Question

the properties of phospholipids determine their orientation within the lipid bilayer. the heads are polar and hydrophilic, so each head touches either the fluid in the outside environment or the cytoplasm inside the cell. the tails are nonpolar and hydrophobic, so they form the inner core of the membrane, away from fluid. this arrangement prevents certain molecules from crossing the lipid bilayer on their own. the phospholipids are tightly packed, which means large molecules cannot fit between them. small nonpolar molecules can cross, but ions and most polar molecules cannot cross because they are repelled by the nonpolar fatty - acid tails. some very small polar molecules, like water, are able to pass through, but they do so at a slow rate. which of the following molecules can pass through the lipid bilayer without assistance? select all that apply. sodium ion, a charged molecule water, a very small polar molecule glucose, a large polar molecule oxygen, a small nonpolar molecule

Explanation:

The lipid - bilayer is composed of phospholipids with hydrophilic heads and hydrophobic tails. Large molecules and ions and most polar molecules cannot pass through on their own due to the tight - packing of phospholipids and repulsion by the non - polar tails. Small non - polar molecules can pass through easily. Water, a very small polar molecule, can pass through slowly. Sodium ion is a charged molecule and cannot pass through without assistance. Glucose is a large polar molecule and cannot pass through without assistance. Oxygen is a small non - polar molecule and can pass through the lipid bilayer without assistance.

Answer:

Oxygen, a small non - polar molecule