Question

Electron microscope has revealed that cell wall of plants is made up of a number of layers of

• A. Cavities
• B. Suberin
• C. Plasmodesmata
• D. Micelle

Answer 1

The correct option is D Micelle

The plant cell wall is made up of cellulose fibrils. The structural hierarchy of these fibrils is macrofibrils (0.5$\mu$m), microfibrils (250$\mathring{A}$), elementary fibril or micelle (100$\mathring{A}$), cellulose chains, glucose molecule. The macrofibrils are visible under the light microscope. The macrofibrils are bundles of microfibrils. The microfibrils and subsequent structures are visible only under an electron microscope. The microfibril, in turn, consists of a bundle of micelles or elementary fibrils. The micelle contains about 100 cellulose chains. Cellulose is a polymer of glucose molecules. In the primary cell wall, the macrofibrils are arranged at random. In the secondary cell wall, they are closely packed and arranged parallel to one another. They are oriented in different directions in the different layers of the cell wall.

Thus, the correct answer is option D.