Ecosystem is a living system, where living organisms interacts with their environment and among each other. 
Due to some hazardous processes like, Global warming, Green-house effect, increasing pollution, ecosystem is degrading. 
We live in our Ecosystem, if it will get destroyed, our existence would be impossible. So, in order to save ourselves, we need to save it.
That's why biologists, concerned about ecosystem disruption
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It reproduce by a process call Binary Fission
        
             
        
        
        
The second law describes the relationship between force, mass and acceleration; like Force (Newtons) equals Mass Time Acceleration. Newton's first law defines inertial reference frame as that reference frame where an object will move with constant velocity if no forces are acting on point mass.
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The correct option is INTRODUCTION OF EXOTIC SPECIES;
Exotic species refers to an introduced specie of an animal which is alien to the ecosystem in which it found itself and which has been transported to that ecosystem either intentionally or by accident. Exotic species normally have varieties of effects on the ecosystem to which they are introduced, sometimes the effect will be good and sometimes the effects could be devastating depending on the particular situation. 
Factors which promote diversity include: larger size of the ecosystem, longer growing seasons and climatic stability.<span />