Answer:
because it is a living thing.
and plants are living organisms?
 
        
             
        
        
        
We need carrier proteins for steroid hormones because they help in the transportation from the cell they were released from to their target cell.
let me know if you have any further questions
:)
        
             
        
        
        
Answer:
Organelle (oppitional, I don't put this on my paper but you can if you want), cells, tissues,  
Explanation:
 
        
             
        
        
        
No, polar bears does not migrate.