Final answer:
Elodea, Protococcus, cheek cells, and Volvox are all eukaryotic because they possess cells with a nucleus enclosed within membranes.
Step-by-step explanation:
In the question regarding eukaryotic organisms, Elodea, Protococcus, cheek cells, and Volvox are all mentioned. Eukaryotes are organisms whose cells have a nucleus enclosed within membranes, unlike prokaryotes (Bacteria and Archaea), which do not. Elodea is a type of aquatic plant, and like all plants, it is composed of eukaryotic cells. Protococcus is a genus of green algae, which is also eukaryotic. Cheek cells are human cells, and since humans are eukaryotic organisms, cheek cells are likewise eukaryotic. Lastly, Volvox is a colonial organism made up of algae cells, each of which has its own nucleus, and is thus eukaryotic. So, the answer is that all the listed entities (Elodea, Protococcus, cheek cell, and Volvox) are eukaryotic.