C. They study true movement of earthquake waves
Virions are physical entities containing nucleocapsid, capsid and sometime envelop. It exists extracellularly. Viruses are genetic material that occur intracellularly
Cell wall - Adds structural support to the cell. Holds the cells together
Cell membrane - Serves as a barrier to the cell and allows more nutrient and molecules to move in and out of the cell without letting things that can harm the cell in.
Outer membrane - Serves the same basic functions a the cell membrane. (Depending on how complicated the class your in is, I would visit this website for more information... https://en.wikipedia.org/wiki/Bacterial_outer_membrane )
Pili - Help the cell move and attach the bacteria to surfaces are other cells.
DNA - Contains the genetic instructions on what the cell can physically do, operate, and reproduce.
Flagellum - Helps the cell move. It kind of acts like a propeller for the cell so that it can move around.
