Deck 22: Population and Evolutionary Genetics

Question 1

The discipline within evolutionary biology that studies changes in allele frequencies is known as ________.

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

Answer 1

A

Question 2

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

Answer 2

The sum of the relevant individual alleles in a population is equal to 100 percent of those alleles.

Question 3

List at least three factors that change gene frequencies in populations.

Answer 3

mutation,migration,selection,genetic drift

Question 4

A certain form of albinism in humans is recessive and autosomal.Assume that 1 percent 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 are expected to be heterozygous?

Question 5

What does the variable 2pq represent?

Question 6

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

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

Question 7

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

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

Question 8

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)fluorometry
E)in situ hybridization

Question 9

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

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

Question 10

In a population of 10,000 individuals,in which 3600 are MM,1600 are NN,and 4800 are MN,what are the frequencies of the M alleles and the N alleles?

Question 11

In a population that meets the Hardy-Weinberg equilibrium assumptions,81 percent 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?

Question 12

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

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

Question 13

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

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

Question 14

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

Question 15

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 16

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

Question 17

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

Question 18

List at least five of the assumptions that pertain to a population in a Hardy-Weinberg equilibrium.

Question 19

Briefly define the term genetic equilibrium.

Question 20

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.

Question 21

Contrast directional and stabilizing forms of selection.

Question 22

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

Question 23

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

Question 24

What is the original source of genetic variation in a population? Which natural factors affect changes in this original variation?

Question 25

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

Question 26

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 27

What type of evolutionary information can be gained by examining the amino acid sequence of a protein such as cytochrome c?

Question 28

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

Question 29

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

Question 30

The difference between fitness of a given genotype and another genotype considered optimal is called the selection coefficient (s).What is the selection coefficient for a genotype (aa)that produces an average of 99 offspring when Aa individuals produce an average of 100 offspring?

Question 31

Define the term speciation.

Question 32

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 33

Present a rationale for using DNA sequence polymorphisms as an index of genetic diversity.Is genetic diversity directly proportional to evolutionary (phylogenetic)diversity?

Question 34

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

Question 35

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 36

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

Question 37

Why are some proteins more likely than others to diverge within a species?

Question 38

What are the genetic consequences of inbreeding?

Question 39

List and briefly describe three factors that contribute to the phenomenon of natural selection.

Question 40

Define the term fitness and relate it to the meaning of selection coefficient.

Question 41

If a gene has three alleles in a population,their frequencies must add up to 1.5.

Question 42

Natural selection occurs when there is nonrandom elimination of genotypes from a population due to differences in viability or reproductive success.

Question 43

In the case of complete dominance in a population in equilibrium,we cannot tell which individuals are homozygous dominants and which are heterozygous,but by knowing the frequency of the homozygous recessives,we can estimate the frequency of homozygous dominant and heterozygous genotypes.

Question 44

Genetic drift is primarily associated with relatively small breeding populations.

Question 45

Selection is the differential reproduction of genotypes,resulting from their variable fitness.

Question 46

Given an inheritance pattern of incomplete dominance and 81 flowers that are red (R¹?¹),18 flowers that are pink (R¹?²),and 1 flower that is white (R²?²),the frequency of the R¹ allele is 0.9.

Question 47

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

Question 48

Inbreeding by itself can change gene frequencies.

Question 49

Conservation of amino acid sequence among distantly related groups of organisms is suggestive of an important function of that sequence.

Question 50

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 51

In large random mating populations,random genetic drift is usually a significant factor in changing gene frequencies.

Question 52

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

Question 53

For a given locus,in a population with two alternative alleles,the allele frequencies
p + q = 1.0.

Question 54

Evolution is dependent on genetic diversity in the evolving population.

Question 55

In directional selection,both phenotypic extremes are equally selected against.

Question 56

What are phylogenetic trees?

Question 57

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

Question 58

Mutations are regarded as a strong evolutionary mechanism for changing allelic frequencies.