0 is a protective pattern around the branches of / trunk of a specific & protecting is a kind of function ->  bark is used to protect the tree  a room window provides thwart / physicist / size / disorganized for a vegetable room & protecting is a kind of function -> a cell wall is used to protect a plant cell a cell wall is used to protect a plant cell  bark is used to protect the tree & a room window is used to protect a vegetable room -> a cell wall has a similar function to the bark of a tree