Chapter 22                                     Transport and                                    Nutrition in Plants       ...
Plants Are Organized to    Transport Water      and Solutes                          22-2
22.1 Transport begins in both the leaves and the roots of plants Xylem   Carries water and minerals from the roots to   ...
22.1 Transport begins in both the leaves and the roots of plants Phloem   Transports sugar to all parts of the plant   ...
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.                              ...
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.                              ...
HOW SCIENCE PROGRESSES22A Competition for resources is   one aspect of biodiversity Minnesota grasslands often harbor mor...
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.   Copyright © The McGraw-Hill...
Figure 22A.3 Results of a study linking water availability to biodiversity                                                ...
Xylem Transport Depends on   the Properties of Water                             22-10
22.2 Water is pulled up in xylem   by evaporation from leaves How is it possible for water to rise to the  top of a plant...
Figure 22.2A Conducting cells of xylem                                Copyright © The McGraw-Hill Companies, Inc. Permissi...
Figure 22.2A Conducting cells of xylem (Cont.)               Copyright © The McGraw-Hill Companies, Inc. Permission requir...
Figure 22.2B Guttation                         22-14
22.2 Water is pulled up in xylem   by evaporation from leaves Cohesion-Tension Model   Requires no expenditure of energy...
22.2 Water is pulled up in xylem   by evaporation from leaves What happens in the leaf?   Evaporation of water through l...
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.                              ...
Figure 22.2C            Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.   Coh...
22.3 Guard cells regulate         water loss at leaves Stoma (pl., stomata) – small pore in leaf  epidermis bordered by m...
Figure 22.3A A stoma opens when turgor pressure increases in guard     cells due to the entrance of K+ followed by the ent...
Figure 22.3B A stoma closes when turgor pressure decreases due to             the exit of K+ followed by the exit of water...
22.3 Guard cells regulate        water loss at leaves 3 other factors aside from water  availability regulate whether sto...
HOW BIOLOGY IMPACTS OUR LIVES 22B Plants Can Clean Up Toxic Messes Phytoremediation   Use of plants to clean up pollutan...
Figure 22B Scientist Gary Bañuelos in a field of canola plantsCanola plants are grown in California’s San JoaquinValley to...
Phloem Function Depends on Membrane Transport                          22-25
22.4 Pressure flow explains         phloem transport Plants transport the organic molecules resulting  from photosynthesi...
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.                              ...
22.4 Pressure flow explains         phloem transport Pressure-flow model   Explanation for the movement of organic    ma...
Figure 22.4B Bulk flow due to a pressure gradient                   Copyright © The McGraw-Hill Companies, Inc. Permission...
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.                              ...
Plants Require Good Nutrition   and Therefore Good Soil                            22-31
22.5 Certain nutrients are         essential to plants Approximately 95% of a typical plant’s dry  weight is carbon, hydr...
22.5 Certain nutrients are         essential to plants Minerals as Nutrients    Essential nutrients divided into       ...
Figure 22.5A                                                                Overview of                                   ...
22-35
22-36
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.                              ...
Figure 22.5B Effects                                                                                     of nutrient defic...
22.6 Roots are specialized for the  uptake of water and minerals Soil is a mixture of mineral particles (sand, silt,  and...
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.                              ...
22.6 Roots are specialized for the  uptake of water and minerals In order for water to reach the xylem of a root, it  mus...
Figure 22.6B Apoplast and symplast routes                  Copyright © The McGraw-Hill Companies, Inc. Permission required...
Figure 22.6B Apoplast and symplast route of uptake (cont.)                 Copyright © The McGraw-Hill Companies, Inc. Per...
22.7 Adaptations of plants help     them acquire nutrients Root Nodules   Some plants, such as legumes, soybeans, and al...
Figure 22.7A Root nodules               Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction o...
Figure 22.7B Mycorrhizae result in better growth                       Copyright © The McGraw-Hill Companies, Inc. Permiss...
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.                              ...
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.                              ...
Connecting the Concepts:           Chapter 22 The evolution of a transport system was critical,  however, in order for pl...
