Question 1

What mechanism leads to changes in allele frequencies through random chance?
A)Genetic drift
B)Natural selection
C)Sexual selection
D)Neutral variation
E)Gene flow

Accepted Answer

Genetic drift is the mechanism that leads to changes in allele frequencies through random chance. This can happen due to chance events such as migration or random mating, rather than natural selection or other factors. As a result, genetic drift can have significant effects on the genetic makeup of a population over time, leading to changes in allele frequencies and potentially even the formation of new species.

Question 2

The human b-globin gene has two alleles,H^S and H^A,individuals that are homozygous for H^S have sickle-cell anemia and a lower fitness.Individuals that are heterozygotes (H^SH^A)do not show sickle-cell symptoms and have a resistance to malaria.Individuals that are homozygous for H^A have the highest fitness but are susceptible to malaria.If a vaccine for malaria was created that was 100% effective,affordable,and widely available,how would the frequency of the H^S allele be most likely to change? A)The H^S allele would increase in regions where malaria is prevalent and decrease in regions where malaria is absent or rare. B)The H^S allele would decrease in regions where malaria is prevalent and increase in regions where malaria is absent or rare. C)Due to balancing selection,the frequency of the H^S allele would remain stable in all regions. D)The H^S allele would increase in regions where malaria is prevalent and remain stable in regions where malaria is absent or rare. E)The H^S allele would decrease in regions where malaria is prevalent and remain stable in regions where malaria is absent or rarE.

Accepted Answer

With a 100% effective malaria vaccine, the selective advantage of the H allele in providing malaria resistance would be eliminated, leading to a decrease in its frequency in regions where malaria is prevalent. In regions where malaria is absent or rare, the frequency of the H ~~allele would likely remain stable as it already has no advantage.~~

Question 3

Select the examples that can undergo microevolution.
A) A poison ivy vine growing up an oak tree.
B) A small group of Cactus finches living in the Galapagos Islands.
C) An Emperor penguin encountering melting ice due to climate change.
D) A cluster of endangered Venus Flytraps in North Carolina's Green Swamp.
E) A large herd of caribou in Alaska.

Accepted Answer

Microevolution refers to changes in allele frequencies within a population over time. B, D, and E involve populations of organisms that can undergo genetic changes due to factors like natural selection, genetic drift, or gene flow.

Question 4

The human b-globin gene has two alleles,H^S and H^A,individuals that are homozygous for H^S have sickle-cell anemia and a lower fitness.Individuals that are heterozygotes (H^SH^A)do not show sickle-cell symptoms and have a resistance to malaria.Individuals that are homozygous for H^A have the highest fitness but are susceptible to malaria.In areas where malaria is prevalent the H^S allele is maintained in the population.Which type of selection is occurring with the b-globin gene? A)stabilizing B)directional C)disruptive D)balancing E)negative frequency dependent

Accepted Answer

Balancing selection is occurring with the b-globin gene because heterozygotes have a higher fitness than either of the homozygotes. This means that both alleles are maintained in the population at relatively high frequencies. The presence of malaria is likely driving this balancing selection as each allele confers a different advantage in response to the disease.

Question 5

Blue flower color (B allele)is dominant to white (b allele).If a population of plants contains white flowers (bb)at a frequency of 0.04,what is the frequency of the blue flower allele (B)?
4-9-2013
A)0.2 or 20%
B)0.64 or 64%
C)0.32 or 32%
D)0.8 or 80%
E)0.96 or 96%

Accepted Answer

The frequency of the white flower allele (b) is the square root of 0.04, which is 0.2 or 20%. Therefore, the frequency of the blue flower allele (B) is 1 - 0.2 = 0.8 or 80%.

Question 6

Fitness is a measure of reproductive success.If an individual with genotype BB produces 6 offspring,and a heterozygous individual (Bb)produces 10 offspring,and a third individual with genotype bb produces 5 offspring,what is the fitness value for the individual with BB genotype?
A)1.0.
B)0.5.
C)0.6.
D)0.4.
E)1.1

Accepted Answer

Fitness is calculated relative to the most successful genotype. Here, the Bb genotype has the highest number of offspring (10), so its fitness is set as 1.0. The fitness of the BB genotype is calculated as the number of offspring it produces (6) divided by the number of offspring produced by the most successful genotype (10), which equals 0.6.

