The Precambrian era envelopes the major bulk of the history of the Earth, beginning from the creation of the planet approx 4.5 billion years ago and terminating with the origination of composite, multicelled forms of life approximately 4 billion years after.
The Precambrian refers to the earliest of the geologic ages that are signified by the distinct layers of sedimentary rock. The Earth was about more than six hundred million years old when life started. The planet had cooled down from its native molten state, creating a solid crust and oceans formed by water vapor in the atmosphere.
At about three billion years ago, the atmosphere of the Earth was virtually devoid of oxygen. At approximately 2.4 billion years ago, oxygen was discharged from the seas as a waste product of photosynthesis by cyanobacteria. The levels of the gas slowly raised, attaining about 1 percent around two billion years ago.
Approximately 800 million years ago, the levels of oxygen attained about 21 percent and started to breathe life into more composite species. The oxygen-rich ozone layer was also created, protecting the surface of the Earth from the harmful solar radiation.
<h3>Answer: <u><em>Hope this helps </em></u></h3><h3><u><em /></u></h3><h3>Explanation: </h3><h3><u><em>This pattern of energy transfer continues with each successive level of the pyramid. Secondary consumers receive 10% of the energy available at the primary consumer level (1% of the original energy). Tertiary consumers receive 10% of the energy available at the secondary level (0.1% of the original energy).</em></u></h3><h3><u><em /></u></h3>
Answer: science
Explanation: she was a scientist
The answer is: "2A" or "IIA" or "2" or "II";
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In which "II" stands for the Roman numeral representing the number: "2 (two)".
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Produces water should be in the only aerobic section of the diagram. Aerobic respiration end products are carbon dioxide and water. Anaerobic respiration end products are lactic acid in animals and carbon dioxide and ethanol in yeast and plants. (:
