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90 Cards in this Set
- Front
- Back
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when did life begin |
4 bya, shortly after or during heavy bombardment |
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precambrian |
lasted 4 bil years, first evidence of life |
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phanerozoic |
542 mya-present |
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3 lines of evidence to date origin of life |
stromatolites - 3.5 bya microfossils - 3.5 isotopes - 3.95 bya, lower C13 in living organisms |
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where did life begin |
shallow ponds, underwater vents, underground protection against uv |
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early earth conditions |
very little o2, no ozone to protect |
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miller urey experiment |
demonstrated that organic building blocks can form naturally and easily - glass flask, water vapor, gases replicating early atmosphere, electricity = organic compounds, amino acids |
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early sources of organic molecules |
deep sea vent chemical reactions meteorites from space heat and pressure from impacts |
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rna world hypothesis |
rna was first hereditary molecule steps:short rna forms from clay catalysis > rna peels away from clay and folds, some are capable of catalyzing reactions >folded rna attaches > longer strands can perform more catalysis > eventually self replicate |
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pre cells |
enclosing reactions allow more replication >evolution precells formed naturally, lipids mixing with water > membrane, or cooling amino acid solution |
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metabolism first hypothesis |
simple molecules > metabolism > complex molecules > rna |
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panspermia |
theory that life molecules migrated to earth from asteroid |
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LUCA |
last universal common ancestor, chemoautotroh hydrothermal vents |
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early evolution rate |
DNA replication with limited enzymes = more mistakes, more mutations |
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photosynthesis evolution |
3.5 bya evolved rapidly nonphotosynthetic ancestor evolved light absorbing pigment, anaerobic used H2S |
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eukaryotic evolution |
Infolding of membranes creates nucleus around dna endosymbiosis of aerobic bacteria provides energy, mitochondria eukarya offshoot of archea |
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multicellular organisms |
evolved seperately 2.1 bya Africa, 1.2 bya similar to red algea |
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earliest animals |
resemble sponges, 650 Mya |
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ediacaran fauna |
600-542 Mya, 200 species, soft body plants and animals |
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Cambrian explosion |
origin of nearly all modern phyla triggers: rise in o2, more genetic diversity, snowball earth, lack of predators |
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colonization of land |
required buildup of ozone plants and maybe fungi first 475 Mya animals within 75 mya |
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carboniferous forests |
360 Mya, fossil fuels |
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age of dinosaurs |
Mesozoic |
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age of mammals and birds |
cenozoic |
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primary property of oxygen |
highly active, would disappear if not continually produced |
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importance of oxygen |
promotes ATP, more efficient energy= more adaptations |
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banded iron deposits |
2-3 bya atmosphere had less than 1% of oxygen |
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mass extinction events |
ordivician devonian Permian triassic cretaceous/ KT |
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KT extinction |
65 Mya impact, global cataclysm rabid cooling |
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what factors made earth habitable |
breathable atmosphere, surface water, habitable temp and pressure, protection from uv |
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3 requirements for life |
materials energy liquid medium |
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how many elements and what are the essential core elements |
25 out of 92 elements used for life, CHON make up 96% of living organisms |
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energy sources |
photosynthesis, consuming, inorganic chemical reactions |
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limitations of chemical energy |
need liquid medium and atmosphere to be in contact and form reactions |
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roles of water in metabolism |
dissolves charged molecules, transport into and out of cells, metabolic reactions |
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advantages of water as liquid medium |
high liquid temp range, ice floats, charge differentiation (polar molecules dissolve) |
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moon and mercury habitability |
small and no geological activity, no atmosphere, water ice but no liquid |
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venus habitability |
extreme temp and pressure, runaway greenhouse effect keeps it very hot, phoshine gas biomarkers |
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outer planets |
massive, less dense, gaseous H, He, water, methane, no solid surface |
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jupiter and saturn |
cloud layers - ammonia, ammonium, water strong vertical winds |
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uranus and neptune |
cold, little sunlight Rocky core, possible liquid water /methane layer, gas hydrogen |
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dwarf planets |
ceres, eris, pluto - evidence subsurface water and geo activity |
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flyby missions |
voyager 2 |
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orbiters |
mars reconnaissance |
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landers /probes |
Galileo - jupiter Cassini - saturn |
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mars characteristics |
