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5 Cards in this Set
- Front
- Back
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What are the gases found in our atmosphere today?
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Nitrogen and Oxygen
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What was early Earth's atmosphere?
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Early Earth had little Oxygen. There were frequent volcanic eruptions, earthquakes, and violent weather.
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Explain what Earth's 1st life forms may have been like as per scientists' hypothesis?
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1. They did not need oxygen to survive.
2. They were probably unicellular. 3. They probably lived in the ocean. |
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Explain how life first formed on the Earth.
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Small chemical units of life formed gradually over millions of years in Earth's waters. Some joined to form large chemical building blocks found in cells. Eventually, large chemicals accumulated and became forerunners of the first cells.
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Fossils
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Traces of ancient organisms that have been preserved in rock or other substances.
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