CHAPTER 14 Section 1 Fossil any preserved evidence of an organism Paleontologist a scientist who studies fossils Relative dating a method used to determine the age of rocks by comparing them with those in other layers Law of superposition states that younger layers of rock are deposited on top of older layers Radiometric dating uses the decay of radioactive isotopes to measure the age of a rock Half-life the amount of time it takes for half of the original isotope to decay Geologic time scale a record of Earth’s history Epoch the smallest units of geologic time (last several years) Period divisions of geologic time consisting of two or more epochs (last tens of millions of years.) Era unit of geologic time consisting of two or more periods (last hundreds of millions of years Eon the longest unit of time in the geologic time scale and can include billions of years Cambrian explosion the rapid diversification of most major animal groups marking the start of the Paleozoic era K-T boundary a layer of iridium,-rich material between rocks of the Cretaceous period and rocks of the Paleogene period that provides evidence of a meteorite impact Plate tectonics describes the movement of several large plates that make up the surface of Earth Ch. 14:The History of life Sec. 1: Fossil Evidence of Change 1. fossil Any preserved evidence of an organism. 2. paleontologist Is a scientist who studies fossils. 3. Relative dating Method used to determine the age of rocks by comparing them with those in other layers. 4. Law of superposition 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. 5. Radiometric dating Method used to determine the age of rocks using the rate of decay of radioactive isotopes. 6. half -life Amount of time required for half of a radioactive isotope to decay. 7. geologic time scale Record of Earth’s history 8. Epochs Smallest units of geologic time 9. Periods divisions of geologic time consisting of two or more epochs. 10. era Unit of geologic time consisting of two or more epochs. 11. eon Longest unit of time in the geologic time scale and can include billions of years. 12. Cambrian explosion Rapid diversification of most major animal groups making the start the Paleozoic era. 13. K-T boundary Layer of iridium-rich material between rocks of the Cretacious period and rocks of the Paleogene period that provides evidence of a meteorite impact. 14. Plate tectonics Geologic theory that Earth’s surface is broken into several huge plates that move slowly on a partially molten rock layer. Sec. 2: The Origin of life 1. Spontaneous generation Idea that life arise from nonlife 2. Theory of biogenesis States that only living organisms can produce other living organisms. 3. Endosymbiont theory Explains that eukaryotic cells may have evolved from prokaryotic cells. Ch. 15: Evolution Sec. 1: Darwin’s Theory of evolution by Natural Seection 1. Artificial selection The process of directed breeding to produce offspring with desired traits, referred to as selective breeding 2. 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. 3. evolution Hereditary changes in groups of living organisms over time Sec. 2: Evidence of Evolution 1. Derived traits ew features that had not in common ancestors. 2. Ancestral traits More -primitive characteristic that appeared in common ancestors. 3. Homologous structures Automatically similar structure inherited from a common ancestor. 4. Vestigial structures Reduced form of a functional structure that indicates shared ancestry. 5. Analogous structures Structure that has the same function but different construction and was not inherited from a common ancestor. 6. Embryo Organism’s early prebirth stage of development. 7. Biogeography Study of that creates and maintains databases of plants and animals on Earth. 8. Fitness Is a measure of the relative contribution that an individual trait makes to the next generation. 9. Camouflage Morphological adaptations that allow organisms to blend into their surroundings. 10. Mimicry Morphological adaptation in which one species evolves to resemble another species for protection or other advantages. 1. Hardy- Weinberg principle States that allelic frequencies in populations stay the same unless they are affected by a factor that cause change. 2. Genetic drift Random change in allelic frequencies in a population. 3. 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. 4. bottleneck Process in which a large population declines in number, then rebound. 5. Stabilizing selection Most common type of natural selection that removes the extreme expressions of a trait and leaves only the average expression. 6. Directional selection Shift of a population toward an extreme version of a beneficial trait. 7. Disruptive selection Process in which individuals with average traits are removed , creating two populations with extreme traits. 8. Sectual selection Type of natural selection in which a change in the frequency of a trait is based on the ability to attract a mate. 9. Prezygotic isolating mechanism Factor that prevents individuals from different species from mating: operates before fertilization. 10. postzygotic isolating mechanism Factor that prevents a hybrid zygote from developing, or prevents hybrid offspring from reproducing: operates after fertilization. 11. Allopatric speciation Occurs when a population divided by a geographic barrier evolves into two or more populations unable to interbreed. 12. Sympatric speciation Occurs when a species evolves into a new species in an area without a geographic barrier. 13. Adaptive radiation Diversification of a species into a number of different species into different number of different species, often over a relatively short time span. 14. gradualism Theory that evolution occurs in small, gradual steps over time. 15. Punctuated equilibrium Theory that evolution occurs with relatively sudden periods of speciation followed by long periods of stability Parenchyma cell Most flexible, thin-walled cells in a plant; used for storage photosynthesis, gas exchange, protection, tissue repair and replacement Collenchyma cell Plant cells that often are elongated and occur in cells Sclerenchyma cell Plant cells with NO cytoplasm; provide support and transport of materials meristem Regions of rapidly dividing cells; large nuclei, small or NO vacuole Vascular cambium Thin cylinder of meristematic tissue that runs the entire length of roots and stems; makes new transport cells in some roots and stems Cork cambium Lateral meristems that makes tough outer cell walls epidermis Outer layer of cells on a plant Guard cell The two cells that form a stoma; changes in the shape = open and closing xylem Water-carrying vascular tissue made of specialized vessel and tracheid cells Vessel element Tubular cells that are stacked end-to-end that make the xylem tracheid Long, cylindrical cells with pitted ends phloem Main food carrying tissue transports sugars and other organic compounds through plant Sleeve tube member Contains cytoplasm but NO nucleus or ribosomes when mature Companion cell Has nucleus and works together with sieve tube member Ground tissue Consists of parenchyma, collenchyma and sclerenchyma cells 1. auxin Plant hormone that stimulates the lengthening of cells in the growing tip 2. gibberellins The group of plant hormones 3. ethylene Only known gaseous hormone, a simple compound composed of two carbon and four hydrogen atoms. 4. cytokinin Plant hormone that stimulates the final stage in cell division, cytokinesis; also involved in the growth of side branches 5. Nastic response A plant response that causes movement that is not dependent on the direction of the stimulus 6. tropism Plant’s growth response to an external stimulus.
