12 Plant exchange and transport

Water

90-95% of the weight of soft tissues

turgor pressure

a force within the cell that pushes the plasma membrane against the cell wall

Water’s function to plants

growth, metabolic, transpiration, transport, excretion and secretion

Extrafascicular

kind of water conduction within the cell itself and neighboring cells and tissues

symplast

interconnection of cells through plasmodesmata

Fascicular

long distance water conduction. occurs only at longitudinal axis

transpiration

Loss of water vapor from leaves. occurs mainly through stomatamajor force in the global cycling of water

transpiration

provides the pull for the ascent of xylem sap, and the cohesion of water molecules transmits this pull along the entire length of the xylem from shoots to roots

adhesion

Adhesion is the attractive force between water molecules and other polar substances (e.g. water and

cellulose)

cohesion

Cohesion is the attractive force between molecules of the same substance (water has high cohesive

force)

rhizines

absoprtive surface of the root hairs