The paramecium was the only unicellular organism that Stella viewed through her microscope. All the other organisms were multicellular. How was the unicellular specimen different from the multicellular organisms?

The difference between a unicellular specimen and other multicellular organisms will be the NUMBER OF CELLS. See detailed explanation below.

Explanation:

Cells are the simplest and basic unit of life. Living organisms has been classified as unicellular or multicellular depending on the number of the cells that make them up. A unicellular organism is that which possess only one cell to carry out all its life functions. According to the question, the Paramecium is an example of unicellular organism.

On the other hand, a multicellular organism is made up of many cells that specializes to perform the different life functions of the organism. This means that a specific kind of cell carries out a specific life function, this is called Cell differentiation. Examples of multicellular organisms include plants, all eukaryotic fungi etc.

Therefore, Stella's unicellular specimen, which is the Paramecium, will be different from other multicellular organisms in the number of cells possessed by each of them. The unicellular specimen will possess just a single cell while the multicellular organisms will possess more than one cell as viewed by the microscope.