Deck 20: Genes Within Populations

Question 1

In the Hardy-Weinberg equations,the frequencies of 2 alleles in a population (where there are only 2 alleles to consider)can be designated as

A)(p + q)².
B)p and q.
C)p² and q².
D)2pq.
E)1 - p and 1 - q.

Answer 1

B

Question 2

Selection cannot alter a trait with little or no genetic variation and will not eliminate _________ alleles.

A)dominant
B)recessive
C)detrimental
D)neutral

Answer 2

B

Question 3

A restriction in genetic variability caused by a drastic reduction in population size is called a

A)founder effect.
B)Hardy-Weinberg effect.
C)bottleneck effect.
D)polymorphic effect.
E)adaptive effect.

Answer 3

C

Question 4

Features that increase the likelihood of survival and reproduction by an organism in a particular environment are called

A)genes.
B)fitness.
C)mutations.
D)adaptations.
E)selection.

Question 5

The founder principle explains how rare alleles may become more common in new

A)populations.
B)clines.
C)bottleneck areas.
D)migratory areas.
E)genomes.

Question 6

The key point in Darwin's proposal is that the ___________ imposes the conditions that determine the results of selection and thus the direction of selection.

A)parent
B)gene
C)individual
D)environment

Question 7

The genetic contribution of an individual to succeeding generations,compared with that of other individuals in the population,is known as

A)variation.
B)microevolution.
C)macroevolution.
D)fitness.
E)adaptive makeup.

Question 8

Biologists examined the question of variation in different genes through studies on

A)blood groups only.
B)enzymes only.
C)learning only.
D)blood groups,enzymes,and learning.
E)blood groups and enzymes.

Question 9

Migration and hybridization between individuals of adjacent populations causes gene _______.

A)blending
B)flow
C)mutation
D)dominance

Question 10

A locus with more variation than can be explained by mutation is referred to as

A)dominant.
B)polynomial.
C)polymorphiC.
D)heterozygous.
E)somatic.

Question 11

The frequency of a particular allele within a population can be changed,over time,by

A)genetic outflow.
B)large population size.
C)selection.
D)inheritance of acquired characteristics.
E)random mating.

Question 12

Darwin proposed that natural selection occurs in an environment by

A)favoring heritable features that make the organism better suited to survive and reproduce.
B)producing a constant number of offspring while in that environment.
C)surviving for a fixed amount of time.
D)resisting the environment and keeping the environment from changing.
E)favoring those individuals with the most favorable acquired characteristics.

Question 13

The gene pool includes

A)all of the fitness within a population.
B)all of the individuals within a population.
C)all of the mutations within a population.
D)all of the adaptations within a population.
E)all of the alleles of genes within a population.

Question 14

Natural selection as a mechanism of evolution that acts on variants within populations and ultimately leads to the evolution of different species was proposed by

A)Mendel.
B)Lyell.
C)Malthus.
D)Darwin.
E)Founder.

Question 15

What percentage of the enzyme loci of a typical human being are heterozygous?

A)1%
B)5%
C)10%
D)50%
E)100%

Question 16

"The inheritance of acquired characteristics" proposal was put forward by

A)Darwin.
B)Lamarck.
C)Wallace.
D)Founder.
E)Hardy-Weinberg.

Question 17

A _________ locus exhibits more variation than is expected by mutation.

A)polymorphic
B)double
C)mosaic
D)allelic

Question 18

Genotypes are said to be in ___________ equilibrium if there is random mating and no other forces tend to alter the proportions of alleles from one generation to the next.

A)steady state
B)homeostatic
C)Hardy-Weinberg
D)Medelian

Question 19

The Hardy-Weinberg equations only hold true,that is,a population is only in equilibrium

A)when immigration in and out of the area are held constant.
B)when changes only take place over long periods of time.
C)when it includes episodes of extinction.
D)when the population is designed to survive in new habitats.
E)when all of the Hardy-Weinberg assumptions are met.

Question 20

The genetic preservation of the features that increase the likelihood of survival and reproduction of some individuals within a population is called the process of

A)natural selection.
B)creation of new species.
C)genetic drift.
D)outcrossing.
E)increasing evolutionary resistancE.

Question 21

Certain small towns in the western United States have remained isolated and inbred since their settlement many years ago.Some alleles are more common in these communities as compared to the rest of the population.This effect is known as

A)artificial selection.
B)directional selection.
C)disrupting selection.
D)Hardy-Weinberg principle.
E)founder principlE.

Question 22

The type of non-random mating that causes the frequencies of particular genotypes to differ greatly from those predicted by the Hardy-Weinberg equilibrium is called

A)mutation.
B)migration.
C)genetic drift.
D)assortative mating.
E)selection.

