AP BIOLOGY

Detailed explanation-1: -Lignin constitutes the second most abundant organic polymer on earth, after cellulose. Lignin in plant secondary cell walls contributes to the rigidity and hydrophobic nature of specialized cells that provide mechanical support and carry out water transport.

Detailed explanation-2: -The cellulose molecules provide tensile strength to the primary cell wall.

Detailed explanation-3: -Lignin is an important organic polymer which is abundant in cell walls of some specific cells. It has many biological functions such as water transport, mechanical support and resistance to various stresses.

Detailed explanation-4: -Complete answer: The cell wall is composed of hemicellulose, polysaccharides cellulose, and pectin. The cell wall also possesses some polymers like suberin, lignin, or cutin. Lignin is responsible for providing strength and rigidity to the cell wall of some algae and vascular plants.

Detailed explanation-5: -Lignin is a polymeric constituent of the plant cell wall that serves supportive and impermeability functions in the vascular tissue and plays a role in defense against pathogens5.