Answer:
The cells present in the stem are part of the xylem and phloem conductive tissues. They are characterized by being elongated and in tubular form because they transport the substances, the xylem transports  water and  inorganic mineral sales that the root absorbs from the soil. The phloem is responsible for transporting substances synthesized in photosynthesis.
Its tubular and elongated shape facilitates the transport of these substances
 
        
             
        
        
        
Malleable because the rest are chemical
        
             
        
        
        
Some species we see in Alaska and nowhere else in the Wolrd are:
Bats
Shrews
Bears
Seals
White Wolfs
Sea lions
Racoons
Walrus. 
Bears, Seals, White Wolfs and Sea lions survive the cold weather much more than those other animals. 
 
        
        
        
Yes our lungs will be clean and perfect.
        
                    
             
        
        
        
Answer:
The findings demonstrates an optimal foraging hypothesis based on maximizing caloric intake alone is probably incorrect in this case.
Explanation:
This example can also be explained by optimal foraging theory which helps in predicting the behavior of an animal which it is searching for food. Food provides energy to the animal but searching and capturing the food requires both energy and time. 
So in order to maximize fitness , an animal adopts a foraging strategy which provides the most benefit which in this case is energy, for the lower cost and by maximizing the net energy gained.