The cell membrane, or cell wall, is an inanimate derivative of the plasma membrane, it preserves the shape of the cells and protects their internal contents. The basis of the shell is fibrils — cellulose filaments, which are lignified in some plants, that is, they are impregnated with lignin, tannin, calcium salts and silica. Lignified fibrils of cell membranes form a solid plant framework, which gives it strength.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.