Photo Synthesis would be as plants grow from the sun or gain energy from the sun, where as Cellular Respiration is when cells divide into two or more. (I believe)
        
                    
             
        
        
        
Cells are the basic unit of structure and function in organisms.
Needless to say, organisms can’t be a thing if cells didn’t exist.
        
             
        
        
        
Natural selection doesn't favor traits that are somehow inherently superior. Instead, it favors traits that are beneficial (that is, help an organism survive and reproduce more effectively than its peers) in a specific environment. Traits that are helpful in one environment might actually be harmful in another.
(one again, I hope this helps ^^)