1. Section 3.4
Transport in Plants

2. Cohesion & Adhesion Water clings to each other, and to other molecules
Helps aid in transport of water
Attraction of water molecules to each other is called cohesion

3. Cohesion & Adhesion Due to polar nature of water molecules
Remember, positives and negatives attract
Also means water is attracted to other molecules
The attraction of water molecules to other substances is called adhesion

4. Root Pressure Rate of transpiration is low
Roots still collecting minerals
Water is forced from higher pressure in roots to lower pressure in leaves

5. Water Transport
Transport of water in plants is due to a combination of factors
Differences in pressure caused by osmosis & transpiration
See diagram in text on pg 318 for summary

6. Water Transport
Evaporation of water through stomata or lenticels creates
Tension (or) transpiration pull
This draws water up xylem to leaves
Then can be moved into ground tissue and out through stomata
In ideal conditions, water can move 75 cm per MINUTE!!

7. Tonicity
Tonicity refers to solutions being hypertonic, hypotonic or isotonic
When solute concentration around a plant cell changes, there is an effect on the cell

8. Tonicity
Plasmolysis  shrinking of cytoplasm and plasma membrane away from cell wall
Due to outflow of water in hypertonic solution
Observed only in cells with rigid cell walls

9. Sugar Transport What happens if you removed the phloem?
Plant would die
Cells would not be receiving products of photosynthesis

10. Sugar Transport Where sugar is manufactured
The leaf
Called the source
Where sugar is used or stored
Throughout the plant
Called the sink

12. Section 3.5
Control Systems

13. Response to Stimuli Not as pronounced as in animals
Do have responses to
specific stimuli
Light
Gravity

14. Response to Stimuli Plants grow towards light Phototropism
Movement of the plant in response to the stimulus
Shoots towards light
Roots away from light

15. Response to Stimuli Response to gravity Called gravitropism
Roots grow towards gravitational force
Shoots grow away from it

16. Tropisms Plant Part Stimulus Tropism Stem Light Positive phototropism
Root
Weak negative phototropism
Gravity
Negative gravitropism
Positive gravitropism

17. Auxin Another plant hormone
Ability to initiate cell elongation response
Discovered by F.W. Went in Holland

18. Other Control Mechanisms
Respond to touch
To temperature, chemicals and water
To photoperiod

19. Germination Need specific conditions Water Oxygen Temperature
should be a moist environment
Oxygen
plenty of access
Temperature
usually around 15°C
moderate

20. Apical meristems responsible for plant length
Found in roots and shoots
Lateral meristems responsible for increase in plant girth