Question

What is symbiosis ? Give one example.

Answer 1

Symbiosis is the relationship between two different organisms living close to each other where either both benefit or one benefits. There are many types of symbiotic relationships like parasitism (one benefits, the other loses), mutualism (both benefit) and commensalism (one benefits, the other has no effect) 
Example:
Parasitism: Heartworm (dog gets harmed, heartworm benefits), etc
Mutualism: Rhizobium bacteria and peanut plant.  (Both benefit.) 

Answer 2

Symbiosis is the form of existence in which two different species of organisms live in close approximation for mutual benefits and at the same time obligatory. Relation is very close and life of one is impossible to exist in the absence of the other. For example:- termites and their intestinal flagellates.