1. Stem Structure
Bud
Stem
Petriole
Internode
Node

2. Leaf Structure
Cuticle
Protects from water loss, insect invasion, UV light
Upper epidermis
Palisade Mesophyll
Additional protection
Large number chloroplast
Spongy Mesophyll
Xylem
Lightly packed – allows for gas exchange
Transport water from roots
Vein/ Vascular bundle
Phloem
Guard Cells
Transport sugar to rest of plant
Open/Close stomata
Lower epidermis
Stomata
CO2(g)
Gas exchange
H2O(g)

3. Xylem Cells
Dead Cells
Thickened cellulose, lignified 2⁰ walls
Strengthens cell walls
Waterproofs plant
Protects against pathogens
Tapered to form continuous column
Most modern plants
Ancient plants
Allows water to mover laterally

4. Stomata Operations
Open/close due to cell turgor of guard cell
Bulge to outside  opens
Cell wall thickness uneven
Caused by absisic acid (plant hormone)
Blue light triggers ATP powered pumps
Produced in root during water definicency K+
Causes K+ to move into guard cells
CO2 levels circadian rhythms
Higher solute = osmosis
Cells sag due to water loss (close)

5. Transpiration
Cohesion-Tension Theory
2. Water lost by transpiration is replaced by water from xylem
1. Water moves down concentration gradient (out of plant)
Creates negative pressure
3. Vessel water column is maintained by cohesion/adhesion
4. Water is pulled from root cortex into xylem cells
5. Water is pulled from the soil into the roots

6. Root Structure
Root Hairs: increase surface area = more absorption of water/minerals x3
Fully differentiated  functional cells
Enlarging cells (G1 phase)
Start differentiating
Zone of cell division (M phase)
‘Stem’ cells – undifferentiated cells
Protects apical meristem

7. Cross Section of Root
Water movement: due to osmosis (higher solute concentration inside root)
Root Hair
Epidermis
Endodermis
Xylem
Vascular Bundle
Pericycle
Phloem
Cortex

8. Mineral Ion Movement
Fungal Hyphae: symbiotic relationship
Increases surface area for absorption
Active Transport: high concentration of solute in root
Need more or ion cannot pass lipid bilayer  hypertonic situation
Diffusion of mineral ions by mass flow of water
Passively flow due to low solute concentration in root

9. Movement within roots
All particles need to go symplastic at endodermis to get to xylem
Water and Minerals
Movement between cell walls
Movement within cells – water/minerals pass through plasmodesmata

10. Factors that affect transpiration
Increase evaporation
Removes humidity from stomata
Increase kinetic energy - evaporation
Cause guard cells to lose turgor – close stomata
Reduces difference in water concentration gradient
Less soil water, water stream stopped at roots, stomata close

11. Xerophytes
thickened
Crypt/pit – increases humidity
Reduced number
Decreases surface area for transpiration
Trap water vapor, increases humidity
Go dormant in dry months
Alternative photosynthetic pathway
CAM: stomata open at night
Succulents – fleshy stems
C4: rapid uptake of CO2

12. Halophytes: high levels of salinity
Sunken stomata
Leaf surface area reduced
Succulents: dilute salt concentration
Compartmentalize Na+ and Cl- in vacuoles
Prevents salt toxicity
Salt glands: secrete salt