Question 7

Over generations in a population,individuals with higher fitness values will
A)become less prevalent in the population.
B)become more prevalent in the population.
C)stay at the same frequency in the population.
D)decrease the population's mean fitness.

Accepted Answer

Fitness is a measure of an individual's ability to survive and reproduce in a given environment. Individuals with higher fitness values have a greater likelihood of passing their traits on to their offspring. Over time, this leads to an increase in the prevalence of these traits in the population, resulting in more individuals with higher fitness values.

Question 8

If a population satisfies the Hardy-Weinberg equilibrium model,what can you assume about that population?
A)It is relatively small.
B)Evolution is occurring.
C)Gene flow is occurring.
D)Allele and genotype frequencies are stable.

Accepted Answer

If a population satisfies the Hardy-Weinberg equilibrium model, it suggests that the population's allele and genotype frequencies are stable and not changing over generations. This could be due to several factors, such as no mutations, no genetic drift, no migration, no selection, and random mating. This can occur in populations of any size, and when evolution is not occurring. Gene flow is not occurring because it implies the transfer of alleles between different populations or subpopulations, which could disrupt the Hardy-Weinberg equilibrium.

Question 9

In _____ selection,individuals intermediate in a phenotypic distribution have greater reproductive success.
A)stabilizing
B)directional
C)disruptive
D)balancing
E)negative frequency-dependent

Accepted Answer

Stabilizing selection favors individuals with intermediate phenotypes and reduces variation in a population, leading to a narrower range of phenotypic traits. This occurs when extreme phenotypes are less fit than intermediate phenotypes, and the population stabilizes around the intermediate trait, resulting in greater reproductive success for individuals with intermediate traits.

Question 10

Microevolution involves
A)changes to the number of individuals in a population.
B)changes in a population's gene pool.
C)a change in the ratio of males to females in a population.
D)the fixation of an allele over a long period of time.

Accepted Answer

Microevolution refers to small-scale changes that occur within a population, and these changes are typically related to alterations in the frequency of alleles within the gene pool of that population. Therefore, option B is the correct answer. Option A is incorrect because changes in population size are not necessarily indicative of microevolutionary changes. Option C is not correct because the ratio of males and females in a population can change without necessarily indicating any specific genetic changes in that population. Option D is incorrect because the fixation of an allele refers to a specific event that can occur during microevolution, but it does not encompass all possible changes that can occur within a population.

Question 11

A population undergoing microevolution would show Hardy-Weinberg disequilibrium.

Accepted Answer

Hardy-Weinberg equilibrium assumes that a population is not undergoing any changes in allele frequencies due to non-random mating, natural selection, migration, genetic drift or mutation. Thus, if a population is undergoing microevolution or any of the aforementioned processes, it would result in deviations from the Hardy-Weinberg equilibrium and would show Hardy-Weinberg disequilibrium.

Question 12

In a species of salamander,there are two forms,red and yellow.As the yellow form becomes less common due to predation and the red form more common,the yellow form becomes less likely to be eaten and more likely to survive and reproduce.The yellow form then becomes more common and roles of red and yellow forms reverse.This is an example of
A)negative frequency-dependent selection.
B)directional selection.
C)disruptive selection.
D)balancing selection.
E)intrasexual selection.

Accepted Answer

This is an example of negative frequency-dependent selection, where the fitness of a phenotype decreases as it becomes more common in the population. As the yellow form becomes less common, it becomes less likely to be preyed upon and its fitness increases, making it more likely to survive and reproduce. However, as the yellow form becomes more common, its fitness again decreases, and the roles of the red and yellow forms reverse.

Question 13

Blue flower color (B allele)is dominant to white (b allele).If a population of plants contains white flowers (bb)at a frequency of 0.04,what is the frequency of the heterozygous genotype?
A)0.96 or 96%
B)0.2 or 20%
C)0.32 or 32%
D)0.64 or 64%
E)0.8 or 80%

Accepted Answer

Since the frequency of the homozygous recessive genotype (bb) is 0.04, the frequency of the dominant allele (B) in the population is sqrt(0.04) = 0.2. Thus, the frequency of the heterozygous genotype (Bb) can be calculated as 2pq = 2(0.2)(0.8) = 0.32 or 32%.