half the size of earth, roughly same surface area, 38% gravity, 1/10 mass, 1.5 au |
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mars atmosphere |
96% CO2, low pressure |
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mars seasons |
due to axis tilt north summer long and cool, winter short and mild south summer brief and warm, winter long and freezing |
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mars seasons |
due to axis tilt north summer long and cool, winter short and mild south summer brief and warm, winter long and freezing |
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mars polar ice caps |
CO2 ice, grow in winter |
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mars north hemisphere |
fewer craters, thin crust |
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mars south hemisphere |
heavily cratered, thick crust |
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mars eras |
Noachian /early - before 3.7 bya Hesperain/middle - 3.7-3 bya Amazonian /recent - 3 bya to present |
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most lava flows on Mars? |
tharsis bulge |
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Olympus mons |
tallest known mountain, 26 km above surface, 3 times higher than Mt everest |
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Valles marineris |
huge canyon on Mars, 8km deep longer than US |
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orbital evidence for past water on Mars |
channels 3.byo, riverbeds crater rims eroded orbital spectra images show clay minerals, hydrated sulfates, opal - form in water |
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evidence found by mars rovers |
opportunity - hematite blueberries form in salty water spirit - gusev crater flooded curiosity - gale crater sedimentary rocks and dry clay, rounded pebbles |
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evidence for water on ancient mars |
similar to earth floodplains (chaos terrain) |
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where is ice on Mars now and how much would it melt |
polar ice caps, small amount in soil, melted would form ocean 20-30 meters deep |
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how much water has mars lost over time |
more than 50 meters deep covering surface |
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mars express orbiter found? |
subsurface water table |
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why did mars lose water |
small size - no magnetic field, solar stripping, no out gassing |
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mars axis tilt climate |
when axis is more tilted summer pole gets more direct sunlight |
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viking carbon assimilation experiment |
mars soil + tagged CO2 and Co, carbon incorporated into soil, suggests chemical rather than bio process |
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viking gas exchange experiment |
mars soil + nutrient broth, oxygen release suggested photosynthesis but it was likely chemical process |
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viking labeled release experiment |
mars soil with radio tagged nutrients, radioactivity rose and then leveled as nutrients were used up |
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viking mass spec experiment |
found no organic material in mars soil |
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explanation for viking experiments |
perchlorate in soil releases oxygen and destroys organic molecules when heated |
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mars methane |
methane seeps out of the ground and dissipates during the day curiosity found methane at night, exomars found no methane during day |
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alh84001 meteorite |
4.1 bya has layered carbonate, PAHs, magnetite crystals, rod shaped structures all have a non biological explanation |
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Galileo |
discovered the moons of jupiter - Io, Europa, Ganymede, callisto |
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Huygen |
Discovered Titan, moon of saturn |
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how is Triton unique? |
orbits backward relative to neptunes rotation |
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how does compositions of moons relate to distance from sun |
farther from sun > less dense, more water /ice |
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synchronous rotation |
moons rotate with the same face to planet at all times, caused by tidal friction |
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tidal friction |
difference in attraction between moon and planet tries to stretch planet, creating tidal bulges |
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tidal heating |
tidal forces grim elliptical orbit flex interior and cause heating |
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orbital resonance |
when moons and planet line up in orbit causing gravitational tugs |
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Io |
most volcanically active world, a lot of tidal heating |
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Europa composition |
Iron core, silicate rock mantle, thick ice crust |
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evidence for subsurface ocean on Europa |
lack of impact craters surface features (similar to arctic, lineae and lenticulae) magnetic field suggests salty fluid ocean atmosphere - water vapor |
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Europa ocean size |
100 or more km |
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Europa requirements for life |
has liquid and source of elements, energy source unsure |
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possible energy sources on Europa |
hydrothermal vents, undersea volcanoes circulating water and eroding rock less energy potential than earth |
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Ganymede |
largest moon similar composition to Europa - iron core, rocky mantle, ice layer, liquid ocean, ice crust |
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callisto |
more craters induced mag field, possible ocean |
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titan atmosphere |
due to gravity and cold temps mostly nitrogen, almost no oxygen, also methane argon ethane |
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titan life |
surface - would use methane instead of water, affects cell membrane, can't have phospholipids possible subsurface water ocean |
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enceladus |
ice plumes with methane possible methanogens CHNOPS detected in plumes, phosphorus important 30 km deep ocean |
