1. 9.3 Water/Sugar Transport in Plants p. 331 – 340
Water transport in xylem vessels
Sugar transport in phloem vessels
Uptake of water in roots

2. NO PUMP!!!! So what happens? Root pressure (osmosis)
Cohesion/adhesion of water
Transpiration
Water enters the root due to osmosis
Water moves up the xylem by cohesion/adhesion of water
Water leaves the leaves through transpiration

3. Plant Vascular System Interconnected tubes Extend throughout plant
Made of Xylem and Phloem = specialized TISSUES that transport water, minerals and sugars throughout the plant

4. Xylem Transports water and dissolved minerals from soil to leaves
Start out as living cells then DIE
Only the cell walls remain
Cells linked end to end to make long tubes called XYLEM VESSELS

5. Xylem Vessels

6. Xylem Vessels

7. Several cell types: tracheids and vessel elements

9. Phloem
Transport sugar (sap) from leaves to rest of plant

10. Phloem Vessels
Live cells
Arranged end to end in long connecting tubes

11. SPECIALIZED PHLOEM CELLS
Sieve tubes and companion cells are
specialized to carry sap (sugar water)

12. How does water move through the plant without a pump????

13. H20 absorption in roots
Root hairs increase surface area for osmosis

14. 1. Root Pressure
Soil outside root is hypotonic to root cell so water enters cell by osmosis

15. 2. Cohesion of Water Molecules
Water sticks to other water molecules and forms a long chain of water molecules and pull each other along

16. 3. Adhesion of Water Molecules
Water sticks to inside walls of xylem

17. 4. Transpiration of water out of leaves
The water concentration is higher inside the leaf cells than outside (in air)
Therefore, water moves from an area of high concentration (HYPOTONIC inside the cells) to an area of lower concentration (HYPERTONIC outside the cells)
As water molecules move out, they “pull” the string of water molecules up through the xylem

18. Transpiration - animation

19. VIDEO CLIPS: WATER TRANSPORT
VIDEO 1 – Water transport in plants B7Tu3Y
VIDEO 2 – Vascular System
XiM
VIDEO 3 - Transpiration

23. PHLOEM TRANSPORT – SUGAR
1. Glucose is produced in the leaves (palisade cells and spongy mesophyll cells)

24. PHLOEM TRANSPORT
2. Sugars are actively transported from the LEAVES to the PHLOEM tissue
What does “active transport” mean? a) b)

26. PHLOEM TRANSPORT
3. Once the sugars are “pumped” into the phloem tissue, the water follows due to osmosis
After the sugars have left the phloem tissue, what is the tonicity of the palisade cells in relation to the phloem tissue?
Which way does the water flow?

27. PHLOEM TRANSPORT
4. After the water flows INTO the phloem tissue, pressure is very high (ie – many particles in a confined space)
Pressure gradients always try to reach equilibrium – therefore, the sap/water moves from high pressure to low pressure (ie – DOWN the phloem tubes to the roots)
The pressure in the root cells is relatively low compared to the phloem tubes

28. PHLOEM TRANSPORT
1/biology11/sugartransport.html

29. Malpighi’s Experiment – Tree Girdling
In 1686, Italian scientist Marcello Malpighi
wanted to find out what would happen if
he removed a ring of phloem tissue from
a tree.

30. He learned that a swelling developed above the ring and a sweet-tasting fluid oozed out of this swelling.

31. He also discovered that his trees became weakened and died soon after the ring was removed.
Why did the trees die?

32. ASSIGNMENT: Check Your Understanding
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