Concept:Unicellular organisms that remain attached end-to-end form filamentous structures.Explanation:Spirogyra is a green alga in which many cylindrical cells are joined end-to-end to form long, unbranched filaments.Each cell in the filament is unicellular and carries out life processes independently, but the cells remain connected in a chain.This arrangement gives Spirogyra its filamentous appearance, with strands reaching several centimetres in length.Amoeba, Euglena, and Chlamydomonas are free-living unicellular organisms that do not form filaments.
