Regulating transport of substances in and out of the cell is the

Water, carbon dioxide, and oxygen are among the few simple molecules that can cross the cell membrane by diffusion (or a type of diffusion known as osmosis ). Diffusion is one principle method of movement of substances within cells, as well as the method for essential small molecules to cross the cell membrane.

true, i don't really know what you're asking but from the info you provided im guessing the answer is true.