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Ch 25 The History of Life on Earth

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the pattern of evolution over large time scales
abiotic synthesis of small organic molecules, ex. amino acids, nucleotides
joining of monomers into polymers, ex. proteins, nucleic acids
packaging of molecules into membrane-bound droplets ex. liposomes and protobionts
origin of self-replicating molecules which eventually made inheritance possible
water vapor, nitrogen and nitrogen oxides, carbon dioxide, methane, ammonia, hydrogen sulfide
water vapor condensed to form oceans, hydrogen went out into space
thought atmosphere was reducing (add electrons and hydrogens onto molecules), so organic molecules could be synthesized. E for reactions from lighting and UV light
tested Oparin hypothesis by recreating early atmospheric conditions in lab, made amino acids and other organic compounds
early atmosphere didn't have enough methane or ammonia to be reducing (Miller test does not work without these)
probably small areas that contained the right mix of chemicals to form organic compounds, by volcanoes, deep sea vents
collections of abiotically produced molecules surrounded by a membrane-like structure, can form spontaneously
simpler than DNA, can take various 3-d shapes, can act as ribozyme to catalyze reactions, more copying errors and variation, can self-replicate, can be acted on by natural selection
order of fossils in the rock strata
based on the decay of radioactive isotopes, when a radioactive parent isotope decays to a daughter isotope at a constant rate
time required for 50% of the parent isotope to decay
measurements of magnetism between rock layers, reversals of north and south magnetic poles over time can be matched with corresponding patterns in the rock
distinct age in the history of Earth and its life
era, period, epoch
4.6 bya-543mya
first life on earth- stromatolites, cyanobacteria, prokaryotes
layered rocks that form when certain prokaryotes bind thin films of sediment together
oxygen revolution
oxygen produced by photosynthesizing prokaryotes, doomed anaerobic organisms, cell respiration and chemiosmosis evolved, ozone layer began to protect organisms from UV light
oxygen bonded with iron in the oceans and formed bands of iron oxides in the rocks
first eukaryots
mitochondria and chloroplasts independently living prokaryotes, ingested by other prokaryotes and lived inside them
inner membranes of both have enzymes and transport systems like proks, both replicate by binary fission, both have a singular DNA piece without a lot of histones, similar size, sequences, and antibiotic sensitivity, ribosomes similar to proks
first multicellular organisms, probably started as colonies
severe ice ages between 750 and 580 mya sent most life to deep sea vents, hot springs, or near equator
mitochondria evolved before plastids through a sequence of endosymbiotic events
543 mya-245 mya
ferns and arthropods (insects, spiders)
535-525 mya, huge adaptive radiation: hard shells, predator/prey, claws, spines, body armor
500 mya, colonization of land by plants, fungi, and animals
adaptions that allowed reproduction on land and prevented dehydration
plates of the earth's crust move over time in a process called continental drift
supercontinent, caused Permian extinction
245 mya, occurred in 5 million to a few thousand years. 96% of marine life died
enormous volcanic eruptions in Siberia, too much lava and ash, CO2 heated planet and oxygen deficit
245 mya-65mya
gymnosperms and reptiles (dinosaurs)
65 mya, extinction of dinosaurs, cause a large asteroid or comet
65 mya-present time
angiosperms and mammals
65 mya, adaptive radiation of mammals
195000ya, modern humans appear
more than 1000 species extinct in 400 years- 10000 times typical rate
period of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles in their communities
subduction of oceanic plate=volcano, mountain building, slide past=earthquakes, plate separate=deep sea, new earth surface
ocean basins got deeper, se levels lowered, severe continental climate, less coastline, alters ocean currents, promotes speciation
it is forever, takes 5-10 million years to recover, lead to adaptive radiation
mammals after dinos, cambrian explosion after predators formed, photosynthesis, colonization of land after photo., regional adaptations
changes in developmental genes determines shape of organism
retain juvenile body feature in the adult
master regulatory genes
changes in hox genes, duplication of genes, changes in gene regulation

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