Evolution & Speciation Quiz
Questions and Answers
- 1.
Natural selection is based on all of the following except
- A.
Genetic variation exists within populations.
- B.
The best-adapted individuals tend to leave the most offspring.
- C.
Only a fraction of the offspring produced by an individual may survive.
- D.
Populations tend to produce more individuals than the environment can support.
- E.
Individuals adapt to their environments and, thereby, evolve.
Correct Answer
E. Individuals adapt to their environments and, thereby, evolve.Explanation
Natural selection is the process by which individuals with traits that are better suited to their environment have a higher chance of survival and reproduction, passing on their advantageous traits to future generations. This process is driven by several factors, including genetic variation within populations, the differential reproductive success of individuals, the high mortality rate of offspring, and the overproduction of individuals compared to available resources. However, the statement that individuals adapt to their environments and, thereby, evolve is incorrect because natural selection acts on individuals with preexisting traits, rather than individuals actively adapting and evolving in response to their environment.Rate this question:
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- 2.
Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails, as do fish, even though their closest relatives were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal fins and tails of ichthyosaurs and fish are
- A.
Homologous.
- B.
Examples of convergent evolution.
- C.
Adaptations to a common environment.
- D.
A and C only
- E.
B and C only
Correct Answer
E. B and C onlyExplanation
The correct answer is B and C only. This is because the dorsal fins and tails of ichthyosaurs and fish are examples of convergent evolution, where similar traits evolve independently in unrelated species due to similar selective pressures in their environment. Additionally, these traits can also be considered adaptations to a common environment, as both ichthyosaurs and fish lived in aquatic environments and needed these structures for efficient swimming.Rate this question:
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- 3.
Which of the following pairs of structures is least likely to be homologous?
- A.
The wings of a bat and the arms of a human
- B.
The hemoglobin of a baboon and that of a gorilla
- C.
The mitochondria of a plant and those of an animal
- D.
The wings of a bird and those of an insect
- E.
The brain of a cat and that of a dog
Correct Answer
D. The wings of a bird and those of an insectExplanation
The wings of a bird and those of an insect are least likely to be homologous because they have different evolutionary origins. Birds have wings made of feathers, while insects have wings made of chitin. Feathers and chitin are structurally and compositionally different, indicating that the wings of birds and insects have evolved independently and are not derived from a common ancestor. In contrast, the other options involve structures that are more likely to be homologous, as they are found in closely related species or have similar functions in different species.Rate this question:
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- 4.
A trend toward the decrease in the size of plants on the slopes of mountains as altitudes increase is an example of
- A.
A cline.
- B.
A bottleneck.
- C.
Relative fitness.
- D.
Genetic drift.
- E.
Geographic variation.
Correct Answer
A. A cline.Explanation
A trend toward the decrease in the size of plants on the slopes of mountains as altitudes increase is an example of a cline. A cline refers to a gradual change in a trait or characteristic of a population along a geographic gradient. In this case, as the altitude increases, the size of plants decreases, indicating a gradual change in plant size along the mountain slope. This pattern suggests that the environmental conditions and selective pressures vary with altitude, leading to the observed variation in plant size.Rate this question:
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- 5.
In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.4. What is the percentage of the population that is homozygous for this allele?
- A.
4
- B.
16
- C.
32
- D.
36
- E.
40
Correct Answer
B. 16Explanation
In a Hardy-Weinberg population, the frequency of a specific allele can be calculated by squaring the frequency of the homozygous dominant genotype and adding it to twice the frequency of the heterozygous genotype. Since the population is in equilibrium, the frequency of the heterozygous genotype is 2pq, where p is the frequency of allele A and q is the frequency of allele a. Given that the frequency of allele a is 0.4, the frequency of allele A is 0.6 (1 - 0.4). Therefore, the frequency of the heterozygous genotype is 2(0.6)(0.4) = 0.48. Since the question asks for the percentage of the population that is homozygous for allele a, we subtract the frequency of the heterozygous genotype from 1, resulting in 1 - 0.48 = 0.52. Multiplying this by 100 gives us 52%, so the correct answer is 16%.Rate this question:
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- 6.
