Name the meristem which is responsible for the increase of girth of root.

What is the chemical substance that makes the cells of the sclerenchyma hard? Mention where this tissue is likely to be present.

Which is not a function of epidermis?

Explain the significance of the following:
$(a)$ Hair-like structures on epidermal cells
$(b)$ Epidermis has a thick waxy coating of cutin in desert plants
$(c)$ Small pores in the epidermis of a leaf
$(d)$ Numerous layers of epidermis in cactus
$(e)$ Presence of a chemical suberin in cork cells.

Find out the reason behind the following statements:
$(a)$ Epidermis is thicker in desert plants,though it is usually single-layered.
$(b)$ Presence of a waxy layer (secreted by the epidermis) on the outer surface of plants.
$(c)$ Meristematic cells have a prominent nucleus and dense cytoplasm but lack a vacuole.

Which structure protects the plant body against the invasion of parasites?