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Download Outline 35,36,39 - Mead`s Fabulous Weebly
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AP Biology Lap 8B Plant Structures and Function Chapters 35, 36, 39 35.1 Plant Body A. 3 Basic Plant Organs Vascular tissue ◦ Connects root system and stem system (stems and leaves) ◦ Xylem ◦ Phloem ◦ Monocots vs Eudicots Fig 30.12 p603 Roots ◦ Function ◦ Taproot ◦ Fibrous roots ◦ Root hairs ◦ Mycorrhizae ◦ Root nodules ◦ Modified Roots, Fig 35.4 Stems ◦ Nodes ◦ Internodes ◦ Axillary buds ◦ Terminal bud ◦ Apical dominance ◦ Modified stems, Fig 35.5 Leaves ◦ Function ◦ Blade ◦ Petiole ◦ Veins ◦ Simple, Fig 35.6 ◦ Compound Leaflet ◦ Modified leaves, Fig 35.7 Tendrils Spines Storage Bracts Reproductive B. Types of Plant Cells, Fig 35.9 Parenchyma Collenchyma Sclerenchyma Water conducting cells of Xylem ◦ Tracheids ◦ Vessel elements Food conducting cells of Phloem ◦ Sieve tube members ◦ Companion cells C. 3 Levels of tissue organization Dermal ◦ Epidermis ◦ Root hairs ◦ Cuticle Vascular ◦ Xylem ◦ Phloem Ground 35.2 Meristems and Growth A. Indeterminate growth ◦ Embryonic, developing and maturing tissue ◦ Determinate growth of animals B. 3 types of life cycles ◦ Annuals ◦ Biennials ◦ Perennials C. Meristem: embryonic tissue ◦ Initials and derivitives ◦ Apical meristem, Fig 35.10 ◦ Lateral meristem ◦ Primary growth Apical meristem Herbaceous plants ◦ Secondary growth Lateral meristem Woody plants Vascular cambium Cork cambium 35. 3 Primary Growth A. Roots, Fig 35.12 ◦ 3 zones of growth 1. Zone of cell division Apical meristem Primary meristems Quiescent center Protoderm epidermis Procambium vascular cylinder Ground meristem ground tissue Parenchyma and cortex 2. Zone of elongation 3. Zone of maturation ◦ Monocot and Eudicot, Fig 35.13 ◦ Endodermis ◦ Formation of lateral roots, fig 35.14 Arises from pericycle B. Shoots ◦ Shoot apical meristem, Fig 35.15 Leaf primordia Axillary buds ◦ Primary tissue of stems, Fig 35.16 No central vascular cylinder Monocot and Eudicot ◦ Primary tissue of leaf, Fig 35.17 Dermal: Epidermis/cuticle Stomata and guard cells Vascular tissue: xylem and phloem Ground tissue Spongy and Palisade Mesophyll Parenchyma cells 35.4 Secondary Growth A. Lateral meristems B. 2 types ◦ Vascular cambium Secondary xylem: Wood Secondary phloem: Bark ◦ Cork cambium Produces cork Primary meristems 1. Primary tissues Lateral meristems 1a. 2a. Apical Meristem 2. 2d. 2c. 2b. 3. Secondary tissues 3a. 2e. 3b. 3c. 36.2 Roots Absorb Water and Minerals A. Adaptations that Increase Surface Area ◦ Increases absorption ◦ Near root tips ◦ Root hairs Soil solution adheres Epidermal cell walls Cortex parenchyma cells Selectively permeable membrane ◦ Mycorrhizae Fungal symbiosis Fig 36.10 ◦ Lateral transport of water/minerals in root, Fig 36.9 1. Apoplastic route: soil solution moves into cell walls and travels inward 2. Symplastic route: solution moves into the cells -Into the symplast -Through plasmodesmata 3. Water and minerals continue to move into symplast 4. Casparian strip: waxy strip that blocks passageway of water and minerals a. Can only enter through symplast b. Must cross plasma membrane of endodermal cells and enter symplast 5. Water and minerals pass into cell walls of xylem and move upwards B. Endodermis ◦ Surrounds vascular cylinder ◦ Contains Casparian strip ◦ Forces water to pass over selectively permeable membrane selective transport ◦ Prevents solutes in xylem from leaking out 36.3 Transport of Xylem Sap A. Pushing Xylem Sap: Root Pressure ◦ Root cells use energy to pump ions into xylem ◦ Water flows into xylem to equalize concentration ◦ Positive pressure builds up = root pressure ◦ Can cause gluttation, Fig 36.11 B. Pulling Xylem Sap: Transpiration-Cohesion-Tension Mechanism 1. Transpirational Pull Air spaces in mesophyll cells contain water vapor Water diffuses out of leaf through stomata Negative pressure/tension generates in leaf Water evaporates from surface of mesophyll cells Causes water film to shrink Increases tension Tension pulls water out of xylem 2. Cohesion and Adhesion of Water Transpiration pull transmitted from leaves to roots Cohesion Def Result Adhesion Def Result Tracheid Vessel element cells 3. Water uptake from soil B. Bulk Flow, Fig 36.13 36.4 Regulation of Transpiration A. Guard Cells 1. Photosynthesis-Transpiration Compromise a. Stomata lead to air spaces CO2 into meosphyll Internal surface area Increases photosynthesis Also increases evaporation 90% water loss b. Transpiration stream: water in xylem Replaces water lost in leaves