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EXAM III - Coggle Diagram
EXAM III
Vascularization
Evolutionary Perspective
Tracheophytes
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Synapomorphy
These distinguish bryophytes like Tracheids(in the xylem), Phloem, A branches sporophyte independent of the gametophyte, and true orangs(roots, leaves, stems).
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- Created towering forest during carboniferous
Xylem
No specialized cells
Poikilohydric
- water content changes with the moisture in the surrounding environment
- Equilibrate water potential through environmental source
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- Stayed small to reduce demand for water
- Live in perennially wet substrates (stream sides)
- More derived homoiohydric
Hydroids
- Bryophytes
- Water-conducting cell
- Apomorphic trait (similar function but different origin) to true vascular tissue
- No lignin
Tracheary elements
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- Thickened lignin walls,waterproofing,structural support
Stepwise progression
- Partially thickened- Rhynia - Vascular tissue not lingnified
- Lignified tracheids-Horneophyton-Annular cell wall -Helical cell wall
- During Devonian - Increase in Xylem content -Increase in tracheid size -Increase in tracheid reinforcement
Early tracheids
- Water transport only (no support)
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- Fern-Tracheids + vessel elements in rhizomes of some species
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True tracheids
- Lignified with ornamented walls - Banded ot pitted
- Evolved likely once- Tracheophytes
- Function in both- Water transport- Support
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Pine tracheids
- Function in water movement & support
- Torus-margo pit membrane- Move to prevent cavitation
Vessel elements
- Angiosperms- Homogenous pit membrane
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Gymnosperm vs Angiosperm
- Vessels can have greater- maximum diameters- Maximum lengths
- Vessel elements may be short but the vessel can be much longer
- yields greater conductivity in vessel elements
- Lowers the cost (construction & transpiration)
- Having vessels permits more fiber (hardwood vs softwood)
- Downside is greater cavitation risk
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Pholem
Food conducting cells
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- Specialized plasmodesmata in end walls
- Alignment along longitudinal arrays of endoplasmic microtubules- Plastids- Mitochondria- ER vesicles
- Breakdown of tonoplast- Mix vacuolar & cytoplasmic contents
- Rarely some species have nuclear breakdown
- Features common to sieve cells
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Sieve tube contents
- P-protein- May help in plug pores in response to leakage
- Forisomes- Legumes- Plug pores
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- Endoplasmic reticulum- Lost ribosomes- Highly folded
Phloem differentiation
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- Cytoplasmic clearing- No ribosomes
- Callose deposited around terminal plasmodesmata
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- Formation of sieve plate & pores
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Roots
Roots body plant
Root Types
Primary root, main root, derived from radicle, in monocot, lateral root,dominant in monocot, derived from stems and leaves.
General root plan,
- Highly differentiated multicellular axis
- Found only in sporophytes of vascular plants
- Functions- absorbed water, absorbed dissolved mineral,
Apical meristem- Behind root cap, rarely divide, backup plan, maintain initial cells
Root cap, Evolved independently-lycophyte- euphyllophyte, protect underlying tissue, secret mucilage
Pericycle- just inside the endodermis, pluripotent, initiation of lateral root developments
Root Hairs- single cells, delicate, short lived, absorption of water and mineral,
Cortex- large storage area, bounded by endodermis and epidermis.
Endodermis- casparian strips, prevent apoplastic movements of water,
Organizational Diversity
Lycophyte- no root cap, no hair.
Monocot- Diversity, Pith in center, endodermis surrounded by cortex
Monocot Detail- epidermis, endodermis, cortex, percycle, xylem, phloem, pith
Eudicot- diversity, no pith, endodermis, cortex.
Eudicot Detail- epidermis,cortex, endodermis, pericycle,xylem,pholem
Origins
Rhizoid
- ni-multicellular projections,Genes-predate land plants- play a role in root hair development,ome with mineral uptake, anchorage.
Rhizomorphs
- No root caps, similar to roots, no stomata,no chlorophyll, highly branched and covered in root hair
Shoot turned out
Rhynie chert, Zosterophyllophyta, Early Devonian
Upright stem, prostrate stems, downward (rootlike) stems
Root Transition, early without root hair, anticlinal division only, donovian lycophyte,independent evolution of root cap and endodermis
Root Meristem,number of initial cell differ, similar gene across plant taxa, and shoot in root.
Leaves
Phyllad Organization
monocot- epidermis, mesophyll, veins
eudicot- epidermis, mesophyll, veins
Lycophyll-• Microphyll, Single vascular trace along center of blade, Vascular strand connects directly to stem, Mesophyll, Epidermis, Stomata
Phyllad Tissue
Chlorenchyma- ground tissue, specialized parenchyma, contain chloroplast
Collenchyma-• Ground tissue, Thickened primary cell walls, Main function in flexible support, Found in bundle sheath of veins in some species
Aerenchyma- Ground tissue, Specialized parenchyma, Contains air spaces from cells being digested, Main function permit gas-exchange, Large air pockets for buoyancy in aquatic plants
Vascular tissue- xylem, phloem, in veins.
Phyllad Evolution
Initial constraints- high atmospheric global temperature, low stomatal densities,lackinf vascular transport in leaves,
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Zimmerman telome theory- evolution of euphylls, overtopping, plantation, webbing,devonian euphyll widespread
Transportation
Cohesion- Tension Theory
Cohesion-tension theory
• Transpiration stream, Water movement from soil to atmosphere, Follows relatively high to low moisture level, From less negative to more negative water potential
Water evaporates out of open stomata to drier atmosphere, creating water potential differential
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Water pases through endodermis, filtering solution, preventing embolism and foreign invaders
Pressure Flow Theory
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Increases osmotic concentration, decreases water potential in sieve tube
Water enters sieve tube from xylem due to water potential differential, creating turgor pressure
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