In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.1. What is the percentage of the population that is heterozygous for this allele?
- A.
90
- B.
81
- C.
49
- D.
18
- E.
10
Correct Answer
D. 18Explanation
In a Hardy-Weinberg equilibrium, the frequency of heterozygotes can be calculated using the equation 2pq, where p is the frequency of allele A and q is the frequency of allele a. Since the frequency of allele a is given as 0.1, q = 0.1. The frequency of allele A can be calculated as 1 - q, which is 0.9. Plugging these values into the equation, we get 2 * 0.9 * 0.1 = 0.18. Multiplying by 100 gives us 18%, which represents the percentage of the population that is heterozygous for this allele.Rate this question:
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- 7.
In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.2. What is the frequency of individuals with Aa genotype?
- A.
0.20
- B.
0.32
- C.
0.42
- D.
0.80
- E.
Genotype frequency cannot be determined from the information provided.
Correct Answer
B. 0.32Explanation
In a Hardy-Weinberg population, the frequency of individuals with a certain genotype can be calculated using the equation p^2 + 2pq + q^2 = 1, where p and q represent the frequencies of the two alleles. In this case, the frequency of allele a is given as 0.2, so the frequency of allele A would be 0.8 (1 - 0.2). Using the equation, we can calculate the frequency of individuals with the Aa genotype as 2pq = 2(0.8)(0.2) = 0.32.Rate this question:
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- 8.
In a hypothetical population of 1,000 people, tests of blood-type genes show that 160 have the genotype AA, 480 have the genotype AB, and 360 have the genotype BB. What is the frequency of the B allele?
- A.
0.36
- B.
0.42
- C.
0.60
- D.
0.72
- E.
0.84
Correct Answer
C. 0.60Explanation
The frequency of the B allele can be calculated by adding up the number of individuals with the BB genotype (360) and half the number of individuals with the AB genotype (480/2 = 240), which gives a total of 600 individuals with the B allele. To find the frequency, divide this number by the total number of individuals in the population (1,000), resulting in a frequency of 0.60.Rate this question:
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- 9.
In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?
- A.
0.36
- B.
0.60
- C.
0.64
- D.
0.75
- E.
0.80
Correct Answer
E. 0.80Explanation
In Hardy-Weinberg equilibrium, the frequency of the dominant allele (p) plus the frequency of the recessive allele (q) equals 1. We are given that there are 36 purple-flowering plants (genotype RR) and 64 white-flowering plants (genotype rr) in the population. Since the purple-flowering plants (RR) represent the frequency of the dominant allele (p^2), we can calculate p as the square root of 36/100, which is 0.6. Therefore, q would be 1 - p, which is 1 - 0.6, equal to 0.4. However, since the question asks for the value of q, we need to take the square root of q, which is 0.4, resulting in 0.8. Hence, the correct answer is 0.80.Rate this question:
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- 10.
When we say that an individual organism has a greater fitness than another individual, we specifically mean that the organism
- A.
Lives longer than others of its species.
- B.
Competes for resources more successfully than others of its species.
- C.
Mates more frequently than others of its species.
- D.
Utilizes resources more efficiently than other species occupying similar niches.
- E.
Leaves more viable offspring than others of its species.
Correct Answer
E. Leaves more viable offspring than others of its species.Explanation
When we say that an individual organism has a greater fitness than another individual, it means that the organism is able to produce more viable offspring compared to others of its species. Fitness is a measure of an organism's ability to survive and reproduce in its environment, and leaving more viable offspring indicates a higher level of reproductive success. This means that the organism's genetic traits are being passed on to the next generation at a higher rate, leading to an increase in the overall fitness of the species.Rate this question:
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- 11.
Fossil evidence indicates that horses have gradually increased in size over geologic time. Which of the following terms best describes this?
- A.
Balancing selection
- B.
Directional selection
- C.
