Deck 18: Evolution of Populations

Question 1

In a population of 100,000 flies, 30,000 have the AA genotype, 20,000 carry the Aa genotype, and 50,000 have the aa genotype. What is the frequency of the A allele?

A)1.00
B)0.80
C)0.40
D)0.30

Answer 1

B

Question 2

New alleles arise by

A)nonrandom mating.
B)allele frequency.
C)genetic drift.
D)mutation.

Answer 2

D

Question 3

What is the total number of alleles present for any given gene in a population of 100 individuals?

A)50
B)100
C)200
D)400

Answer 3

C

Question 4

Which of the following statements concerning evolution is false?

A)Natural selection requires variation in the population.
B)An individual that is better adapted than others in a population will always be more reproductively successful.
C)Genetic drift causes little evolutionary change in large populations.
D)Evolution involves a change of frequency of alleles in the gene pool.

Question 5

Which of the following is not likely to be a cause of rapid evolution in a population?

A)a changing environment
B)an organism that exhibits a rapid rate of mutation
C)an organism that reproduces very slowly
D)the immigration of individuals carrying a new allele that significantly increases reproductive success

Question 6

The frequency of the genotype AA in a population is 0.36. What is the frequency of Aa?

A)0.40
B)0.48
C)0.64
D)This cannot be determined with the information provided.

Question 7

The geese shown in the figure below are all members of the same population. What is the genotype frequency of AA?

A)0.29
B)0.57
C)0.71
D)0.43

Question 8

Which of the following is true with regard to mutations?

A)Mutations occur in response to environmental pressures.
B)Mutations are more common in slowly growing organisms.
C)Mutations appear without regard to environmental pressures.
D)Several mutations must occur at one time for a new phenotype to appear.

Question 9

The Hardy-Weinberg equation predicts the following genotype frequencies for a particular gene: BB = 0.36, Bb = 0.48, and bb = 0.16. The population you are studying exhibits the following frequencies: BB = 0.42, Bb = 0.5, and bb = 0.08. What can you conclude?

A)Your population is evolving.
B)Your population is undergoing natural selection.
C)Your population has experienced a bottleneck.
D)A new allele has just entered your population.

Question 10

If a given population has 30 RR individuals, 10 Rr individuals, and 10 rr individuals, what is the allele frequency of R?

A)0.10
B)0.30
C)0.50
D)0.70

Question 11

Which of the following is not a step in the evolutionary process?

A)Mutation results in the formation of new alleles and sexual reproduction results in new combinations of alleles.
B)New genes are introduced into a population when members of that population mate with members of other species.
C)Genetic variation is inherited by the next generation of a population.
D)Genetic drift, gene flow, and or natural selection cause allele frequencies to change over time.

Question 12

The human allele that causes six fingers per hand is dominant over the allele that produces five fingers per hand, yet most humans have five fingers per hand. Why is this so?

A)A Punnett square shows this situation to be impossible.
B)The F2 generation never expresses the dominant trait.
C)The heterozygote expresses the recessive trait.
D)The six-finger allele exists at a low frequency in the human population.

Question 13

Which of the following is not a cause of evolution?

A)mutation
B)gene flow
C)stable environmental conditions
D)sexual selection

Question 14

Microevolution

A)does not alter the genotype frequencies of a population.
B)is caused by speciation.
C)occurs only in microorganisms.
D)is the smallest scale at which evolution occurs.

Question 15

One factor that complicates the treatment of AIDS is the

A)low mutation rate of HIV.
B)high mutation rate of HIV.
C)random mating between viral particles.
D)nonrandom mating between viral particles.

Question 16

The frequency of the genotype aa in a population is 0.09. What is the frequency of the allele a in the population?

A)0.7
B)0.81
C)0.3
D)0.0081

Question 17

If p is the frequency of the W allele in a population, why do we equate the WW individuals with the p² portion of the Hardy-Weinberg equation?

A)The Hardy-Weinberg equation describes the frequencies of dominant alleles only.
B)The WW individuals have two copies of the allele represented by p.
C)The ww individuals are all killed by lethal recessive genes.
D)The frequency of p is always equal to the frequency of q.

Question 18

A population has a total of two alleles, G and g, for a given gene. Which one of the following sets of genotype frequencies is possible for that population?

A)GG = .25, Gg = .75, and gg = .35
B)GG = .70, Gg = .25, and gg = .30
C)GG = .75, Gg = .15, and gg = .10
D)GG = .45, Gg = .15, and gg = .75

Question 19

If a given population has 30 RR individuals, 10 Rr individuals, and 10 rr individuals, what is the genotype frequency of Rr?

