Question

The material in plant cell wall impervious to gases and water is-
a) Pectin
b) Hemicellulose
c) Suberin
d) Chitin

Answer 1

Hint: plants have cells as the basic unit, cells are organized into tissues and in turn tissues are organized into organs. Organs are nothing but clusters of tissues and tissues are clusters of cells. tissues are groups of cells having common origin and usually performing common function too. Cell wall is meant to protect the plant’s internal organs and its structures.

Complete answer:
a) Pectin: in cell wall structures of plants one of the components is pectin. It's a structural heteropolysaccharide found in terrestrial plants' primary and middle lamellae, as well as their cell walls. It contributes to the cell growth of plants and also in cell differentiation and so determines the integrity and rigidity of plant tissue.
So, option A is incorrect.
b) Hemicellulose- hemicellulose is another plant cell wall component in almost all terrestrial plants. It is a branched polymer of pentose and hexose sugars in the plant cell wall. They form the microfibrils which are organized into macro fibrils that mediate the structural stability in the plant cell wall.
So, option B is incorrect.
c) Suberin- in a plant cell wall, the main component of middle lamella is pectin. The suberized cells of cork tissue are separated from the contents of the cell by a cellulose wall. Suberin is impermeable to water and gases due to its lipid composition. Suberin is hydrophobic in nature.
So, option C is correct.
d) Chitin- in fungi, as we know the cell wall is made up of chitin, glucans and mannan protein complex. It is a fibrous substance made up primarily of polysaccharides that is found in the exoskeleton of arthropods and the cell walls of fungi.
So, option D is incorrect.

Option C is correct.

Note:
As we discussed above about the importance of the cell wall in plant cells, each plant component performs different qualities and functions in developing and maintaining a plant throughout its life. These components are nothing but polymers, which are not only present in plants but also in other organism’s cell structure.