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18 Cards in this Set
- Front
- Back
biodiversity
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variety and variability among all genes, species, and ecosystems - on the planet
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phase 1: the formation of small molecules containing carbon and hydrogen
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under conditions similar to those on early earth, small organic molecules form, and these molecules have some chemical properties of life
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phase 2: the formation of self-replicating information-containing molecules
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earliest life on earth, which resembled bacteria, appeared about 3.5 billion years ago, not long after the earth was formed; no one is certain how life arose, but evidence supports the idea that self-replicating molecules - possibly RNAs - may have formed in earth's early environment
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RNA world hypothesis
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proposes that the world may have been filled with RNA-based life before it became filled with the DNA based life we see today
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phase 3: the development of a membrane, enabling metabolism and creating the first cells
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self-replicating molecules later acquired or developed membranes, enabling them to replicate and making metabolism possible, the 2 conditions that define life
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microspheres
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compartmentalization of self-replicating information containing molecules into microspheres may have been an important stage as the first living cells arose
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species
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biologists use this world to label different kinds of organisms
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biological species concept
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species are populations of organisms that interbreed or could possibly interbreed with each other under natural conditions and that cannot interbreed with organisms outside their own group
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reproductive isolation
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the inability of individuals from 2 populations to produce fertile offspring with each other - making it impossible for gene exchnage between the populations to occur
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prezygotic barriers
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make it impossible for individuals to mate with other or if they can mate, make it impossible for the male's reproductive cell to fertilize the female's reproductive cell
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postzygotic barriers
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occur after fertilization and generally prevent the production of fertile offspring from individuals of 2 different species - called hybrids
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organization of life
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-domain (bacteria, archaea, eukarya)
-kingdom (protists, plants, fungi, animals) -phylum: giraffe (chordata) -class (mammalia) -order (artiodactyla) -family (giraffidae) -genus (giraffa) -species (giraffa camelopardalis) |
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postzygotic barriers
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occur after fertilization and generally prevent the production of fertile offspring from individuals of 2 different species - called hybrids
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organization of life
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-domain (bacteria, archaea, eukarya)
-kingdom (protists, plants, fungi, animals) -phylum: giraffe (chordata) -class (mammalia) -order (artiodactyla) -family (giraffidae) -genus (giraffa) -species (giraffa camelopardalis) |
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the biological species concept doesn't always work
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1-classifying asexual species: asexual reproduction does not involve interbreeding so the concept of reproductive isolation is no longer meaningful
2- classifying fossil species: differences in size and shape of fossil bones cannot reveal whether there was reproductive isolation between the individuals from whom the bones came 3- determining when one species has changed into another: there is rearely a definitive moment making the transition from 1 species to another |
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biological species concept #2
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4- classifying ring species: 2 non-interbreeding populations may be connected to each other by gene flow through another population so there is no exact point where 1 species stops and the other begins
5- classifying hybridzing species: hybridization- the interbreeding of closely related species - sometimes occurs and prouduces fertile offspring, suggesting that the borders between the species are not clear cut |
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speciation
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in which 1 species splits into 2 distinct species, occurs in 2 phases and requires more than just evolutionary change in a population
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microbes
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the most abundant organisms on earth- don't have skeletal, respiratory, circulatory, digestive or nervous systems because they are too small to need them
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