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Example Questions
Example Question #1 : Natural Selection
Which of the following statements reflecting Darwin's theory of evolution is false?
Genetic variations can be inherited
Members of a population produce more offspring than the environment can support
Accumulation of adaptations leads to speciation
All answer choices reflect correct statements about Darwin's theory of evolution
All answer choices reflect correct statements about Darwin's theory of evolution
Darwin's Theory of Evolution can be described by the following statements.
1) Individuals of any population vary from one another in many characteristics, due to mutation.
2) Genetic variations can be inherited.
3) Members of a population produce more offspring than the environment can support, leading to competition for resources
4) Those individuals whose inherited characteristics fit them best to their environment are likely to leave more offspring than less fit individuals.
5) Over generations of natural selection, favorable adaptations are perpetuated in a species. Accumulation of these favorable changes eventually results in speciation.
Example Question #1 : Understanding Types Of Selection
Charles Darwin described four key observations pertaining to natural selection from his voyage around the world. Which of the following is NOT one of Darwin’s observations of nature?
Traits are inherited from parents to offspring
Individuals of a population evolve through interaction with their environment
Members of a population often vary greatly in their traits
All species are capable of producing more offspring than their environment can support
Individuals of a population evolve through interaction with their environment
During his travels, Darwin essentially developed the fundamental principles of evolution. Included in these observations were that traits are inherited from parent to offspring, members of a population exhibit genetic diversity (numerous traits), and that organisms are capable of producing more offspring than the environment can support. The fourth observation was that, owing to a lack of food or other resources, many offspring do not survive. Together, these observations helped shape Darwin's theories of natural selection and biological fitness to explain the trends that he had seen.
A key point about natural selection is that it is the population that evolves over time, not individual members of a population lifetime. Individuals that may have inherited advantageous traits are likely to produce more offspring than other members of the population, which drives natural selection within the context of the environment. Environmental pressures can affect the forces of natural selection, but cannot directly result in the production of new traits or the inheritance of those traits.
Example Question #2 : Natural Selection
Darwin described his theory of natural selection as which of the following?
Punctuated equilibrium
Inheritance of acquired characteristics
Descent with modification
Survival of the fittest
Descent with modification
Darwin described his theory as "descent with modification," meaning that offspring inherit their genetic material from their parents, but with slight modifications. Darwin proposed that those slight modifications which provided a fitness benefit (made it more likely that an organism would reproduce) were more likely to be passed on.
Example Question #1 : Natural Selection
Charles Darwin's voyage to the Galapagos islands and study of the beak shape of finches was integral to his research and subsequent ideas about __________ through __________.
sympatric speciation . . . evolution
natural selection . . . evolution
evolution . . . natural selection
phenotypic degradation . . . selection pressures
temporal isolation . . . predator-prey relationships
evolution . . . natural selection
Charles Darwin studied finches in the Galapagos, which prompted his work on natural selection. This was observed as only the finches who were evolutionarily prepared reproduced, thus increasing their traits in the gene pool
Example Question #3 : Natural Selection
Why do biologists not normally distinguish between micro- and macro- evolution?
They are differences between population change and speciation, and the term "species" is impossible to define.
"Micro" vs. "Macro" evolution is an outdated principle of Lamarckian evolution.
The terms "micro" and "macro" do not apply to the biological process.
"Micro" and "macro" are terms only used to try to disprove evolutionary theory.
The line between "micro" and "macro" is mostly arbitrary and depends on the individual's definition.
The line between "micro" and "macro" is mostly arbitrary and depends on the individual's definition.
Both "microevolution" and "macroevolution" are driven by the same biological process: natural selection. While the former refers to change within species and the latter refers to change to a new species, the line between what constitutes a species change is difficult to define. Since both terms refer to the same process of natural selection, the term evolution applies to both, whether as a single adaptation or a series of adaptations that culminate into a single species.
