Question

What is the innermost portion of a mature plant cell wall called as?

• A. Primary cell wall
• B. Secondary cell wall
• C. Lamella
• D. Tonoplast

Answer 1

The correct option is B Secondary cell wall

Cell wall consists of three layers: the primary cell wall, secondary cell wall and the middle lamella.
The middle lamella- It is the first layer formed during cell division. This layer is rich in pectin. It is the outermost layer, joins together adjacent plant cells and holds them together.

The primary cell wall- It is formed after the middle lamella. It is composed of pectin compounds, hemicellulose and glycoproteins. The layer consists of a framework of cellulose microfibrils, in a gel-like matrix. It is a thin, flexible and extensible layer.

The secondary cell wall- It is a thick layer formed inside the primary cell wall. It is extremely rigid and provides strength. It is composed of cellulose, hemicellulose and lignin.