Each of the following terms has some anatomical significance. What do these terms mean ? Explain with the help of line diagrams.
$(A)$ Plasmadesmoses / Plasmodesmata
$(B)$ Middle lamella
$(C)$ Secondary wall
$(A)$ Plasmodesmata :
$\Rightarrow$ Structure : It is a narrow pathway connecting cell wall between two cells.
Function : It makes transport and communication possible between two nearly cells.
$\Rightarrow$ Plasmodesmata allow molecules to travel between plant cells through the symplastic pathway.
$(B)$ Middle lamella :
$\Rightarrow$ Structure : It is a layer located in cell wall. It is mainly made up of calcium pectate.
Function : It connects two near by cells.
$(C)$ Secondary Wall :
$\Rightarrow$ Structure : It is such a wall that cannot expand. It is made up of hemicellulose fibre in cell wall of plant cell.
$\Rightarrow$ Function: It provides firmness to cells.
The youngest layer of secondary xylem in the wood of dicot plant is located
Early wood is formed in dicot plant during
Identify $X$ and $Y$
$A$ : Oldest layer of sapwood lies just outside vascular cambium.
$R$ : Sapwood contains actively conducting vessels and occupies central part of stem.
The wood is, in fact a