13.E: Evolution and Natural Selection (Exercises)
13.1: Discovering How Populations Change
Multiple Choice
Which scientific concept did Charles Darwin and Alfred Wallace independently discover?
A. mutation
B. natural selection
C. overbreeding
D. sexual reproduction
- Answer
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B
Which of the following situations will lead to natural selection?
A. The seeds of two plants land near each other and one grows larger than the other.
B. Two types of fish eat the same kind of food, and one is better able to gather food than the other.
C. Male lions compete for the right to mate with females, with only one possible winner.
D. all of the above
- Answer
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D
What is the difference between micro- and macroevolution?
A. Microevolution describes the evolution of small organisms, such as insects, while macroevolution describes the evolution of large organisms, like people and elephants.
B. Microevolution describes the evolution of microscopic entities, such as molecules and proteins, while macroevolution describes the evolution of whole organisms.
C. Microevolution describes the evolution of populations, while macroevolution describes the emergence of new species over long periods of time.
D. Microevolution describes the evolution of organisms over their lifetimes, while macroevolution describes the evolution of organisms over multiple generations.
- Answer
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C
Population genetics is the study of ________.
A. how allele frequencies in a population change over time
B. populations of cells in an individual
C. the rate of population growth
D. how genes affect embryological development
- Answer
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A
Free Response
If a person scatters a handful of plant seeds from one species in an area, how would natural selection work in this situation?
- Answer
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The plants that can best use the resources of the area, including competing with other individuals for those resources, will produce more seeds themselves and those traits that allowed them to better use the resources will increase in the population of the next generation.
Explain the Hardy-Weinberg principle of equilibrium.
- Answer
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The Hardy-Weinberg principle of equilibrium states that a population’s allele frequencies are inherently stable. Unless an evolutionary force is acting upon the population, the population would carry the same genes at the same frequencies generation after generation, and individuals would, as a whole, look essentially the same.
13.2: Evidence of Evolution
Multiple Choice
The wing of a bird and the arm of a human are examples of ________.
A. vestigial structures
B. molecular structures
C. homologous structures
D. analogous structures
- Answer
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C
The fact that DNA sequences are more similar in more closely related organisms is evidence of what?
A. optimal design in organisms
B. adaptation
C. mutation
D. descent with modification
- Answer
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D
Free Response
Why do scientists consider vestigial structures evidence for evolution?
- Answer
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A vestigial structure is an example of a homologous structure that has apparently been reduced through evolution to a non-functional state because its function is no longer utilized by the species exhibiting it; therefore, any mutations which might reduce its structure are not selected against. The fact that the species has vestiges of the structure rather than no structure at all is evidence that it was present in an ancestor and evolved to non-functionality through accumulation of random mutations.
13.3: Mechanisms of Evolution
Multiple Choice
Galápagos medium ground finches are found on Santa Cruz and San Cristóbal islands, which are separated by about 100 km of ocean. Occasionally, individuals from either island fly to the other island to stay. This can alter the allele frequencies of the population through which of the following mechanisms?
A. natural selection
B. genetic drift
C. gene flow
D. mutation
- Answer
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C
In which of the following pairs do both evolutionary processes introduce new genetic variation into a population?
A. natural selection and genetic drift
B. mutation and gene flow
C. natural selection and gene flow
D. gene flow and genetic drift
- Answer
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B
Free Response
Describe a situation in which a population would undergo the bottleneck effect and explain what impact that would have on the population’s gene pool.
- Answer
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Answers may vary.
A bottleneck effect occurs when a significant portion of a population is suddenly reduced due to a catastrophic event or other factors, leading to a drastic reduction in genetic diversity within the population. An example of this might be a natural disaster, such as a volcanic eruption, wildfire, or hurricane, that kills a large number of individuals in a population of animals, leaving only a small, random subset of the original population to survive and reproduce. The resulting effect of the gene pool would be and overall decrease in the genetic diversity of the population, since the genetic make up of the survivors does not necessarily represent the original population, and an increase in inbreeding since the population is small. These factors lead the population ot be less adaptable to fututre changes in the environment.
13.4: Natural Selection - A Deeper Dive
Multiple Choice
Which type of selection results in greater genetic variability in a population?
A. stabilizing selection
B. directional selection
C. diversifying selection
D. positive frequency-dependent selection
- Answer
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C
When males and females of a population look or act differently, it is referred to as ________.
A. sexual dimorphism
B. sexual selection
C. diversifying selection
D. a cline
- Answer
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A
The good genes hypothesis is a theory that explains what?
