Answer:
It is the property of a membrane that does not allow solutes to pass through, from a certain size, depending on the thickness of the membrane and the size of the pores
Step-by-step explanation:
The cells require nutrients from outside and must eliminate waste substances from metabolism and keep their internal environment stable. The membrane has a selective permeability, since it allows the passage of small molecules, provided they are lipophilic, but regulates the passage of non-lipophilic molecules. Then, most of the water-soluble ions and molecules are unable to spontaneously cross this barrier, and require the concurrence of special carrier proteins or protein channels. In this way the cell maintains concentrations of ions and small molecules different from those prevailing in the external environment.