Question 14

What would be the frequency of pink flowers in a population where the allele frequency of C^R is 0.4 and the population is in Hardy-Weinberg equilibrium? Assume that C^R C^R is red,C^RC^W is pink,and C^wC^w is white. A)0.04 or 4% B)0.16 or 16% C)0.2 or 20% D)0.8 or 80% E)0.48 or 48%

Accepted Answer

In a population in Hardy-Weinberg equilibrium, the frequency of genotypes can be calculated using the equation p^2 + 2pq + q^2 = 1, where p and q represent the frequencies of two alleles, and 2pq represents the frequency of the heterozygous genotype. Given that the allele frequency of C^R is 0.4 (p = 0.4), the frequency of the other allele (q) would be 0.6 (since p + q = 1). The frequency of pink flowers, which are heterozygous (C^RC^W), would be represented by 2pq. Therefore, 2pq = 2 * 0.4 * 0.6 = 0.48 or 48%.

Question 15

In red-wing blackbirds,females tend to choose males with the most desirable territories and males compete with each other for territories.
True or false: Redwing blackbirds demonstrate both intersexual selection and intrasexual selection.

Accepted Answer

Redwing blackbirds demonstrate intersexual selection, where females choose males with desirable territories, and intrasexual selection, where males compete with each other for those territories. Therefore, both types of selection are present in this species.

Question 16

A mutation arises in an individual that decreases its fitness.This means that this individual's
A)probability of survival will decrease.
B)ability to find food will decrease.
C)ability to migrate long distances will decrease.
D)contribution to the gene pool of the next generation will decrease.
E)likelihood of having healthy offspring will increasE.

Accepted Answer

Fitness can be defined as an individual's ability to survive and reproduce in a given environment. A mutation that decreases fitness will typically reduce an individual's ability to survive and reproduce, ultimately decreasing the contribution of its genes to the gene pool of the next generation. Therefore, choice D is the best answer. Choices A, B, and C are not necessarily always true in every case of reduced fitness; it depends on the specific mutation and its impact on the individual's traits. Choice E is not true because reduced fitness would likely result in less healthy or viable offspring.

Question 17

What phenomenon would violate the conditions for Hardy-Weinberg equilibrium?
A)The population is isolated from other populations.
B)Females select males based on secondary sex traits.
C)The population is large.
D)No genotypes within the population have a reproductive advantage.
E)Genetic drift within the population does not change allele frequencies.

Accepted Answer

Females selecting males based on secondary sex traits would violate the condition of random mating, which is required for Hardy-Weinberg equilibrium.

Answer: D
 No genotypes having a reproductive advantage would mean that there is no natural selection acting on the population, which is one of the conditions for Hardy-Weinberg equilibrium.

Note: Choices A, C, and E are all conditions that promote Hardy-Weinberg equilibrium, so they would not violate it.

Question 18

What are the two principal factors that lead to microevolution?
A)new genetic variation and genetic mutations
B)genetic mutations and evolutionary mechanisms
C)new genetic variation and evolutionary mechanisms
D)evolutionary mechanisms and migration
E)nonrandom mating and new genetic variation

Accepted Answer

Microevolution refers to small-scale changes within a population, and the two principal factors that lead to it are new genetic variation and evolutionary mechanisms. New genetic variation can occur through mechanisms such as genetic drift, gene flow, mutation, or recombination, while evolutionary mechanisms include natural selection, genetic drift, gene flow, and sexual selection. These processes can result in changes in the frequency of alleles within populations over time.

Question 19

A population of voles (small mammals)lives in a shady forest.Originally,the voles are a light tan color,but then a dark brown coloration arises by a new mutation.The darker voles are harder for predators to see in the leaf litter,thus they are less susceptible to predation.After 10 generations,the majority of voles in the population are the dark brown color.In the figure below,the solid red line represents the number of light colored individuals before the mutation and the black dashed line represents the number of dark brown individuals after 10 generations.What type of natural selection is the population of voles experiencing? 
A)Directional selection
B)Stabilizing selection
C)Diversifying selection
D)Balancing selection
E)Negative frequency-dependent selection

Accepted Answer

The population of voles is experiencing directional selection because the shift in coloration towards the dark brown coloration is driven by the selective advantage of being less visible to predators, leading to an increase in the frequency of the beneficial trait (dark brown coloration) over time.

