Life on earth top down (week 5) Flashcards
1
Q
how did the cambrian explosion allow progression of life
A
- record number of thriving marine ecosystems and complex food webs
- ## race to advance hunting and adapt to resist this selection pressure
2
Q
when did eukaryotes develop
A
only half way through history
- complex life very new
- microbial life dominates
3
Q
how has earth remained habitable since the beginning of life
A
- faint young sun paradox- earths surface temperatures remained within a narrow range due to the faint sun paradox
- greenhouse gases adjustment to counteract changes through metabolic changes
4
Q
what do many early metabolisms prodcuce
A
methanogens which produce methane
- produced methane rich haze
- enhanced greenhouse effect to maintain habitable temperatures
5
Q
- atmosphere before vs after life
A
- used to be volcanic gases
- interior was more radioactive so more carbon dioxide and hydrogen
6
Q
what did the great oxidation event do
A
- alterted many biogeochemical cycles
- collapse of methane greenhouse
- added oxygen to oceans
- allowed major revolution but also caused posion death to much early life
7
Q
what caused the biggest extinction in earths history
A
- late permian
- led to 95% of species going extinct
- caused by massive volcanism, widespread oxygen depletion, poison
8
Q
crital steps in the evolution of complex life on earth
A
- prokaryotes
- photosynthesis/great oxidation
- eukaryotic differentiation
- evolution
8
Q
crital steps in the evolution of complex life on earth
A
- prokaryotes
- photosynthesis/great oxidation
- eukaryotic differentiation
- evolution
