What do '$P$','$Q$',and '$R$' represent in the given figure?

Identify the $A$ to $E$ in the following diagram.

$A$: Eight cells of the octant stage in dicot embryogeny are formed by $2$ vertical and $1$ transverse division in the embryonal cell.
$R$: These cells are arranged in epibasal and hypobasal tiers.

In the given diagram, identify and label the parts indicated by the lines.

The scutellum observed in the grains of maize or wheat can be compared to which part of the seed in other monocotyledonous plants?

In this diagram showing the $L$.$S$. of an embryo of grass,identify the answer having the correct combination of alphabets with the right part.