The root nodules of leguminous plants houses nitrogen-fixing bacteria called Rhizobia. Rhizobia has a symbiotic relationship with leguminous plants that allows both to benefit from each other. 
By binding to hydrogen, the Rhizobia bacterium is able to  convert or fix nitrogen gas into ammonia , a form that the plant can use. Likewise, the legume plant provides the rhizobia bacterium with carbohydrate which the rhizobia depends on for energy. It is important to note that the carbohydrate sent to the nodules for the rhizobia is also what is used as a source of hydrogen to help the bacterium convert nitrogen to ammonia.
        
             
        
        
        
We have polluted it— the air, water and the ground. 
Some people have tried to clean up the environment
        
                    
             
        
        
        
Answer:
Persepolis and Susa, which replaced Pasargadae as capital of the Persian empire
Explanation:
 
        
             
        
        
        
<span>The Phylogenetic trees are also commonly referred to as the Evolutionary Tree. This tree shows the inferred relationship between a certain set of organisms or group of organisms which are called as taxa. The tip of the branch represent the taxa and the node of the branch is for the ancestor. </span>