AP BIOLOGY

Detailed explanation-1: -The major compounds of the wood cell walls are cellulose, hemicelluloses and lignin. Together, these polymers form so-called lignocellulose complex that provides structural rigidity and protects the wood cells from microbial attack (Mäkelä et al., 2014).

Detailed explanation-2: -The cell wall surrounds the plasma membrane of plant cells and provides tensile strength and protection against mechanical and osmotic stress. It also allows cells to develop turgor pressure, which is the pressure of the cell contents against the cell wall.

Detailed explanation-3: -Both lignin and cellulose are found in the rigid cell walls of the xylem cells (those that conduct water) in the primitive plant Selaginella.

Detailed explanation-4: -The walls of xylem cells are lignified (strengthened with a substance called lignin ). This allows the xylem to withstand pressure changes as water moves through the plant.