Example Question #1 : Natural Selection
What aspect of the environment did Darwin hypothesize had caused the Galapagos mockingbirds to differentiate into four different species?
None of these
Each bird species had been created separately from the other, with little variation over time.
Because each species had a different food source, each parent bird acquired advantageous changes during its lifetime for accessing that food source, which it passed onto its offspring.
What Darwin had mistaken to be new species were actually the same species with slight colorations depending on the environment.
Each species was found on a different island. Because the populations were separated from each other, they acquired different changes from each other over time.
Each species was found on a different island. Because the populations were separated from each other, they acquired different changes from each other over time.
Speciation occurs when two populations are separated from each other and accumulate different changes due to different environments. When the birds migrated to the Galapagos and made homes on each island, they became physically different from each other over time. This was one observation to the theory of natural selection.
Example Question #1 : Natural Selection
Which of the following is most affected by natural selection?
Influenza
Merlot grapes
Angora rabbits
Poodles
Influenza
Influenza (the flu virus) is a real-life example of natural selection that is most evident during an annual time period when the influenza virus infection peaks. The repeated or cyclical nature of flu outbreaks is caused by the natural selection of the virus for traits that allow it to evade the immune system and replicate, a process that actually results in new distinct strains of influenza virus.
In contrast, the other answers are all examples of artificial selection by which the specific variety or breed has been purposely selected for specific traits. Poodles and Angora rabbits have been purposely bred by humans to select for traits that affect their fur. Merlot wine is produced from a certain strain of grapes that have been bred for their taste. Note that artificial selection differs from genetic modification, as no new traits have been introduced to these strains.
Example Question #1 : Understanding Types Of Selection
A population of giraffes lives in a forest with trees of varying heights. Following a flood in the area, all shorter plants were destroyed and only tall trees remain. After many generations, it is noted that giraffes living in this forest have longer necks, on average, than giraffes living in the same forest prior to the flood.
What type of selection has occurred?
Directional selection
Stabilizing selection
Extreme selection
Destabilizing selection
Disruptive selection
Directional selection
Directional selection is natural selection that favors a phenotype at an "extreme" for a particular trait. In this example, we are looking at the height trait. Individuals with taller phenotypes exhibit greater fitness due to their ability to reach the food source more easily. The new environment favors taller giraffes, and thus, after many generations, the phenotype of the population as a whole will be skewed towards the tall end of the height spectrum.
Stabilizing selection favors the average phenotype for a given trait. Disruptive selection favors both extremes of a phenotype, but favors against the average.
Example Question #2 : Understanding Types Of Selection
White mice are homozygous for a recessive pigmentation trait. Brown mice are homozygous dominant for the same pigmentation trait, and beige mice are heterozygous for the trait. In a particular ecosystem, natural selection favors the beige mice because they blend in with the brush and leaves. What concept explains to this type of selection?
Balancing selection
Directional selection
Founder effect
Frequency-dependent selection
Heterozygote advantage
Heterozygote advantage
Heterozygote advantage occurs when heterozygotes at a particular locus, such as pigmentation, have greater fitness than do both kinds of homozygotes. If the heterozygote favors an intermediate phenotype, such as beige mice, it is also stabilizing selection. Frequency-dependent selection occurs when the fitness of a phenotype depends on how common it is in the population. Together, heterozygote advantage and frequency-dependent selection lead to a balancing system. The founder effect occurs when a few individuals of a population become isolated and form a new population whose gene pool differs from the original population. Directional selection occurs when conditions favor individuals at one extreme of a phenotypic range, thereby shifting a population’s frequency curve for the phenotypic character in one direction or another.
Example Question #5 : Natural Selection
Which of the following best describes the impact of purifying selection?
It removes variation from the population
It increases genetic diversity
It is the same as disruptive selection
It increases frequency of an allele
It removes variation from the population
Purifying selection is a type of natural selection impacts genetic diversity. Purifying selection removes variation from a population, meaning that there is a decrease in genetic diversity.
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