A. why more fit individuals are more likely to have more offspring
B. why alleles that confer beneficial traits or behaviors are selected for by natural selectio
C. why some deleterious mutations are maintained in the population
D. why individuals of one sex develop impressive ornamental traits
- Answer
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D
Free Response
Describe natural selection and give an example of natural selection at work in a population.
- Answer
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The theory of natural selection stems from the observation that some individuals in a population survive longer and have more offspring than others, thus passing on more of their genes to the next generation. For example, a big, powerful male gorilla is much more likely than a smaller, weaker gorilla to become the population’s silverback, the pack’s leader who mates far more than the other males of the group. The pack leader will, therefore, father more offspring, who share half of his genes, and are thus likely to also grow bigger and stronger like their father. Over time, the genes for bigger size will increase in frequency in the population, and the population will, as a result, grow larger on average.
List the ways in which natural selection can affect population variation and describe how they influence allele frequencies.
- Answer
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Natural selection affects population variation in these ways:
- Directional Selection: Favors one extreme trait, increasing its alleles and shifting traits in one direction.
- Stabilizing Selection: Favors average traits, increasing those alleles and reducing variation
- Disruptive Selection: Favors both extremes, increasing variation and potentially leading to new species.
Each type influences allele frequencies by increasing or decreasing certain traits in a population
13.5: Speciation
Multiple Choice
Which situation would most likely lead to allopatric speciation?
A. A flood causes the formation of a new lake.
B. A storm causes several large trees to fall down.
C. A mutation causes a new trait to develop.
D. An injury causes an organism to seek out a new food source.
- Answer
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A
What is the main difference between dispersal and vicariance?
A. One leads to allopatric speciation, whereas the other leads to sympatric speciation.
B. One involves the movement of the organism, whereas the other involves a change in the environment.
C. One depends on a genetic mutation occurring, whereas the other does not.
D. One involves closely related organisms, whereas the other involves only individuals of the same species.
- Answer
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B
Which variable increases the likelihood of allopatric speciation taking place more quickly?
A. lower rate of mutation
B. longer distance between divided groups
C. increased instances of hybrid formation
D. equivalent numbers of individuals in each population
- Answer
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B
Free Response
Why do island chains provide ideal conditions for adaptive radiation to occur?
- Answer
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Organisms of one species can arrive to an island together and then disperse throughout the chain, each settling into different niches, exploiting different food resources and, evolving independently with little gene flow between different islands.
Two species of fish had recently undergone sympatric speciation. The males of each species had a different coloring through which females could identify and choose a partner from her own species. After some time, pollution made the lake so cloudy it was hard for females to distinguish colors. What might take place in this situation?
- Answer
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It is likely the two species would start to reproduce with each other if hybridization is still possible. Depending on the viability of their offspring, they may fuse back into one species.
13.6: Common Misconceptions about Evolution
Multiple Choice
The word “theory” in theory of evolution is best replaced by ________.
A. fact
B. hypothesis
C. idea
D. alternate explanation
- Answer
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A
Why are alternative scientific theories to evolution not taught in public school?
A. more theories would confuse students
B. there are no viable scientific alternatives
C. it is against the law
D. alternative scientific theories are suppressed by the science establishment
- Answer
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B
Free Response
How does the scientific meaning of “theory” differ from the common, everyday meaning of the word?
- Answer
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In science, a theory is a thoroughly tested and verified set of explanations for a body of observations of nature. It is the strongest form of knowledge in science. In contrast, a theory in common usage can mean a guess or speculation about something, meaning that the knowledge implied by the theory may be very weak.
Explain why the statement that a monkey is more evolved than a mouse is incorrect.
- Answer
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The statement implies that there is a goal to evolution and that the monkey represents greater progress to that goal than the mouse. Both species are likely to be well adapted to their particular environment, which is the outcome of natural selection.
Contributors and Attributions
Remixed and/or curated from the following works:
Fowler, S., Roush, R., & Wise, J. (2013). 11.E Evolution and Its Processes (Exercises) . In Concepts of Biology . OpenStax (CC BY 4.0; Access for free at https://openstax.org/books/concepts-biology/pages/1-introduction ).
Clark, M. A., Douglas, M., & Choi, J. (2018). 19 Review Questions and 19 Critical Thinking Questions . In Biology 2e . OpenStax (CC BY 4.0; Access for free at https://openstax.org/books/biology-2e/pages/1-introduction ).