Which types of molecules are able to diffuse across the cell membrane? water molecules
small molecules
very large molecules
fat-soluble molecules

Water molecules

Explanation: The structure of the lipid bilayer allows small, uncharged substances such as oxygen and carbon dioxide, and hydrophobic molecules such as lipids, to pass through the cell membrane, down their concentration gradient, by simple diffusion. Small nonpolar molecules, such as O2 and CO2, are soluble in the lipid bilayer and therefore can readily cross cell membranes. Small uncharged polar molecules, such as H2O, also can diffuse through membranes, but larger uncharged polar molecules, such as glucose, cannot.

water molecule, small molecule, and fat-soluble molecules

Explanation:

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