Speciation

How do these events contribute to speciation?

• A. They reduce adaptation by introducing gene flow.

• B. They drive adaptation by changing the environment.

• C. They drive adaptation by reducing population sizes.

• D. They reduce adaptation by increasing biodiversity.

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Which TWO statements describe why populations that are reproductively isolated can develop into different species?

• Different beneficial traits increase in isolated populations.

• Reproductively isolated populations maintain genetic similarities.

• Reproductively isolated populations have two separate gene pools.

• There is an increase in gene flow between two isolated populations.

• Biodiversity increases when populations become reproductively isolated.

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According to most scientists, which sequence best represents the order in which these events occurred?

• Y → W → X

• X → Y → W

• W → X → Y

• X → W → Y

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What does this discovery show about scientific knowledge?

• It shows that it is durable, and new evidence can change scientific thinking.

• It shows that the previous knowledge for studying skeletons was accurate.

• It shows that there is now only one knowledgeable way to study skeletons.

• It shows that scientific knowledge is static, and it can never be altered.

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Biologists study the physical structures of species and compare them to the fossil record. New technology allows scientists to examine the DNA of different species, and they have discovered that species that appear very different actually share many DNA sequences. What does this evidence suggest?

• These species may share a common ancestor.

• DNA sequences are almost identical in every species.

• These species must be from the same geographical region.

• DNA sequences do not determine species' physical characteristics.

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The diagram shows the development of three species over time. Which explanation can be constructed using this graph?

• A. A new species can emerge from a pre-existing species.

• B. A species evolves multiple times into one single new species.

• C. An original species becomes extinct after a new species emerges.

• D. All organisms emerge from different ancestors and evolve into new species.

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What aspect of the scientific process does this best illustrate?

• Once a scientific theory is backed up by repeated experiments, it becomes a law.

• New discoveries sometimes discredit long-standing scientific theories.

• New discoveries continually expand and improve existing scientific theories.

• Scientists sometimes arrive at the same theories independently of each other.

Which statement best describes evolution?

• A. Evolution is a change in the gene frequency in a population over generations.

• B. Evolution is a change in the environmental conditions over a short period of time.

• C. Evolution is a change in the phenotypic makeup of a population over generations.

• D. Evolution is a change in the genetic makeup of an individual over a short period of time.

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