Final answer:
Lipid bilayers are impermeable to ions, polar molecules, and large molecules. They selectively allow lipid-soluble molecules to pass through.
Step-by-step explanation:
Lipid bilayers are highly impermeable to ions, polar molecules, and large molecules such as sugars and proteins. The hydrophobic interior of the lipid bilayer does not allow these molecules through because they are hydrophilic or water-loving. Lipid-soluble molecules, such as carbon dioxide and oxygen, can easily pass through the lipid bilayer. Therefore, the lipid bilayer selectively allows certain molecules to pass through it based on their size and polarity.