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Chapter 23: Plant Structures Roots, Stems, Leaves

Chapter 23: Plant Structures Roots, Stems, Leaves. Higher Level Vascular Plants. 1. Gymnosperms (cone-bearing)/ “naked seeds” 1 st seed plants Reduced gametophytes Depend on wind-pollination 2. Angiosperms (flowering plants) 90% of all living species Greatly reduced gametophytes

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Chapter 23: Plant Structures Roots, Stems, Leaves

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  1. Chapter 23: Plant StructuresRoots, Stems, Leaves

  2. Higher Level Vascular Plants 1. Gymnosperms (cone-bearing)/ “naked seeds” • 1st seed plants • Reduced gametophytes • Depend on wind-pollination 2. Angiosperms (flowering plants) • 90% of all living species • Greatly reduced gametophytes • Depends on self/ cross-pollination • Double fertilization (zygote; endosperm) • 2 classes: monocots & dicots

  3. Plant Tissues • DERMAL outermost layer of cells (protect) - consist of single layer of epidermal cells - ex: cork cells, root hair cells, guard cells 2. VASCULAR plant’s bloodsteam - ex: xylem & phloem 3. GROUND cells that lie b/t dermal & vascular - makes up bulk of plants - parenchyma makes up most of ground ex: can store food (roots)/ palisade mesophyll cells photosynthesis - collenchyma & sclerenchyma support

  4. 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)

  5. B. TRANSPORT SYSTEM 1. ORGANIC NUTRIENTSPHLOEM 2. WATER & MINERALSXYLEM 3. GASES 4. WASTES

  6. Phloem Cells LIVING CELLS!!! 1. Sieve tube elements (STE) (main ones) cells walls have small holes/ food & sugars carried in watery stream 2. Companion cells support STE and aids in movement of substances in/ out of cell

  7. Xylem Cells DEAD CELLS! Tracheids long, narrow tubes w/ walls impermeable to H20 Vessel Elements (VE) much wider, continuous tubes thru which H2O can move freely

  8. LEAF ANATOMY CROSS SECTION

  9. 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 (FIRM), WHICH OPENS THE STOMA. • WHEN NO LIGHT, NO PHOTOSYNTHESIS • GUARD CELLSCOLLAPSE (FLACID), CLOSE STOMA Epidermal cells *No chloroplast *Chloroplast ***VIEW OF BOTTOM OF LEAF- LOWER EPIDERMIS

  10. 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

  11. 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 WATERCONCENTRATION, 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

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

  13. MERISTEMS zones of actively dividing cells • Apical meristems located at tips of roots and shoots (stems) - Primary growth (increase in length) - found in mono- & dicots 2. Lateral meristems located near the perphery of plants (usu in cylinder) - Secondary growth (increase in girth) a. Vacular cambium- produces secondary xylem & phloem b. Cork cambium- produces cells of outer bark

  14. Root Cap cover at tip of root/ protects apical meristem as root pushes thru soil (primary growth)

  15.  H2O proof, prevents backflow of H2O out of vas cylinder into root cortex

  16. MONOCOT STEMS *** “MONKEY FACE”  VASCULAR BUNDLES MONOCOT PLANTS: 1. ONE COTYLEDON (CORN, GRASSES, SUGAR CANE, BAMBOO) 2. LACK PERMANENT CAMBIUM (2NDARY GROWTH ABSENT) - HERBACEOUS--> NONWOODY, GREEN & FLEXIBLE STEMS 3. SCATTERED VASCULAR BUNDLES 4. PARALLEL VEINS (LEAF) 5. FIBROUS ROOT (BRANCHING) 6. FLOWER PARTS IN 3’S 7. STEM VASCULAR BUNDLES SCATTERED  support pith & cortex supporting tissue

  17. DICOT STEMS • DICOT PLANTS 1. TWOCOTYLEDONS (BEAN) 2. PERMANENT CAMBIUM (2NDARY GROWTH- WOODY) 3. VASCULAR BUNDLES ARRANGED IN CIRCLE AROUND CAMBIUM 4. NETTED VEINS (LEAF) 5. TAP ROOT(LIKE CARROT) 6. FLOWER PARTS IN 4 OR 5’S (pith)

  18. DICOT & MONOCOT STEMS

  19. DICOT ROOT

  20. Dicot Root

  21. MONOCOT ROOT

  22. D. MOVEMENT OF ORGANIC NUTRIENTS (PHLOEM) • PRESSURE-FLOW OR BULK-FLOW HYPOTHESIS 1. PLANT NUTRIENTS MOVE FROM AN AREA OF GREATER TO LESSERCONCENTRATION OF THAT NUTRIENT LEAF: GLUCOSE  SUCROSE (PGAL) (STORAGE) ***SINK  cell where sugars are used/ stored (roots, stems, flowers) ***SOURCE cells that produce sugars (leaf)

  23. 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

  24. PRESSURE-FLOW OR BULK-FLOW HYPOTHESIS

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