Diversification of Life Flashcards
When is it thought that Earth formed?
4600 million years ago.
What is the Theory of Panspermia?
It suggests that meteorites brought organic molecules to Earth from elsewhere in the Universe.
What is the Chemosynthetic Theory?
Suggests that organic molecules on early Earth developed through chemical bonding.
How old are the oldest prokaryotic molecules?
3500 million years old.
Were the first prokaryotes heterotrophic or autotrophic?
Heterotrophic (supposedly).
Why did atmospheric oxygen levels rise dramatically 2700 million years ago?
Photosynthesis occuring in prokaryotic autotrophs.
How old are the oldest eukaryotic fossils?
2200 million years old
How did the first eukaryotes develop?
Endosymbiosis
Why were radiation levels very high on early Earth?
There was no ozone layer.
What indicated that atmospheric oxygen levels had changed?
Bonded iron formations.
What selection pressures did early life on Earth have to withstand?
High radiation, high heat, low oxygen availability, frequent storms, volcanic lava, and volcanic gases.
When did life first colonise land?
0.5 billion years ago.
