Question

The chlorophyte (green algae) genera Ulva and Caulerpa both have macroscopic leaf-like and stem-like structures, but only Ulva species are considered truly multicellular. Explain why.

a) Ulva species have a holdfast structure that Caulerpa lacks, enabling attachment to substrates.
b) Ulva species possess differentiated tissues and cellular organization, while Caulerpa doesn’t.
c) Ulva species have a multicellular reproductive organ, whereas Caulerpa lacks this structure.
d) Ulva species have a colonial organization of cells, unlike Caulerpa's unicellular structure.

Answer 1

Ulva species are considered truly multicellular due to their differentiated tissues and multicellular structures, whereas Caulerpa species are large multinucleate single cells that do not complete cytokinesis.

Step-by-step explanation:

Among the chlorophytes, the genera Ulva and Caulerpa both have macroscopic structures that are leaf-like and stem-like, but only Ulva species are truly multicellular. The key distinction lies in their cellular organization: Ulva exhibits differentiated tissues and true multicellular structures, with intercellular connections that enable cellular communication and cooperation.

On the other hand, species of Caulerpa, although large and complex in appearance, are actually single cells containing many nuclei—they undergo nuclear division without completing cytokinesis, resulting in a single, gigantic cell with multiple nuclei.