THE SKELETAL SYSTEM | human anatomy

Root Hair

THE STRUCTURE OF THE ROOT HAIR

Root hairs are adapted to perform their function by:

• Increasing the surface area for absorption because they extend beyond the cell;
• Having cell walls that are thin and permeable for quick diffusion;
• Containing a very large vacuole to maintain the concentration gradient; and
• The absence of a cuticle on any root cells.

Transpirational Pull

Transpiration pull

Stomata are found on the leaf surface.
The suction force of transpiration is caused by the loss of water vapour through the stomata.
Transpiration pull is the force responsible for moving water all the way up the stem, to the leaves and is the most powerful of the three forces.
Water moves from the xylem in the main vein of the leaf, through the spongy parenchyma, into the intercellular air spaces and out through the stoma as water vapour.
The water moves from the leaf surface by evaporation.
This creates a water potential around the leaf, resulting in a negative pressure developing in the xylem.
This suction force is transferred along the leaves and stem, resulting in a decrease in the water potential of the roots.
Transpiration may cause excess water loss resulting in the plant wilting.
Excess wilting will cause death.

Gutattion

Guttation through Hydathodes !

Guttation Vs Transpiration

Guttation

(i) It 'occurs through hydathodes in the leaves.
(ii) It is exuded in the form of liquid.
(iii) It takes place either in the morning or during the night.
(iv) The hydathode remains open whole day and night.
(v) Oozed out water is not pure and contains inorganic and organic substances.
(vi) It occurs through hydathodes.
(vii) It takes place mostly in herbaceous plants.
(viii) It has no relation with the temperature.
(ix) It takes place due to development of root pressure.

Transpiration

(i) It occurs through stomata, cuticle and lenticels.
(ii) Water is lost in the form of water vapour.
(iii) It occurs only in day time.
(iv) The stomata of leaves usually remain open during day and get closed at night.
(v) Water is pure and contains no salt.
(vi) Major loss of water takes place through stomata.
(vii) It takes place in all higher terrestrial plants.
(viii) Transpiration maintains the temperature of the plant,
(ix) Root pressure is not involved.