Define the following terms:
$1.$ Embryo sac
$2.$ Monosporic development

(N/A) $1$. Embryo sac: The embryo sac,also known as the female gametophyte,is located within the nucellus of the ovule. It is the structure where the egg cell is produced and fertilization occurs.
$2$. Monosporic development: This is a type of embryo sac formation where the female gametophyte develops from a single functional megaspore,while the other three megaspores degenerate. This is the most common type of development in angiosperms.