1. 9.2 Transport in Angiosperms

2. 9.2.1: Root System
Huge, ever growing root system increases the surface area for absorption of water and essential nutrients
Surface area is also increased by the addition of root hairs
Cortex cells have a structure that also facilitates the uptake of water
Water can move in two routes symplastic and apoplastic

3. Symplastic and Apoplastic

4. 9.2.2: Ion Uptake Minerals needed by the plants and found in soil are:
N as NO3- or NH4+
K as K+
P as PO43-
Ca as Ca2+
Diffusion
Minerals are more concentrated in the soil than in the root
When dissolved in water the minerals will diffuse into the roots
Fungal Hyphae
Plants work together with fungus to absorb minerals
Threads of the fungus grow through the soil and absorb the minerals
The threads also grow into the roots and transport the minerals into the roots
These minerals would not be absorbed without the fungus
Plants give the fungus sugars
Mass flow of water
Uptake of water which includes dissolved minerals

6. 9.2.3: Active transport of Minerals
Xylem- Stem:Tracheids & Vessel Members (see photo)
Use of metabolic energy to obtain minerals in root
Can occur against the concentration gradient
Cytosol of the cell holds some reserves of ions
Allows the cells to pull in more of these ions when available
Cells tend to horde ions
Highly selective – plant will choose from different forms of the same ion
Ions cross into the cell through pump molecules
If roots are deprived of oxygen then active transport stops
The formation of the necessary metabolic energy is from respiration

8. Vessel Members and Tracheids are dead at maturity and are arranged end to end
Thick lignified walls have pits or pores so water can move laterally

9. Sodium Potassium Pump

10. 9.2.4: Plant Support
Stem is used to support the leaves of the plant and to transport water, ions and organic nutrients
Made up mostly of ground tissues (non-woody plants)
Cells are known as parenchyma
Stay rigid using cell turgor: exerting pressure on surrounding cells using a water filled vacuole
Outermost layers have additional layers of thickened cellulose laid down unevenly
Called collenchyma cells
In woody plants
Xylem tissue has cellulose thickenings that are hardened with a chemical called lignin
Provides almost all the strength of the stem

13. 9.2.5: Transpiration
The loss of water vapor form the leaves and stems of a plant
Water generally moves into plants through their roots and upwards through the vascular system and out of the stomata in the leaves

14. 9.2.6: Transpiration Stream
Water transport occurs in the xylem
Begins as elongated cells connected end to end
During development the end walls are dissolved away so long hollow tubes develop
Living tissues of xylem lay down cellulose which is thickened by lignin
Water lost by transpiration raises the osmotic pressure in the cells causing water uptake from surrounding cells
Water comes from the xylem
As water leaves the xylem more is pulled up through transpiration pull
As water leaves the xylem more is pulled into the xylem at the root
Water coheres to the lateral walls of the xylem maintaining a continuous column of water
Much of the water pulled into the plants is lost to evaporation

15. 9.2.7: Stomata Transpiration is regulated by the stomata
Tiny pores for gas exchange
Occur mostly in the leaves but sometimes found in the stem
Made of 2 elongated guard cells
attached to normal epidermis cells on one side
Not attached to each other
Open and close based on turgor pressure
Open when water is absorbed by the guard cell from its neighboring epidermis cell
Water is then lost through the pore
Close when enough water is lost that the cell becomes flaccid
Tend to be open during the day and closed at night
Will close during the day if plant becomes short of water
Regulates transpiration & prevents excess water loss

17. 9.2.8: Hormone Regulation of the Stomata
Abscisic acid (ABA) is a plant growth hormone that helps regulate the rate of transpiration in plants
In time of physiological stress (like drought) the levels of ABA increase in the leaves
Maintains stomata closure preventing excess water loss

18. 9.2.9: Abiotic Factors and transpiration
Light
Stomata tend to be open in light
Light can warm the leaf and raise its temperature
Temperature
Causes evaporation of water molecules from the surface cells of the plant
Evaporation rate doubles for every 10 degree increase in temperature
Wind
Sweeps away water vapor causing an increase in transpiration
Humid Air
Decreases transpiration
Soil Water
-If intake of water at roots does not keep up stomata then close
Carbon Dioxide
-High Carbon Dioxide levels usually cause stomata to close

19. C4 and CAM Plants
C4 ("four-carbon") plants initially attach CO 2 to PEP to form the four-carbon compound OAA (oxaloacetate) using the enzyme PEP carboxylase. This takes place in the loosely packed cells called mesophyll cells. OAA is then pumped to another set of cells, the bundle sheath cells, which surround the leaf vein. There, it releases the CO 2 for use by Rubisco. By concentrating CO 2 in the bundle sheath cells, C4 plants promote the efficient operation of the Calvin-Benson cycle and minimize photorespiration. C4 plants include corn, sugar cane, and many other tropical grasses.
CAM ("crassulacean acid metabolism") plants initially attach CO 2 to PEP and form OAA. However, instead of fixing carbon during the day and pumping the OAA to other cells, CAM plants fix carbon at night and store the OAA in large vacuoles within the cell. This allows them to have their stomata open in the cool of the evening, avoiding water loss, and to use the CO 2 for the Calvin-Benson cycle during the day, when it can be driven by the sun's energy. CAM plants are more common than C4 plants and include cacti and a wide variety of other succulent plants.

21. 9.2.10: Adaptations of Xerophytes
Thick cuticle
Prevents water loss through the external wall of the epidermis
Hairs on the epidermis
Traps moist air over the leaf
Reduction in number of stomata
Reduces areas where loss can occur
Rolled or folded leaves
Reduces area for transpiration to occur
Lower epidermis is rolled inside the leaf protecting it
Superficial roots
Takes advantage of condensation on the soil overnight
Deep and extensive roots
Allows access to the deep water
Reduced leaf numbers
Less surface area for transpiration
Low growth
Limits plant exposure to wind
Often show CAM photosynthesis

24. 9.2.11: Phloem Translocation
The movement of manufactured food (sugars&amino acids)
Occurs in the phloem
Takes sugars to new growth in young plants & to storage in older plants
Amino acids are produced in the roots and transported to where they are needed for protein synthesis (usually growing parts of the plant)
Chemicals sprayed on the plant also moved in this manner
Phloem tissue
Sieve tubes: narrow elongated cells connected end to end; no real organelles
Sieve plates: end walls which have pores for material to move through
Companion cells: services and maintains the sieve tubes; attached to the sieve tube by cytoplasm strands
Transport requires energy
Can occur in any direction