In museum study, a green unicellular organism moves through pond water by a long whip-like structure. The specimen or feature is best linked with:

Euglena moves mainly by a flagellum. It is often studied as an animal-like protist because it can move actively, but it also contains chloroplasts and can photosynthesize. This MCQ belongs to the Euglena topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.