Vascular Tissue- Chapter 20
Concept 20.2
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Root System
 Anchor & Support
 Absorb minerals and water
 Monocot root- fibrous-mat -grass
 Dicot root-tap root-1 vertical root-carrot
Shoot System
 Stems, leaves, flowers
 Support
 Transport-transport tissue
Plant Root and Shoot System
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Shoot System= stems, leaves, flowers
 Undeveloped shoots are buds.
 Terminal buds- stem tip
 Axillary- in the axils (angles) between leaf and main
stem. Growth from here produces plant branches.
 Blade- main part of the leaf.
 Petiole- stalk connecting the leaf to the stem.
 Veins- carry water and nutrients-vascular tissue and
support tissue.
 Examples of modified leaves Celery stalks- petioles; spines on cactus, tendrils
 Grass-no petioles.
Plant tissue system-3 types
1.
2.
Dermal
Outer covering- “skin”- epidermis
Protects
Vascular Tissue- 2 types
 Transport
 Xylem- water and minerals from rootsshoots
 Phloem-food from leaves down.
 Roots-in center
 Stems- in vascular bundles.
 Monocot vs dicot differences
Monocot vs Dicot Root
Monocot vs Dicot stems
3. Ground Tissue- mostly parenchyma cells
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Fills in between the dermal and vascular tissues.
Functions in photosynthesis, storage, and support
in young shoots.
Plant Tissue
Is made up of more than 1 type of plant cell.
Different cell types
Parenchyma- thin c. wall & large vacuoles.
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Most abundant in fruit. Makes up phloem.
Collenchyma- thick, uneven; provides support;
elongates.
Sclerenchyma- support; forms skeleton; makes
up the water-conducting cells of xylem.
Primary Growth- Concept 20.3
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Plants grow throughout their lifetime.
Meristematic Tissue- differentiates into the
3 main tissues- dermal, vascular, ground.
Apical meristems- found tips of roots and
shoots.
Primary Growth- growth in length
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roots- below ground
shoots- above the ground
Primary Growth in Roots and Shoots
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Primary Growth- growth in length
Figure 20-13 –
Root cap-protects delicate cells of apical
meristem.
Primary growth -3 cylinders of developing
tissues
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Outermost cylinder- dermal tissue
Middle- cortex
Inner cylinder- vascular tissue
Xylem
 Phloem
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Concept 20.4Secondary Growth
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Woody plants – vines, shrubs, trees
Growth in plant thickness- width
Cell division in 2 meristematic tissues:
vascular cambium and cork cambium
Vascular cambium
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A cylinder of actively dividing cells
Between the xylem and phloem
Adds cells both sides
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Secondary xylem-wood.
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Secondary xylem inside
Secondary phloem outside
Growing season
Dormant in winter
Stem / root thickens with each new xylem
Sapwood- new xylem actively transporting water
Heartwood- old xylem not transporting water
Secondary phloem- outside vascular cambium.
Cork cambium
meristem- produces cork
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When cork cells die-thick waxy wallsprevent water loss
Barrier of protection
Bark- everything to the outside of the
vascular cambium
Includes phloem, cork cambium, and cork
Secondary Growth
Tree rings
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Age from annual rings = year of growth
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Easiest to count dark bands of secondary phloem
from outside to inside.
Environmental conditions- differences in ring
width.
Each ring
Spring- cool, plenty of water conditions
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Produce large, thin walled cells of xylem
carry lots of water.
Summer- hot, dry conditions
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Narrow thick walled cells
Tree Rings- History of the Plant
What nutrients do plants need?
Concept 21.1
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Plant get nutrients from _____ and _____.
Air supplies carbon dioxide and ________.
Water supplies hydrogen and serves as a
solvent for dissolved minerals.
Plants have simpler needs than animals
Plants require 17 chemical elements for
their life cycles
Chemical elements needed/function
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Nitrogen- proteins and nucleic acids
Sulfur- proteins
Phosphorous- nucleic acid and ATP
Potassium – protein synthesis and osmosis
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Na+-K+ pump
Calcium-cell wall, enzyme activity
Magnesium- chlorophyll synthesis, enzyme
activity
Consequences of poor nutrition
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Growth –stunted
No flowers produced
Stems, roots, leaves may die
Yellow leaves if no chlorophyll produced
Vascular transport Concept 21.2
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Roots –absorb water and minerals
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Root hairs & Mycorrhizae
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Xylem- moves water and minerals upward
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2 forces1. Root pressurePushes water up the xylem (at night)
 Root epidermal and ground tissue cells use ATP to
get minerals – into xylem
 Endodermis around vascular tissue-waxy cellsprevents leakage of water.
 Water enters xylem by osmosis
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2. Transpiration-pull
Main force- pulls xylem up
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Transpiration- loss of water thru leaves due to
evaporation.
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Cohesion : same kind molecules stick together
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water –water
Adhesion : attraction between unlike molecules (
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water – cellulose (xylem walls)
Regulating water loss
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Stomata (singular-stoma)
 Pores on underside epidermis of leaf
 gas exchange – CO2
 Guard cells surround stoma open and close stoma by changing
shape
 Open- day- to let in CO2
 Closed- night- to prevent water
loss.
 Leaf Diagram- Structure
Water follows potassium ions
from surrounding cells into guard cells.
Leaf Structure
Leaf Cross-section
Flow of Phloem
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Phloem- “food phloem down”
 Transports sugar and organic
compounds + water.
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From source (mature leavesphotosynthesis) to sink (where
needed- roots, fruits, developing
shoots).
Pressure-flow mechanism Water follows sugar; high conc. to
low conc.
Sieve tubes carry phloem sap
Pressure-Flow mechanismhypothesis for movement of
phloem sap.
21.3 Carnivorous Plants
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Some plants – N from animals
Ex: sundews, Venus's flytraps, pitcher
plants
Little organic N where they live (wetlands,
cold, acidic water, decay slow)
Still photosynthesize
Ch. 22.1 Plant hormones
–chemical messengers
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Control:
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Germination
Growth
Flowering
Fruit production
1. Auxins
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Apical meristems – shoot tips
Cell elongation
Secondary growth – vascular cambium
Seeds – auxin – signal ovary to fruit
Auxins - no pollination  seedless fruit
Phototropism
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Auxin builds – shaded side
Shaded cells lengthen more, more water
Uneven sides = bending
2. Cytokinins
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Cell division – made in roots
Cytokinin with auxin
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Fewer / shorter branches near tip
3. Gibberellins
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Fruit – seedless, larger
4. Abscisic Acid (ABA)
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Limits cell division
Stops growth
Dormancy
“stress hormone”
5. Ethylene
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Fruit ripening
“leaf drop”
22.2 Plant Responses
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Rapid plant movements
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Touch
Rapidly reversible
Tropisms – slowly grow toward or away
from a stimulus
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Slow to reverse
1. Thigmotropism
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Touch
Climbing plants – tendrils
Seedling - obstacle
2. Phototropism
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Light
Uneven auxins – light one side
3. Gravitropism
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Gravity
Seedling root / shoot
Disease
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Viruses, bacteria, fungi
Adaptations
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Epidermis
Chemicals – lignin
Resistant genes
Thorns, poisons