Ask A Scientist© Biology Archive

Author:      nancy n
Text:        What is the most classic example of symbiosis?

Response #:  1 of 1
Author:      moodywj
Text:        Probably nitrogen-fixing bacteria on the roots of legumes (peas 
and beans and alfalfa).  The bacteria convert nitrogen into a chemical form 
that the plant can use, the plant supplies the bacteria with sugar and other 
nutrients.  This is an example of "mutualism", in which both symbiont and host 
benefit.  The other 2 types of symbiosis are commensalism, in which the 
symbiont benefits without affecting the host one way or the other, and 
parasitism, in which the symbiont (the parasite in this case), benefits at the 
expense of the host.