CBSE Class 12-science Answered

(i) Mutualism: It is a positive interaction in which both the interacting species favour the growth and survival of each other. It is of two types:

(1) Protocooperation, in which both the species are mutually beneficial but the association is facultative so that the partners can live separately.

Example: Hermit crab and sea anemone association

(2) Symbiosis, in which both the species are mutually beneficial but the association is obligatory.

Example: Lichens, a symbiotic relationship of fungus with the alga