Explanation: some cells are specialized to do certain stuff. Like the breaking down of glucose wouldn't happen in the cells found in your leg.
        
                    
             
        
        
        
A
biology is branch of science which deals with life
 
        
             
        
        
        
I think the answer is a hurricane.
Hurricane is made of warm and cool air. Warm air has a higher temperature and less dense than cool air. It causes the warm air to move upward while the cool air moves downward. The warm air carries water vapour and it will condense after elevated, releasing the heat and makes the air cool. 
If these events repeated continuously, there will be a constant movement of air.