Stabilizing selection
- D.
Diversifying (disruptive) selection
- E.
Sexual selection
Correct Answer
B. Directional selectionExplanation
Directional selection is the best term to describe the gradual increase in size of horses over geologic time. Directional selection occurs when individuals with a particular trait that is advantageous in a specific environment have higher fitness and survival rates, leading to a shift in the population towards that trait. In this case, larger size may have provided horses with advantages such as increased speed or ability to defend against predators, resulting in the gradual increase in size over time.Rate this question:
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- 12.
The recessive allele that causes phenylketonuria (PKU) is harmful, except when an infant's diet lacks the amino acid, phenylalanine. What maintains the presence of this harmful allele in a population's gene pool?
- A.
Heterozygote advantage
- B.
Stabilizing selection
- C.
Diploidy
- D.
Neutral variation
- E.
Extensive methylation
Correct Answer
C. DiploidyExplanation
Diploidy refers to the presence of two copies of each gene in an individual. In the case of the recessive allele that causes phenylketonuria (PKU), individuals who are heterozygous (having one copy of the harmful allele and one copy of the normal allele) do not exhibit the harmful effects of PKU. This is because the normal allele can mask the effects of the harmful allele. Therefore, individuals carrying one copy of the harmful allele can still survive and reproduce, maintaining the presence of the harmful allele in the population's gene pool.Rate this question:
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- 13.
In seedcracker finches from Cameroon, small- and large-billed birds specialize in cracking soft and hard seeds, respectively. If long-term climatic change resulted in all seeds becoming hard, what type of selection would then operate on the finch population?
- A.
Diversifying (disruptive) selection
- B.
Directional selection
- C.
Stabilizing selection
- D.
Balancing selection
- E.
No selection would operate because the population is in Hardy-Weinberg equilibrium.
Correct Answer
B. Directional selectionExplanation
If long-term climatic change resulted in all seeds becoming hard, the finch population would experience directional selection. This is because the selection pressure would favor the large-billed birds, which are specialized in cracking hard seeds. As a result, the population would gradually shift towards having a higher proportion of large-billed birds, as they would have a higher fitness advantage in the new environment. This would lead to a directional change in the trait distribution within the population.Rate this question:
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- 14.
Male satin bowerbirds adorn structures that they build, called "bowers," with parrot feathers, flowers, and other bizarre ornaments in order to attract females. Females inspect the bowers and, if suitably impressed, allow males to mate with them. The evolution of this male behavior is due to
- A.
Frequency-dependent selection.
- B.
Stabilizing selection.
- C.
Sexual selection.
- D.
Natural selection.
- E.
Directional selection.
Correct Answer
C. Sexual selection.Explanation
The male satin bowerbirds' behavior of adorning their bowers with ornaments to attract females is a clear example of sexual selection. Sexual selection refers to the process by which certain traits or behaviors that increase an individual's reproductive success are favored and passed on to future generations. In this case, the male bowerbirds' elaborate displays and decorations are directly linked to their ability to attract mates and successfully reproduce. This behavior has evolved over time as a result of females choosing mates based on these elaborate displays, thus leading to the evolution of this male behavior.Rate this question:
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- 15.
When imbalances occur in the sex ratio of sexual species that have two sexes (i.e. other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of
- A.
Sexual selection.
- B.
Diversifying (disruptive) selection.
- C.
Directional selection.
- D.
Stabilizing selection.
- E.
Frequency-dependent selection.
Correct Answer
E. Frequency-dependent selection.Explanation
When there is an imbalance in the sex ratio of a species, the members of the minority sex receive a greater proportion of care and resources from parents. This suggests that the fitness of the offspring is dependent on the frequency of their sex in the population. If the minority sex is favored and receives more resources, it will have a higher chance of survival and reproduction, leading to an increase in its frequency. This is an example of frequency-dependent selection, where the fitness of a phenotype depends on its frequency in the population.Rate this question:
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- 16.
Sparrows with average-sized wings survive severe storms better than those with longer or shorter wings, illustrating
- A.
