SAT II Biology E : Other Evolution Principles

Study concepts, example questions & explanations for SAT II Biology E

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Example Questions

Example Question #1 : Other Evolution Principles

A bat's wing and a bird's wing are considered __________.

Possible Answers:

derived traits

divergent traits

vestigial structures

homologous structures

analogous structures

Correct answer:

analogous structures

Explanation:

A bat's wing and a bird's wing are analogous structures, as the development of these structures does not share an evolutionary history. The common ancestor of bats and birds did not have wings, therefore these traits arose independently. Therefore, they are not homologous, but represent convergent evolution, as similar traits arose from different lineages due to environmental pressures.

Example Question #2 : Other Evolution Principles

Which of the following does not contribute to evolution?

Possible Answers:

Natural selection

Migration

Genetic drift

A constant environment

Mutation

Correct answer:

A constant environment

Explanation:

Mutation, migration, natural selection, and genetic drift all change the presence and proportion of alleles in a given population, contributing to evolution. An unchanging environment would not contribute to changes in alleles and, therefore, does not contribute to evolution.

Example Question #3 : Other Evolution Principles

A farmer has 1000 chickens. A disease is introduced into the population that infects almost all of the chickens. The farmer loses 500 chickens to this disease. The chickens that were infected but didn't die produce fewer eggs than the chickens that were never sick, so generations later, there are more chickens that are immune to the disease than chickens who can be infected with the disease. A few generations of chickens later, the genetic diversity of the chickens is drastically reduced. What evolutionary processes are at play?

Possible Answers:

Natural selection and mutation.

Natural selection and population bottleneck.

Natural selection and genetic drift.

Mutation and population bottleneck and genetic drift.

Mutation and genetic drift.

Correct answer:

Natural selection and population bottleneck.

Explanation:

We see natural selection because those chickens that are entirely immune to the disease produce more offspring than those chickens who were infected but survive. The gene(s) that offers protection against contracting the disease is retained at a greater rate than the gene(s) that protects the chicken from dying of the disease. If the genetic diversity of the population is reduced generations later, this suggests that the chickens experienced a population bottleneck when the population number dropped to half of its original number.

Example Question #1 : Other Evolution Principles

Which of the following is an example of founder effect?

Possible Answers:

A fatal mutation appears in a population of Sumatran tigers.

A new predator is introduced into the ecosystem.

A hurricane destroys half of a population of monarch butterflies in Mexico.

A small number of humans form an isolated colony on a deserted island.

A dog breeder decides she only wants to sell dalmatians that weigh more than 45 pounds, so she only allows males and females above this weight to breed.

Correct answer:

A small number of humans form an isolated colony on a deserted island.

Explanation:

The founder effect is when genetic variability is lost due to a small number of individuals from a larger population forming a new population. The smaller population only breeds with each other and is not genetically representative of the larger group from which it was founded. Thus, the humans on a deserted island are an example of this. The hurricane might be an example of a population bottle neck and the breeder might be causing a population bottleneck by only breeding certain dogs, but the humans are a better example of the deliberate formation of a new breeding population.

Example Question #5 : Other Evolution Principles

A new animal has been discovered in the rainforest. It is very similar in appearance to a known species, and has similar anatomy and dietary patterns; however, it cannot mate with the known species to produce viable offspring.

Given only the above information, which of the following statements is correct?

Possible Answers:

The two animals belong to the same species.

None of the above can be concluded from the information provided alone.

The two animals do not belong to the same species.

The two animals are adapted to live in completely different environments.

The two animals represent closely related variants of the same species.

Correct answer:

The two animals do not belong to the same species.

Explanation:

In order for animals to belong to the same species, they must, by definition, be able to mate with one another to produce viable offspring. The question stem says that these two animals cannot mate to produce viable offspring; therefore, they cannot belong to the same species. Since they cannot belong to the same species, they cannot "represent closely related variants of the same species," either. Although they are not the same species, the information about their similar anatomy and diet suggests that they likely evolved from a common ancestor, making the answer choice "The two animals are adapted to live in completely different environments" also incorrect.

Example Question #6 : Other Evolution Principles

Which of the following changes is most likely to increase the evolutionary fitness of an organism?

Possible Answers:

A mutation that enables it to live in a new environment

A mutation that enables it to eat more food than its peers

A mutation that enables it to produce a larger number of viable offspring than its peers

A mutation that enables it to be stronger than its peers

A mutation that enables it to be bigger than its peers

Correct answer:

A mutation that enables it to produce a larger number of viable offspring than its peers

Explanation:

An organism's evolutionary fitness is defined by the number of offspring that it produces. Mutations that increase the number of offspring that an organism can have will, by definition, increase its evolutionary fitness. Evolutionary fitness is not defined by strength, size, or habitat. While it is theoretically possible that each of the wrong answers might increase the fitness of an organism in the right circumstances, none of the wrong answers are guaranteed to increase the number of offspring produced by the organism.

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