Could an elodea or paramecium from a freshwater lake be expected to survive if transported to the ocean? why or why not?

They probably wouldn't. The internal environments of the elodea and paramecium probably have the same saline concentrations as the freshwater lake. When transferred to the ocean, which is far saltier, water would rush out of the elodea and paramecium to try and balance out the two concentrations to make them more similar. As a result, the two organisms would lose most of the water that gives them structure and shape. The elodea would undergo plasmolysis, where the plasma membrane pulls away from the cell wall. The paramecium would shrivel up as there is no cell wall to retain its structure.