Review of cells: surface-to-volume ratio; tonicity and osmosis.

Allium (Onion) (cell wall, nucleus, vacuole)	Cheek (plasma membrane, nucleus)
Elodea (cell wall, vacuole, chloroplasts): turgid and plasmolyzed . Euglena ( flagella, chloroplasts )	Paramecium ( cilia , contractile vacuole )