Which part of the cells forms the Outer boundary of the cell? Also it acts as a barrier to wamster-soluble materials inside and outside the cell?

The plasma membrane is the part of the cell that forms the outer boundary of the cell. It also acts as a barrier to certain soluble materials inside and outside the cell. The plasma membrane is also known as the cytoplasmic membrane or plasmalemma.

It is composed of a phospholipid bilayer which is embedded with proteins. The plasma membrane is selectively permeable to ions and organic molecules and regulates the movement of substances in and out of cells. The plasma membrane helps to keep toxic substances out of the cell. It also contains receptors and carrier proteins to allow molecules access to the battery.