Question

Why apoplast can't operate beyond endodermis

Answer 1

The endodermis prevents the water and any solutes dissolved in water, from passing through this layer via the apoplast pathway. Water can also pass through the endodermis by crossing the membrane of endodermal cells twice. Water moving in and out of the xylem which is a part of the apoplast can thereby be regulated since it must enter the symplast in the endodermis.