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Anatomy of the Leaf
And
Transpiration
Leaves are the primary site of photosynthesis
in a plant.
Three kinds of layers makes up a leaf
1. Epidermis: outer layer
2. Mesophyll: Middle layer
3. Vascular bundles: Transports Materials
through the mesophyll
Cross section of
a leaf
Transport in Plants
Veins are the basic structure of
transport in the plant.
1. H2O and minerals need to
move from the root
system to the rest of the
plant (xylem)
2. Sugar needs to move from
the leaves to storage area
and other places energy is
needed in the plant
(phloem)
Transpiration Pulls Water Up in A Plant
Transpiration is the loss of water vapor from a
plant.
*occurs through the stomata
-the stomata can open for gas exchange in
photosynthesis (CO2/O2)
-Loss of water vapor creates “suction”
drawing water up through the xylem
from the root system - like a straw
-90% of water taken in by the roots is lost
through the leaves
*regulated by the guard cells
-stoma opens and closes because of
water pressure within the guard cells
-high water pressure causes the cells to
“bow” and the stoma to open
*the inside edge of the cell is thicker
causing the cell to bow when it
swells with water
-low water pressure causes the cell to
“relax” and the stoma to close
Stomata