Chapter 23: Plant Structures Roots, Stems, Leaves

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Chapter 23 Plant StructuresRoots, Stems, Leaves
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A. 4 MAJOR PLANT ORGANS (ANGIOSPERMS)

• 1. LEAF? PHOTOSYNTHESIS
• 2. STEM? TRANSPORT, SUPPORT OF LEAVES FLOWERS,
  STORAGE (STARCH)
• 3. ROOT? ABSORPTION OF WATER AND MINERALS,
  ANCHORAGE, STORAGE,
• SYNTHESIS OF PROTEINS (RESPIRATION)
• 4. FLOWER? SEXUAL REPRODUCTION (RESPIRATION)

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B. TRANSPORT SYSTEM

• 1. ORGANIC NUTRIENTS? PHLOEM
• 2. WATER MINERALS? XYLEM
• 3. GASES
• 4. WASTES

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NUTRIENT CELLS MECHANISM RESPONSIBLE
1. ORGANIC NUTRIENTS (GLUCOSE/ SUCROSE) PHLOEM? ALIVE SIEVE TUBES COMPANION CELLS BULK-FLOW HYPOTHESIS (PRESSURE FLOW) FOLLOWS CONCENTRATION GRADIENT FROM LEAF ? ROOT, STEM, OR FLOWER COMPANION CELLS ? TRANSLOCATION
2. WATER MINERALS XYLEM? DEAD VESSEL CELLS TRACHEIDS COHESION-TENSION THEORY (PUSH/PULL) ROOT ? LEAF, STEM, OR FLOWER
3. GASES LEAF STOMA? CONTROLLED BY GUARD CELLS WATER EVAPORATION- TRANSPIRATION? DIFFUSION OF CO2 H2O IN AND OUT
4. WASTES ALL CELLS DIFFUSION GAS WASTES THRU LEAF STOMA SOME WASTES EXCRETED BY ROOT SYSTEM
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Xylem Cells
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Phloem Cells
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LEAF ANATOMY CROSS SECTION
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STOMA GUARD CELLS

• WHEN LIGHT IS PRESENT,
• PHOTOSYNTHESIS IS GOING ON IN GUARD CELLS
• GUARD CELLS
• BECOME HYPERTONIC
• TO SURRONDING CELLS AND TAKE IN H2O
• THEY BECOME TURGID (FULL), WHICH OPENS THE
• STOMA.
• WHEN NO LIGHT, NO PHOTOSYNTHESIS
• GUARD CELLS COLLAPSE
• (FLACID), CLOSE STOMA

Epidermal cells No chloroplast
Chloroplast
VIEW OF BOTTOM OF LEAF- LOWER EPIDERMIS
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3. COHESION-TENSION THEORY

• FACTORS RELATED TO XYLEM TRANSPORT
• 1. TRANSPIRATION? LOSS OF WATER FROM LEAF DUE
  TO EVAPORATION (DUE TO CO2
• INTAKE)
• 2. COHESION? ATTRACTION OF LIKE MOLECULES
  WATER MOLECULES ARE POLAR
• (CHARGED)

Hydrogen Bond
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CONT. FACTORS RELATED TO XYLEM TRANSPORT

• 3. ADHESION? ATTRACTION OF UNLIKE MOLECULES-
  ATTRACTION OF H2O TO SIDES OF XYLEM CELLS
  (RESULTS IN CAPILLARY ACTION)
• 4. ROOT PRESSURE? FORCE EXERTED FROM ROOTS AS A
  RESULT OF H2O ABSORPTION (OSMOSIS)
• ROOT CELLS ARE HYPERTONIC TO SOIL
• 5. OSMOSIS? MOVEMENT OF WATER FROM A REGION OF
  GREATER TO LESSER WATER CONCENTRATION, THROUGH
  SEMI-PERMEABLE MEMBRANE
• ROOT EPIDERMAL CELLS ARE HYPERTONIC TO SOIL (H2O
  ENTERS CELLS)
• A CONTINUOUS COLUMN OF H2O IS PRODUCED
  THROUGHOUT PLANT DUE TO THESE PHYSICAL FORCES
  WORKING AT THE SAME TIME

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• ROOT HAIRS INCREASE SURFACE AREA FOR ABSORPTION.
  
• - H2O IS PUSHED BY THE ROOTS, PULLED BY THE
  LEAVES

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MONOCOT STEMS

MONKEY FACE ? VASCULAR BUNDLES

• MONOCOT PLANTS
• 1. ONE COTYLEDON (CORN, GRASSES, SUGAR CANE,
  BAMBOO)
• 2. LACK PERMANENT CAMBIUM
• 3. SCATTERED VASCULAR BUNDLES
• 4. PARALLEL VEINS (LEAF)
• 5. FIBROUS ROOT (BRANCHING)

? support
pith cortex
supporting tissue
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DICOT STEMS

• DICOT PLANTS
• 1. TWO COTYLEDONS (BEAN)
• 2. PERMANENT CAMBIUM
• 3. VASCULAR BUNDLES ARRANGED IN CIRCLE AROUND
  CAMBIUM
• 4. NETTED VEINS (LEAF)
• 5. TAP ROOT (LIKE CARROT)

(pith)
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DICOT MONOCOT STEMS
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DICOT ROOT
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MONOCOT ROOT
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D. MOVEMENT OF ORGANIC NUTRIENTS (PHLOEM)

• PRESSURE-FLOW OR BULK-FLOW HYPOTHESIS
• 1. PLANT NUTRIENTS MOVE FROM AN AREA OF GREATER
  TO LESSER CONCENTRATION OF
• THAT NUTRIENT
• LEAF
• GLUCOSE ? SUCROSE
• (PGAL) (STORAGE)

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PRESSURE-FLOW OR BULK-FLOW HYPOTHESIS
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• 2. LEAF REPRESENTS AREA OF HIGHER CONCENTRATION
  OF GLUCOSE OR SUCROSE.
• GLUCOSE FLOWS THROUGH PHLOEM SIEVE TUBE CELLS
  FROM LEAVES TO OTHER PLANT ORGANS HAVING LOWER
  CONCENTRATIONS
• A) STEMS CELL RESPIRATION
• B) FLOWERS CONSUMES GLUCOSE
• C) ROOTS CONVERT IT TO ATP