A learner makes a note: a flagellate living inside a termite gut receives shelter while helping digest cellulose for the host. The missing scientific idea is:

Mutualism is a symbiotic relationship in which both partners benefit. Termite gut flagellates help digest cellulose, while the termite provides food and a protected habitat. This MCQ belongs to the Symbiosis topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.