Question 1

Many male birds will expend a great deal of energy building nests. Females will mate with the males who build the best nests. This is best described as an example of ____.
A)natural selection
B)sexual selection
C)runaway selection
D)an invasive species
E)disruptive selection

Accepted Answer

This is an example of sexual selection, where females choose mates based on certain traits or behaviors that are attractive to them, such as the ability to build a good nest. This can lead to the evolution of exaggerated traits, as males with the most extreme versions of these traits are favored in mating.

Question 2

The observation that female lions prefer male lions with darker manes is an example of ____.
A)directional selection
B)disruptive selection
C)dominance
D)a sexual handicap
E)sexual selection

Accepted Answer

The preference by female lions for males with darker manes is an example of sexual selection, where certain traits are favored by one sex in choosing mates. This preference for darker manes is likely a result of the trait being a signal of health and fitness, displaying the ability of a male lion to survive and thrive.

Question 3

In a tropical forest some leaves are dark green and some are light green. In a population of caterpillars, homozygous dominant dark green caterpillars thrive eating the dark green foliage, while homozygous recessive light green caterpillars thrive eating light green foliage. However, heterozygous caterpillars of an intermediate color green are easily seen by birds and eaten, thus their numbers are far less than the dominants or recessives. This is an example of ____ selection.
A)directional
B)stabilizing
C)disruptive
D)frequent
E)mutational

Accepted Answer

Disruptive selection is illustrated here, where extreme traits (dark green and light green caterpillars) are favored over the intermediate trait, leading to a decrease in the population of heterozygous, intermediate-colored caterpillars.

Question 4

In a population of rabbits, those able to outrun predators will survive to reproduce, eventually leading to a population of faster rabbits. This is an example of ____ selection.
A)directional
B)stabilizing
C)disruptive
D)mutational
E)restricted

Accepted Answer

In directional selection, there is a shift in a population towards a particular trait, in this case, the ability to outrun predators. As faster rabbits are more likely to survive and reproduce, over time the population will gradually have more and more individuals with this advantageous trait, leading to a population of faster rabbits.

Question 5

A random change in allele frequency over time that is brought about by chance alone is known as ____.
A)genetic drift
B)gene flow
C)natural selection
D)disruptive selection
E)balanced polymorphism

Accepted Answer

Genetic drift is the random fluctuation in the frequency of alleles in a gene pool brought about by chance events. This process can result in the loss of genetic variation within a population or the fixation of new alleles. Gene flow involves the movement of individuals or gametes from one population to another and can result in the transfer of alleles between populations. Natural selection involves the differential survival and reproduction of individuals with certain inherited traits, leading to a higher frequency of those traits in future generations. Disruptive selection occurs when individuals with extreme phenotypes have higher fitness than individuals with intermediate phenotypes, leading to a bimodal distribution of traits. Balanced polymorphism refers to the maintenance of two or more alleles at a locus in a population due to their heterozygote advantage.

Question 6

Heterozygotes for the sickle cell trait have an adaptive advantage in areas where malaria is prevalent. This is an example of ____.
A)a fixed allele
B)genetic drift
C)a balanced polymorphism
D)sexual selection
E)disruptive selection

Accepted Answer

Heterozygotes for the sickle cell trait have an adaptive advantage in areas where malaria is prevalent because the sickle cell allele also confers some resistance to malaria. This results in a balanced polymorphism, where both the sickle cell allele and the normal allele are maintained in the population at relatively high frequencies. This is because individuals who are homozygous for the sickle cell allele may have sickle cell anemia and suffer from health problems, while individuals who are homozygous for the normal allele may have lower resistance to malaria. Therefore, the heterozygotes have a selective advantage and are more likely to survive and reproduce.

Question 7

Exposure of wild rat populations to warfarin led to the evolution of warfarin-resistant rats. These rats had a mutated version of the VKORC1 gene, indicating that ____ had occurred in these resistant rat populations.
A)extinction
B)stabilizing selection
C)microevolution
D)macroevolution
E)artificial selection

Accepted Answer

The presence of a mutation in the VKORC1 gene is evidence of genetic changes occurring within the wild rat populations, indicating microevolution. The other options do not fit the scenario described in the question - extinction would mean that there wouldn't be any rats left, stabilizing selection would suggest that there hasn't been any change in the rat population, macroevolution involves the development of new species, and artificial selection would require human intervention.

