Question

What is symbiosis give one example

Answer 1

Symbiosis is the phenomenon by which two organisms maintain relationship with each other to be mutually benefitted. In symbiotic mode, organisms develop a special relationship with certain other organisms to obtain nourishment. Organisms involved in this type of relationship are called as symbionts.

e.g. Rhizobium bacteria and Leguminous plants are symbionts exhibiting symbiosis.

Answer 2

Symbiosis is any type of a close and long-term biological interaction between two different species, be it mutualistic, commensalistic, or parasitic. In 1879, Heinrich Anton de Bary defined it as "the living together of unlike organisms".

There are several kinds of symbiosis to consider when looking for examples of symbiosis:

Commensalism
Parasitism 
Mutualism
Eendosymbiosis
Ectosymbiosis