Question 1

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.

Accepted Answer

Sexual selection is a mode of natural selection where members of one biological sex choose mates of the other sex to mate with, and compete with members of the same sex for access to members of the opposite sex. The choice of a mate based on showy plumage and courtship dance in peacocks is a classic example of sexual selection.

Question 2

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.

Accepted Answer

Gene flow occurs when organisms or their gametes move from one population to another and interbreed, introducing new genetic material into the receiving population. The movement of field mice across the highway and breeding with a new population is a classic example of gene flow, as it involves the transfer of alleles between populations.

Question 3

Why does malaria persist in the human population?
A) Too few humans have died of malaria to end the disease.
B) Heterozygote advantage maintains both the normal allele and the sickle cell allele in the population.
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.

Accepted Answer

Heterozygote advantage refers to the phenomenon where individuals who are heterozygous for a certain gene have a survival advantage over those who are homozygous. In the case of malaria, individuals who are heterozygous for the sickle cell allele (carrying one sickle cell allele and one normal allele) have a reduced risk of severe malaria compared to individuals with two normal alleles. This advantage maintains the presence of the sickle cell allele in populations where malaria is prevalent, thereby perpetuating the existence of malaria within the human population.

Question 4

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.

Accepted Answer

Cheetahs show extreme genetic similarity due to a past bottleneck event, which greatly reduced their population size, leading to a decrease in genetic diversity.

Question 5

Microevolution is influenced by which of the following?
A) mutation
B) gene flow
C) natural selection
D) genetic drift
E) All of the above answers describe factors that influence microevolution.

Accepted Answer

Microevolution refers to small-scale changes within populations over time, influenced by mutation, gene flow, natural selection, and genetic drift. These mechanisms contribute to the variation and adaptation seen within species.

Question 6

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.

Accepted Answer

The use of DDT selected for mosquitoes that had genetic mutations conferring resistance to the insecticide, leading to directional selection. This means that the allele frequencies in the mosquito population shifted in favor of those alleles that provided resistance to DDT, allowing those individuals to survive and reproduce more than those without resistance.

Question 7

A population of bacteria is not in Hardy-Weinberg equilibrium. Through repeated exposure to an antibiotic, the frequency of a 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.

Accepted Answer

The recessive allele is likely responsible for resistance to the antibiotic, which explains its rapid increase in frequency. Bacteria with this allele survive and reproduce more successfully in the presence of the antibiotic, leading to a shift in allele frequencies.

Question 8

A fraction of a green frog population survives a hurricane to reproduce and generate a new population. This event is an example of
A) natural selection.
B) genetic drift.
C) founder effect.
D) industrial melanism.
E) gene flow.

Accepted Answer

This event is an example of genetic drift, specifically a bottleneck effect, where a random event like a hurricane drastically reduces the population size, leading to a change in allele frequencies in the surviving population.

Question 9

What is the genotype of an individual that has 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

Accepted Answer

Individuals with the Hb ^AHb ^S genotype have one normal hemoglobin allele and one sickle-cell allele, providing some protection against malaria without causing sickle-cell disease.

Question 10

The members of a population survive and successfully reproduce due to the specific phenotypes they posses. This is an example of
A) natural selection.
B) genetic drift.
C) founder effect.
D) industrial melanism.
E) gene flow.

Accepted Answer

Natural selection is the process by which individuals with certain heritable traits tend to survive and reproduce more successfully than other individuals because of those traits. This leads to the adaptation of populations over time.

Question 11

Directional selection in the modern horse is demonstrated by
A) populations consisting of only very dark and very light colored horses.
B) the rapid decrease in size over the last 200 years.
C) the gradual increase in size over millions of years.
D) fossils which show the horse has not changed in millions of years.
E) the extinction of other horse species.

Accepted Answer

Directional selection is a form of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype. The gradual increase in size over millions of years in the modern horse is an example of directional selection, where larger size was likely favored in various environmental contexts, leading to the modern horse's increased size compared to its ancestors.

Question 12

Biotic environments that influence natural selection include all but which of the following?
A) competition
B) predation
C) parasitism
D) weather
E) disease

Accepted Answer

Weather is considered an abiotic factor, not a biotic one. Biotic factors involve living components of the environment, such as competition, predation, parasitism, and disease, which directly influence natural selection by affecting survival and reproduction.

Question 13

In the process of natural selection, individuals that are most fit are the ones that
A) survive the longest.
B) reproduce the most.
C) migrate every year.
D) have the most genetic mutations.
E) are the most physically fit.

Accepted Answer

In the context of natural selection, fitness refers to an organism's ability to survive and reproduce in its environment. Therefore, individuals that reproduce the most are considered the most fit because they pass on their genes to the next generation more effectively.

Question 14

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

Accepted Answer

Disruptive selection, unlike the other options, directly encourages the divergence within a population by favoring individuals at both extremes of a trait over those with intermediate traits. This can lead to the formation of two distinct groups within the population that may eventually become separate species if the divergence continues over time.

Question 15

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.

Accepted Answer

Industrial melanism is the term used to describe the evolutionary process where darker phenotypes become more common in a population due to selective pressures, such as increased pollution, which makes darker individuals less visible to predators or better suited to their environment.

Question 16

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.

Accepted Answer

This is an example of disruptive selection, where extreme phenotypes are favored over intermediate phenotypes, leading to a split in the population into two distinct groups.

Question 17

If p ² = 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

Accepted Answer

The answer of If p ² = 0.04, what is...

Question 18

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.

Accepted Answer

In random mating, mate choice is not influenced by any factor, meaning individuals do not preferentially choose mates based on any specific criteria, such as attractiveness, genetic makeup, or species/subspecies. This concept is fundamental in population genetics to model gene frequencies under the Hardy-Weinberg equilibrium.

Question 19

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) a polluted environment
E) an environment that is cold and rainy

Accepted Answer

Individuals who are heterozygous for the sickle-cell trait have a resistance to malaria, making this trait advantageous in environments where malaria is prevalent.

Quiz 15: Evolution on a Small Scale

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

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

Why does malaria persist in the human population?

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

Microevolution is influenced by which of the following?

The usage of the insecticide DDT to control mosquitoes resulted in

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

A fraction of a green frog population survives a hurricane to reproduce and generate a new population. This event is an example of

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

The members of a population survive and successfully reproduce due to the specific phenotypes they posses. This is an example of

Directional selection in the modern horse is demonstrated by

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

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

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

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

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

If p 2 = 0.04, what is the frequency of homozygous recessives in the population?

In random mating

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

If p ² = 0.04, what is the frequency of homozygous recessives in the population?