Ch. 35 Warm-Up

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Ch. 35 Warm-Up

• What effect does pinching back a house plant
  have on the plant?
• Most H2O and minerals taken up from the soil by a
  plant are absorbed by _______.
• What is the largest organelle in a plant cell?

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Ch. 35 Warm-Up

• Define meristem. Which are primary?
• Compare monocots to dicots.
• From an evolutionary view, why are monocots and
  dicots different?

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Ch. 35/36 Warm-Up

• You have a plant that has
• Fibrous root system
• No petioles
• Parallel leaf veins
• Thick lignified cells
• Vascular cambium
• What type of plant do you have?
• monocot or dicot?
• woody or herbaceous?
• How do stomates open?

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Chapter 35

• Plant Structure, Growth, and Development

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What you must know

• The function of xylem and phloem tissue.
• The specific functions of tracheids, vessels,
  sieve-tube elements and companion cells.
• The correlation between primary growth and apical
  meristems versus secondary growth and lateral
  meristems.

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Introduction to Plants

• Kingdom Plantae
• Plants
• Cell wall
• Autotroph (photosynthesis)
• Multi-cellular
• 12 Divisions (Phylum)
• Anthophyta Angiosperms (flowering plants)
• Largest of species (250,000 - 90 plants)
• Seed plants product seed w/in a fruit
• Key adaptations flowers fruits
• Sporophytes are trees, shrubs, herbs that flower
• 2 groups Monocots Dicots

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Monocots compared to dicots
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Monocot Dicot
One cotyledon (seed leaf) Two cotyledon
Parallel veins in leaves Netted veins in leaves
Fibrous root system Taproot
Floral parts in multiples of 3 Floral parts in multiple layers of 4 or 5
Complex vascular arrangement Ring vascular arrangement
Eg. grass, corn, palm, onion, tulip, bamboo Eg. bean, pea, rose, sunflower
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Concept 35.1 The plant body has a heirarchy of
organs, tissues, and cells
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I. Plant organs
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• Above ground
• Stems, leaves

Shoot system

• Underground (usually)
• Roots

Root system
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A. Roots

• Anchors plant, absorbs H2O minerals, stores
  sugars/starches
• Root hairs tiny extensions of epidermal cells,
  increase surface area for H2O and mineral
  absorption
• Mycorrhizae symbiosis with fungi

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Fibrous Roots Taproots
Mat of thin roots spread just below surface One thick, vertical root
Shallow Many lateral (branch) roots
Increased surface area Firmly anchors
Monocots Stores food in root
Dicots
Fibrous Root (scallion)
Taproot (carrot)
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Modified Roots
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Mangrove forest in Florida
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B. Stems

• Alternating system of nodes (leaf attachment) and
  internodes
• Function display leaves
• Terminal bud growth concentrated at apex (tip)
• Apical dominance terminal bud prevents growth of
  axillary buds growth directed upward, toward
  light
• Axillary buds located in V between leaf and
  stem forms branches (lateral shoots)
• Pinching/pruning removing terminal bud

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Modified Stems
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Modified stems

• Runner or stolin
• Aspen, strawberries, grass
• Grow on surface
• For asexual reproduction
• Rhizome
• Iris, ginger, potato, onion
• Grow underground
• Store food DNA for new plant
• Tuber end of rhizome
• Bulb underground shoot
• Onion
• storage leaves

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C. Leaves

• Main photosynthetic organ
• Has blade petiole

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Simple vs. Compounds Leaves
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Modified leaves
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II. Plant Tissues
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Three Tissue Systems
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3 Types of Tissue (Pg. 717)

• Ground Tissue System
• Most extensive, makes up bulk of plant
• Vascular Tissue System
• Conducting tissues that distribute water and
  solutes throughout plant
• Dermal tissue system
• Covers and protects plant surfaces

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A. Dermal Tissue

• Single layer, closely packed cells that cover
  entire plant
• Protect against water loss invasion by
  pathogens
• Cuticle waxy layer
• Epidermis, periderm

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B. Vascular Tissue

• Continuous throughout plant
• Transports materials between roots shoots
• Xylem transport H2O and minerals up from root
• Phloem transports food from leaves to other
  parts of plant

stele
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C. Ground Tissue

• Anything that isnt dermal or vascular
• Function storage, photosynthesis, support
• Pith inside vascular tissue
• Cortex outside vascular tissue

