Question 1

Which best describes the effect of positive assortative mating in a population?
A) It causes natural selection.
B) It increases homozygosity.
C) It changes allele frequencies.
D) It stabilizes genotype frequencies.
E) It produces more mutations each generation.

Accepted Answer

Positive assortative mating, where individuals preferentially mate with others that are similar to themselves, tends to increase homozygosity in a population because it increases the likelihood that similar alleles will be paired together.

Question 2

A population of people who have lived in the middle of the jungle for thousands of years without coming in contact with other individuals would show evidence of:
A) genetic stasis.
B) polymorphism.
C) random mating.
D) genetic equilibrium.
E) increasing nonharmful alleles.

Accepted Answer

The answer of A population of people who have lived...

Question 3

The movement of 25-year-old fertile individuals between Mexico and Canada will eventually contribute to:
A) mutation.
B) gene flow.
C) genetic drift.
D) natural selection.
E) directional selection.

Accepted Answer

Gene flow occurs when individuals or their gametes move from one population to another, thereby mixing their genetic material with the new population. The movement of fertile individuals between Mexico and Canada would contribute to gene flow by introducing new genetic variations into the populations they join.

Question 4

Due to a rapid change in the environment, a population of ants was reduced from one million to one thousand. What type of genetic drift will occur in the gene pool of this population when it expands again?
A) Gene flow
B) Migration
C) Natural selection
D) The founder effect
E) A genetic bottleneck

Accepted Answer

A genetic bottleneck occurs when a population's size is significantly reduced for at least one generation, leading to a loss of genetic variation. The scenario described, where the ant population decreases drastically, is a classic example of a bottleneck event. When the population expands again, the genetic diversity will be based on the reduced gene pool of the survivors, not the original population.

Question 5

In cases of_____________________, the fitness of a particular phenotype depends on how frequently it appears in the population.
A) frequency-dependent selection
B) genetic variation
C) gene flow
D) genetic polymorphism
E) stabilizing selection

Accepted Answer

Frequency-dependent selection occurs when the fitness of a phenotype depends on its frequency relative to other phenotypes in a population. This means that the advantage or disadvantage of a trait changes as its frequency changes.

Question 6

Negative frequency-dependent selection acts to decrease the frequency of which phenotype in a population?
A) The least common phenotype
B) The most common phenotype
C) The most conspicuous phenotype
D) The most camouflaged phenotype
E) The phenotype at an extreme of the normal distribution

Accepted Answer

Negative frequency-dependent selection tends to decrease the frequency of the most common phenotype in a population, as it confers a selective advantage to rarer phenotypes, helping to maintain genetic diversity.

Question 7

Variation that does not alter the ability of an individual to survive and reproduce, and therefore not an adaptive variation, is called:
A) frequency-dependent selection
B) genetic variation
C) gene flow
D) genetic polymorphism
E) neutral variation

Accepted Answer

Neutral variation refers to genetic differences that do not confer any selective advantage or disadvantage. This means these variations do not affect an organism's fitness and are not subject to natural selection.

Question 8

___________is the mechanism of evolution first proposed by Darwin.
A) mutation.
B) genetic drift.
C) natural selection.
D) neutral variation.
E) geographic variation.

Accepted Answer

Natural selection is the mechanism of evolution first proposed by Darwin, where organisms better adapted to their environment tend to survive and produce more offspring.

Question 9

Variation that does not alter the ability of an individual to survive and reproduce is therefore considered:
A) neutral.
B) genetic.
C) geographic.
D) heterozygous.
E) frequency-dependent.

Accepted Answer

Neutral variation does not affect an organism's fitness and therefore does not influence its ability to survive or reproduce. This type of variation is often maintained in a population through genetic drift rather than natural selection.

Question 10

With respect to the alleles for sickle cell anemia, which genotype(s) is (are) at a disadvantage to persons residing in tropical areas of Africa?
A) Heterozygous
B) Homozygous dominant
C) Homozygous recessive
D) Both heterozygous and homozygous dominant
E) Both homozygous dominant and homozygous recessive

Accepted Answer

The answer of With respect to the alleles for sickle...

Question 11

Which mechanism results in changes in allele frequencies in a population from one generation to another due to random sampling?
A) Gene flow
B) Mutation
C) Genetic drift
D) Natural selection
E) Disruptive selection

Accepted Answer

Genetic drift is the mechanism that results in changes in allele frequencies in a population from one generation to another due to random sampling. It is a stochastic effect that occurs especially in small populations.

Question 12

A population in which the allele and genotype frequencies do not change over time is said to be in:
A) genetic stasis.
B) allele balance.
C) genetic equilibrium.
D) population stability.
E) phenotype equilibrium.

Accepted Answer

Genetic equilibrium, also known as Hardy-Weinberg equilibrium, refers to a state in a population where allele and genotype frequencies remain constant from generation to generation, assuming no evolutionary influences are acting on the population.

