is given to the measure of the proportion of offspring that a particular phenotype will contribute to the next generation?

Question 30

One of the Hardy- Weinberg assumptions states that the population is infinitely large.What influence might a small population size have on a Hardy- Weinberg equilibrium?

Question 31

What type of evolutionary information can be gained by examining the DNA sequence of a gene for a protein such as cytochrome c?

Question 32

What single event is probably common to all occurrences of speciation?

Question 33

Why is mitochondrial DNA often used in construction of phylogenetic trees?

Question 34

Briefly describe how the founder effect can impact the allelic frequencies in a population.

Question 35

Mutation and migration introduce new alleles into populations.What is the most likely principal force that will shift allelic frequencies within large populations?

Question 36

Which would change allele frequencies more quickly: selection against a dominant allele or selection against a recessive allele?

Question 37

One of the Hardy- Weinberg assumptions states that all genotypes in the population are free of selective advantage.What influence might a selective advantage of a genotype have on a Hardy- Weinberg equilibrium?

Question 38

Define the term fitness.

Question 39

Two species that have experienced several thousand years of isolation from one another are now incapable of producing viable offspring despite mating efforts.What type of reproductive isolating mechanism developed between the two species?

Question 40

Which natural factors affect changes in genetic variation?

Question 41

Would one expect a linear relationship between DNA sequence divergence and phylogenetic distance? Why or why not?

Question 42

For a given locus,in a population with two alternative alleles,the allele frequencies p + q = _______.

A)1.0
B)p × q
C)0
D)100

Question 43

What information have the results of mitochondrial DNA analysis offered concerning the phylogenetic relationships between Neanderthals and modern humans?

Question 44

Natural selection occurs when there is nonrandom elimination of genotypes from a population due to _______.

A)differences in reproductive isolation mechanisms
B)similarities in viability or reproductive success
C)decreased predation
D)differences in viability or reproductive success

Question 45

Inbreeding will change_______ .

A)mating isolation mechanism
B)species
C)diet
D)gene frequencies

Question 46

If a gene has three alleles in a population,their frequencies must add up to _______ .

A)1.0
B)3.0
C)1.5
D)0

Question 47

Directional selection generates a phenotypic shift _______.

A)toward an extreme of the phenotype
B)away from either extreme of the phenotype
C)toward the mean of the extremes of the phenotype
D)toward both extremes of the phenotype

Question 48

What is regarded as a strong evolutionary mechanism for changing allelic frequencies?

A)selection
B)migration
C)mutations
D)recombination

Question 49

Cytochrome c is a respiratory pigment found in the mitochondria of eukaryotes.Compared with some other proteins,it has changed very slowly over long periods of time.Why?

Question 50

In the case of complete dominance in a population in equilibrium,we cannot tell which individuals are homozygous dominants and which are heterozygous,what information is needed to determine the frequency of homozygous dominant and heterozygous genotypes?

A)the frequency of homozygous recessive genotype
B)the frequency of heterozygous recessive genotype
C)the mutation rate in the population
D)the size of the sample population

Question 51

What is the differential reproduction of genotypes,resulting from their variable fitness?

A)genetic drift
B)discrimination
C)evolution
D)selection

Question 52

Evolution is dependent on _______in the evolving population.

A)equilibrium
B)genetic diversity
C)inbreeding
D)constant gene frequencies

Question 53

In the evolutionary sense,what is meant by the term molecular clock?

Question 54

Conservation of amino acid sequence among distantly related groups of organisms is suggestive of an_______ .

A)lack of common ancestor
B)important function for that sequence
C)intrinsic resistance to mutations in that sequence
D)lack of selective pressure on that sequence

Question 55

What are phylogenetic trees?

Question 56

Given an inheritance pattern of incomplete dominance and 81 flowers that are red R¹R¹ ,18 flowers that are pink R¹R² ,and 1 flower that is white R²R² ,what is the frequency of the R¹ allele?

A)0.9
B)0.1
C)0.8
D)0.2

Question 57

Genetic drift is primarily associated with what size breeding populations?

A)mid- sized
B)very small
C)very large
D)Genetic drift has the same effect on all population sizes.

Question 58

Genetic drift arises from all the following EXCEPT_______ .

A)mutations
B)a genetic bottleneck
C)a small breeding population
D)a founder effect