1. TRANSPORT IN PLANTS

2. 2 types of transport tissue: XYLEM & PHLOEM

3. Vascular Cambium
creates new xylem cells on the inside, and new phloem cells on the outside.

4. XYLEM & PHLOEM anatomy:
sieve cells
companion cells
plasmodesmata

5. XYLEM~ moves water and minerals
Acts like a bundle of straws
functions via. negative pressure
“sucking”

6. XYLEM cells (transport water & dissolved minerals) ~2 kinds of cells:
Tracheid = single cell, elongated, tapered ends (wall composed of cellulose)
* Pits (holes) between and surrounding these~
* Dead & hollow at maturity
* Conifers, have only these

7. XYLEM cells~ 2 kinds:
Vessel Element = numerous elongated cells make up this tube. (typically smaller in length than tracheids, but wider in diameter)
* Have “pits” or openings on their ends and are stacked to create one long “pipe”
* Carry more water than tracheids
* Dead & hollow at maturity
* Conifers do not have these

8. XYLEM ~ water movement b/c of 2 forces:
Transpirational pull - via. negative pressure as water is evaporated out of the stomata

9. XYLEM ~ water movement b/c of 2 forces:
Transpirational pull - via. negative pressure

10. 2) Root Pressure - more negative water potential in the root as compared to the outside soil

11. 2) Root Pressure - water moves from the soil… into the root

12. PHLOEM~ has 2 types of cells:
companion cells
sieve tube cells

13. PHLOEM companion cells: nucleus sieve tube cells: no nucleus
both types are alive

14. ..
How do solutions move through the PHLOEM ~ Ernst Munch PRESSURE FLOW HYPOTHESIS

15. ..
How do solutions move through the PHLOEM ~ Ernst Munch PRESSURE FLOW HYPOTHESIS
Solutes move through plants as a result of pressure gradients, not negative pressure (aka. pulling)

16. SOURCE = area of excess sugar supply aka. leaf in the summer
SINK = area of storage aka. roots in the summer & winter

17. SINK = area of storage aka. leaf are in the spring
SOURCE = area of excess sugar supply aka. roots in the spring.

18. TRANSPORT OF SAP sugar source
(Photosynthesizing cell)
sugar
Phloem companion cell
source
SOURCE, sucrose moves from mesophyll cells into companion cells via. active transport

19. TRANSPORT OF SAP sugar source
Photosynthesizing cell
Photosynthesizing cell
sugar
Phloem companion cell
source
2) Companion cells move sap into SIEVE TUBE CELLS via. active transport

20. Mineral absorption Proton pumps
active transport (ATP) of H+ ions out of cell
chemiosmosis
H+ gradient
creates membrane potential
difference in charge
drives cation uptake
creates gradient
cotransport of other solutes against their gradient
ATP H+ H+ H+ H+ H+ H+ H+ H+ H+
sugar

21. TRANSPORT OF SAP sugar source
Phloem companion cell
source
3) Sugar accumulates in SIEVE TUBES, thus decreasing (lowering) water potential (aka. making more negative)

22. TRANSPORT OF SAP H2O sugar source
Phloem companion cell
source
4) WATER then, moves in from the XYLEM (as a result)… thus increasing turgor pressure in SIEVE TUBES -->

23. Maple sugaring

24. TRANSPORT OF SAP H2O sugar source
Phloem companion cell
source
5) thus moving sugar to areas of lower pressure (the sink).

25. TRANSPORT OF SAP sugar source
Phloem companion cell
source
sink, sugar is unloaded from sieve tubes, thus INCREASING water potential...

26. TRANSPORT OF SAP H2O sugar source
Phloem companion cell
source
7) Water moved back into xylem… and UP via. negative pull

27. Pressure Flow Hypothesis

28. Do you think a fruit is a source or a sink?
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Do you think a fruit is a source or a sink?