Root hair cells are actually modified epidermal cells of the roots. A root hair cell has a long and narrow protrusion (may also be referred to as hair-like structure). A root hair cell has a large vacuole with lots of mitochondria in the cytoplasm. Root hair cell have the following adaptations to fillfull its functions:-
(a) The hair-like structure helps to increase the surface area of the root hair cell, thus helps the root hair cell to absorb more water and mineral salts.
(b) The hair-like structure which is long and narrow helps the root hair cell to penetrate in between soil particles in search of water and mineral salts.
(c) The presence of mitochondria in large number in the cytoplasm of the root hair cell, helps for more absorption of mineral salts by active transport (Remember, active transport will only occur in the presence of energy provided by the mitochondria).
(d) The large vacuole enable more water and mineral salts to be stored after being absorbed. (Note: the absence of chloroplasts actually helps the vacuole to stretch out).