origins of life on earth

Question 1

when did earth form?

Answer 1

Earth formed approx. 4.6 billion years ago

Question 2

what was earth’s condition when it formed?

Answer 2

• More frequent and intense lightning 
	• Volcanic activity 
	• Primitive atmosphere with CH4, NH3, CO2, N2, H2, and H2O 
	• No O3 layer -> intense UV radiation 
	• "reducing atmosphere"  bc no oxygen 
Plenty of energy

Question 3

evidence of earth’s condition?

Answer 3

• Evidence: 3.8 billion year old C-isoptopes in greenland (bc organic compounds)

Question 4

what was the first living organism?

Answer 4

• Probably prokaryotic (lacking membrane bound organelles/nucleus) - simplest cell
Parsimony- look for the simplest solution

Question 5

what are stromatolites? where are they found?

Answer 5

• Some are as old as 3.5 billion years
• Dome shaped sedimentary rocks
• Found in western Australia, believed to be strand of fossil porkaryoticc cells (early fossil evidence of life) , southern Africa, and northern Canada.
linn margoulis contributed - collecting bacterial matts etc

Question 6

whats the difference between igneous rock and sedimentary rocks?

Answer 6

Igneous rock - formed from within the compound of the earth - aged with half life of radioactive compound in it
• Sedimentary rocks - created by layers and layers of rock - more likely to find fossils in these, but they are difficult to age
Life probably originated earlier than 3.5 by ago bc the oldest rock is 3.5 byo