Final answer:
Phosphatidylserine is the phospholipid found exclusively on the intracellular leaflet of the plasma membrane, playing a crucial role in cell signaling and the identification of apoptotic cells.
Step-by-step explanation:
The phospholipid found exclusively on the intracellular leaflet at the plasma membrane is Phosphatidylserine. The plasma membrane is composed mainly of phospholipids, which form a bilayer with hydrophilic heads facing the aqueous environment and hydrophobic tails facing each other, away from water. Phospholipids like Phosphatidylcholine, Phosphatidylethanolamine, and Phosphatidylinositol make up the membrane, but Phosphatidylserine is typically located on the cytoplasmic side, which is the side facing the interior of the cell. It plays a key role in cell signaling and helps to identify apoptotic cells for phagocytosis.