Water Absorbing Organ

Estimated time: 2 minutes

Maharashtra State Board: Class 12

Key Points: Water Absorbing Organ

Roots are the main water and mineral-absorbing organs. Terrestrial plants absorb liquid water from soil; epiphytic plants (e.g., orchids) absorb water vapour using special roots with velamen tissue.
The root tip has four regions: the root cap, the meristematic zone, the elongation zone, and the maturation zone. Absorption occurs in the zone of maturation.
Root hairs are unicellular, tube-like extensions of epiblema cells present in the zone of absorption.
Each root hair is 1–10 mm long, colourless, unbranched, short-lived, with a large central vacuole and a thin cytoplasm layer.
Root hair cell wall is two-layered — outer pectin, inner cellulose (freely permeable); plasma membrane is selectively permeable.

Define the following:

Gravitational water

Fill in the column 'B' with appropriate answer:

	Column A		Column B
(I)	Water adsorbed on soil particles	(a)	______
(ii)	Water penetrated deep in soil	(b)	______
(iii)	Water present as hydrated oxides	(c)	______
(iv)	Water present between soil particle	(d)	______

(Capillary water, Combined water, Hygroscopic water, Gravitational water)

In which forms water is available to roots for absorption?

Water imbibed or adsorbed on soil particles.

Define the following:

Hygroscopic water

Define the following:

Combined water

Define the following:

Capillary water

Water present in the form of hydrated oxides of Silicon, Aluminium is called ______.