A)0.10
B)0.20
C)0.30
D)0.50

Question 20

A gene has two alleles, D and

A)0.2
B)0.8
C)0.4
D)0.64
D) The frequency of the D allele is 0.2. What is the frequency of the d allele?

Question 21

Compared to a large mainland population, genetic drift in a small island population is

A)less important because there is less variation with which to work.
B)less important because only a few individuals do all the breeding.
C)more important because of a smaller gene pool.
D)more important because of the absence of competition.

Question 22

A fisherman catches one trout from each of two ponds. Pond A contains 100 trout and pond B contains 1,000 trout. Which population is more affected by the fisherman?

A)Pond A; the fisherman has a greater likelihood of completely removing alleles from the gene pool by taking a fish from the smaller population.
B)Pond A; fewer fish are able to move into a small pond and find mates.
C)Pond B; the fisherman is more likely to catch a fish that is undergoing evolution in a bigger population.
D)Pond B; the process of evolution occurs more slowly in large populations and removing a fish speeds up the process.

Question 23

What is genetic drift?

A)gene mutation within, or between, populations
B)chance evolutionary change occurring in small populations
C)natural selection acting on large populations
D)shifts in allelic frequencies due to mutation

Question 24

While on a camping trip, you collect a white tadpole from a pond and take it home. The tadpole develops into a white bullfrog. When the frog gets too big, you release it into a local pond. The next year, several white bullfrogs are observed in the pond. This is an example of

A)genetic drift.
B)natural selection.
C)gene flow.
D)sexual selection.

Question 25

Which of the following is a valid interpretation of this data regarding prairie chicken populations in several states in the Midwest?

A)Prairie chicken populations in Illinois have a lower mutation rate than those in the other listed states.
B)Illinois prairie chickens lost genes from their genome as a result of a population crash.
C)Smaller populations of prairie chickens have greater reproductive success.
D)Larger populations of prairie chickens tend to have greater genetic diversity in their gene pools.

Question 26

In your backyard, you step on a dandelion and one of its seeds gets trapped in the tread of your shoes. The next day, you go on a long hike in the wilderness wearing the same shoes. When you step in a mud puddle, the seed sticks in the mud. The seed grows into a dandelion, but no other dandelions are present to mate with it. This is an example of

A)gene flow.
B)genetic drift.
C)natural selection.
D)sexual selection.

Question 27

According to the figure below, the r allele is less frequent in generation II of this flower population. The frequency of r decreases in this population because

A)of genetic drift.
B)recessive alleles are always less common than dominant alleles.
C)p + q must always equal 1.
D)R alleles are more likely to "hide" r alleles in generation II.

Question 28

Several related bird species live in a desert. One species is much smaller than the other species. This species nests in holes in cacti. Because the bird is so small, it can easily squeeze between the spines of the cactus and create a well-protected nest. This is an example of

A)genetic drift.
B)mutation.
C)natural selection.
D)gene flow.

Question 29

In the figure below, the flying bird moves permanently into the population shown on land. As a result, the allele frequency of A in the population changes from

A)1 to 0.75.
B)0 to 0.25.
C)0 to 0.75.
D)1 to 0.25.

Question 30

A population of 8,250 mice occupies the sand dunes in a coastal area. A severe hurricane washes out several miles of sand dunes. As a result, only 50 mice remain. The population has experienced

A)horizontal gene transfer.
B)gene flow.
C)founder effect.
D)a bottleneck.

Question 31

Is the effect of an individual permanently leaving a population likely to have a greater genetic effect if the home population was large or if the home population was small?

A)Large, because this is an example of disruptive selection.
B)Large, because natural selection will cause a bottleneck to occur in the remaining individuals.
C)Small, because the loss of just a few individuals may greatly reduce the remaining genetic variation.
D)Small, because the remaining individuals will no longer be able to practice nonrandom mating.

Question 32

Gene flow occurs

A)as a result of genetic drift.
B)if gametes, rather than individuals, move among populations.
C)as a result of mutations in one population but not in another.
D)when individuals within a population interbreed.

Question 33

Which of the following is an example of gene flow?

A)Pollen from a population A plant lands on the same plant (mating with itself).
B)Pollen from a population A plant lands on another population A plant.
C)Pollen from a population A plant lands on a population B plant.
D)Pollen from a population B plant lands on a population B plant.

Question 34

In natural selection, _____ that increase survival and reproductive success become more common in a population.

