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Unformatted text preview: BRIEF H ISTORY OF L I FE ON EARTH LIFE 1.2; 26-26.1; 4.5 1.2 How is all life on earth related?-species on Earth share a common ancestor-the greater the differences between the genomes of two species, the more distant was their common ancestor 1.2.1 Life arose from nonlife via chemical evolution-complex biological molecules first arose through the random physical association of chemicals in that environment 1.2.2 Biological evolution began when cells formed-Scientists postulate that about 3.8 billion years ago, this natural process of membrane formation resulted in the first cells with the ability to replicate themselvesan event that marked the beginning of biological evolution-first unicellular organisms were prokaryotes 1.2.3 Photosynthesis changed the course of evolution-The sum total of all the chemical reactions that go on inside a cell constitutes the cells metabolism- photosynthesis : transforms energy of sunlight into energy to power the synthesis of biological molecules vast quantities of oxygen formed layer of ozone in atmosphere thick layer intercepted UV rays organisms started living on land 1.2.4 Eukaryotic cells evolved from prokaryotes-evolution of cells w/ organelles eukaryotes-chloroplast and mitochondria may have been engulfed by a larger eukaryote 1.2.5 Multicellularity arose and cells became specialized1....
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- Spring '08