Answer:
Photosynthesis.
Explanation:
Photosynthesis may be defined as the process by which the plants prepare their own food by the use of sunlight and chlorophyll. The light energy is converted into chemical energy for food storage.
The early environment of the Earth's atmosphere is highly reducing. The photosynthesis at an early environment causes the formation of the traces of oxygen. The water molecule will breakdown into the hydrogen and oxygen by the use of the ultraviolet light.
Thus, the answer is photosynthesis. 
 
        
             
        
        
        
Sir Issac Newton was the one who purposed the gravity theory.
        
             
        
        
        
Answer:
true, Kepler's first law demonstrates that each planet has an elliptical orbit of unique size and shape with the Sun at one focus.
 
        
             
        
        
        
Plant And Animal Cells Are Eukaryotic.
Prokaryotic Are Single Cells
        
             
        
        
        
Frogs lay eggs under water.  When they hatch they are called tadpoles.  After a time as tadpoles they undergo metamorphosis where they grow legs and lungs and become the little friendly hippidy hoppidy guys you see on your porch every night.