Question

What is the molecular structure of wood?

Answer 1

Hint :We know that wood is the fibrous and the porous structure element of the plant that is present in the stems or the trunks of the trees. The secondary xylem is a dead tissue that forms the trunk in the case of the plants. This trunk is usually woody.

Complete Step By Step Answer:
Wood is the secondary xylem. The secondary xylem is formed from the cells of the cambium ring during secondary growth. It leads to an increase in the diameter of the plant.it is the secondary meristem. The xylem tissue is made up of tracheids, vessels, xylem fibers, and xylem parenchyma. Organically, wood is made up of cellulose fibers. The matrix of the wood is made up of lignin. When the cells in the stellar zone differentiate then the cells of the secondary xylem slowly increase in number causing the formation of the wood. The bark is the outermost layer of the tree. It helps in protecting the wood and the trunk. All the layers formed outside of the vascular cambium ring form the bark. Interestingly, the bark doesn't have the secondary xylem.
Like other vegetation, wood is cellular in structure. The walls of the cells are made of a mixture of cellulose and hemicellulose( 40-50 %), cellulose(15-25 %) and these are impregnated with 15-30 % of the substance known as lignin. Cellulose is a crystalline polysaccharide whilst hemicellulose is a more amorphous analogue of cellulose. Polysaccharides are basically polymers of sugars. Lignin is a complex biopolymer; you can see the structure of lignin.

Note :
Remember that the wood has two components. The heartwood and the sapwood. The heartwood is deep-colored and nonfunctional. It is, however, of great commercial importance. The sapwood is the light-colored and functional part. In temperate zones inside the secondary xylem, there is a formation of many concentric rings called the annual rings. The age of the tree can be estimated by counting the number of annual rings in the trunk of the tree. Each ring contains one autumn wood and one springwood.