Question 23

Gene flow,defined as the movement of genes from one population to another,can take place by migration,as well as

A)mating with certain trait-containing individuals.
B)mating with dominant phenotypes.
C)hybridization between individuals of adjacent populations.
D)removing the barriers between the populations.
E)physical movement of genes within an individual by transposons.

Question 24

Which one of the following is not an agent of natural evolutionary change?

A)mutation
B)migration
C)genetic drift
D)non-random mating
E)artificial selection

Question 25

In order for natural selection to occur within a population,certain conditions must be met.One such condition is

A)phenotypic differences resulting from environmental conditions.
B)frequent mutations that are inherited.
C)low rates of immigration.
D)phenotypic variations that are genetic.
E)heterozygosity must be very low.

Question 26

The phenomenon in which rare alleles become more common in new populations is called

A)founder effect.
B)gene flow.
C)genetic drift.
D)assortative mating.
E)mutation.

Question 27

In some populations the drive is to mate with individuals that are phenotypically different at a variety of loci.This leads to large numbers of heterozygotes and is called

A)neutral theory.
B)disassortative mating.
C)shifting balance theory.
D)bottleneck effect.
E)founder effect.

Question 28

Sometimes a restriction in genetic variability is imposed on populations by natural catastrophes such as flooding,earthquake,etc.The surviving individuals reflect only a small,random genetic sample of the population affected.This process is termed

A)mutation.
B)migration.
C)genetic drift.
D)assortative mating.
E)bottleneck effect.

Question 29

Which one of the following is not an agent of evolutionary change?

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

Question 30

In small populations,frequencies of certain alleles may change by chance alone.Such random change in the frequency of alleles is called

A)mutation.
B)migration.
C)genetic drift.
D)nonrandom mating.
E)selection.

Question 31

Compared with Hardy-Weinberg predictions,populations that have practiced assortative mating have

A)fewer homozygotes.
B)less natural selection.
C)more heterozygotes.
D)more homozygotes.
E)more mutations.

Question 32

When selection acts to eliminate one extreme from an array of phenotypes it is called

A)natural selection.
B)stabilizing selection.
C)disruptive selection.
D)directional selection.
E)artificial selection.

Question 33

Although it was a rare trait in the mainland population,one of the original female mice is homozygous for very large ears.This will lead to a population with a higher incidence of big ears than the mainland population because of

A)bottleneck effect.
B)founder effect.
C)mutation.
D)genetic drift.
E)selection pressurE.

Question 34

The Hardy-Weinberg equilibrium conditions for populations of organisms result in

A)polymorphic alleles.
B)assortive mating.
C)natural selection.
D)maintenance of recessive alleles in the gene pool.
E)no evolutionary changes.

Question 35

Populations of humans are known to have founder effects.For instance there are small populations in the US that frequently show

A)6 fingers.
B)4 fingers.
C)complete hairlessness.
D)blue hair.
E)No human populations are known to have founder effects.

Question 36

Hardy-Weinberg pointed out that the original proportions of the genotypes in a population would remain constant from generation to generation if certain assumptions are met.Which one of the following is not a Hardy-Weinberg condition?

A)The population is very large.
B)No gene flow occurs.
C)No selection occurs.
D)Random mating occurs.
E)No polymorphic loci exist in the population.

Question 37

For a gene with two alternative alleles,a (frequency p)and a (frequency q),the term in the algebraic form of the Hardy-Weinberg equilibrium for the heterozygote genotype frequency is

A)p².
B)q².
C)2pq.
D)(p+q)².
E)2Aa.

Question 38

About 80% of the alleles present in thoroughbred horses can be dated back to 31 known ancestors from the late eighteenth century.As a result,one would expect

A)low rates of mutation.
B)many polymorphic alleles.
C)little variation in physiology and behavior.
D)Hardy-Weinberg equilibrium.
E)random mating.

Question 39

Cheetahs have been through a genetic bottleneck;evidence for this is that

A)little natural selection occurs in this species.
B)the body is long,thin,and graceful.
C)there is very little genetic variability.
D)these cats are members of an endangered species.
E)they originally came from small areas of Africa.

Question 40

The total of all the alleles of all the genes in a population can be thought of as

A)an allele mixture.
B)a gene pool.
C)a genetic melting pot.
D)a genome.
E)variant genes.

Question 41

At least some of the requirements for a Hardy-Weinberg equilibrium would be in effect on the island.For instance there is probably

A)high rates of immigration.
B)a very large population size.
C)little gene flow.
D)no mutation.
E)random mating.

