External respiration (correct answer) involves the exchange of oxygen and carbon dioxide within the environment. 
The exchange of wastes through the skin is just called excretion by sweating. 
There is no exchange of nutrients that occur in the lungs but rather absorption of nutrients is the function of the gastrointestinal tract.
The exchange of oxygen and carbon dioxide within the cell is called cellular respiration and involves carrying oxygen from the blood to the cell then the cell uses it as the final electron acceptor in the electron transport chain. The metabolic wastes of the cell, primarily carbon dioxide, goes now to the bloodstream to be exchanged for oxygen in the lungs.
        
             
        
        
        
Answer:
A cell is the smallest unit of a living thing.
 
        
                    
             
        
        
        
The increased temperature melts glaciers, ice caps etc. and thus increases the sea levels
        
                    
             
        
        
        
Answer:
The main role of DNA in the cell is the long-term storage of information.The major function of DNA is to encode the sequence of amino acid residues in proteins, using the genetic code.
Explanation: