Answer :

The cell is the smallest living unit. The cell wall is like the cell's rigid outer skin that supports the cell. But cell walls themselves are not alive because anything smaller than a cell isn't. That's just a rule.
A plants cell wall is made of cellulose, this is chains of beta glucose molecules joined together to form fibrals which then join to form cellulose fibres. It on its own is not living but it provides a vital part of the cell so when together with the rest of the cell, the cell is alive.