AP Biology : Identify evolutionary change mechanisms

Study concepts, example questions & explanations for AP Biology

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Example Questions

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Example Question #31 : Identify Evolutionary Change Mechanisms

When a small group of individuals leaves a population and moves to a new location, the allelic frequency of this new population is likely to different from the original population. This is known as which of these?

Possible Answers:

Natural selection

The Founder Effect

The Hardy-Weinberg Equilibrium Principle

A type of mutation

Dominance

Correct answer:

The Founder Effect

Explanation:

The Founder Effect is due to a sampling error. By taking a small sample of an existing population and creating a new population, there is zero probability that the new population will have all of the same alleles as the old population. Therefore, the alleles of the new population are likely to differ from the original population. 

Example Question #32 : Identify Evolutionary Change Mechanisms

Which of the following is not required for natural selection to occur?

Possible Answers:

Variation

Heredity

Differential reproduction

Gene flow

Correct answer:

Gene flow

Explanation:

The three key requirements for natural selection are variation, differential reproduction, and heredity. That is, there must be variation in the population, and that variation must affect the mating success of some individuals (differential reproduction). Organisms who successfully mate must be able to pass on their genes to their offspring (heredity).

Gene flow refers to movement of alleles between populations, and is not necessary for natural selection to occur.

Example Question #33 : Identify Evolutionary Change Mechanisms

Males in a population of frogs compete for territory along the edge of a pond. During mating season, the males guard their territory and croak loudly when females approach. Which of the following types of selection does this most closely resemble?

Possible Answers:

Directional selection

Stabilizing selection

Sexual selection

Territorial selection

Correct answer:

Sexual selection

Explanation:

Because the males croak loudly when females approach, this behavior is suggestive of sexual selection. It is likely the males are demonstrating for the females in an effort to attract a mate. Sexual selection occurs when one sex (usually females) choose a mate based on a trait that does not directly affect survival (here, the frog's croak). There is not enough information to determine if the selection is stabilizing, directional, or neither. Territorial selection is not one of the types of a natural selection.

Example Question #278 : Evolution And Genetics

A student is asked to suggest a possible reason that snowshoe hares have white fur. The student proposes that snowshoe hares needed white fur, so over many generations natural selection acted to lighten their fur color until it was almost snow-white. Is this a reasonable theory?

Possible Answers:

Yes. The fitness of the hares will continue to increase, so traits that the hares need to increase their fitness will be selected for.

No. It is incorrect to think about the changes that occur by natural selection as responses to a population's needs. Natural selection selects among variants in a population based on reproductive success. 

There is not enough information to determine if the student's theory is reasonable.

Yes. Natural selection provides what organisms needs to survive and reproduce, increasing their fitness over time.

Correct answer:

No. It is incorrect to think about the changes that occur by natural selection as responses to a population's needs. Natural selection selects among variants in a population based on reproductive success. 

Explanation:

It is incorrect to think of natural selection as a response to a "need." Natural selection will select among variants in a population, resulting in evolution. Individuals and populations cannot influence the course of natural selection based on wants or needs.

Example Question #279 : Evolution And Genetics

__________ is the development of similar characteristics in unrelated species, resulting from adaptations to similar environmental conditions.

Possible Answers:

Genetic drift

Divergent evolution

Speciation

Convergent evolution

Coevolution

Correct answer:

Convergent evolution

Explanation:

Convergent evolution is the development of characteristics in unrelated species, resulting from adaptations to similar environmental conditions whereas the other choices identify other variations of evolution. Divergent evolution is the loss of similar structures in related species due to different environmental conditions. Speciation is the process by which new species evolve as a result of environmental conditions. Genetic drift is the change in allele frequencies within a population due to the imperfections of random sampling techniques. Coevolution is the phenomenon characterized by the evolution of two organisms simultaneously as a result of their interaction with each other. 

Example Question #280 : Evolution And Genetics

A type of natural selection in which genetic diversity decreases as the population stabilizes with respect to a particular trait value is __________.

Possible Answers:

nonspontaneous selection

stabilizing selection

None of these

directional selection

diversifying selection

Correct answer:

stabilizing selection

Explanation:

A type of natural selection in which genetic diversity decreases as the population stabilizes with respect to a particular trait value is stabilizing selection. In this mode of natural selection, the "average" phenotype is selected for and its proportion in the population increases over time. Directional selection is a type of natural selection in which a polarized phenotype is selected for over the other phenotypes, causing a shift toward the extremes with respect to proportion of individuals with that phenotype. Diversifying selection is another type of natural selection in which both extremes of a phenotype are selected for, causing an increase in the proportion of those alleles in the population. Nonspontaneous selection is not a type of natural selection.

Example Question #34 : Identify Evolutionary Change Mechanisms

Which of the following is not a type of selection?

Possible Answers:

Stabilizing selection

Disruptive selection

Artificial selection

Sexual selection

Domestic selection

Correct answer:

Domestic selection

Explanation:

Stabilizing selection favors the intermediate phenotypes in a population while disruptive selection favors extreme phenotypes. Artificial selection is frequently practiced by humans in breeding livestock, pets, and crops. Sexual selection is dependent on interaction between males and females within a population. Domestic selection is not a real term.

Example Question #281 : Evolution And Genetics

A population of birds with varying beak size feeds on seeds. The birds with smaller beaks feed on small seeds, those with medium-sized beaks feeds on a medium-sized variety of seeds, and those with larger beaks feed on a large variety of seeds. Invasive insects wipe out all of the plants that produce medium-sized seeds, and the following generation of birds has no individuals with medium-sized beaks. This is an example of what type of selection?

Possible Answers:

Sexual selection

Disruptive selection

Artificial selection

Directional selection 

Stabilizing selection

Correct answer:

Disruptive selection

Explanation:

Quantifiable traits, like beak size, in a population tend to form a bell curve when graphed. Selection that leads to more individuals on either end of the graph compared to individuals in the center is disruptive, and in this case leads to a lack of medium sized birds since birds with either small or large beaks were favored. Selection that favors individuals on one side of the graph is directional, and selection that favors individuals in the center of the graph is stabilizing.

Example Question #33 : Identify Evolutionary Change Mechanisms

In a snowy area, the white beetle is able to blend in with the snow, while the black beetle can blend in with the dark barks of trees. However, the gray beetle stands out, and is picked on by predators. As a result, the white and black beetles are favored, but not gray beetles. This is an example of

Possible Answers:

Disruptive selection

Stabilizing selection

The Hardy-Weinberg principle

Directional selection

Relative fitness

Correct answer:

Disruptive selection

Explanation:

Disruptive selection happens when the environment favors individuals on the extreme ends of a phenotype.

Directional selection favors individuals on one end of a phenotype (for example, a different environment may only favor black beetles, but not white or gray).

Stabilizing selection favors against extreme phenotypes (for example, a different environment may favor gray beetles, but not black or white beetles). 

Example Question #35 : Identify Evolutionary Change Mechanisms

In animals, which of the following does not increase inheritable genetic variation?

Possible Answers:

Mutation

Mitosis

Crossing over

Meiosis

Correct answer:

Mitosis

Explanation:

Mitosis does not create genetic variation. The primary roles of mitosis are growth and healing.

Crossing over refers to the exchange of genetic material between chromosomes during metaphase I of meiosis, and is largely responsible for enhancing the genetic variation of eukaryotes. Mutation is necessary to introduce new genetic factors and adaptations into a population, thus furthering evolution and promoting variation.

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