Natural selection! In the theory of natural selection, those with less beneficial traits won't live to reproduce, but those with beneficial traits will be able to reproduce and pass on those traits to their offspring, which significantly increases the frequency of those beneficial traits.
        
             
        
        
        
Yes, because even though other trees produce more oxygen, the small trees will still produce some oxygen. On top of this there are more small trees than big trees, so even though they make less oxygen, in whole they end up making more when added together!
        
             
        
        
        
Answer:
Agroforestry is a collective name for land-use systems and technologies where woody perennials (trees, shrubs, palms, bamboos, etc.) are deliberately used on the same land-management units as agricultural crops and/or animals, in some form of spatial arrangement or temporal sequence.
 
        
             
        
        
        
Isotonic cells stay the same hypertonic the cells shrink and hypotonic the cells grow or swell