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VASCULAR TISSUE AND TRANSPORT
• Plants rely on specialized tissue, called
vascular tissue, to transport water, nutrients,
and the products of photosynthesis around
the plant.
• The 2 types of vascular tissue are xylem and
phloem.
Xylem (zy-lum)
What is xylem? Transports water from the roots up
to the rest of the plant in one way flow.
What are tracheids? Hollow cell in xylem with thick cell
walls that resist turgor pressure
Capillary Action & Transpiration
• Water rises through the thin tubes by a process
called capillary action (cohesion of h20 molecules
and adhesion to solid surface). The thinner the
tube, the higher the water will rise.
• Plants lose water through their stomata in a process
called transpiration. As the leaves lose water, more
is drawn up the plant (like liquid through a straw).
• The actions of these two forces, along with root
pressure (Root pressure occurs in the xylem when the soil moisture
level is high either at night or when transpiration is low during the
day),
allows water to be delivered to the entire plant,
even to ones that are a hundred feet tall.
Phloem
• Vascular tissue that transports sugars (glucose)
produced by photosynthesis to plants in a twoway flow to the roots of the plant.
-dripping sap(sugars) coming from a tree is usually from the phloem
Guard cells:
• cells that open and
close the stoma
Stomata: openings in
leaf’s surface; when
open:
• GAS EXCHANGE:
Allows CO2 in & O2
out of leaf
• TRANSPIRATION:
Allows excess H2O
out of leaf
GUARD CELL WITH STOMATA
1. Transpiration: loss
of excess water from plant
leaves
2. Significance:
a. Transpiration causes
enough pressure to help
pull water (& required
nutrients) up stem from
roots.
b. As part of the water cycle,
trees transpire water back
into the atmosphere.
c. Transpiration provides
much of the daily rain in
rainforest.
A average size maple tree can
transpire 200 liters of water
per hour during the summer.
Transpiration is the #1 driving
force for pulling water up
stems from roots.