Biology Vocab And Key Concepts For Chapter 17 The History Of Life

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paleontologist

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scientists who study fossils

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fossil record

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information about past life; organisms grouped together and arrange them in the order in which they lived from oldest to most recent

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extinct

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species died out

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relative dating

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age of a fossil determined by comparing its placement with that of fossils in othe layers of rock

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index fossil

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used to compare the relative ages of fossils; exist short period but have had a wide geographic range

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half-life

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length of time required for half of the radioactive atoms in a sample to decay

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radioactive dating

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use of half-lives to determine the age of a sample

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geologic time scale

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represents evolutionary time- Precambrian time, Paleozoic, Mesozoic, Cenozoic

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era

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division of the time between the Precambrian and the present into three eras

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periods

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eras subdivided

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what can be learned from the fossil record?

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the fossil record provieds evidence about the historyof life on Earth. it also shows how different groups of organisms have changed over time.

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which type of dating provides an aboslute age for a given fossil? describe how this is done.

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in radioactive dating, scientists calculate the age of a sample based on the amount of remaining radioactive isotopes it contains.

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how are eras and periods related?

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after precambrain time, the basic divisions of the geologic time scale are eras and periods.

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proteinoid microsphere

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tiny bubbles formed by large organic molecules under certain conditions; similar to living cells

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microfossil

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microscopic fossils

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endosymbiotic theory

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eukaryotic cells formed from a symbiosis among several different prokaryotic organisms

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what substances probably made up Earth's early atmosphere?

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Earth's early atmosphere probably contained hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide and water

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what molecules were the end products in Miller and Urey's experiments?

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Miller and Urey's experiments suggested how mixtures of the organic compounds necessary for life could have arisen from simpler compounds present on a primitive Earth

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How did the addition of oxygen to Earth's atmosphere affect life of that time?

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the rise of oxygen in the atmosphere drove some life forms to extinction, while other life forms evolved new, more efficient metabolic pathways that used oxygen for respiration.

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according to the endosymbiotic theory, how might chloroplasts and mitochondria have originated?

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the endosymbiotic theory proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms.

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mass extinction

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many types of living things became extinct at the same time; affected plants and animals

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where did life exist during the early Paleozoic Era?

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early in the paleozoic era, the fossil record became rich with evidence of many types of marine life.

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what evolutionary milestone involving animals occurred during the Devonian Period?

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During the Devonian, animals began to invade the land.

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what are the two key events from the Mesozoic era?

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events during the mesozoic include the increasing dominance of dinosaurs, the mesozoic is marked by the appearance of flowering plants.

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what happened during the cenozoic era?

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during the cenozoic, mammals evolved adaptations that allowed them to live in various environments- on land, in water, and even in the air.with some climate changes from warm in Tertiary and an ice age in the quaternary

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macroevolution

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large scale evolutionary changes that take place over long periods of time

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adaptive radiation

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a single species or a small group of species has evolved into several different forms that live in different ways

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convergent evolution

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unrelated organisms come to resemble one another

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coevolution

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two species evolve in response to changes in each other over time

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punctuated equilibrium

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pattern of long, stable periods interrupted by brief periods of more rapid change.

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describe patterns of macroevolution

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mass extinctions, adaptive radiation, convergent evolution, coevolution, puncuated equilibrium, developmental genes

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how did hox genes help reveal how evolution occurred?

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1st-molecular studies show that homologous hox genes extablish body plans in animals as different as insects and humans
2nd-major evolutionary changes may be based on hox genes
3rd- small changes in timing of genetic control during embryonic develpment makes difference between long legs and short ones- variation involved in natural selection