1. Transport in Plants
Section 3.4
Unit C

2. Objectives distinguish between cohesion and adhesion, giving examples
describe water transport from root to leaf including different processes used
relate tonicity of plant environment to movement of water in and out of the cell
summarize the process of sugar transport in plants

3. Review What is osmosis? What is diffusion? What is active transport?
What is transpiration? Where does it take place?

4. Plant Transport of Water: 3 Main Steps
1) Water uptake in roots – root pressure
2) Cohesion & Adhesion in Xylem
3) Leaf transpiration

6. Animation:

7. Root Pressure Movement of water from roots to leaves
Pressure built up in xylem
Dissolved minerals in root cells due to active transport
Water enters cell, creating positive pressure, forcing fluid up the xylem
Water forced from area of higher pressure in roots to area of lower pressure in leaves

8. Root Pressure
When would root pressure not be the complete explanation for water movement in plants?
When the plant is very large (maximum of a few metres)
Overall process affected by transpiration

9. Cohesion and Adhesion Cohesion
Attraction of water molecules to other water molecules
Due to polar nature of water (slightly positive end attracts slightly negative end of another water molecule)

10. Cohesion and Adhesion Adhesion
Attraction of water molecules to molecules of other substances
Usually polar interactions

11. Cohesion & Adhesion in the plant
Cohesion and adhesion are two properties of water that helps it to travel from roots to leaves.
Cohesion
Causes water molecules to cling to each other
Adhesion
allows water to pull itself up
the plant
Video:

12. Trees & Capillary Action: http://www. davidlnelson

13. Transpiration
Evaporation of water through stomata and lenticels through transpiration creates a tension or transpiration pull.
When combined with cohesion, adhesion, and root pressure, water is able to be drawn up the xylem.
Transpiration is dependent on temperature. Higher temperatures increase the rate of evaporation and cause rapid movement in xylem.

14. Video: Plant Transport - Summary

15. Why would the carnation/celery change color?
How is it related to root pressure and transpiration?
Transpiration causes the loss of water through the stem and leaves.
This water must be replaced, drawing water up from the roots
Note that only certain cells in the celery are stained
Which cells might these be?
Xylem

16. Do Now
Individually, write a story of water transport in a large plant using the information on p You are writing it from the point of view of the water molecule.
Explain in your story how the plant uses adhesion and cohesion properties of water to its advantage
Include the different transport mechanisms used at different parts of the plant
Root Pressure, Adhesion, Cohesion, Transpiration

17. Tonicity & its Effect on the Plant
Tonicity  concentration of solute particles in an solution
Related to hypertonic and hypotonic (which one would have a higher tonicity?)
What will happen to a plant cell that is placed in a concentrated salt solution?
Water leaves the plant cell by osmosis
Effect = plasmolysis (cell looks shrunken)
Water leaves vacuole, cell contents pull into center,
cell membrane becomes visible

18. Hypertonic solution
Hypotonic solution

19. Question
What would happen to a plant that was placed in a hypertonic solution (salt solution)?
Becomes flaccid
What would happen to the plant when it was moved from this solution to a hypotonic environment?
Becomes turgid

20. Sugar Transport Phloem is essential
Removal causes plant death
Takes sugar from source (leaves) to place to be used/stored (sink)
Composed of sieve tube cells
Need companion cells to control its activity
Why?
Uses carrier proteins and active transport to take in sugar molecules

21. Sugar Transport
If sugar is being moved into the cells, what else will follow it?
Water!
Increased pressure pushes water and sugars through phloem to rest of plant
Called the pressure-flow theory

23. Sugar Uses
Actively transported from sieve cells in phloem to adjacent cells
Use:
Growth
Respiration
Other life processes
Stored in roots, stems, or leaves
Water follows movement of sugar and can:
Increase turgidity of other cells
Leave through transpiration
Move into xylem