Evidence Of Life Flashcards
What evidence helps us to predict when life started on earth
Stromatolites
Microfossils
Metamorphic
At what time was life believed to have started
About 3.5 billion years ago
At what point in time did the bombardment of the earth end
About 3.8 to 4.0 billion years ago
Why couldn’t life survive on land
- Because of the harmful UV rays which could break molecules
- Because there was no oxygen
- There was no ozone layer
Where was life originally thought to Begin from
Shallow ponds
What features of stromatolites helps us to predict when life started
- It is identical to a mass microbes
2.it contains both sediments and microbes - The upper layer of stromatolites photosynthesis while the lower layer feeds of it’s by products
What features of microfossils help us to predict when life started
Some structures contain organic carbon
What type of carbon is preferred for carbon dating
Carbon 12 and 13
Why is difficult to find microfossils
It hard to distinguish between them and mineral structures
At what point in time was life believed to rise and dominate the earth
About 100 - 500 million years ago
Why is it not possible that life started in shallow ponds
Because the water wasn’t deep enough
And during evaporation the quantity reduces
Where was life later confirmed to begin
Deep sea vents/ hot springs
What is spontaneous generation
This is the hypothesis that life regularly arises from non living things
What period was the earth believe to be formed
4.6 billion years ago
What did Earth’s early atmosphere contain
CO2, CO, Nitrogen, ammonia and methane
What’s another name for spontaneous generation
Abiogenesis
Who was the first to carry out experiments to disprove spontaneous generation
Francesco redi
In what year did Francesco redi carry out his experiment to disprove spontaneous generation
1668
What country was Francesco redi from
Italy
Why were deep sea vents hospitable for early life
- The temperature
- It had greater volume of water and
was less likely to evaporate - There was greater chemical energy
Who performed the second experiment to disprove spontaneous generation
Louis pasteur
In what year did Louis pasteur perform his experiments to disprove spontaneous generation
1859
What time was it believed that the earth cooled down enough to hold liquid water
3.8 billion years ago
What were the first true cells
Prokaryotes