The bottleneck effect.
- B.
Stabilizing selection.
- C.
Frequency-dependent selection.
- D.
Neutral variation.
- E.
Diversifying selection.
Correct Answer
B. Stabilizing selection.Explanation
Stabilizing selection occurs when individuals with average traits have higher fitness compared to those with extreme traits. In this case, sparrows with average-sized wings are more likely to survive severe storms, suggesting that extreme wing lengths (either longer or shorter) are less advantageous. This selection process helps maintain the population's average wing size, leading to stabilizing selection.Rate this question:
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- 17.
Several closely related frog species of the genus Rana are found in the forests of the southeastern United States. The species boundaries are maintained by reproductive barriers. Males of one species sing only when its predators are absent; males of another species sing only when its predators are present. Which type of reproductive barrier does this represent?
- A.
Behavioral isolation
- B.
Gametic isolation
- C.
Habitat isolation
- D.
Temporal isolation
- E.
Mechanical isolation
Correct Answer
A. Behavioral isolationExplanation
This scenario represents behavioral isolation as a reproductive barrier. The singing behavior of the males is specific to their respective species and is influenced by the presence or absence of predators. This behavioral difference prevents interbreeding between the species, maintaining their species boundaries.Rate this question:
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- 18.
Several closely related frog species of the genus Rana are found in the forests of the southeastern United States. The species boundaries are maintained by reproductive barriers. One species lives only in tree holes; another species lives only in streams. Which type of reproductive barrier does this represent?
- A.
Behavioral isolation
- B.
Gametic isolation
- C.
Habitat isolation
- D.
Temporal isolation
- E.
Mechanical isolation
Correct Answer
C. Habitat isolationExplanation
The correct answer is habitat isolation. Habitat isolation occurs when species live in different habitats and therefore do not come into contact with each other to reproduce. In this case, one species lives in tree holes and another species lives in streams, preventing them from interbreeding and maintaining their species boundaries.Rate this question:
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- 19.
Several closely related frog species of the genus Rana are found in the forests of the southeastern United States. The species boundaries are maintained by reproductive barriers. One species mates at the season when daylight is increasing from 13 hours to 13 hours, 15 minutes; another species mates at the season when daylight is increasing from 14 hours to 14 hours, 15 minutes. Which type of reproductive barrier does this represent?
- A.
Behavioral isolation
- B.
Gametic isolation
- C.
Habitat isolation
- D.
Temporal isolation
- E.
Mechanical isolation
Correct Answer
D. Temporal isolationExplanation
Temporal isolation is the correct answer because the reproductive barriers in this scenario are based on differences in the timing of mating seasons. Each species mates during a specific window of time when the daylight is increasing by a specific duration. This temporal difference prevents the species from interbreeding and maintains their species boundaries.Rate this question:
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- 20.
Several closely related frog species of the genus Rana are found in the forests of the southeastern United States. The species boundaries are maintained by reproductive barriers. Males of one species are too small to perform amplexus with females of all other species. Which type of reproductive barrier does this represent?
- A.
Behavioral isolation
- B.
Gametic isolation
- C.
Habitat isolation
- D.
Temporal isolation
- E.
Mechanical isolation
Correct Answer
E. Mechanical isolationExplanation
The correct answer is mechanical isolation. This is because the reproductive barrier in this scenario is based on physical incompatibility between the males and females of different species. The males of one species are too small to physically engage in amplexus (mating position) with females of other species, preventing successful reproduction. This physical incompatibility acts as a barrier to gene flow between the species, maintaining their distinct identities.Rate this question:
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- 21.
Two species of frogs belonging to the same genus occasionally mate, but the offspring fail to develop and hatch. What is the mechanism for keeping the two frog species separate?
- A.
Hybrid inviability
- B.
Hybrid breakdown
- C.
Hybrid sterility
- D.
Gametic isolation
- E.
