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what is the best evidence about how our universe began?
began with a "big bang" 13.7 billion years ago
How old is the earth and the solar system?
more than 4.5 billion years old
How did the earth and solar system form?
from the coming together of pre-existing debris joined by gravity
How did the elements settle in the earth?
settled by density in early earth
How old are the oldest rocks and how were they discovered?
oldest rocks over 4 billions years old and discovered by radioactive isotopes
when did surface water stabilize into oceans?
about 4 billion years ago
what were the 5 major elements found in the surface and atmosphere?
- Very little O2
when did the origin of life begin?
more than 3 billion years ago
O2 is destructive to bonds in ____________ .
what are some things that define a living thing? List at least 7.
- ability to grow
- transforms energy
- respond to stimuli
How old are the oldest fossils?
3.1-3.7 billion years
what are some evidence that life may have began earlier, before atmosphere stabilized? (2)
- old fossils
- ambiguous chemicals
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
how does methane and the green house effect relate?
methane may have warmed the climate via the green house effect
when did photosynthesis evolve?
more than 2.5 billion years ago
which organism might have been the first to use photosynthesis?
what are stromatolites?
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
how did rising oxygen levels affect early life? why?
probably poisoned many kinds of early life because oxygen very reactive
when did eukaryotes first appear?
about 2 billion years ago
when did the first animals appear?
about 600 million years ago
A great diversification of animals occurred in which period?
- the Cambrian explosion(all these animal groups were aquatic)
when did the first plants and fungi appear?
about 500 million years ago
how old are humans?
about 200 000 years olds
what are 2 ways the earth is still changing?
- climate is changing (global warming)
- species are evolving and going extinct
what does the chemical origin of life suggest?
theory suggest that life began abiotically (ex. chemicals)
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
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
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
what did Miller and Urey find after their experiment?
found several amino acids had formed
Monomers forming into polymers is called?
how can dehydration synthesis occur in the early earth?
can occur if dilute monomer solutions drip onto hot rocks or sand
what natural elements can increase reaction rates? (2)
- clay: have polar and charged areas
- some metals: like iron in pyrite act as catalysts
what unnatural elements speed up reactions? (3)
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
what are protobionts?
"pre-cells" (membrane bags)
how can protobionts be made abiotically?
phospholipids in water
what evidence could suggest that organic molecules got here from space?
amino acids and strings of sugars have been found in meteorites
what evidence could suggest that organic molecules began in the ice?
bits of nucleic acids can be formed in ice in the lab
As water freezes, other molecules are concentrated into tiny __________________ within it.
liquid water bubbles
what element can be formed in the ice when in a lab?
bits of nucleic acids