Middle lamella is made up of

$A$ plant cell is distinguished from an animal cell by the presence of which of the following features?

$A$: The cell wall is present as an outer covering around the plasma membrane.
$R$: The cell wall is semi-fluid and functionally dynamic.

Which of the following is $NOT$ a function of the cell wall?
$(I)$ Provides shape to the cell.
$(II)$ Protects the cell from mechanical damage and infection.
$(III)$ Helps in cell-to-cell interaction.
$(IV)$ Provides a barrier to undesirable macromolecules.
$(V)$ Endosmosis of water.

$P -$ Statement: The middle lamella is composed of cellulose plates.
$Q -$ Statement: During the formation of gametes,cell division occurs by mitosis.

What is the middle lamella composed of?