The cell membrane of a plant cell would be like the city border of a city, because the cell membrane is a thin semi-permeable membrane that surrounds the cytoplasm. It protect the interior of the cell after the cell wall.
Citation of picture:
"Maps." Charlotte Chamber -. N.p., n.d. Web. 16 Feb. 2015.
"Maps." Charlotte Chamber -. N.p., n.d. Web. 16 Feb. 2015.