Download S10 9.3 Notes

S10
WATER and SUGAR TRANSPORT IN PLANTS
9.3 pg. 331
Water is transported in xylem vessels. Sugar is transported in phloem vessels
XYLEM transports water and dissolved minerals
from the soil to the leaves. Xylem starts out as
living cells that DIE, leaving hollow tubes for
water transport because only the cell walls
remain.
The xylem cells link end to end and make long
tubes called XYLEM VESSELS; there are 2 types:
tracheids and vessel elements
PHLOEM transports sugar (sap) made in the
leaves to rest of plant. Phloem are live cells
arranged end to end in long connecting tubes
made of sieve tubes and companion cells.
phloem
HOW DOES WATER MOVE THROUGH THE PLANT WITHOUT A PUMP???? With a
push and a pull!
ROOT PRESSURE - PUSH
H20 is absorbed by root hairs because root cell is hypertonic to the soil so water enters the root
cell cell by osmosis (PUSH), and enters the xylem. Water then moves by capillary action
(adhesion and cohesion) in a column up the xylem to the leaves. Notice that the root pressure
can only push the water up the root for about 100 mm.
TRANSPIRATION PRESSURE – PULL
As water flows out of stomata in leaves
(transpiration) by diffusion the empty air
spaces created are filled in by new water
molecules by diffusion and capillary action
(adhesion and cohesion).
Together, these actions pull the whole column of
water up the xylem from the roots to the leaves.
HOW DO SUGARS MOVE IN PHLOEM WITHOUT A PUMP? BY ACTIVE TRANSPORT AND
WATER PRESSURE
Sugars made in leaves is actively
transported into the phloem.
Removing the sugars from the palisade
cells and spongy mesophyll cells makes
them hypotonic (higher concentration
of water) to phloem. This makes the
water in these cells move into the
phloem by osmosis and creates water
pressure that sends the sugar and
water (sap) down the phloem from the
leaves (source) to the root (sink).
 Check out these clips:
http://www.pearsoned.ca/school/science11/biology11/sugartransport.html
https://www.youtube.com/watch?v=xGCnuXxbZGk&list=PLXwnjgs_UWpIQhMZ1YObcd338AHk
QzPHW
 ASSIGNMENT: Answer questions Pg. 340 # 2, 3, 4, 5, 6
Pg. 351 #16