AP BIOLOGY

Detailed explanation-1: -The plasma membrane is virtually impermeable against larger, uncharged polar molecules and all charged molecules including ions.

Detailed explanation-2: -Polar and charged molecules have much more trouble crossing the membrane. Polar molecules can easily interact with the outer face of the membrane, where the negatively charged head groups are found, but they have difficulty passing through its hydrophobic core.

Detailed explanation-3: -Small uncharged molecules can diffuse freely through a phospholipid bilayer. However, the bilayer is impermeable to larger polar molecules (such as glucose and amino acids) and to ions.

Detailed explanation-4: -Large molecules, polar molecules, and ions, cannot easily pass through the cell membrane. Large molecules, such as glucose, amino acids, and proteins, are simply too big to fit through the phospholipid bilayer.

Detailed explanation-5: -The cell membrane’s main trait is its selective permeability, which means that it allows some substances to cross it easily, but not others. Small molecules that are nonpolar (have no charge) can cross the membrane easily through diffusion, but ions (charged molecules) and larger molecules typically cannot.