A)genotypes
B)allele frequencies
C)bottlenecks
D)phenotypes

Question 35

A used car is shipped from Australia to the United States. Stowed away in the trunk of the car is a piece of wood infected with Australian termites. Once in the United States, the buyer of the car finds the rotting wood and dumps it on the side of the road. The termites survive and establish a colony on the side of the road, but do not mate with local termite populations. This is an example of

A)genetic drift.
B)mutation.
C)natural selection.
D)gene flow.

Question 36

Although millions of prairie chickens once occupied Illinois, in 1993 only 50 remained. Starting in 1992, scientists moved almost 300 prairie chickens from large populations in other states to Illinois to _____ Illinois prairie chicken populations.

A)prevent the development of nonheritable mutations in
B)introduce genetic variation back into
C)induce stabilizing selection in
D)cause genetic drift in

Question 37

Gene flow between two populations

A)makes the genetic composition of the two populations more similar.
B)eliminates harmful alleles.
C)magnifies the effects of genetic drift.
D)creates genetic differences between the populations.

Question 38

A gene has two alleles, B and

A)0.
B)0.33.
B) If the b allele becomes "fixed" in the population, its frequency will be
C)0.5.
D)1.

Question 39

Genetic drift has a greater effect on

A)moths than on birds.
B)individuals than on populations.
C)small populations than on large populations.
D)natural selection than on gene flow.

Question 40

A water plant gets wrapped around the propeller of a boat in Round Pond. This particular plant exhibits an unusual allele that gives it extra branches. The boat owner moves his boat to Big Lake without cleaning the plant off the propeller. The same species of water plant already exists in Big Lake, but none of the plants exhibit the "extra branches" allele. One year later, the frequency of the extra branches allele in Big Lake is much higher. This is an example of

A)genetic drift.
B)mutation.
C)natural selection.
D)gene flow.

Question 41

Which of the following is not a mode of natural selection?

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

Question 42

If the genotype values predicted by the Hardy-Weinberg equation are greatly different from the values found in the real population, we can say that the population is ____________________.

Question 43

Scientists have hypothesized that the reason European men have darker skin color than European women is that more than 10,000 years ago, these men preferred to mate with lighter-skinned females. If this is true, skin color is an example of _____ in Europeans.

A)gene flow
B)a genetic bottleneck
C)sexual selection
D)recombination

Question 44

____________________ is the only mechanism of evolutionary change that is not influenced by chance events.

Question 45

When a population shrinks, causing low genetic variation or the fixation of a harmful allele, a genetic ____________________ has occurred.

Question 46

____________________ are the original source of genetic variation within a population.

Question 47

The fur in a species of mice ranges from white to black (intermediate phenotypes are different shades of gray). A population of these mice lives in an environment that contains both regions of white sand and regions of black lava rocks. When a scientist examines the frequencies of the different alleles in the population, she finds that, although white mice and black mice are common, gray mice are rare. This is an example of _____ selection.

A)disruptive
B)stabilizing
C)directional
D)sexual

Question 48

____________________ promote rapid evolution by giving bacteria with resistance genes a selective advantage.

Question 49

A student with Strep throat (caused by a strain of bacterium)is given a prescription for an antibiotic and is told to take the drug for two weeks. After a week, the student feels better and stops taking the drug. Two months later, the student again shows symptoms of Strep throat and decides to finish the leftover antibiotic rather than going to the doctor again. Two months later, the student develops Strep throat for a third time and returns to the doctor. This time, the antibiotic does not work. The doctor runs a test and discovers that the bacterial strain the student is carrying is antibiotic resistant. What most likely happened?

A)Because the use of antibiotics lowers the effectiveness of the immune system, the student continually reinfected himself with the bacteria. The third time, the student happened to be reinfected with a resistant strain.
B)When the student stopped taking the drug, a small number of bacteria-those that were more drug resistant-still survived in his body. Those bacteria repopulated his throat and over time, drug-resistant alleles became more common.
C)The student must have eaten produce that had been genetically engineered with antibiotic-resistant genes. When he consumed them, the bacteria in the student's throat picked up these genes through horizontal gene transfer.
D)The antibiotic caused mutations in the bacterium. The more exposure to the antibiotic, the more mutations. Even one random mutation can confer antibiotic resistance.

Question 50

A scientist is studying beak length in a species of hummingbird. The scientist establishes a population of birds with beaks ranging from very small to very long and allows the population to breed for 10 years. At the end of the experiment, she finds that the majority of birds in the population have very long beaks. This is an example of _____ selection.

