Essential Idea : structure and function are correlated in the xylem of plan Is
Vascular plants have two types of transport tissue , xylem and phloem (to move . needed materials between specialized tissues .
Transpiration is the loss of water vapor from the stems and leaves of plants .
•
Light energy converts water in the leaves to vapor , which evaporates from the leaf via stomata .
•
New water is absorbed from the soil ( low ) and NOT ( high )
by the root ,
creating a di Frere rice in pressure between the lead
•
Water will flow
,
via the xylem, along the pressure gradient to replace the water lost from leaves (transpiration stream ).
Stomata are pore on the underside of the leak which facilitate
gas exchange ( needed for
photosynthesis )
•
As photosynthetic gas exchange requires stomata to be open , transpiration will be arrested
by the level of photosynthesis .
•
Hence, transpiration is an inevitable consequence of gas exchange in the tear .
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•
Transpiration is the evaporation of water from the leaves , stems and flowers? It is the movement of water vapour out the leaf and through the
stomata .
Evaporation :
occurs when some of the light energy absorbed by the leaf is convened to heat , thereby raising the temperature inside the leaf
changing the water into water vapour .
leaves called stomata
•
Majority of water lost during transpiration is
through openings on the bottom of the .
•
Transpiration at pull :
results when water evaporates from the leaves and stems More water is drawn up through the .
plant to replace the
water that is lost .
The loss of water generates negative pressure and transpirationat pull water molecules in the xylem
•
a a on .
Transpirationat Pull results from the combined forces of cohesion and adhesion
•
.
.
Water moves into the roots osmosis cell walls and through the cytoplasm because the concentration solutes inside
by through the of
•
the cells is greater than outside the root cells due to active transport of mineral and ions .
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•
xylem vessels are transport tissue found in vascular plants composed of a number
of different types of cell , including long , continuous , thin , usually dead cells .
•
cell walls are thickened to make the xylem vessels stronger .
•
The walls of the xylem are thickened and strengthened by a polymer lignin .
•
Lignin may be deposited in different ways such as rings or spiral .
•
since atmospheric pressure is greater than the pressure inside the xylem vessels , the
ridged structure prevent them from collapsing .
•
The responsible for transport of water and soluble mineral nutrients the
xylem is the from
roots to the different pans of the plants that use water .
•
This also allows minerals absorbed from the soil to be transported through the xylem to the
leaves .
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