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Biology
Chapter 25
| Term | Definition |
|---|---|
| Stromalites | the first single-celled organisms and the oldest known fossils; rocks formed by the accumulations of sedimentary layers on bacterial mats. |
| oxygen revolution | from 2.7 to 2.3 billion years ago caused the extinction of many prokaryotic groups. |
| endosymbiotic theory | proposes that mitochondria and plastids (chloroplats and related organelles) were formerly small prokaryotes living within larger host cells. |
| endosymbiont | a cell that lives within a host cell. |
| serial endosymbiosis | supposes that mitochondria evolved before plastids through a sequence of endosymbiotic events. |
| the "snowball Earth hypothesis" | suggests that periods of extreme glaciation confined life to the equational region or deep sea vents from 750 to 580 million years ago. |
| Ediacaran biota | an assemblage of larger and more diverse soft-bodied organisms that lived from 575 to 535 million years ago. |
| Cambrian explosion | the sudden appearance of fossils resembling modern animal phyla in the Cambrian period (535 to 525 million years ago). |
| Permian extinction | the boundary between the Paleozoic and Mesozoic eras 251 million years ago. |
| Cretaceous mass extinction | 65.5 million years ago separates the Mesozoic from the Cenozoic; caused the extinction of the dinosaurs |
| adaptive radiation | the evolution of diversely adapted species from a common ancestor. |
| heterochrony | an evolutionary change in the rate or timing of developmental events |
| paedmorphosis | the rate of reproductive development accelerates compared with somatic development. |
| homeotic genes | determine such basic features as where wings and legs will develop on a bird or how a flower's parts are arranged. |
| hox genes | a class of homeotic genes that provide posotional information during development. |
| binomial | the two part scientific name of a species. |
| epithet | unique for each species within the genus. |
| taxon | the taxonomic unit at any level of hierarchy. |