Answer:
A
Explanation:
Typically across all life, the plasma membrane of cells is made up of a bilipid layer of phospholipids. The phosphate ends of the molecules, which are hydrophilic hence ‘face’ the interior and exterior of the cells. The fatty acid chains, which are hydrophobic are embedded in between because they no charges hence do not interact well with charged molecules. The phosphate ends, on the other hand, are negatively charged hence can interact well with the polar water molecules. It is therefore usually a challenge for molecules with charges to diffuse across the membrane without the help of channel proteins that will help them cross the hydrophobic layer.
