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Chapter 31 and 33
 

Chapter 31 and 33

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More Plant Notes

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    Chapter 31 and 33 Chapter 31 and 33 Presentation Transcript

    • Chapter 31 Plant Structure, Reproduction, and Development (Sections 7 and 8) 0
      • A Gentle Giant
        • Gymnosperms
          • Are one of two groups of seed plants
          • Bear seeds in cones
      0
        • Angiosperms, or flowering plants
          • Are the most familiar and diverse group of plants
      0
    • TALKING ABOUT SCIENCE
      • 31.1 Plant scientist Natasha Raikhel studies the Arabidopsis plant as a model biological system
        • Natasha Raikhel
          • Is one of America’s most prominent plant biologists
      Figure 31.1A
        • Dr. Raikhel works with Arabidopsis
          • A popular model organism for studying biological systems
      Figure 31.1B
    • PLANT STRUCTURE AND FUNCTION
      • 31.2 The two main groups of angiosperms are the monocots and the dicots
        • Monocots and dicots differ in
          • The number of seed leaves and in the structure of roots, stems, leaves, and flowers
      Figure 31.2 Fibrous root system MONOCOTS Seed leaves Leaf veins Stems Flowers Roots One cotyledon Main veins usually parallel Vascular bundles in complex arrangement Floral parts usually in multiples of three Two cotyledons Main veins usually branched Vascular bundles arranged in ring Floral parts usually in multiples of four or five Taproot usually present DICOTS
      • 31.3 A typical plant body consists of roots and shoots
        • A plant’s root system
          • Anchors it in the soil
          • Absorbs and transports minerals and water and stores food
        • The shoot system of a plant
          • Is made up of stems, leaves, and adaptations for reproduction, flowers
        • The body of a dicot
      Figure 31.3 Terminal bud Blade Petiole Axillary bud Stem Taproot Root hairs Epidermal cell Root hair Internode Node Flower Shoot system Root system Leaf
      • 31.4 Many plants have modified roots, stems, and leaves
        • Some plants have unusually large taproots
          • That store food in the form of carbohydrates
      Figure 31.4A
        • Many plants have modified stems
          • That store food or function in asexual reproduction
      Figure 31.4B Strawberry plant Potato plant Stolon (runner) Taproot Rhizome Tuber Ginger plant Rhizome Root
        • Other types of plants have modified leaves
          • That function in protection or climbing
      Figure 31.4C
      • 31.5 Plant cells and tissues are diverse in structure and function
        • Most plant cells have three unique structures
          • Chloroplasts, the sites of photosynthesis
          • A central vacuole containing fluid
          • A cell wall that surrounds the plasma membrane
      Figure 31.5A Chloroplast Central vacuole Cell walls Primary cell wall Middle lamella Secondary cell wall Plasma membrane Cell walls of adjoining cells Plasmodesmata Pit Plasma membrane Microtubules Ribosomes Golgi apparatus Mitochondrion Endoplasmic reticulum Nucleus
        • Plants have five major types of cells
          • Parenchyma, which perform most of the metabolic functions
          • Collenchyma, which provide support
      Figure 31.5B Figure 31.5C Primary cell wall (thin) Pit Starch-storing vesicles LM 270  Primary cell wall (thick) LM 270 
          • Sclerenchyma, the main component of wood
      Figure 31.5D Secondary cell wall Pits Fiber cells Primary cell wall Secondary cell wall Primary cell wall Pits Sclereid cells Fiber Sclereid LM 266  LM 200 
        • Angiosperms have water-conducting cells
          • Tracheids and vessel elements
      Figure 31.5E Pits Openings in end wall Vessel element Tracheids Pits Colorized SEM 150 
        • Sieve-tube members
          • Are food-conducting cells
      Figure 31.5F Sieve plate Companion cell Primary cell wall Cytoplasm
        • Two kinds of vascular tissue are
          • Xylem, which conveys water and minerals
          • Phloem, which transports sugars
      • 31.6 Three tissue systems make up the plant body
        • Each plant organ is made up of three tissue systems
          • The dermal, vascular, and ground tissue systems
      Figure 31.6 Vein Guard cells Cuticle Upper epidermis Mesophyll Lower epidermis Stoma Xylem Phloem Dicot leaf Dicot stem Sheath Vascular bundle Cortex Pith Epidermis Monocot stem Vascular bundle Epidermis Epidermis Vascular cylinder Xylem Phloem Cortex Endodermis Dicot root Key Dermal tissue system Ground tissue system Vascular tissue system
        • The dermal tissue system
          • Covers and protects the plant
        • The vascular tissue system
          • Contains xylem and phloem and provides long-distance transport and support
        • The ground tissue system
          • Consists of parenchyma cells and supportive collenchyma and sclerenchyma cells
    • PLANT GROWTH
      • 31.7 Primary growth lengthens roots and shoots
        • Meristems, areas of unspecialized, dividing cells
          • Are where plant growth originates
        • Apical meristems
          • Are located in the tips of roots and in the terminal and axillary buds of shoots
          • Initiate primary (lengthwise) growth by producing new cells
      Figure 31.7A Terminal bud Axillary buds Root tips Arrows = direction of growth
        • Roots are covered with a root cap
          • That protects the cells of the apical meristem
      Figure 31.7B Vascular cylinder Root hair Cortex Epidermis Zone of maturation Zone of elongation Zone of cell division Root cap Apical meristem region Cellulose fibers Key Dermal tissue system Ground tissue system Vascular tissue system
        • Axillary bud meristems
          • Are found near the apical meristems
      Figure 31.7C Apical meristem Leaves Axillary bud meristems 1 2 LM 103 
      • 31.8 Secondary growth increases the girth of woody plants
        • Secondary growth arises from cell division
