Roots are useful to the plants because:

1. Roots help the plant to abosorb water, mineral from the soil.
2. Firmly helds the plant in soil.

Xylem vessels carry water and mineral salts upwards from root to plant parts.

Phloem

Semi-permeable membrane is a membrane that allows certain molecules or ions to pass through it by diffusion but prevents the entry of any larger molecules.

The movement of water molecules from a dilute solution to a concentrated solution across a semi-permeable membrane is called osmosis.