Is this a book you working in on ?
        
             
        
        
        
Answer:
Aerobic respiration is far more energy-efficient than anaerobic respiration. Aerobic processes produce up to 38 ATP per glucose. Anaerobic processes yield only 2 ATP per glucose
 
        
             
        
        
        
A constant variable would be an element that remains unchanged and constant throughout the course of the experiment / investigation. 
        
             
        
        
        
The sequence of amino acids determines the protein