Question 42

Which of the following would be expected to produce the smallest evolutionary change in a given period of time in a population of birds?

A)mutation
B)natural selection
C)migration
D)assortive mating
E)gene flow

Question 43

The recessive phenotype of a trait occurs in 20% of a population.There are no selection pressures affecting this trait.What would be the expected frequency of the dominant allele after six generations of continued non-selection?

A)0.2
B)0.306
C)0.447
D)0.494
E)0.553

Question 44

Which one of the following could not be involved in gene flow?

A)wind-blown pollen
B)gametes dispersed by ocean currents
C)zygotes dispersed by ocean currents
D)disassortive mating within a population
E)hybridization between neighboring populations

Question 45

Assortive and disassortive mating are similar in that both

A)change only the expected Hardy-Weinberg allele frequencies in a population.
B)change only the expected Hardy-Weinberg genotype frequencies in a population.
C)change both the expected Hardy-Weinberg allele and genotype frequencies in a population.
D)are kinds of selection pressure.
E)are examples of random mating.

Question 46

In some instances environmental change causes a situation where one phenotype is favored for a period of time,and then a different phenotype is favored.This oscillating selection causes

A)the maintenance of genetic variation in the population.
B)elimination of rarer genotypes because of uneven selection.
C)an increase in point mutations.
D)high population increase to maintain phenotypic variation.
E)extinction of the population.

Question 47

The text discusses sickle-cell anemia,which is a classic example of

A)founder effect.
B)genetic bottleneck.
C)point mutation.
D)heterozygote advantage.
E)heterozygosity.

Question 48

In directional selection,over time

A)a population goes extinct.
B)the most extreme outliers of a population are eliminated (e.g. ,the largest beaks and smallest beaks are eliminated).
C)the population is strongly selected for in one direction (e.g. ,larger beak size).
D)the population is strongly selected for in two directions (e.g. ,larger beak size and smaller beak size).
E)a population increases its variation (E.g. ,a wide selection of all beak sizes).

Question 49

The disease,sickle-cell anemia is common in malaria-infested areas because individuals that are heterozygous for the gene (AS)have enhanced resistance to malaria over normal individuals (AA).Individuals with severe sickle-cell anemia (SS)usually die before reproduction.Assume that a population under Hardy-Weinberg equilibrium has allele frequencies of A = 0.8 and S = 0.2.Assume that this population is then subject to the following selection forces:
AA: 15% die of malaria
AS: 5% die of malaria
SS: 100% die of severe sickle-cell anemia
What will be the frequency of the S allele after selection occurs?

A)0.0
B)0.04
C)0.15
D)0.18
E)0.3

Question 50

You are studying a population of geese in which there are two color phases,brown and gray.Color in this species is controlled by a single gene,with brown dominant to gray.A random sample of 250 geese shows that 210 are brown.What percentage of the brown geese are heterozygous? (Assume that the population is in Hardy-Weinberg equilibrium. )

A)36%
B)43%
C)48%
D)57%
E)84%

Question 51

In negative frequency-dependent selection,such as in the study done on the water boatman insect,the incidence of predation leads to an

A)elimination of a rare genotype.
B)even distribution of genotype frequencies.
C)increase in a rare genotype.
D)increase in variation within the population.
E)increase in a rare genotype and an increase in variation within the population.

Question 52

The recessive phenotype of a trait occurs in 20% of a population.There are no selection pressures affecting this trait.What would be the expected frequency of the heterozygote genotype after six generations of continued non-selection?

A)0.2
B)0.306
C)0.447
D)0.494
E)0.553

Question 53

Antigens on red blood cells are hereditary traits that allow blood to be typed in different ways.One system is based on a gene with two alleles,M and N.If the frequency of the M allele in a population is 0.4,then according to the Hardy-Weinberg rule,the expected frequency of the heterozygous MN genotype is ____.

A)0.16
B)0.24
C)0.36
D)0.48
E)0.6

Question 54

If the frequency of an autosomal recessive trait in humans is 1 out of 4000 births,what would be the expected frequency of heterozygote carriers for the trait if we assume that the gene is in Hardy-Weinberg equilibrium?

A)0.00025
B)0.0158
C)0.031
D)0.969
E)0.984

Question 55

Which of the following would be expected to produce the largest evolutionary change in a given period of time in a population of birds?

A)mutation
B)natural selection
C)migration
D)random mating
E)Hardy-Weinberg equilibrium

Question 56

A gene is represented in the gene pool of a population of 10,000 individuals by a dominant (W)and recessive allele (w).If the initial frequency of W in the pool is 0.7,how many generations of complete selection against it would be required to eliminate all W alleles from the population? Assume that there is no mutation and the population meets all other Hardy-Weinberg conditions.

