* Viruses: Viruses are the smallest of the three. They are so small that they can only be seen with an electron microscope.
* Bacteria: Bacteria are larger than viruses but still microscopic. They are typically measured in micrometers (µm).
* Yeast: Yeast is a type of fungus and is significantly larger than bacteria. They are visible under a light microscope.
In summary: Viruses are the smallest, followed by bacteria, and then yeast.
