bio final ch25.txt
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How old is the Earth?
Approximately 4.6 billion years old.
When was the Earth cool enough to sustain life?
Approximately 4.0 billion years ago.
When did life begin?
Approximately 3.4 billion years ago.
When did atomspheric oxygen appear on Earth?
Approximately 2.8 billion years ago.
When did the first single-cell eukaryotes arise?
Approximately 2.1 billion years ago.
When did multicellular eukaryotes arise?
Approximately 1.6 billion years ago.
When did animals first appear on Earth?
Approximately 0.5 billion years ago.
When was the first colonization of land?
Approximately 0.4 billion years ago.
The theory that a divine being created all life on Earth. This theory cannot be scietifically proven.
The theory that life appeared on Earth from outer space. This theory can be scietifically proven. Remember how they found the monomers of macromolecules on meteors, and how they documented a big signal from outer space.
What is Abiongenesis?
The theory that life on Earth began by simple processes. This theory can be scientifically proven. Remember synthesis of monomers of macromolecules, assembly of monomers of macromolecules, and formation of lipososmes.
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