Final answer:
The polarity of water molecules helps phospholipids to form a stable bilayer, essential for constructing cellular membranes. This causes the polar heads to face the water and the non-polar tails to be shielded away, resulting in a selectively permeable lipid bilayer. Therefore correct option is A
Step-by-step explanation:
The property of water molecules that allows phospholipid molecules to form a stable bilayer and thus create a membrane is polarity. Phospholipids have a unique structure with a polar (hydrophilic) head and a non-polar (hydrophobic) tail. When phospholipids are placed in water, they orient their heads towards the polar water molecules, and tails in the interior, away from the water, creating a bilayer. This characteristic is vital for the structure of the plasma membrane because it results in the arrangement of phospholipids with their hydrophobic tails facing each other and their hydrophilic heads facing out. This forms a lipid bilayer—a double-layered phospholipid barrier that separates the environments on each side of the membrane.
The hydrophilic nature of the heads and the hydrophobic nature of the tails lead to the formation of micelles or liposomes in an aqueous environment. This amphipathic nature of phospholipids is crucial for the selective permeability of the membrane, allowing only certain molecules to pass through unaided while others require assistance. The structure of the cell membrane enables it to maintain homeostasis by regulating the movement of substances in and out of the cell.