I am the cell wall. I provide structure to plants, the main reason why plants stand up. I defend against bacterial and fungal attack. Also, I am not alone as there is two of me, the primary and secondary cell wall. For example, all wood is mostly a secondary cell wall, thus I had played a major role in human history, as when humans hunted, their tools were mostly wooden and had depended on the durability of me to not break. Without me, all plants you know of would be in a dire situation without my protection to keep them from bursting apart and could not intake fresh water. Without me giving the cell its structure, the plants would more resemble formless blobs. Because I exist, plants have structure and be able to not burst apart. The plant cell depends on me to keep the cell from bursting apart like a balloon struck by a needle.