Water Uptake By Roots:
A.Carried out by root hairs located at the zone of differentiation.
B. Many root hairs increase the surface area available for water absorption.
C. Fugal hyphae attached to roots also absorb water and pass it on to roots.
D.The process of water intake at the roots is called osmosis. Osmosis is the movement of a substance through a membrane. Water moves because the overall water potential (amount of water) in the soil is higher than the water potential in the roots and plant parts. Water continues to diffuse from the inside of the root hairs, through the ground tissue and into the xylem of the root. The water can then travel up through the xylem of the root and stem, into the petiole, and into the leaves of the plant.
Transpiration
Transpiration is the loss of water by the plant out through its stomata in the leaves.
Guard cells control the openings to the stomata.
There is a continuous column of water from the roots up through the stems to the leaves in the xylem vessels.
hen water is lost more water is pulled up the column.
A number of factors affect the rate of transpiration:
–Temperature
–Leaf area
–Number of stomata
–Air movement
Transpiration
Water is lost from the plant leaves by evaporation
To replace this water lost, water is drawn from the xylem tissue in the leaves
A combination of root pressure, cohesion and adhesion forces allows the continuous movement of water up the xylem vessels.
Translocation
Translocation is the transport of organic materials (sugars) in the phloem tissue of plants.
Sugars made during photosynthesis are transported up and down the plant to storage sites and to areas of growth.
Minerals enter the root by the root hairs. The entry of these minerals requires energy. This is called active transport of materials. Root hairs contain many mitochondria to supply this energy. Mitochondria are organelles within the cytoplasm of cells which convery carbohydrates into energy by cellular respiration.
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