LIFE SCIENCE

Detailed explanation-1: -Xylem is composed of four kinds of elements. They are tracheids, vessels, fibres, xylem parenchyma. The elongated or tube-like cells with tapering ends are the tracheids. Vessels are long and cylindrical cells.

Detailed explanation-2: -The xylems structure consists of lignified tracheary elements like tracheids and vessel elements which are dead at maturity. Both tracheary elements are long hollow cells with tapered end walls.

Detailed explanation-3: -The xylem tracheary elements consist of cells known as tracheids and vessel members, both of which are typically narrow, hollow, and elongated. Tracheids are less specialized than the vessel members and are the only type of water-conducting cells in most gymnosperms and seedless vascular plants.

Detailed explanation-4: -Xylem walls contained 28% lignin, 4% pectin, 29% hemicellulose, and 39% cellulose as compared to 15% lignin, 25% pectin, 30% hemicellulose, and 30% cellulose in nonxylem walls. Fungal enzymes hydrolyzed 22 and 73% of the structural carbohydrates in xylem and nonxylem walls, respectively.