Question

Sclerenchymatous cells in their cell walls have a large percentage of
a. Cellulose
b. Pectin
c. Lignin
d. Silica

Answer 1

Hint: Sclerenchyma is a simple permanent tissue that is composed of dead cells. The walls of sclerenchyma consist of the deposition of cellulose, hemicellulose and lignin.

Complete answer :
Sclerenchyma, in plants, is associated with structural support. The tissue is characterised with the composition of hard woody cells. Features of Sclerenchyma cell:
> They are usually dead cells when matured.
> The cells have heavily thickened secondary walls.
> The secondary wall has a deposition of lignin.
> The cells are rigid and lose the stretch property.
> Usually found in nongrowing regions of plant bodies, such as the bark or mature stems.
> Sclerenchyma is one of the components of ground(fundamental) tissue in plants.
> Sclerenchyma cells have a variety of shapes and sizes.
> Two main types of sclerenchyma are fibres and sclereids.
Fibres are elongated cells found in
> stems
> Roots
> Vascular bundles of leaves.
Sclereids are found in different shapes
> Spherical
> Oval
> Cylindrical
They are present in various plant tissues such as the periderm, cortex, pith, xylem, phloem, leaves, and fruits. The hardness of the shell of nuts, the coat of many seeds, and the stone of drupes (cherries and plums) is due to the sclereids. Sometimes they may impart a grainy texture in fruits. This is because they are found scattered in the parenchymatous tissue. For example- in pears and quinces.

Hence, the correct answer is (C) Lignin.

Note: The mature Sclerenchyma tissue is composed of dead cells with heavy thickened walls. The walls are found with lignin deposition. They got high cellulose content (60%–80%). It provides structural support to plants. Two types of cell walls are found in Sclerenchyma cells: primary and secondary walls. The secondary highly lignified (15%–35%) that makes it thick. It imparts a great rigidity and hardness to the cell and tissue. Sclerenchyma cells are of two main types: fibers and sclereids.