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The flashcards below were created by user
CanuckGirl
on FreezingBlue Flashcards.
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what is the best evidence about how our universe began?
began with a "big bang" 13.7 billion years ago
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How old is the earth and the solar system?
more than 4.5 billion years old
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How did the earth and solar system form?
from the coming together of pre-existing debris joined by gravity
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How did the elements settle in the earth?
settled by density in early earth
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How old are the oldest rocks and how were they discovered?
oldest rocks over 4 billions years old and discovered by radioactive isotopes
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when did surface water stabilize into oceans?
about 4 billion years ago
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what were the 5 major elements found in the surface and atmosphere?
- N2
- CO2
- HCN
- NH3
- H2O
- Very little O2
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when did the origin of life begin?
more than 3 billion years ago
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O2 is destructive to bonds in ____________ .
organic molecules
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what are some things that define a living thing? List at least 7.
- order
- cells
- reproduction
- evolution
- metabolism
- ability to grow
- transforms energy
- homeostasis
- respond to stimuli
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How old are the oldest fossils?
3.1-3.7 billion years
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what are some evidence that life may have began earlier, before atmosphere stabilized? (2)
- old fossils
- ambiguous chemicals
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why did the first organisms use a process other than cellular respiration to transform energy? what was the alternative?
- because there was very little oxygen in the atmosphere
- may have released methane
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how does methane and the green house effect relate?
methane may have warmed the climate via the green house effect
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when did photosynthesis evolve?
more than 2.5 billion years ago
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which organism might have been the first to use photosynthesis?
cyanobacteria
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what are stromatolites?
photosynthetic prokaryotes
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what did photosynthetic bacteria add to the atmosphere and water bodies? what is the proof?
- added oxygen
- rust is evidence b/c oxygen was not present therefore no rust formed on metals
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how did rising oxygen levels affect early life? why?
probably poisoned many kinds of early life because oxygen very reactive
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when did eukaryotes first appear?
about 2 billion years ago
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when did the first animals appear?
about 600 million years ago
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A great diversification of animals occurred in which period?
- the Cambrian explosion(all these animal groups were aquatic)
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when did the first plants and fungi appear?
about 500 million years ago
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how old are humans?
about 200 000 years olds
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what are 2 ways the earth is still changing?
- climate is changing (global warming)
- species are evolving and going extinct
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what does the chemical origin of life suggest?
theory suggest that life began abiotically (ex. chemicals)
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why is it unlikely that new forms of life are forming from simple chemicals today? (2)
- lots of reactive oxygen around (prevents molecules from combining into organic molecules)
- existing organisms would consume organic molecules before they could assemble into something more complicated
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what are the 4 potential steps in the chemical origin of life?
- abiotic synthesis of organic monomers
- monomers being converted it polymers
- origin of self-replicating molecules (allowing for inheritance)
- packaging into membrane-enclosed bags
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what did Miller and Urey try to do?
tried to recreate the conditions of the early earth to test how monomers might have formed on the young earth
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what did Miller and Urey find after their experiment?
found several amino acids had formed
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Monomers forming into polymers is called?
dehydration synthesis
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how can dehydration synthesis occur in the early earth?
can occur if dilute monomer solutions drip onto hot rocks or sand
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what natural elements can increase reaction rates? (2)
- clay: have polar and charged areas
- some metals: like iron in pyrite act as catalysts
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what unnatural elements speed up reactions? (3)
- heat
- catalyst
- concentration
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what are 5 reasons of why RNA may have come before DNA?
- single strand
- short pieces can be made abiotically
- is autocatalytic
- binds to amino acids, helping them to join
- DNA is more stable and must have come after
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what are protobionts?
"pre-cells" (membrane bags)
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how can protobionts be made abiotically?
phospholipids in water
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what evidence could suggest that organic molecules got here from space?
amino acids and strings of sugars have been found in meteorites
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what evidence could suggest that organic molecules began in the ice?
bits of nucleic acids can be formed in ice in the lab
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As water freezes, other molecules are concentrated into tiny __________________ within it.
liquid water bubbles
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what element can be formed in the ice when in a lab?
bits of nucleic acids
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