Scientists agree that the early Earth, before 2.4 billion years ago, contained only trace quantities of oxygen and that the oceans were full of dissolved iron, Data collected point toward oxygen poor, iron-rich conditions for 90% of Earth's history, with oxygen and
hydrogen sulfide present and found mostly to the surface layers and along the margins of the oceans, Scientist also agree that most
Life forms evolved initially in marine habitats. How did the marine environment change to help foster the evolution of so many life
forms?
A)
With the advent of photosynthesis, oxygen began to build up in the oceans.
B)
Volcanic lava added oxygen to Earth's crust and is dissolved in ocean
water
C)
Oxygen was the by-product of the chemical decomposition of early
Lithospheric rocks
Anaerobic cellular respiration of prokaryotes produced dissolved oxygen in
D)
the oceans
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