Question 8

Peahens prefer to mate with peacocks that have the brightest and largest tail displays. The peacock's tail is a disadvantage to the males, because it is large and cumbersome and hinders them from escaping from predators. Given these facts, why isn't the peacock's tail selected against by natural selection?
A)peacocks lack the mutations to allow selection to work
B)only a few peacocks have large tail displays
C)in spite of the disadvantage, peacocks with larger tails leave more offspring
D)it is selected against, but because a peahen gives birth to so many males, the population is not greatly affected
E)peacocks do not reproduce sexually

Accepted Answer

Despite the disadvantage of a large and cumbersome tail, peahens prefer to mate with peacocks with the brightest and largest tail displays. This preference leads to greater reproductive success for males with larger tails, resulting in more offspring. Therefore, even though the tail may hinder escape from predators, it is still selected for by natural selection due to its attractiveness to females.

Question 9

The increased variability in the frequency of the b+ allele in the smaller flour beetle population in the graph above is an example of ____.
A)genetic drift
B)gene flow
C)the founder effect
D)a fixed allele
E)a dimorphic trait

Accepted Answer

Genetic drift is the random fluctuation of allele frequencies in a population due to chance events. In this case, the smaller flour beetle population is more susceptible to genetic drift, as chance events can have a greater impact on the frequency of the b+ allele. This results in increased variability in the frequency of the allele in this population. The other choices do not adequately describe the scenario shown in the graph.

Question 10

____ selection occurs when individuals choose mates with a particular desirable trait.
A)Stabilizing
B)Sexual
C)Artificial
D)Asexual
E)Disruptive

Accepted Answer

Sexual selection occurs when individuals choose mates with a particular desirable trait, often in order to increase their chances of reproductive success. This can involve competition among individuals of the same sex, as well as mate choice based on traits like physical appearance or displays of strength or aggression. Stabilizing selection, disruptive selection, and artificial selection all refer to different types of natural or human-driven selection pressures, but they do not involve mate choice specifically. Asexual reproduction also does not involve mate choice, as offspring are produced without the need for a partner.

Question 11

The graphs below show the frequency of the b+ allele over twenty generations in two populations of heterozygous flour beetles (data for a population of ten individuals is shown in graph A; data for a population of one hundred individuals is shown in graph B). Why does the frequency of the b + allele increase in both populations? 
A)b+ is a lethal allele
B)b+ is a balanced polymorphism
C)b+ is a fixed allele
D)the b+ allele is adaptive
E)b+ is a neutral mutation

Accepted Answer

The answer of The graphs below show the frequency of...

Question 12

The Old Order Amish in Lancaster County is descended from one man and woman and has an unusually high frequency of a recessive allele that causes Ellis-van Creveld syndrome. This is an example of ____.
A)a bottleneck
B)mutation
C)a founder effect
D)gene flow
E)genetic drift

Accepted Answer

The fact that the Old Order Amish in Lancaster County have an unusually high frequency of a recessive allele is due to a founder effect. This occurs when a small group of individuals become isolated and form a new population with a limited genetic pool. In this case, the population is descended from one man and woman, which has led to the high frequency of the Ellis-van Creveld syndrome allele.

Question 13

A small Dutch population settled in South Africa in the 17th century and became known as Afrikaners. By chance, a few Dutch settlers carried the gene for Huntington's disease. Today, Huntington's disease occurs at a relatively high frequency in this population. This is an example of ____.
A)the bottleneck effect
B)the founder effect
C)gene flow
D)artificial selection
E)natural selection

Accepted Answer

The situation described is an example of the founder effect. A small group of Dutch settlers (founders) carried the gene for Huntington's disease, which is now relatively common in the Afrikaner population.

Question 14

In the universal ABO blood grouping system, there are four phenotypes - A, B, AB, and O - which are determined by three different alleles. The presence of three alleles in the ABO blood grouping system is an example of ____.
A)a polymorphism
B)genetic drift
C)the bottleneck effect
D)a dimorphism
E)the founder effect

Accepted Answer

A polymorphism is a genetic variation that is present in more than 1% of the population, and the presence of three alleles in the ABO blood grouping system is a classic example of this. Polymorphisms are important for maintaining genetic variation within a population, which can contribute to the adaptation and survival of a species over time.

Question 15

Overhunting of species, such as tigers, reduces their numbers and their genetic diversity. This is an example of _____.
A)a bottleneck
B)a mutation
C)a founder effect
D)gene flow
E)genetic drift

Accepted Answer

Overhunting can lead to a decrease in population size and genetic diversity, which is characteristic of a bottleneck event.

Question 16

The movement of alleles among populations is called _____.
A)bottleneck
B)mutation
C)founder effect
D)gene flow
E)genetic drift

Accepted Answer

Gene flow refers to the movement of alleles from one population to another. This can occur through the migration of individuals, the transfer of gametes, or the movement of seeds or spores. Gene flow can increase genetic variation within a population and can also decrease genetic differences between populations.

Question 17

Which population is more likely to be affected by genetic drift?
A)12 squirrels in a forest
B)49 herons in a colony
C)215 fleas on a dog
D)1350 mice in a house
E)3000 zebra in a herd

Accepted Answer

Genetic drift is the random fluctuation in allele frequencies in a small population. Therefore, a population of 12 squirrels in a forest is the smallest population on the list and is more likely to be affected by genetic drift.

Question 18

What is one result of the bottleneck effect?
A)balanced alleles
B)heterozygosity
C)decreased genetic diversity
D)disruptive selection
E)random mating

Accepted Answer

The bottleneck effect occurs when a population goes through a drastic reduction in size, resulting in a loss of genetic variation. This decreased genetic diversity can lead to a higher likelihood of genetic disorders and reduced ability to adapt to environmental changes. Therefore, C) decreased genetic diversity is the correct answer. Choices A, B, D, and E are not directly related to the bottleneck effect.

Question 19

In Cameroon, seedcrackers have either small bills (adapted for feeding on soft sedge seeds)or large bills (adapted for feeding on hard sedge seeds). During competition for scarce resources, these birds primarily feed on the seeds for which they are best adapted. This is an example of ____ selection.
A)stabilizing
B)disruptive
C)frequent
D)directional
E)mutational

Accepted Answer

The scenario describes disruptive selection, as there are two distinct phenotypes that are being selected for - those with small bills for soft seeds and those with large bills for hard seeds. This leads to a bimodal distribution of the trait, which is the hallmark of disruptive selection.

Question 20

Puppies born too large experience difficulties during birthing and tend to have respiratory and other problems. Puppies born too small often can't compete with their siblings for their mother's milk. Thus, puppies of intermediate size have a survival advantage. This is an example of ____ selection.
A)directional
B)stabilizing
C)disruptive
D)frequency
E)allelic

Accepted Answer

Stabilizing selection favors intermediate traits over extreme traits. In this case, intermediate sized puppies have a higher survival rate than those born too large or too small, leading to a preference for this trait.

Quiz 12: Processes of Evolution

Many male birds will expend a great deal of energy building nests. Females will mate with the males who build the best nests. This is best described as an example of ____.

The observation that female lions prefer male lions with darker manes is an example of ____.

In a population of rabbits, those able to outrun predators will survive to reproduce, eventually leading to a population of faster rabbits. This is an example of ____ selection.

A random change in allele frequency over time that is brought about by chance alone is known as ____.

Heterozygotes for the sickle cell trait have an adaptive advantage in areas where malaria is prevalent. This is an example of ____.

Exposure of wild rat populations to warfarin led to the evolution of warfarin-resistant rats. These rats had a mutated version of the VKORC1 gene, indicating that ____ had occurred in these resistant rat populations.

The increased variability in the frequency of the b+ allele in the smaller flour beetle population in the graph above is an example of ____.

____ selection occurs when individuals choose mates with a particular desirable trait.

The Old Order Amish in Lancaster County is descended from one man and woman and has an unusually high frequency of a recessive allele that causes Ellis-van Creveld syndrome. This is an example of ____.

A small Dutch population settled in South Africa in the 17th century and became known as Afrikaners. By chance, a few Dutch settlers carried the gene for Huntington's disease. Today, Huntington's disease occurs at a relatively high frequency in this population. This is an example of ____.

In the universal ABO blood grouping system, there are four phenotypes - A, B, AB, and O - which are determined by three different alleles. The presence of three alleles in the ABO blood grouping system is an example of ____.

Overhunting of species, such as tigers, reduces their numbers and their genetic diversity. This is an example of _____.

The movement of alleles among populations is called _____.

Which population is more likely to be affected by genetic drift?

What is one result of the bottleneck effect?

Puppies born too large experience difficulties during birthing and tend to have respiratory and other problems. Puppies born too small often can't compete with their siblings for their mother's milk. Thus, puppies of intermediate size have a survival advantage. This is an example of ____ selection.