Answer:
There is no video but ecological relationship will be defined on a general note and it is not always beneficial to organisms.
Explanation:
In an ecosystem, organisms of the same or different species tend to interact with one another. This interaction is referred to as ECOLOGICAL RELATIONSHIP between the involved organisms. An ecological relationship can be of different types depending on the effect. 
SYMBIOSIS is an ecological relationship between two organisms that interact together. SYMBIOSIS can either be mutualistic (both organisms benefit), parasitic (one organism loses and one gains), or commensalistic (one organism benefits and one neither benefits or loses). Another ecological relationship is PREDATION, where one organism called the PREDATOR feeds on part or all of another organism called PREY in order to obtain energy. 
As stated above, some of the organisms involved in an ecological relationship benefits while others lose. Hence, it is not always a beneficial relationship to organisms.
 
        
             
        
        
        
Answer:
Darwinism is a theory of biological evolution developed by the English naturalist Charles Darwin (1809–1882) and others, stating that all species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual's ability to compete, survive, and reproduce.
Explanation:
 
        
             
        
        
        
The main theme of the poem is the regret and sorrow the narrator feels about the end of his relationship with the woman in the poem, described only as "you." The poem suggests that the woman may well have been the one to break off the affair: Pale grew thy cheek and col
        
             
        
        
        
Answer: What substances dissolve in ocean water.
This is the only question that can be answered through scientific investigation because it is the only question that can be tested. The other questions cannot be answered through scientific investigation because they based on opinions which are more abstract.
        
                    
             
        
        
        
The transformer is a static electric machine (because it contains no moving parts) belonging to the broader category of converters. In particular the transformer to convert the parameters of voltage (V symbol unit [V] volts) and current (symbols The unit [A] amperes) input than output, while maintaining constant the amount of power electrical (less the losses due to hysteresis and eddy currents). The transformer is a machine able to operate only in alternating current, because it exploits the principles of electromagnetism linked to variable flows. <span>The transformer has paramount importance in today's world: without it, the electricity transmission grids that connect power plants to millions of homes and industries could not function</span>