Question

Sclereids present in
(a) Fruit walls of nuts
(b) The grit of guava of pear
(c) seed coats of legumes
(d) All of these

Answer 1

Hint: Sclereids belong to a type of simple permanent tissue that is dead due to the deposition of a complex polymer in its wall. This polymer is impermeable to water.

Complete answer:
Sclerenchymatous tissue is a type of simple permanent tissues with highly thickened walls and extremely narrow cavities. Little or negligible protoplasm may be present. They are supportive in function. They are of two types - sclereids and fibers.
Sclereids may occur singly or in bundles, in, either way, provide stiffness to the parts of the plants where they occur. They are found in the grits of guava and pear as little, hard stone cells; epidermal and subepidermal covering of legumes seeds and also in the fruit walls of nuts.

Additional Information:
- Tissues can be meristematic or permanent based on their dividing capabilities.
- Meristematic tissues can divide to form new cells. They are not restricted to perform any particular set of functions.
- On the other hand, permanent cells are the mature cells that have lost the ability to divide as they have attained their destined shape, size, and function. They can be parenchymatous, collenchymatous, or sclerenchymatous.
- Parenchyma is made up of simple, thin-walled, closely packed, with little intercellular spaces between them. They are the most abundant in plants. Their cell wall contains cellulose with uniform thickening around its periphery.
- Collenchyma is a simple permanent tissue with irregular thickenings of pectocellulose in specific areas of their walls. They can be only observed in the aerial parts of the plant like petioles, leaves, and stems of dicots. Collenchyma provides mechanical strength coupled with flexibility.
So, the correct answer is ‘All of these.’

Note: - Parenchyma may be modified to chlorenchyma and aerenchyma.
- Aerenchyma is abundant in aquatic plants where the need for floatation is fulfilled by the storage of gases in the air cavities of aerenchyma. Chlorenchyma, as the name suggests, contains chloroplast and thus takes part in the manufacture of food.
-Sclerenchymatous fibers are elongated and narrow whose ends are interlocked with each other. They are usually dead at maturity except in Tamarix aphylla which possesses living fibers. They provide mechanical strength to the plants as they can bear compression or stretch due to their thick cell wall.