Deck 15: Evolution on a Small Scale

Question 1

All of the genes and all of their associated alleles within a population represent the population's

A) genotype.
B) gene flow.
C) gene pool.
D) genome.
E) Hardy-Weinberg equilibrium. The gene pool is defined as all the alleles of all the genes within a population.

Answer 1

C

Question 2

If the average leg size of a reptile continually got smaller through generations, this would be an example of

A) disruptive selection.
B) stabilizing selection.
C) directional selection.
D) genetic drift.
E) bottleneck effect. Directional selection occurs when one extreme variant is selected, no other phenotypes are as successful, and this trait increases in frequency over time.

Answer 2

C

Question 3

If half of a population is homozygous recessive, what is p?

A) 0.5
B) 0.707
C) 0.25
D) 0.293
E) 0.1 The homozygous recessive genotype = q². So, if q² = 0.5, then q = 0.707. p + q = 1, and therefore p = 0.293.

Answer 3

D

Question 4

If people with freckles preferentially mated with other people with freckles, this would be an example of

A) microevolution.
B) natural selection.
C) genetic drift.
D) nonrandom mating.
E) gene flow. In order for nonrandom mating to occur on freckles, individuals would have to choose mates based on the presence or absence of freckles. This is called preferential mating, and it results in a trait, such as freckles, being selected for and passed along to progeny if the trait is heritable.

Question 5

Which of the following does not generate genetic variation within a population?

A) genetic recombination
B) independent assortment of alleles
C) sexual reproduction
D) mutation
E) adaptation Genetic variation is required for evolution to occur. Genetic variation is generated through mutation, sexual reproduction, independent assortment of alleles, and genetic recombination.

Question 6

What might occur in moth populations if pollution from industry was cleaned up and the color of tree bark returned to its natural color?

A) Dark-colored moths would continue to be the predominant phenotype.
B) Birds would see dark-colored moths more easily than light-colored moths and prey on dark-colored moths more frequently.
C) Dark- and light-colored moths would survive in equal numbers.
D) Birds would prey upon dark- and light-colored moths equally.
E) Selection would favor the hybrid offspring of dark and light moths. Since dark-colored moth populations increased as pollution increased, light-colored moth populations may increase as pollution decreases.

Question 7

Which of the following is not one of the conditions required for a Hardy-Weinberg equilibrium?

A) Mutations must not occur.
B) Natural selection must not occur.
C) Random mating must not occur.
D) Genetic drift must not occur.
E) Assortative mating must not occur. The Hardy-Weinberg equation for equilibrium assumes that mutations, natural selection, genetic drift, gene flow, and nonrandom mating do not occur.

Question 8

Which Hardy-Weinberg condition is violated by sexual selection?

A) no mutations
B) no natural selection
C) random mating
D) no genetic drift
E) no gene flow The Hardy-Weinberg equation for equilibrium assumes that mutations, natural selection, genetic drift, gene flow, and nonrandom mating do not occur.

Question 9

If p = 0.6, what is q?

A) 0.6
B) 0.4
C) 0.36
D) 0.15
E) 0 Knowing the frequency of one allele, use the formula p + q = 1 to determine the frequency of the other allele.

Question 10

In the figure shown here, petal color of a flower population is distributed in a bell-shaped normal curve. If the pink petal color increases in frequency in the population, this would illustrate

A) stabilizing selection.
B) disruptive selection.
C) directional selection.
D) genetic drift. Stabilizing selection selects against individuals that are far from the mean value of a given trait.

Question 11

If a population recovers to its original population size after experiencing a bottleneck, which statement is correct regarding this population?

A) The recovered population is as likely to go extinct as is the population prior to the bottleneck.
B) The bottleneck subjected the population to directional selection.
C) The recovered population shows less genetic diversity than the population prior to the bottleneck.
D) The recovered population shows more genetic diversity than the population prior to the bottleneck.
E) The recovered population is more likely to go extinct as is the population prior to the bottleneck. A bottleneck decreases a population's genetic diversity.

Question 12

Which of the following is most likely to result in the formation of two distinct species?

A) directional selection
B) stabilizing selection
C) disruptive selection
D) genetic drift
E) bottleneck effect Disruptional selection divides a single population into two, which could eventually lead to two distinct species.

Question 13

What characteristic is common of both a genetic bottleneck and a founder effect?

A) Both encounter a population crash.
B) Both involve a portion of a population becoming isolated.
C) Both involve a decrease in a population's genetic diversity.
D) Both affect the entire population.
E) Both are a type of natural selection. A population's genetic diversity decreases in both a founder effect and a bottleneck.

Question 14

Why does malaria persist in the human population?

A) Too few humans have died of malaria to end the disease.
B) Multiple phenotypes survive in a balanced polymorphism.
C) Malaria is a recessive disease and few humans contract it.
D) Humans are protected from the malaria parasite.
E) Malaria is under stabilizing selection. In an environment where malaria is present, the heterozygote is favored.

