All cellular activities that require energy use ATP as a source of energy. 
        
             
        
        
        
Hello! I got the answer! So if you look at the word homo and hetero. Homo means the same and hetero means different. So homology is the study of to show the simliarity between organisms. And heterology is the study of to show difference between organisms. This is my first time answering! Anyways have a good day/night!! 
  
        
             
        
        
        
Reaction. I hope this helped have a great day. 
        
             
        
        
        
They also need energy to move and to stay alive