Final answer:
The statement that the lipid bilayer portion of the plasma membrane is permeable to water is true. Water can diffuse through the plasma membrane on its own or with the help of aquaporins, despite the selective permeability of the membrane.
Step-by-step explanation:
The lipid bilayer portion of the plasma membrane is permeable to water. This is true, as water is a small polar molecule that can pass through the plasma membrane by simple diffusion or facilitated diffusion via aquaporins, which are water channel proteins in the cell membrane. Though the membrane's hydrophobic interior makes it selectively permeable, it still allows the passage of water to some extent due to its small size and the necessity for water regulation in the cell.
The plasma membrane's structure, composed primarily of phospholipids arranged in a bilayer, has hydrophobic tails on the interior and hydrophilic heads on the exterior, contributing to its selective permeability. While nonpolar, uncharged molecules can usually pass through easily, polar molecules, like water, sometimes require assistance. Nonetheless, water is an exception to some of the strict rules of polarity due to its small size and significance in cellular processes. Therefore, the statement is true: the lipid bilayer portion of the plasma membrane is permeable to water.