Question

Identify the plant tissue in which lignin is absent.
A. Collenchyma
B. Sclerenchyma fibers
C. Sclereids
D. Xylem tracheae

Answer 1

Hint: Lignin are those which are formed due to the formation of cell walls mostly in the wood and bark of trees. So, accordingly it can be found based on the presence of lignin in these plant tissue and then examined.

Complete answer:
Collenchyma is a plant tissue, which is present in plants and acts as the supportive tissue with irregular cell walls. They have thick deposits of cellulose in their walls. It appears polygonal in the cross section. The following are the functions of Collenchyma. They are as follows:
It provides support, mechanical strength, and flexibility to the leaf, stem of the small plants which allows bending without any breakages.
It is mostly composed by the elongated living cells of uneven primary thick walls, which possess hemicellulose, cellulose and pectin materials.
These cells are found in the cortex of both stem and leaves.
These are supportive tissue and they have irregular cell walls.
This was discovered by Scheilden.
The strength results according to the longitudinal interlocking of cells and thickening of cells. The hardening agent, known as lignin is absent in their primary walls.
So, the correct answer is “Option A”.

Additional Information:
Collenchyma tissues have the thick deposit of cellulose.
These cell walls are unevenly thickened.
It has thickening mostly on their tangential walls.

Note:
Collenchyma tissue cell walls are thickened, when they become thick at the corners where cells are joined it is angular. Lamellar collenchyma is thickened at their tangential walls which are parallel with the surface. Hence, Lignin is absent in collenchyma.