The organelle that keeps a cell in homeostasis is cell membrane. The plasma membrane keep homeostasis by controlling what goes in and out. Selectively permeable means selectively choose to let in. Homeostasis means stay the same. The semipermeable membrane allows molecules to allow small molecules to pass through partly but not large ones. Yes, the plasma membrane is a semi-permeable membrane. The role of lipids in the plasma membrane provide a flexible barrier between the cell and its environment. Two layers of lipids makes up the plasma membrane. The role of protein in the plasma membrane, channels/pumps large molecules in and out of the cell. The role of carbohydrates on the plasma membrane help cells recognize one another. Buffers help