Question 20

In the Hardy-Weinberg equation,p + q =_______,where p and q represent _________.
A)0,allele frequencies
B)1,genotype frequencies
C)2,allele frequencies
D)2,genotype frequencies
E)1,allele frequencies

Accepted Answer

The Hardy-Weinberg equation states that p + q = 1, where p and q represent the frequency of the two alleles in a population, indicating allele frequencies, not genotype frequencies.

Quiz 19: An Introduction to Evolution and Population Genetics

What mechanism leads to changes in allele frequencies through random chance?

Select the examples that can undergo microevolution.

Blue flower color (B allele) is dominant to white (b allele) .If a population of plants contains white flowers (bb) at a frequency of 0.04,what is the frequency of the blue flower allele (B) ? 4-9-2013

Fitness is a measure of reproductive success.If an individual with genotype BB produces 6 offspring,and a heterozygous individual (Bb) produces 10 offspring,and a third individual with genotype bb produces 5 offspring,what is the fitness value for the individual with BB genotype?

Over generations in a population,individuals with higher fitness values will

If a population satisfies the Hardy-Weinberg equilibrium model,what can you assume about that population?

In _____ selection,individuals intermediate in a phenotypic distribution have greater reproductive success.

Microevolution involves

A population undergoing microevolution would show Hardy-Weinberg disequilibrium.

Blue flower color (B allele) is dominant to white (b allele) .If a population of plants contains white flowers (bb) at a frequency of 0.04,what is the frequency of the heterozygous genotype?

What would be the frequency of pink flowers in a population where the allele frequency of C^R is 0.4 and the population is in Hardy-Weinberg equilibrium? Assume that C^R C^R is red,C^RC^W is pink,and C^wC^w is white.

In red-wing blackbirds,females tend to choose males with the most desirable territories and males compete with each other for territories. True or false: Redwing blackbirds demonstrate both intersexual selection and intrasexual selection.

A mutation arises in an individual that decreases its fitness.This means that this individual's

What phenomenon would violate the conditions for Hardy-Weinberg equilibrium?

What are the two principal factors that lead to microevolution?

In the Hardy-Weinberg equation,p + q =_,where p and q represent ___.

Quiz 19: An Introduction to Evolution and Population Genetics

What mechanism leads to changes in allele frequencies through random chance?

Select the examples that can undergo microevolution.

Blue flower color (B allele) is dominant to white (b allele) .If a population of plants contains white flowers (bb) at a frequency of 0.04,what is the frequency of the blue flower allele (B) ? 4-9-2013

Fitness is a measure of reproductive success.If an individual with genotype BB produces 6 offspring,and a heterozygous individual (Bb) produces 10 offspring,and a third individual with genotype bb produces 5 offspring,what is the fitness value for the individual with BB genotype?

Over generations in a population,individuals with higher fitness values will

If a population satisfies the Hardy-Weinberg equilibrium model,what can you assume about that population?

In _____ selection,individuals intermediate in a phenotypic distribution have greater reproductive success.

Microevolution involves

A population undergoing microevolution would show Hardy-Weinberg disequilibrium.

Blue flower color (B allele) is dominant to white (b allele) .If a population of plants contains white flowers (bb) at a frequency of 0.04,what is the frequency of the heterozygous genotype?

What would be the frequency of pink flowers in a population where the allele frequency of CR is 0.4 and the population is in Hardy-Weinberg equilibrium? Assume that CR CR is red,CRCW is pink,and CwCw is white.

In red-wing blackbirds,females tend to choose males with the most desirable territories and males compete with each other for territories. True or false: Redwing blackbirds demonstrate both intersexual selection and intrasexual selection.

A mutation arises in an individual that decreases its fitness.This means that this individual's

What phenomenon would violate the conditions for Hardy-Weinberg equilibrium?

What are the two principal factors that lead to microevolution?

In the Hardy-Weinberg equation,p + q =_______,where p and q represent _________.

What would be the frequency of pink flowers in a population where the allele frequency of C^R is 0.4 and the population is in Hardy-Weinberg equilibrium? Assume that C^R C^R is red,C^RC^W is pink,and C^wC^w is white.

In the Hardy-Weinberg equation,p + q =_,where p and q represent ___.