GK
SOLAR SYSTEM
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Scientists hypothesize that ____ put oxygen in to the atmosphere.
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photosynthesis by algae (stromatolites)
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outgasing by volcanoes
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comets
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None of the above
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Explanation:
Detailed explanation-1: -Besides their impressive age, stromatolites – or, rather, the cyanobacteria that they once were – are credited with adding more oxygen to our atmosphere, Trujillo said.
Detailed explanation-2: -Conical stromatolites are thought to be robust indicators of the presence of photosynthetic and phototactic microbes in aquatic environments as early as 3.5 billion years ago.
Detailed explanation-3: -Scientists think that algae first evolved approximately 2.7 billion years ago, and soon after this oxygen began to exist in the atmosphere. Photosynthesis by primitive plants and algae released oxygen, which gradually built up in the atmosphere.
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