A)1
B)2
C)5
D)20
E)can never be eliminated

Question 57

The genotype frequencies in a population with no evolution occurring are AA = 0.25,Aa = 0.5,aa = 0.25.By removing all AA individuals before they reproduce and assuming the population will remain under Hardy-Weinberg conditions,what will be the frequency of aa individuals in the next generation?

A)0.25
B)0.33
C)0.5
D)0.67
E)0.75

Question 58

In disruptive selection,over time

A)a population goes extinct.
B)the most extreme outliers of a population are eliminated (e.g. ,the largest beaks and smallest beaks are eliminated).
C)the population is strongly selected for in one direction (e.g. ,larger beak size).
D)the population is strongly selected for in two directions (e.g. ,larger beak size and smaller beak size).
E)a population increases its variation (E.g. ,a wide selection of all beak sizes).

Question 59

Coloration in the peppered moth (Biston betularia)is determined by a single gene with two alleles showing complete dominance.Dark moths are homozygous dominant or heterozygous for the gene,light moths are homozygous recessive.In a sample of 100 moths,you determine that 64 of the moths are dark.According to the Hardy-Weinberg rule,the expected frequency of the dominant allele is ____.

A)0.4
B)0.36
C)0.6
D)0.64
E)cannot be determined

Question 60

In a large population of randomly reproducing rabbits,a recessive allele r comprises 80% of the alleles for a gene,while a dominant allele R comprises the remaining 20%.What percentage of the rabbits would you expect to have the recessive phenotype?

A)4%
B)32%
C)64%
D)80%
E)none

Question 61

One extreme of an array of phenotypes is favored.

A)directional selection
B)stabilizing selection
C)disruptive selection
D)guppies with pike cichlids and killifish
E)guppies with killifish

Question 62

Small,drab,early reproduction is favored.

A)directional selection
B)stabilizing selection
C)disruptive selection
D)guppies with pike cichlids and killifish
E)guppies with killifish

Question 63

Both extremes of an array of phenotypes are favored.

A)directional selection
B)stabilizing selection
C)disruptive selection
D)guppies with pike cichlids and killifish
E)guppies with killifish

Question 64

The several hundred species of picture-winged fruit flies of the Hawaiian Islands are genetically very similar,yet they all differ markedly from their ancestral population in Asia.This is probably an example of

A)sexual selection.
B)directional selection.
C)disruptive selection.
D)founder effect.
E)gene flow.

Question 65

Large,colorful,later reproduction is favored.

A)directional selection
B)stabilizing selection
C)disruptive selection
D)guppies with pike cichlids and killifish
E)guppies with killifish

Question 66

The California populations of the Northern elephant seal are descendants from a very small population of seals that was over-hunted in the 1890s.Heterozygosity in this population would be expected to be ________ due to ________________.

A)slight;a bottleneck effect
B)slight;the founder effect
C)great;disruptive selection
D)great;a bottleneck effect
E)great;assortive mating

Question 67

Which of the following statements about disruptive selection is false?

A)It involves multi-gene inheritance.
B)It results in polymorphism.
C)It results in a bimodal distribution of phenotypes within a population.
D)It increases heterozygosity within the population.
E)It selects against individuals with intermediate phenotypes.

Question 68

The midrange of an array of phenotypes is favored.

A)directional selection
B)stabilizing selection
C)disruptive selection
D)guppies with pike cichlids and killifish
E)guppies with killifish

Question 69

Which of the following examples is not evidence that natural selection is at work?

A)The color of a caterpillar larva matches the color of the leaves of its host plant.
B)Turtles hatched from eggs in moist sand are larger than those hatched from eggs in dry sand.
C)A species of lizard is dark if it lives on cooled lava,but white if it lives on sand.
D)Enzyme polymorphism in a widespread species changes with geography.
E)An insect population becomes resistant to a commonly used insecticidE.

Question 70

Which of the following statements about the laboratory and field studies on evolution of protective coloration in the guppy (as described in the textbook)is false?

A)Pike cichlids are only found below waterfalls.
B)Guppies transferred to pools above waterfalls remained drab if killifish were present there.
C)Guppy predation was greater in pools below waterfalls than above waterfalls.
D)Killifish can be found both above and below waterfalls.
E)Substantial evolutionary changes in guppy populations can occur in as few as several years.

Question 71

The fitness of an individual may depend on all of the following factors except

A)life span of the individual.
B)climate change.
C)offspring produced per mating.
D)frequency of individual's phenotype in population.
E)presence of many pleiotropic genes.