Answer: (1) photosynthesis occurred
Explanation: The photosynthesis process in cianobacteria changed the composition of earth's atmosphera, rising oxygen levels. This could be possible since photosynthesis used energy from the sun to produce energetic intermediaries to synthesize sugars, and as byproduct due to water photolisis, is oxygen.
Emphasis made of finding cost effective ways to reduce air pollution.
Answer:
50%
Explanation:
Since A is only repeated twice, it could be 50%.
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Internal regulators allow the cell cycle to proceed only when certain processes have happened inside the cell. ... Cancer cells do not respond to the signals that regulate the growth of most cells. As a result, they divide uncontrollably and form masses of cells called tumors that can damage the surrounding tissues.