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21 Cards in this Set
- Front
- Back
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Species |
A group of similar organisms that can mate with each other and produce fertile offspring |
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Evolution |
The gradual change in a species over time |
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Natural selection |
The process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species |
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Adaptation |
A trait that helps an organism survive and reproduce |
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Scientific theory |
A well-tested concept that explains a wide range of observations |
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Variation |
Any difference among individuals of the same species |
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Fossil |
The preserved remains or traces of an organism that lived in the past |
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Sedimentary rock |
Rock formed when layers of sediments harden over millions of years |
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Petrified fossil |
A fossil formed when minerals replace all or part of an organism |
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Mold |
A type of fossil formed when a shell or other hard part of an organism dissolves, leaving an empty space in the shape of the part |
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Cast |
A type of fossil that forms when a mold becomes filled in with minerals that then harden |
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Relative dating |
A technique used to determine which of two fossils is older |
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Absolute dating |
A technique used to determine the actual age of a fossil |
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Radioactive element |
An unstable particle that breaks down into a different element |
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Half- life |
The time it takes for half the atoms in a radioactive element to break down |
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Fossil record |
The millions of fossils that scientists have collected |
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Extinct |
A species that does not have any living members |
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Gradualism |
The theory that evolution occurs slowly but steadily |
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Punctuated equilibria |
The theory that species evolve during short periods of rapid change |
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Homologous structures |
Body parts that are structurally similar in related species; provide evidence that the structures were inherited from a common ancestor |
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Branching tree |
A diagram that shows how scientists think different groups of organisms are related |
