Answer:
because every year there is a new strain of flu
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Answer:
Natural selection, the keystone of evolution, can switch direction in a matter of months, a novel experiment on lizards reveals.
 
        
                    
             
        
        
        
Answer:
it affects the hardness of the shells because calcium has a high reactivity which causes the shell to be hard
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Answer:
cell wall
Explanation:
if its not one of the options sorry!