Question

Which tissue provides mechanical strength to the plant?
a. Sclerenchyma
b. Xylem
c. Collenchyma
d. Phloem

Answer 1

Hint: A tissue is a group of cells having a common origin and usually performing a common function. Plant tissues are classified into two main groups.
1. Meristematic tissue
2. Permanent tissue

Complete Answer:
1. Meristematic tissue: It is a plant tissue which has the capacity to divide actively throughout its life. Meristematic tissue induces growth and is responsible for the formation of new organs and also heal the injured parts of the plant body.

2. Permanent tissue: The tissues that are completely developed and have lost the ability of division are known as permanent tissues. The meristematic tissues divide and differentiate to form the permanent tissues. It is classified into simple permanent tissue and complex permanent tissue.
a. Simple permanent tissue is further divided into 3 types
(I) Parenchyma: It is a simple permanent living storage tissue and is the most widely distributed tissue in the plant body also called Ground tissue.
- Cell wall is uniformly thin and made up of cellulose.
- Cells store substances like food, water, secretory and excretory products.
- Performs functions like photosynthesis, storage and secretion.

(II) Collenchyma: It is a simple permanent living mechanical tissue.
- It is found in the hypodermal regions of dicot stem, leaf and fruit walls.
- Cell wall is unevenly thickened with cellulose and pectin.
- Provides mechanical support to growing parts of plants such as young stem, petiole of leaf.

(III) Sclerenchyma: It is a simple permanent dead mechanical tissue at maturity.
- Consists of long, narrow cells with thick and lignified cell walls.
- Provides mechanical support to the plant organs.

2. Complex permanent tissue is further classified into 2 types
(I) Xylem: It transports water and minerals from roots to stem and leaves.
- It consists of tracheids, tracheae, xylem fibres and xylem parenchyma.
- It also provides mechanical strength to plants.

(II) Phloem: It transports food materials from leaves to other parts of plants.
- It consists of sieve tubes, companion cells, phloem fibres and phloem parenchyma.

Hence the answer is (a) Sclerenchyma.

Note: Secondary xylem provides the mechanical strength to the plants as its cell walls are thickened by the deposition of lignin but collenchyma is also responsible for the tensile strength of the plants.