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Ch 14 and 15 vocab
| Question | Answer |
|---|---|
| Cambrian explosion | Rapid diversification of most animal groups during Paleozoic era |
| Endosymbiont theory | explains that eukaryotic cells may have evolved from prokaryotic cells. |
| Eon | the longest periods of time |
| Epoch | A period of time, longer or shorter, remarkable for events of great subsequent influence; a memorable period |
| Era | a large division of Earth’s geologic time scale that is further divided into one or more periods. |
| Fossil | preserved evidence of an organism, often found in sedimentary rock, that provides evidence of past life. |
| Geologic time scale | model showing major geological and biological events in Earth’s history. |
| Half-life | amount of time required for half of a radioactive isotope to decay. |
| K-T boundary | layer of iridium-rich material betweeen rocks of the Cretaceous period and rocks of the Paleogene period that provides evidence of a meteorite impact. |
| Law of superstition | states that the oldest layers of rock are found at the bottom and the youngest layers of rock are found at the top of a formation if the rock layers have not been disturbed. |
| Paleontologist | scientist who studies fossils. |
| Period | subdivision of an era on the geologic time scale. |
| Plate tectonics | geologic theory that Earth’s surface is broken into several huge plates that move slowly on a partially molten rock layer. |
| Radiometric dating | method used to determine the age of rocks using the rate of decay of radioactive isotopes. |
| Relative dating | method used to determine the age of rocks by comparing the rocks with younger and older rock layers. |
| Spontaneous generation | idea that life arises from nonliving things. |
| Theory of biogenesis | states that only living organisms can produce other living organisms. |
| Adaptive radiation | diversification of a species into a number of different species, often over a relatively short time span. |
| Allopatric speciation | occurs when a population divided by a geographic barrier evolves into two or more populations unable to interbreed. |
| Analogous structure | structure that has the same function but different construction and was not inherited from a common ancestor. |
| Ancestral trait | more-primitive characteristic that appeared in common ancestors. |
| Artificial selection | Darwin’s term for the selective breeding of organisms selected for certain traits in order to produce offspring having those traits. |
| Biogeography | study of the distribution of plants and animals on Earth. |
| Bottleneck | process in which a large population declines in number, then rebounds |
| Camouflage | morphological adaptations that allow organisms to blend into their surroundings. |
| Derived trait | new feature that had not appeared in common ancestors. |
| Directional selection | shift of a population toward an extreme version of a beneficial trait. |
| Disruptive selection | process in which individuals with average traits are removed, creating two populations with extreme traits |
| Embryo | organism’s early prebirth stage of development |
| Evolution | hereditary changes in groups of living organisms over time. |
| Fitness | measure of a trait’s relative contribution to the following generation. |
| Founder effect | random effect that can occur when a small population settles in an area separated from the rest of the population and interbreeds, producing unique allelic variations |
| Genetic drift | random change in allelic frequencies in a population. |
| Gradualism | theory that evolution occurs in small, gradual steps over time. |
| Hardy-Weinberg principle | states that allelic frequencies in populations stay the same unless they are affected by a factor that causes change. |
| Homologous structure | anatomically similar structure inherited from a common ancestor. |
| Mimicry | morphological adaptation in which one species evolves to resemble another species for protection or other advantages. |
| Natural selection | theory of evolution developed by Darwin, based on four ideas: excess reproduction, variations, inheritance, and the advantages of specific traits in an environment. |
| Post-zygotic isolating mechanism | occurring after formation of a zygote. |
| Pre-zygotic isolating mechanism | occurring before breeding; produces a fertilized egg, or zygote. |
| Punctuated equilibrium | theory that evolution occurs with relatively sudden periods of speciation followed by long periods of stability |
| Sexual selection | change in the frequency of a trait based on competition for a mate. |
| Stabilizing selection | most common form of natural selection in which organisms with extreme expressions of a trait are removed. |
| Sympatric speciation | occurs when a species evolves into a new species in an area without a geographic barrier |
| Vestigial structure | reduced form of a functional structure that indicates shared ancestry |
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