Answer:
Diffusion in cells
Explanation:
The cell regulates the entry and exit of substances through its plasma membrane. Not all molecules can readily pass across this selective membrane due to its structure. The lipid bilayer feature of the plasma membrane prevents the passage of polar molecules. Nevertheless, small nonpolar molecules and ions can pass through the lipid bilayer. The way through which polar molecules can pass through is via the proteins in the plasma membrane. The transmembrane integral proteins are membrane proteins involved in the transport of substances into and out of the cell.
