Cells and cell processes: characteristics of life a. Respond to stimuli c. exchange energy and materials with the environment d. made of cells e. homeostasis f. grow and develop g. reproduce h. evolve: cell theory says three main things about cells: a. All living things are made up of one or more cells. b. Cells are the basic unit of life. c. all cells come from other cells: all cells are organized into levels of structure a. organisms - the entire living thing b. It contains special molecules called phospholipids which keep water from passing through. These molecules are made mostly of fat. b. Not living like the cell membrane iii. because it is not living it requires pores for things to get in and out. iv. made of cellulose. There is more water outside the cell than inside so water will move inside and the cell will swell.