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III. Cell Types

• Parenchyma most abundant
• Perform metabolism, synthesizes stores organic
  products
• Collenchyma grouped in cylinders, support
  growing parts of plant
• Sclerenchyma rigid support cell
• Xylem water conduction
• Tracheids, vessel elements dead, tubular,
  elongated cells
• Phloem sugar, organic cmpd. conduction
• Sieve tubes, plates, companion cells alive
  cells which aid movement of sugar

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PARENCHYMA CELLS
WATER-CONDUCTING CELLS OF THE XYLEM
100 µm
Tracheids
Vessel
Parenchyma cells in Elodea leaf, with
chloroplasts (LM)
60 µm
Pits
COLLENCHYMA CELLS
Cortical parenchyma cells
Tracheids and vessels (colorized SEM)
80 µm
Vessel element
Vessel elements with perforated end walls
Tracheids
SUGAR-CONDUCTING CELLS OF THE PHLOEM
Collenchyma cells (in cortex of Sambucus,
elderberry cell walls stained red) (LM)
Sieve-tube members longitudinal view (LM)
SCLERENCHYMA CELLS
5 µm
Companion cell
Sclereid cells in pear (LM)
Sieve-tube member
25 µm
Plasmodesma
Sieve plate
Cell wall
Nucleus
Cytoplasm
Companion cell
30 µm
15 µm
Fiber cells (transverse section from ash tree)
(LM)
Sieve-tube members longitudinal view
Sieve plate with pores (LM)
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Plant Growth Development

• Growth irreversible increase in mass from cell
  division and expansion
• Development sum of all changes that elaborate an
  organisms body (make it more complex)

Plant Animal
Faster Slower
Mostly H2O Makes new cytoplasm
Indeterminate ? meristems Determinate
Annual (1 year) Biennials (2 years) Perennials (many)
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Concept 35.2 Meristems generate cells for growth

• Meristem perpetually embryonic tissues
• Indeterminate growth (throughout plants life)
• Cell division to make new cells
• Apical meristem growth areas at tips of roots
  buds cause primary growth (increase in length)
• Lateral meristem growth thickens shoots and
  roots secondary growth

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Primary and Secondary Growth
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Concept 35.3 Primary growth lengthens roots and
shoots
Root Hairs
Zone of Maturation growth differentiation
complete fully mature cells
Zone of Elongation cells elongate push root tip
ahead
Zone of Cell Division apical meristem new cells
produced
Root cap protects meristem as it pushes through
soil also secretes polysaccharide lubricant
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Primary Growth of a Root
Cortex
Vascular cylinder
Epidermis
Key
Zone of maturation
Root hair
Dermal
Ground
Vascular
Zone of elongation
Apical meristem
Zone of cell division
Root cap
100 µm
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Primary Growth of Shoots

• Shoot apical meristem dome of dividing cells at
  tip of terminal bud divide and elongate

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Leaf Organization

• epidermis of underside interrupted by stomata
  (pores)
• Mesophyll ground tissue between upper/lower
  epidermis
• Parenchyma sites of photosynthesis

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Concept 35.4 Secondary growth adds girth to stems
and roots in woody plants

• Involves lateral meristems
• Vascular cambium produces secondary xylem (wood)
• Cork cambium produces tough covering that
  replaces epidermis
• Bark all tissues outside vascular cambium

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Primary and Secondary Growth of a Stem
Primary and secondary growth in a two-year-old
stem
Secondary phloem
Vascular cambium
Cork cambium
Late wood
Secondary xylem
Periderm
Early wood
Cork
Epidermis
Pith
Cortex
Primary xylem
Primary phloem
Transverse section of a three-year- old Tilia
(linden) stem (LM)
Vascular cambium
Primary phloem
Vascular cambium
Cortex
Xylem ray
Epidermis
Bark
Primary xylem
Phloem ray
Growth
Pith
0.5 mm
0.5 mm
Xylem ray
Primary xylem
Secondary xylem
Vascular cambium
Secondary phloem
Primary phloem
Cork
First cork cambium
Periderm (mainly cork cambia and cork)
Growth
Primary phloem
Secondary phloem
Secondary xylem (two years of production)
Vascular cambium
Secondary xylem
Vascular cambium
Secondary phloem
Bark
Primary xylem
Most recent cork cambium
Layers of periderm
Pith
Cork