          • In a cylindrical meristem called the vascular cambium
        • The vascular cambium thickens a stem
          • By adding layers of secondary xylem, or wood, next to its inner surface
      Figure 31.8A Year 1 Early Spring Year 1 Late Summer Year 2 Late Summer Growth Growth Growth Primary xylem Vascular cambium Primary phloem Cor tex Epidermis Secondary xylem (wood) Cork Cork cambium Secondary phloem Bark Shed epidermis Secondary xylem (2 years’ growth) Key Dermal tissue system Ground tissue system Vascular tissue system
        • The heartwood and sapwood
          • Consist of different layers of xylem
        • Outside the vascular cambium, the bark consists mainly of
          • Secondary phloem, cork cambium, and protective cork cells
      Figure 31.8B Heartwood Sapwood Rings Wood rays Heartwood Vascular cambium Sapwood Secondary phloem Cork cambium Cork Bark
    • Chapter 33 Control Systems in Plants 0
      • What Are the Health Benefits of Soy?
        • Soy protein
          • Is one of the few plant proteins that contains all the essential amino acids
        • Phytoestrogens, a class of plant hormones
          • Are found in soy
      CH 3 OH HO HO O OH OH O Estrogen (Estradiol) Phytoestrogen (Genistein) Chemical structures of a human estrogen and a plant phytoestrogen
        • Soy products contain isoflavones
          • A type of phytoestrogen that may provide human health benefits
      Soybeans
    • PLANT HORMONES
      • 33.1 Experiments on how plants turn toward light led to the discovery of a plant hormone
        • Plants exhibit phototropism
          • The growth of shoots in response to light
      Figure 33.1A
        • Microscopic observations of plants
          • Indicate that a cellular mechanism underlies phototropism
      Figure 33.1B Shaded side of shoot Illuminated side of shoot Light
      • Showing That Light Is Detected by the Shoot Tip
        • Charles Darwin showed that the tip of a grass seedling detects light
          • And transmits a signal down to the growing region of a shoot
      Figure 33.1C Light Control Tip removed Tip covered by opaque cap Tip covered by trans- parent cap Base covered by opaque shield Tip separated by gelatin block Tip separated by mica Darwin and Darwin (1880) Boysen-Jensen (1913)
      • Isolating the Chemical Signal
        • The hormone auxin
          • Was determined to affect phototropism
          • Promotes faster cell elongation on the shaded site of the shoot
      Figure 33.1D Agar Shoot tip placed on agar block. Chemical (later called auxin) diffuses from shoot tip into agar. Other controls: Blocks with no chemical have no effect. Offset blocks with chemical stimulate curved growth. Control Block with chemical stimulates growth. No light
      • 33.2 Five major types of hormones regulate plant growth and development
        • Even in small amounts, plant hormones
          • Trigger signal transduction pathways
          • Regulate plant growth and development
        • The major types of plant hormones
      Table 33.2
      • 33.3 Auxin stimulates the elongation of cells in young shoots
        • Plants produce auxin (IAA)
          • In the apical meristems at the tips of shoots
        • At different concentrations, auxin
          • Stimulates or inhibits the elongation of shoots and roots
      Figure 33.3A, B Roots Stems 0 0.9 g/L   10 – 8 10 – 6 10 – 4 10 – 2 1 10 2 Increasing auxin concentration (g/L) Elongation Inhibition Promotion
        • Auxin may act by weakening cell walls
          • Allowing them to stretch when cells take up water
      Plasma membrane Cell wall H + 1 2 H + 3 H 2 O Vacuole Cell elongation Cellulose loosens; cell can elongate Cellulose molecule Cross-linking molecule Enzyme Cellulose molecule Cell wall Cytoplasm H + pump (protein) Figure 33.3C
        • Auxin promotes growth in stem diameter
          • By stimulating the development of vascular tissues and cell division in vascular cambium
      • 33.4 Cytokinins stimulated cell division
        • Cytokinins
          • Are produced by growing roots, embryos, and fruits
          • Promote cell division
        • Cytokinins from roots may balance the effects of auxin from apical meristems
          • Causing lower buds to develop into branches
      Figure 33.4 Terminal bud No terminal bud
      • 33.5 Gibberellins affect stem elongation and have numerous other effects
        • Gibberellins
          • Stimulate the elongation of stems
      Figure 33.5A
        • Gibberellins
          • Stimulate the development of fruit
          • Function in embryos in some of the early events of seed germination
      Figure 33.5B
      • 33.6 Abscisic acid inhibits many plant processes
        • Abscisic acid (ABA)
          • Inhibits the germination of seeds
        • The ratio of ABA to gibberellins
          • Often determines whether a seed will remain dormant or germinate
        • Seeds of many plants remain dormant
          • Until their ABA is inactivated or washed away
      Figure 33.6
        • ABA also acts as a “stress hormone”
          • Causing stomata to close when a plant is dehydrated
      • 33.7 Ethylene triggers fruit ripening and other aging processes
        • As fruit cells age
          • They give off ethylene, which triggers a variety of aging processes
      • Fruit Ripening
        • Ethylene
          • Triggers fruit ripening
      Figure 33.7A 1 2 3
      • The Falling of Leaves
        • A changing ratio of auxin to ethylene
          • Is triggered by shorter days
          • Probably causes autumn color changes and the loss of leaves from deciduous trees
      Figure 33.7B Leaf stalk Stem (twig) Abscission layer Protective layer Stem Leaf stalk LM 20 
    • CONNECTION
      • 33.8 Plant hormones have many agricultural uses
        • Farmers use auxin
          • To delay or promote fruit drop
      Figure 33.8
        • Auxins and gibberellins
          • Are used to produce seedless fruits
        • A synthetic auxin called 2,4-D
          • Is used to kill weeds
          • Has safety questions associated with its use