Geology 12 - Historical Geology
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Early Life

Reading: Chapter 9


Terms you should know:

stromatolites -
cyanobacteria -
prokaryote -
eukaryote -
arcritarch -


Key Concepts and Questions:

1. How could life arise from non-living systems?

What did the Miller-Urey experiments show? What were the starting conditions, and what were the results?



What did Sidney Fox's experiments show?



How could DNA spontaneously be contained within a barrier (cell wall)?



How could RNA replicate in the absence of enzymes?



How could replication occur using inorganic templates?



2. What were the earliest organisms?

We assume the earliest organisms were anerobic heterotrophs. Why?


The oldest fossils are cyanobacteria. What is the evidence that these organisms were photosynthetic? Why were these organisms virtually unchanged for 1.5 billion years?



At about 1.75 billion years ago, larger eukaryotes appear. What is the prevailing theory for the origin of the eukaryotes? What evidence supports this theory?



3. How did multicellular life develop?

Why is so little known about Vendian life?



How are Vendian organisms different from later Paleozoic life?



4. What contributed to the Cambrian explosion of shelled animals?







5. What kind of organisms typify the Cambrian?

What are the dominant organisms? How do they differ from modern marine organisms and communities?



What do the Burgess Shale organisms tell us about life in the Cambrian?



1. Origin of life

You should be able to:

2. Earliest life

You should be able to:

3. Multicellular life

You should be able to: