Question

The number of network present in the plant cell wall is
A. Three
B. Two
C. One
D. Four

Answer 1

A plant cell wall is structured in layers and includes microfibrils of cellulose, hemicellulose, pectin, lignin and soluble protein. These components are grouped into three main layers: the primary cell wall, the middle lamella, and the secondary cell wall.

Complete answer:
The cell wall is a rigid framework that protects certain kinds of cells, just below the cell membrane. It may be fluid, tough, and even rough. It provides structural support and defence to the cell and also serves as a filtering mechanism. Cell walls are found in most prokaryotes, in bacteria, fungi and eukaryotes, including plants, but are not found in animals. A significant purpose is to serve as a pressure reservoir, stopping the cell from over-expanding as water enters. The composition of cell walls is different between organisms and can depend on the type of cell and the stage of growth.

The three main cell wall networks in the plant cell are cellulosic, pectin and glycoprotein networks. Cellulose is an essential component of plant cell walls that make plant stems, leaves and branches strong. They are present in the form of cellulose microfibrils in the internal layer of the primary wall. Pectin is an integral polysaccharide present in the cell wall of the plant that enables the expansion of the primary cell wall and the development of the plant. Hydroxyproline-rich glycoproteins are an essential structural feature of cell walls.

Thus, the correct answer is option A i.e., Three.

Note: The primary cell wall of soil plants consists of cellulose polysaccharides, hemicelluloses and pectin. Some polymers like lignin, cutin, and suberin are often anchored to or incorporated in plant cell walls.