A)disruptive
B)stabilizing
C)directional
D)sexual

Question 51

Two populations of geese live near each other. As time passes, the populations are becoming more genetically alike. This is probably due to ____________________.

Question 52

Which of the following is not a reason that farmers give antibiotics to their livestock?

A)to promote faster growth
B)to reduce illness
C)to develop new antibiotics
D)to grow more livestock with less food

Question 53

In the Hardy-Weinberg equation, ____________________ represents the predicted frequency of the heterozygous genotype.

Question 54

The bell-shaped curve at the top of the figure below shows the distribution of a phenotype in a population at the start of an experiment. The three graphs (lettered A-C)beneath predict what the distribution will look like if a certain type of selection occurs. Which graph represents what the phenotypic distribution will look like if the population undergoes stabilizing selection?

A)Graph A
B)Graph B
C)Graph C
D)These graphs all show natural selection, but none show stabilizing selection.

Question 55

Genetic drift causes random changes in ____________________ frequency.

Question 56

A few members of a species establish themselves on a small island far from other populations of that species. They may experience a genetic bottleneck due to the ____________________ effect.

Question 57

Disruptive selection operates whenever

A)natural selection is disrupted by genetic drift.
B)there is a balanced gene pool.
C)only the smallest individuals survive.
D)both the recessive and the dominant homozygotes are more successful.

Question 58

The color of a certain species of beetle is determined by a single gene. Two beetles homozygous for green coloration produce a single offspring with brown coloration. Brown color appeared in this offspring as a result of a ____________________.

Question 59

The shell of a particular species of snail exhibits anywhere from 3 to 10 coils when mature. Over a series of three years, a scientist counts the number of coils in the shells of all the mature individuals in a population of snails. Year after year, the most common phenotype is 7 coils. Snails with 3 coils or 10 coils are very rare. This is an example of _____ selection.

A)disruptive
B)stabilizing
C)directional
D)sexual

Question 60

How do natural selection and sexual selection differ?

A)Natural selection increases the frequency of alleles that contribute to survival, but sexual selection may increase the frequency of alleles that are not beneficial to survival.
B)Natural selection contributes to genetic drift, but sexual selection contributes to gene flow.
C)Natural selection is more random than sexual selection.
D)Natural selection increases the fitness of an allele, but sexual selection increases the dimorphism of an allele.

Question 61

The allele frequency of a recessive allele is always less than the allele frequency of a dominant allele.

Question 62

In ____________________ selection, individuals with one extreme of an inherited phenotypic trait have an advantage over other individuals in the population.

Question 63

Two-way gene flow increases the differences between two populations of the same species.

Question 64

The Amish people began as a colony of just 200 settlers in America. The fact that Ellis-van Creveld syndrome, a genetic disorder also known as six-fingered dwarfism, is more common among the Amish than other human populations is probably a result of founder effect.

Question 65

The Hardy-Weinberg equation can be used to determine the genotype frequencies of a population that is not evolving.

Question 66

Natural selection is a random process.

Question 67

The occurrence of mutation is directed toward a specific goal.

Question 68

If the phenotypic distribution of a population starts out as shown in the graph on the left and ends as shown in the graph on the right, you can conclude that the population is undergoing directional selection.

Question 69

Genetic drift can result in the fixation of a harmful allele in a small population.

Question 70

The four mechanisms that cause microevolution include gene flow, genetic drift, natural selection, and directional selection.

Question 71

In fish undergoing sexual selection, females are more likely to mate with males lacking coloration because brightly colored males are more visible to predators.

Question 72

Mutations generally cause rapid changes in allele frequencies in populations.

Question 73

Although they are protected in many countries, humans still hunt elephants for their ivory tusks. A mutation that results in tuskless elephants is increasing in frequency in some elephant populations as a result of the evolutionary mechanism of ____________________.

Question 74

Allele frequency refers to the rate of mutation in a population.

Question 75

Larger male elephant seals have more mates than smaller male elephant seals because they are better at defending their territory (and mates). This is an example of ____________________.

Question 76

In any given population the genotype frequency is usually the same as the allele frequency.

Question 77

Feeding healthy livestock antibiotics makes it more likely that antibiotic-resistant bacteria will evolve.

Question 78

The increase in antibiotic resistance in E. coli as a result of treating healthy animals with antibiotics is an example of ____________________ driving evolution.

Question 79

A new allele spreads from one large population to another as a result of genetic flow.

Question 80

The shape of the graph below indicates that birth weight is an example of ____________________ selection.