Question 15

Which of the following would not result in a decrease of genetic variation?

A) natural selection
B) genetic drift
C) bottleneck effect
D) founder effect
E) mutation Natural selection, genetic drift, and bottleneck and founder effects all decrease genetic variation, while mutation generates genetic variation.

Question 16

Which of the following examples describes genetic drift?

A) A forest fire kills all plant life south of a highway.
B) Rabbits with longer fur survive the winter.
C) Insects resistant to insecticide survive crop dusting.
D) Colorful lizards living on brown leaves are most often eaten by predators.
E) Plants with larger flowers attract more butterflies than plants with smaller flowers. Genetic drift refers to random survival and reproduction, regardless of adaptive traits.

Question 17

In the Hardy-Weinberg formula, what does q² represent?

A) frequency of the dominant allele
B) frequency of the recessive allele
C) frequency of the heterozygotes
D) frequency of the homozygous dominants
E) frequency of the homozygous recessives

Question 18

In the figure shown here, petal color of a flower population is distributed in a bell-shaped normal curve. If the white petal color increases in frequency in the population, this would illustrate

A) stabilizing selection.
B) disruptive selection.
C) directional selection.
D) genetic drift.

Question 19

Which of the following individuals would be considered the fittest?

A) the individual that has the longest canine teeth
B) the individual that has the greatest number of breeding opportunities
C) the individual that has the best camouflage to avoid predators
D) the individual that controls the largest territory
E) the individual that has the greatest number of offspring Fitness is defined as the individual that can reproduce the greatest number of offspring.

Question 20

The figure shown here represents stabilizing selection. What happens when an individual is produced that possesses a trait far away from the mean value?

A) That extreme individual likely will not survive and reproduce.
B) That extreme individual will be more likely to survive and reproduce.
C) That extreme individual will have neither an advantage nor a disadvantage over other individuals.
D) All phenotypes have equal likelihood of surviving and reproducing.
E) The average phenotype is less likely to survive and reproduce. Stabilizing selection selects against individuals that are far from the mean value of a given trait.

Question 21

Biotic environments that influence natural selection include all but which of the following?

A) competition
B) predation
C) parasitism
D) weather
E) disease An organism's biotic environment consists of all the factors involving living organisms, such as predators, parasites, and competitors.

Question 22

If p² = 0.04, what is the frequency of homozygous recessives in the population?

A) 0.04
B) 0.2
C) 0.32
D) 0.64
E) 0.8

Question 23

The usage of the insecticide DDT to control mosquitoes resulted in

A) directional selection to insecticide resistance in the insects.
B) stabilizing selection to insecticide resistance in the insects.
C) disruptive selection to insecticide resistance in the insects.
D) genetic drift to insecticide resistance in the insects.
E) no change in the insect population. Directional selection occurred in mosquitoes over years of exposure to DDT. Those individual mosquitoes that were resistant to insecticide survived and reproduced. Subsequent generations of mosquitoes showed resistance to DDT.

Question 24

Directional selection in the modern horse is demonstrated by

A) the gradual decrease in size over time.
B) the rapid decrease in size over time.
C) the gradual increase in size over time.
D) the rapid increase in size over time.
E) the extinction of other horse species. Over time, horses gradually increased in overall size as an adaptation to their environment changing from forest to grassland. A directional change such as this indicates directional selection.

Question 25

In what type of environment is being heterozygous in regards to the sickle-cell trait an advantage?

A) an environment that has malaria
B) an environment that is malaria-free
C) an environment that is exposed to a large amount of sunlight year-round
D) an environment that is degraded
E) an environment that is cold and rainy Being heterozygous in an environment that has malaria is advantageous. The heterozygote produces red blood cells that secrete potassium, which causes the malaria parasite to die.

Question 26

The conditions required by the Hardy-Weinberg equilibrium are commonly found in nature.

Question 27

Natural selection can favor directional, stabilizing, and disruptive selection in the same population simultaneously.

Question 28

Dominance causes an allele to become more common.

Question 29

Which of the following is most likely an example of a founder effect event?

A) A random small group of a bird population migrates to an island and then returns to breed.
B) A random large group of a bird population migrates to an island and then returns to breed.
C) A selected small group of a bird population migrates to an island and then returns to breed.
D) A random small group of a bird population migrates to an island and does not return to breed.
E) A random large group of a bird population migrates to an island and does not return to breed. An example of the founder effect would likely be a small random portion of a population, representing a fraction of the entire gene pool, moving to a new location. These individuals take with them few chance alleles, which will occur at a higher frequency than in the original population.

