NEET BIOLOGY

Detailed explanation-1: -Sclerenchyma tissue, when mature, is composed of dead cells that have heavily thickened walls containing lignin and a high cellulose content (60%–80%), and serves the function of providing structural support in plants. Sclerenchyma cells possess two types of cell walls: primary and secondary walls.

Detailed explanation-2: -Sclereids are the sclerenchyma cells with very thick secondary wall deposits and provide mechanical support.

Detailed explanation-3: -Sclereids have very narrow cavities and are hard and inflexible. They have more pits than fibres. They are commonly found in soft tissues, e.g. cortex, phloem, the pulp of fleshy fruits, fruit walls and seed coats. They are found in shells of nuts, fruit pulp of pear, guava, etc., tea leaves and seed coat of legumes.

Detailed explanation-4: -The walls of neighboring plant cells, cemented together to form the intact plant (Figure 19-68), are generally thicker, stronger, and, most important of all, more rigid than the extracellular matrix produced by animal cells.

Detailed explanation-5: -The sclerenchyma cells are long and narrow and their walls are thickened due to a chemical substance lignin. This type of tissue is found in the stem and the veins of the leaf.