Q.In an association of two animal species, one is a termite which feeds on wood and the other is a protozoan Trichonympha present in the gut of the termite. What type of association they establish?

The termite and Trichonympha establish a mutualistic association, specifically an example of symbiosis where both partners benefit and live in close physical contact.

Termites feed on wood but cannot digest cellulose on their own because they lack the enzyme cellulase. The protozoan Trichonympha lives in the termite's gut and produces cellulase, breaking down cellulose into simpler sugars that the termite can absorb and use for nutrition. Without this protozoan, the termite would starve despite eating wood. …

Living organisms rarely exist in isolation. The natural world is woven together by countless interactions, some fleeting and others so intimate that neither partner can survive without the other. When we look at ecological associations, we're really asking: who benefits, who loses, and who remains unaffected?

The termite–Trichonympha relationship is a textbook example of mutualism, a form of symbiosis in which both species gain something essential. Termites feed on wood, but here's the problem: they lack the enzymes needed to digest cellulose, the tough structural carbohydrate that makes up plant cell walls. Without help, all that wood would pass through their gut undigested, leaving the termite starved despite a full stomach.

Enter Trichonympha, a flagellated protozoan that lives in the termite's hindgut. This microorganism produces cellulase enzymes that break down cellulose into simpler sugars the termite can absorb and use for energy. In return, the protozoan enjoys a warm, stable environment and a continuous supply of wood particles delivered straight to its doorstep. Neither can thrive alone: the termite would starve, and Trichonympha would lose its protected niche and food source.

Ask what each partner could and couldn't do alone -- the termite can eat wood but not digest it, the protozoan can digest cellulose but has nowhere to live and no wood supply of its own - …