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17 Cards in this Set
- Front
- Back
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Macroevolution
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Evolutionary change above the species level. Examples of macroevolutionary change include the origin of a new group of organisms through a series of speciation events and the impact of mass extinctions on the diversity of life and its subsequent recovery.
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Protocell
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An abiotic precursor of a living cell that had a membrane-like structure and that maintained an internal chemistry different from that of its surroundings.
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Ribozymes
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An RNA molecule that functions as an enzyme, such as an intron that catalyzes its own removal during RNA splicing.
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Radiometric dating
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A method for determining the absolute age of rocks and fossils, based on the half-life of radioactive isotopes.
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Half-life
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The amount of time it takes for 50% of a sample of a radioactive isotope to decay.
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Geologic record
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The division of Earth’s history into time periods, grouped into three eons— Archaean, Proterozoic, and Phanerozoic—and further subdivided into eras, periods, and epochs.
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Stromatolites
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Layered rock that results from the activities of prokaryotes that bind thin films of sediment together.
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Endosymbiont theory
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The theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by an ancestral eukaryotic cell. The engulfed cell and its host cell then evolved into a single organism.
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Serial endosymbiosis
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A hypothesis for the origin of eukaryotes consisting of a sequence of endosymbiotic events in which mitochondria, chloroplasts, and perhaps other cellular struc- tures were derived from small prokaryotes that had been engulfed by larger cells.
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Cambrian explosion
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A relatively brief time in geologic history when many present-day phyla of animals first appeared in the fossil record. This burst of evolutionary change occurred about 535–525 million years ago and saw the emergence of the first large, hard-bodied animals.
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Plate tectonics
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The theory that the continents are part of great plates of Earth’s crust that float on the hot, underlying portion of the mantle. Movements in the mantle cause the continents to move slowly over time.
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Pangaea
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The supercontinent that formed near the end of the Paleozoic era, when plate movements brought all the landmasses of Earth together.
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Mass extinction
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The elimination of a large number of species throughout Earth, the result of global environmental changes.
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Adaptive radiation
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Period of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles in their communities.
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Heterochrony
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Evolutionary change in the timing or rate of an organism’s development.
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Paedomorphosis
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The retention in an adult organism of the juvenile features of its evolutionary ancestors.
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Homeotic genes
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Any of the master regulatory genes that control placement and spatial organization of body parts in animals, plants, and fungi by controlling the develop-
mental fate of groups of cells. |
