CHAPTER 2

37.Where did much of the initial oxygen produced by photosynthesis end up? a. CO 2. b. Bonded to iron. c. In the atmosphere. d. Outside the atmosphere. e. Dissolved in seawater. 38.The increase of free oxygen during the Proterozic lead to the formation of _____ in seawater which likely contributed to eukaryote expansion. a. carbon dioxide. b ... ................
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