Question 13

What is the only source of all new alleles?
A) Mutation
B) Gene flow
C) Genetic drift
D) Natural selection
E) Genetic polymorphism

Accepted Answer

Mutation is the only source of all new alleles because it involves changes in the DNA sequence, which can introduce new genetic variations into a population. Other options like gene flow, genetic drift, and natural selection are mechanisms of evolution that act on existing genetic variation, but they do not create new alleles. Genetic polymorphism refers to the existence of two or more variants (alleles) at a particular gene locus in a population's genetic makeup, but it is not a source of new alleles itself.

Question 14

Which region displays an example of the founder effect amongst its population?
A) China
B) Iceland
C) Central Africa
D) The United States
E) The United Kingdom

Accepted Answer

Iceland is known for displaying the founder effect due to its relatively small initial population of settlers, leading to a limited genetic pool among the current population.

Question 15

When mutations are not passed on from one generation to the next, then a mutation can:
A) arise in somatic cells.
B) result from genetic drift.
C) arise from the founder effect.
D) be balanced by polymorphism.
E) result from disruptive selection.

Accepted Answer

Mutations that are not passed on from one generation to the next occur in somatic cells, not in germ cells which would affect offspring.

Question 16

Which is an example of nonrandom mating?
A) Selecting a mate by their genotype
B) Selecting a mate by their phenotype
C) Selecting a mate by their species richness
D) Selecting a mate by their family relationship
E) Selecting a mate by their success of defeating another

Accepted Answer

The answer of Which is an example of nonrandom mating?
A)...

Question 17

Evolution that involves changes in allele frequencies over just a few successive generations is referred to as:
A) natural selection.
B) microevolution.
C) macroevolution.
D) stabilizing selection.
E) directional selection.

Accepted Answer

Microevolution refers to small evolutionary changes (typically described as changes in allele frequencies) within a species or population, over a short period of time.

Question 18

_____________________ is a special type of directional selection in which there is a trend in several directions rather than just one.
A) gene flow
B) genetic drift
C) natural selection
D) disruptive selection
E) beneficial mutations

Accepted Answer

Disruptive selection is a form of natural selection where extreme values for a trait are favored over intermediate values, leading to a trend in several directions rather than just one. This can result in two or more contrasting phenotypes in the same population.

Question 19

Which of the following can produce a population of individuals with a relatively high frequency of a harmful or rare allele?
A) Mutation
B) Natural selection
C) The founder effect
D) Artificial selection
E) Migration between large populations

Accepted Answer

The founder effect can lead to a high frequency of a harmful or rare allele in a population because it involves a small group of individuals breaking off from a larger population to establish a new population. This small group may carry rare alleles at a higher frequency than the original population, and these alleles can become more common in the new population due to genetic drift.

Question 20

The migration of breeding individuals between populations causes a corresponding movement of alleles, which is referred to as:
A) mutation.
B) gene flow.
C) genetic drift.
D) natural selection.
E) directional selection.

Accepted Answer

Gene flow refers to the transfer of alleles or genes from one population to another as a result of the movement of fertile individuals or their gametes, which can lead to changes in the genetic composition of a population.

Quiz 19: Evolutionary Change in Populations

Which best describes the effect of positive assortative mating in a population?

A population of people who have lived in the middle of the jungle for thousands of years without coming in contact with other individuals would show evidence of:

The movement of 25-year-old fertile individuals between Mexico and Canada will eventually contribute to:

Due to a rapid change in the environment, a population of ants was reduced from one million to one thousand. What type of genetic drift will occur in the gene pool of this population when it expands again?

In cases of_____________________, the fitness of a particular phenotype depends on how frequently it appears in the population.

Negative frequency-dependent selection acts to decrease the frequency of which phenotype in a population?

Variation that does not alter the ability of an individual to survive and reproduce, and therefore not an adaptive variation, is called:

___________is the mechanism of evolution first proposed by Darwin.

Variation that does not alter the ability of an individual to survive and reproduce is therefore considered:

With respect to the alleles for sickle cell anemia, which genotype(s) is (are) at a disadvantage to persons residing in tropical areas of Africa?

Which mechanism results in changes in allele frequencies in a population from one generation to another due to random sampling?

A population in which the allele and genotype frequencies do not change over time is said to be in:

What is the only source of all new alleles?

Which region displays an example of the founder effect amongst its population?

When mutations are not passed on from one generation to the next, then a mutation can:

Which is an example of nonrandom mating?

Evolution that involves changes in allele frequencies over just a few successive generations is referred to as:

_____________________ is a special type of directional selection in which there is a trend in several directions rather than just one.

Which of the following can produce a population of individuals with a relatively high frequency of a harmful or rare allele?

The migration of breeding individuals between populations causes a corresponding movement of alleles, which is referred to as: