Question 1

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 2

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 of a species can lead to a reduction in its population size, which can create a bottleneck effect. This means that only a few individuals survive, reducing the genetic diversity of the population.

Question 3

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 scenario described is an example of the founder effect, where a small group of individuals with a specific gene move to a new area and establish a population, leading to a higher frequency of that gene in that population.

Question 4

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 emergence of the mutated version of the VKORC1 gene in the warfarin-resistant rats indicates that microevolution had occurred in these populations, as an adaptive response to selective pressure from exposure to the drug.

Question 5

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, the traits that lead to greater survival and reproduction become more common in a population over time. In this case, the ability to outrun predators is a trait that leads to greater survival, so it is likely to become more common in the population over generations.

Question 6

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 Old Order Amish in Lancaster County descended from one man and woman, which is an example of a founder effect. The high frequency of a recessive allele causing Ellis-van Creveld syndrome is also due to this founder effect because the Amish community is isolated and does not have gene flow with other populations.

Question 7

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) P eacocks lack the mutations to allow selection to work.
B) O nly a few peacocks have large tail displays.
C) I n spite of the disadvantage, peacocks with larger tails leave more offspring.
D) I t is selected against, but because a peahen gives birth to so many males, the population is not greatly affected.
E) P eacocks do not reproduce sexually.

Accepted Answer

Despite the disadvantage of the large tail, peacocks with larger tails are preferred by peahens and therefore have a higher chance of mating and leaving offspring. This means that the trait is actually favored by natural selection, as it increases the reproductive success of the individuals possessing it.

Question 8

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

A smaller population size is more likely to be affected by genetic drift, as chance events can have a greater impact on the gene frequencies of a small population. Out of the options given, 12 squirrels in a forest represent the smallest population size.

Question 9

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 is the movement of alleles from one population to another population. This can occur through migration of individuals, transfer of gametes, or other means of gene transfer. Gene flow can alter the allele frequencies of a population and increase genetic variation within a population.

Question 10

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 is a sharp reduction in the size of a population due to a catastrophic event such as a natural disaster or disease outbreak. This can result in a loss of genetic diversity as only a small subset of the original population survives and reproduces. As a result, certain alleles may become more prevalent in the gene pool, while others may be lost altogether. Overall, this reduces the genetic variation of the population, making it more vulnerable to environmental pressures and potentially reducing its long-term viability.

Question 11

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 trait provides some resistance to malaria. This creates a balanced polymorphism in the population where both the sickle cell allele and the normal hemoglobin allele are maintained at relatively high frequencies.

Question 12

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, as the female birds are choosing their mates based on their ability to build a good nest, which is a trait that is not necessarily related to survival or fitness, but rather to the males' ability to attract a mate.

Question 13

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

ABO blood grouping system is an example of polymorphism where multiple forms of a gene (alleles) exist within a population.

Question 14

____ 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. This can often lead to the evolution of exaggerated traits that increase the chances of successful mating.

Question 15

The following graphs show the frequency of the b+ allele over 20 generations in two populations of heterozygous flour beetles (data for a population of 10 individuals is shown in graph A; data for a population of 100 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) b+ allele is adaptive.
E) b+ is a neutral mutation.

Accepted Answer

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

Question 16

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

This is an example of disruptive selection because the individuals with small bills and those with large bills are both favored, while those with intermediate bill sizes are at a disadvantage. As a result, the population may eventually diverge into two distinct groups, each with a different bill size adaptation.

Question 17

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 survival advantage over both large and small puppies, thus stabilizing the trait of size in the population.

Question 18

The increased variability in the frequency of the b+ allele in the smaller flour beetle population in the given graph 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 refers to changes in the frequency of alleles in a population due to random factors, such as chance events that cause certain individuals to produce more offspring than others, or a small subset of the population founding a new population. The increased variability in the frequency of the b+ allele in the smaller flour beetle population suggests that genetic drift is occurring in this population.

Question 19

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 for male lions with darker manes is an example of sexual selection, where females are selecting mates based on certain traits that they find attractive. It is not directional or disruptive selection, as there is no indication of a shift in the population towards one extreme or the other. Dominance might be a factor in lion behavior, but it is not the main explanation for this preference. The existence of a sexual preference for darker manes is not a handicap, but rather a characteristic that could confer advantages in attracting females.

Question 20

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 a process that occurs due to chance events, such as a natural disaster that kills a large portion of a population, causing a change in allele frequencies. Gene flow occurs when individuals migrate into or out of a population, affecting allele frequencies. Natural selection is a process in which certain traits are selected for or against based on fitness in a particular environment. Disruptive selection occurs when two extreme phenotypes have higher fitness than an intermediate phenotype. Balanced polymorphism refers to the maintenance of multiple alleles in a population due to heterozygote advantage or frequency-dependent selection. Out of these options, it is genetic drift that is brought about by chance alone.

Quiz 13: Processes of Evolution

Overhunting of species, such as tigers, reduces their numbers and their genetic diversity. 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 ____.

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.

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.

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 ____.

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

The movement of alleles among populations is called _____.

What is one result of the bottleneck effect?

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

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 ____.

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 ____.

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

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.

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

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

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