Assists transfer of minerals Aids in evaporative cooling of leaves c. Replace with water from soil If available no problem d. Plants have mechanisms to combat transpiration and strike balance: Transpiration-Photosynthesis Compromise 2. Factors that affect evaporation Sunny, warm, dry, windy 3. How guard cells open and close Surround stomata, Fig 36.14 and 36.15 a. Water open and closes stomata Guard cells take in water Become turgid and swell Buckle outward Stomata open Lose water flaccid close b. Transport of K+ ions Causes tugor changes K+ moves in cells Water moves in open K+ moves out cells Water moves out closed c. Usually open in day and closed at night d. Cues to open at dawn e. Environmental stress can cause stomata to close during day B. Xerophytes ◦ Adaptations that reduce transpiration ◦ Arid climates ◦ Leaves ◦ CAM plants: Alternate photosynthesis Fig 10.20 p197 Takes in CO2 at night Runs Calvin cycle during day 36.5 Translocation of Phloem Sap A. Translocation ◦ Def ◦ Sieve tube members ◦ Phloem sap B. Sugar source Sugar sink ◦ Direction is variable ◦ Always from sugar source ◦ To sugar sink C. Phloem loading and uploading, Fig 36.17 ◦ Moves by symplast route from mesophyll cells to sieve-tube members ◦ Moves by chemiosmosis powered by proton pump D. Pressure Flow is Mechanism ◦ Fig 36. 18 1. Phloem loading causes high [solute] at source ◦ Water moves into tube 2. Water pressure builds ◦ Sap is pushed 3. Pressure is relieved at sink ◦ Solute leaves tube into sink 4. Water recycled through xylem 39.1 Signal Transduction Pathways A. 3 steps, Fig 39.3 ◦ Reception ◦ Transduction ◦ Response B. Example: Role of phytochrome in the greening response, Fig 39.4 39.2 Plant Hormones A. Discovery of Plant Hormones ◦ Research on growth and light ◦ Phototropism ◦ Studies of grass seedlings, Fig 39.5 Control Darwin and Darwin Tip removed Tip covered-opaque cap Tip covered-clear cap Base covered-opaque cap Conclusion Boysen-Jensen Tip separated by gel Tip separated by mica Conclusion ◦ Went Fig 39.6 Auxin as messenger Differential effect B. Horomones, Table 39.1 1. Auxin Function Stimulates root growth Developing seeds Make “seedless” fruit 2. Cytokinin Function Stimulate cell division Work with auxin Need both Ratio important Control of apical dominance Work with auxin Checks and balance Anti-aging hormone Inhibit protein breakdown Stimulate RNA and translation 3. Gibberellin Stem elongation Fruit growth, Fig 39.10 Work with auxin Germination, Fig 39.11 High concentration in seed Follows imbibition Causes release of enzymes 4. Brassinosteroids Steroids Growth and devlopment 5. Abscisic Acid Produced in terminal bud Slows growth Stimulates dormancy Fig 39.12 Inhibits secondary growth Drought resistance Role in stomata closure 6. Ethylene Inhibits cell elongation Associated with senescence Apoptosis Triple Response to mechanical stress, Fig 39.13 Avoid obstacles 1. Slow elongation 2.Thicken 3. Curve to horizontal Fruit Ripening Cell walls soften Chlorophyll drops Positive feedback Leaf Abscission Work with auxin Fig 39.16 39.3 Responses to Light A. Light receptors ◦ Blue-light receptors Role in phototropism Light-induced stomata opening Light-induced slowing of hypocotyl growth when it breaks surface ◦ Phytochromes Role in germination and shade avoidance ◦ Lead to responses B. Biological Clocks and Circadian Rhythms ◦ Def ◦ Internal clock ◦ Sleep movements, Fig 39.21 C. Photoperiodism ◦ Def ◦ Control of flowering Short-day plants Long-day plants Experiment 39.22 Critical night length ◦ Flowering hormone? Experiment, Fig 39.24 Expose only one leaf to light Plant flowers ◦ Meristem transition and flowering Combination of environmental and internal cues Photoperiod and hormones Change gene expression to cause flowering Turn “on” gene 39.4 Response to Other Stimuli A. Gravity ◦ Gravitropism ◦ Roots show positive ◦ Shoots show negative ◦ Settling of statoliths B. Mechanical Stimuli ◦ Thigmotropism Def Examples ◦ Touching alters growth Fig 39.26 ◦ Touch sensitive plants Rapid leaf movements Fig 39.27 Mimosa C. Response to stress ◦ Drought Conserve water Decrease transpiration Reduces photosynthesis Root growth effect ◦ Flooding or Oxygen deprivation Too much water in soil O2 is low ◦ ◦ ◦ ◦ Fig 39.28 Salt stress Produce compounds to increase solute concentration Heat stress Transpiration and evaporative cooling Heat shock proteins Cold stress Alter composition of lipid membrane to retain fluidity Increase unsaturated fatty acids Response to Herbivores Physical defenses Chemical defenses Recruit predatory animals Fig 39.29