Mechanical isolation
Correct Answer
A. Hybrid inviabilityExplanation
The mechanism for keeping the two frog species separate is hybrid inviability. This means that when the two species mate, the resulting offspring fail to develop and hatch, preventing the formation of viable hybrids.Rate this question:
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- 22.
A defining characteristic of allopatric speciation is
- A.
The appearance of new species in the midst of old ones.
- B.
Asexually reproducing populations.
- C.
Geographic isolation.
- D.
Artificial selection.
- E.
Large populations.
Correct Answer
C. Geographic isolation.Explanation
Allopatric speciation refers to the formation of new species due to geographic isolation. When a population becomes physically separated by a geographic barrier such as a mountain range or a body of water, it can lead to the accumulation of genetic differences over time, eventually resulting in the formation of new species. In this process, reproductive isolation occurs, preventing gene flow between the separated populations. Therefore, geographic isolation is a defining characteristic of allopatric speciation.Rate this question:
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- 23.
Beetle pollinators of a particular plant are attracted to its flowers' bright orange color. The beetles not only pollinate the flowers, but they mate while inside of the flowers. A mutant version of the plant with red flowers becomes more common with the passage of time. A particular variant of the beetle prefers the red flowers to the orange flowers. Over time, these two beetle variants diverge from each other to such an extent that interbreeding is no longer possible. Which term best describes this scenario?
- A.
Allopatric speciation
- B.
Sympatric speciation
- C.
Habitat isolation
- D.
Behavioral isolation
- E.
Diversifying selection
Correct Answer
B. Sympatric speciationExplanation
The scenario described in the question is an example of sympatric speciation. Sympatric speciation occurs when two populations of a species diverge and become reproductively isolated from each other within the same geographic area. In this case, the original population of beetles preferred the orange flowers, while a variant of the beetles emerged that preferred the red flowers. Over time, these two beetle variants diverged to the point where they could no longer interbreed, leading to the formation of two separate species.Rate this question:
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- 24.
Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian islands have different elaborate courtship rituals that involve fighting other males and stylized movements that attract females. What type of reproductive isolation does this represent?
- A.
Habitat isolation
- B.
Temporal isolation
- C.
Behavioral isolation
- D.
Gametic isolation
- E.
Sexual dimorphism
Correct Answer
C. Behavioral isolationExplanation
The elaborate courtship rituals and behaviors exhibited by males of different species of fruit flies in the same parts of the Hawaiian islands suggest that this represents behavioral isolation. This type of reproductive isolation occurs when individuals of different species have different courtship behaviors or rituals that prevent them from successfully mating with each other. In this case, the specific behaviors and movements performed by the males are unique to their own species and serve to attract females of the same species while deterring males from other species. This behavioral barrier prevents interbreeding between different species of fruit flies.Rate this question:
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- 25.
A taxon, all of whose members have the same common ancestor, is
- A.
Paraphyletic
- B.
Polyphyletic
- C.
Monophyletic
Correct Answer
C. MonophyleticExplanation
A taxon, all of whose members have the same common ancestor, is monophyletic. This means that all the organisms in this taxon share a common ancestor and are descended from it. The monophyletic group includes all the descendants of the common ancestor, and it represents a single branch on the phylogenetic tree. This is in contrast to paraphyletic and polyphyletic groups, which do not include all the descendants of a common ancestor.Rate this question:
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- 26.
The species X, Y, and Z share a common ancestor V. The species R, S, and T share a common ancestor U. A grouping that includes species R, S, Y and Z makes up
- A.
A valid taxon
- B.
A monophyletic clade
- C.
An ingroup, with species X as an outgroup
- D.
A paraphyletic grouping
- E.
A polyphyletic grouping
Correct Answer
E. A polyphyletic groupingExplanation
A polyphyletic grouping is a taxonomic group that includes species from different ancestral lineages. In this case, species R, S, Y, and Z do not share a common ancestor with each other, as they have different ancestors (U and V). Therefore, grouping them together is considered polyphyletic.Rate this question:
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Oct 12, 2023Quiz Edited by
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May 19, 2014Quiz Created by
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