Question 30

British land snails primarily occur in two extreme phenotypes. This is an example of

A) directional selection.
B) stabilizing selection.
C) disruptive selection.
D) genetic drift.
E) mutation. Disruptive selection favors polymorphism, the predominance of two or more phenotypes over an average phenotype.

Question 31

In the figure shown here, petal color of a flower population is distributed in a bell-shaped normal curve. If the white and yellow petal colors increase in frequency in the population, this would illustrate

A) stabilizing selection.
B) disruptive selection.
C) directional selection.
D) genetic drift. Disruptive selection selects for more than one phenotype but not all phenotypes.

Question 32

The increase in frequency of dark phenotypes in response to increased pollution is called

A) genetic drift.
B) founder effect.
C) industrial melanism.
D) assortative mating.
E) stabilizing selection. The increase in frequency of dark phenotypes in response to increased pollution is called industrial melanism. The pollution generated by industry causes the trees to become blackened, which allows dark-colored individuals to blend in with the trees better than light-colored individuals.

Question 33

Today, cheetahs show extreme genetic similarity. This is evidence of

A) past gene flow.
B) a past bottleneck event.
C) a history of directional selection.
D) a history of few genetic mutations.
E) assortative mating. A bottleneck reduces genetic variation within a population.

Question 34

In the process of natural selection, individuals that are most fit are the ones that are

A) most likely to survive.
B) most likely to reproduce.
C) most likely to migrate.
D) most likely to mutate.
E) most likely to be physically fit. The most fit individuals are those that are most likely to produce offspring.

Question 35

A group of field mice crosses a highway and joins a new population of field mice on the other side, producing offspring with this population. This is an example of

A) gene flow.
B) genetic drift.
C) Hardy-Weinberg equilibrium.
D) assortative mating.
E) hybridization. Gene flow, also called gene migration, is the movement of alleles among populations by migration of breeding individuals.

Question 36

Microevolution is not influenced by which of the following?

A) mutation
B) random mating
C) gene flow
D) natural selection
E) genetic drift Microevolution is influenced by mutation, gene flow, nonrandom mating, natural selection, and genetic drift. Microevolution will not occur if all of the Hardy-Weinberg conditions are met, including random mating.

Question 37

A female peacock chooses a mate based on his showy plumage and courtship dance. This is an example of

A) random mating.
B) assortative mating.
C) sexual selection.
D) gene flow.
E) natural selection. Females choosing males based on specific traits is defined as sexual selection.

Question 38

If the survivors of an original population survived due to specific phenotypes that they possessed, then this event is an example of

A) natural selection.
B) genetic drift.
C) founder effect.
D) industrial melanism.
E) gene flow. Selected survival is considered natural selection.

Question 39

In random mating

A) individuals choose the most attractive mate.
B) there is no factor influencing mate choice.
C) breeding occurs between two different species.
D) breeding occurs between two different subspecies.
E) fertile offspring are not produced. Random mating is when there are no factors influencing mate choice.

Question 40

A fraction of the original green frog population survives to reproduce and generate a new population. If the survivors of the original population survived by chance, then this event is an example of

A) natural selection.
B) genetic drift.
C) founder effect.
D) industrial melanism.
E) gene flow. Chance survival is considered genetic drift.

Question 41

Polydactylism possessing more than five fingers per hand) within the Amish population in Pennsylvania is considered an example of the founder effect. This is because the frequency of polydactylism among the Amish in Pennsylvania is identical to its frequency among the Amish population in Germany.

Question 42

What is the genotype of an individual that lives in protection from both sickle-cell disease and malaria?

A) Hb^AHb^A
B) Hb^AHb^S
C) Hb^SHb^S
D) Hb^S Hb^s
E) Hb^A Hb^a Hb^AHb^S is the genotype of a heterozygote for both normal and sickle-cell red blood cells. This individual is resistant to both sickle-cell disease and malaria.

Question 43

Microevolution is the term that applies to which of the following?

A) any evolution at any scale
B) large-scale changes over a long period of time
C) small-scale changes over a long period of time
D) small-scale changes over a short period of time
E) changes of any scale within microorganisms Microevolution is the term applied to small changes in a population over relatively short periods of time.

Question 44

A population of bacteria is not in Hardy-Weinberg equilibrium. Through repeated exposure to an antibiotic, the frequency of the recessive allele is rapidly increasing. What is the most likely explanation for this response?

A) The recessive allele is responsible for susceptibility of the bacteria to the antibiotic.
B) The dominant allele is responsible for susceptibility of the bacteria to the antibiotic.
C) The recessive allele is responsible for resistance of the bacteria to the antibiotic.
D) The population is experiencing gene flow.
E) The population is experiencing disruptive selection. The frequency increase in one allele shows a violation of the Hardy-Weinberg equilibrium. Since the recessive allele is increasing in response to antibiotic exposure a selective agent), this allele must be responsible for an adaptive phenotype, most likely antibiotic resistance.