Deck 25: Population and Evolutionary Genetics

Question 1

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

Answer 1

C

Question 2

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.

Answer 2

C

Question 3

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

Answer 3

D

Question 4

What does the variable 2pq represent?

Question 5

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?

Question 6

In a population of cattle,the following color distribution was noted: 36% red (RR),48% roan (Rr),and 16% 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 7

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 8

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

Question 9

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

Question 10

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 11

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

Question 12

Give a brief definition of the term genetic equilibrium.

Question 13

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

Question 14

What 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 15

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?

Question 16

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

Question 17

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

Question 18

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 19

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 20

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 21

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 22

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

Question 23

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

Question 24

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

Question 25

Contrast directional and stabilizing forms of selection.

Question 26

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

Question 27

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 28

Provide a general definition for the term speciation.

Question 29

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 30

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

Question 31

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

Question 32

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

Question 33

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

Question 34

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

Question 35

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

Question 36

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

Question 37

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 38

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 39

What are the genetic consequences of inbreeding?

Question 40

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 41

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

Question 42

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

Question 43

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

Question 44

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

Question 45

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

Question 46

Genetic drift is primarily associated with relatively small breeding populations.

Question 47

Evolution is dependent on genetic diversity in the evolving population.

Question 48

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

Question 49

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 50

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

Question 51

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

Question 52

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

Question 53

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 54

What are phylogenetic trees?

Question 55

Inbreeding by itself can change gene frequencies.

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),the frequency of the R¹ allele is 0.9.

Question 57

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

Question 58

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