An interaction between two organisms in which one usually benefits is known as

Symbiotic relationship /Interaction  

In a symbiotic relationship, two organisms live in close association and at least one of them is benefited out if this association.  

There are basically three types of symbiotic relationships –

a)Mutualistic Relationship – In this both the organisms living in association get benefited.  

b)Commensalism Relationship – In this association, one organism is benefited while the other is neither benefited nor harmed

c)Parasitic Relationship – In this association, one organism is benefited while the other one is harmed.  

the generally accepted parts of modern cell theory include: all known living things are made up of one or more cells. all living cells arise from pre-existing cells by division. the cell is the fundamental unit of structure and function in all living organisms.

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