PLEASE HELP Which of the following were responsible for changing the oxygen content in Earth's atmosphere from no oxygen to 21% oxygen?
A. Prokaryotes
B. Eukaryotes
C. Ribozymes
D. Protobionts

Ausable water source is one that can be used by humans for drinking or agriculture. identify the water reservoirs as usable or unusable based on their current state. oceans rivers glaciers freshwater lakes groundwater

Which of the following will a bacterium produce when a human gene is added to its genome? question 4 options: human carbohydrates a protein made up of both human and bacterial properties the human protein coded for by the human gene human plasmids that can be isolated from the bacterium

What causes eclipses? check all that apply. earth's rotation on its axis moon's shadow covering the sun earth's shadow covering the moon earth's orbit and moon's orbit occasionally aligning the moon and sun's gravity pulling in the same direction