Question

Middle lamella is made up of
A. Cellulose
B. Suberin
C. Calcium and magnesium pectate
D. Lignin

Answer 1

Hint: The cell wall consists of two regions: primary cell wall and secondary cell wall. In some plants, the cell adds a tertiary wall also. A young plant cell forms a single layer of wall material. This layer is known as the primary cell wall. In mature cells, more layers of wall material are added internally to the primary wall. These layers are called secondary cell walls.

Complete answer: Adjacent cells in plant tissues are held together by a thin, sticky, amorphous layer of cementing material. This layer is called the middle lamella. It is lacking on the outer (exposed) side of the surface cells. Middle lamella is chiefly made up of calcium and magnesium pectate. It is laid down by the joint activity of cells between which it lies. It is formed at the time of cytokinesis as a layer of pectin. In old tissue, soft pectin may become hardened by deposits of calcium to form calcium pectate. In ripening fruits, the pectate compounds of the middle lamella solubilize to a jelly-like material, making the fruits soft.
So the correct answer is option C-Calcium and magnesium pectate.

Note: Presence of cell wall distinguishes plant cells from animal cells. The cell wall varies in thickness from 0.1-10 micrometer in different cells. The cell wall is secreted by the cytoplasm. The cell wall in plants is chiefly composed of insoluble polysaccharide, cellulose. Certain other compounds, such as hemicellulose, pectin, and proteins also occur in the cell wall.