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Bio 100 Chapter 22

  1. 1. Chapter 22 Transport and Nutrition in Plants Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  2. 2. Plants Are Organized to Transport Water and Solutes 22-2
  3. 3. 22.1 Transport begins in both the leaves and the roots of plants Xylem  Carries water and minerals from the roots to the leaves  In addition to other cell types, 2 types of nonliving conductive cells  Tracheids – tapered at both ends, ends overlap, and pits allow water to pass between tracheids  Vessel elements – long and tubular with perforation plates at each end, form a completely hollow pipeline from roots to leaves 22-3
  4. 4. 22.1 Transport begins in both the leaves and the roots of plants Phloem  Transports sugar to all parts of the plant  Composed of several cell types  Sieve-tube members – living conducting cells, contain cytoplasm but have no nucleus  Companion cells – provide proteins to sieve-tube members Water is a large part of xylem sap and phloem sap 22-4
  5. 5. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 22.1 A plant΄s transport system water (blue = phloem; sugar pink =sugar; xylem red = xylem; phloem light blue = water) stoma O2 CO 2 H2O Phloem is transporting sugar from the leaf to the root. sugar H2O 22-5
  6. 6. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 22.1 A plant΄s transport system (blue = phloem; pink =sugar; red = xylem; light blue = water) Xylem transports water and minerals from the root to the leaf. sugar H2O H2O xylem phloem Root 22-6
  7. 7. HOW SCIENCE PROGRESSES22A Competition for resources is one aspect of biodiversity Minnesota grasslands often harbor more than 100 plant species within only a few hectares Competing for soil nitrogen and ability to disperse Mathematical model showed that stable coexistence of a whole range of plant species that differ according to their abilities to compete for nitrogen and to disperse to new areas Found high biodiversity buffers ecosystems against a distrubance 22-7
  8. 8. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Good disperser Poor disperser Good competitor for nitrogen Poor competitor for nitrogenFigure 22A.1 Little bluestem Figure 22A.2 Bent grass 22-8
  9. 9. Figure 22A.3 Results of a study linking water availability to biodiversity Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 Proportion of Pre-Drought Biomass 1/2 1/4 1/8 1/16 0 5 10 15 20 25 Plant Species Richness During Drought 22-9
  10. 10. Xylem Transport Depends on the Properties of Water 22-10
  11. 11. 22.2 Water is pulled up in xylem by evaporation from leaves How is it possible for water to rise to the top of a plant?  Root pressure  Water entering root cells creates a positive (internal) pressure compared to the water in the surrounding soil  May contribute to upward movement, but not the primary mechanism  Guttation – drops of water are forced out of vein endings along the edges of leaves 22-11
  12. 12. Figure 22.2A Conducting cells of xylem Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Vessel Element Vessel Element Single, large opening Series of openings 20 µm 20 µm (both): Courtesy Wilfred A. Cote, from H.A. Core, W.A. Cote, and A.C. Day, “Wood: Structure and Identification” 2/e pits 22-12
  13. 13. Figure 22.2A Conducting cells of xylem (Cont.) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Tracheids pits 50 µm Courtesy Wilfred A. Cote, from H.A. Core, W.A. Cote, and A.C. Day, “Wood: Structure and Identification” 2/e 22-13
  14. 14. Figure 22.2B Guttation 22-14
  15. 15. 22.2 Water is pulled up in xylem by evaporation from leaves Cohesion-Tension Model  Requires no expenditure of energy by the plant and is dependent on the properties of water  Cohesion – tendency of water molecules to cling together  Water molecules form a continuous water column in xylem, from the leaves to the roots  Adhesion – ability of water to interact with the molecules making up the walls of the vessels in xylem  Gives the water column extra strength and prevents it from slipping back 22-15
  16. 16. 22.2 Water is pulled up in xylem by evaporation from leaves What happens in the leaf?  Evaporation of water through leaf stomata is called transpiration  At least 90% of the water taken up by the roots is eventually lost by transpiration  Transpiration exerts a pulling force, or tension, that draws the water column through the xylem to replace the water lost by leaf cells What happens in the root?  Due to the active transport of minerals into the root water enters root hairs passively by osmosis, and from there it enters xylem 22-16
  17. 17. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 22.2C Cohesion-tension model of xylem transport mesophyll xylem cells 1 Leaves stoma •Transpiration creates tension. intercellular •Tension pulls the water space column upward from the H2 O roots to the leaves. cohesion due to hydrogen bonding between water molecules adhesion due to polarity of water molecules cell wall water molecule (tree): © Paul Davies/Alamy 22-17
  18. 18. Figure 22.2C Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cohesion-tension model of xylem transport 2 Stem •Cohesion makes water column continuous. •Adhesion keeps water column in place. xylem root hair3 Roots •Water enters xylem at root. •Water column extends from leaves xylem (tree): © Paul Davies/Alamy 22-18
  19. 19. 22.3 Guard cells regulate water loss at leaves Stoma (pl., stomata) – small pore in leaf epidermis bordered by modified epidermal cells called guard cells  Water enters the guard cells stoma opens  Water exits the guard cells stoma closes Entrance of K+ into guard cells creates osmotic pressure causing water to follow and stoma opens  Stoma closes when turgor pressure decreases due to the exit of K+ followed by the exit of water 22-19
  20. 20. Figure 22.3A A stoma opens when turgor pressure increases in guard cells due to the entrance of K+ followed by the entrance of water Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H2O H2Ovacuole K+guard cell stoma K+ enters guard cells and water follows. 25 µm (Right): © Jeremy Burgess/SPL/Photo Researchers, Inc. 22-20
  21. 21. Figure 22.3B A stoma closes when turgor pressure decreases due to the exit of K+ followed by the exit of water Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H2O H2O K+ K+ enters guard cells and water follows. 25 µm (Right): © Jeremy Burgess/SPL/Photo Researchers, Inc 22-21
  22. 22. 22.3 Guard cells regulate water loss at leaves 3 other factors aside from water availability regulate whether stomata open or close 1. Presence of light causes stomata to open 2. High concentration of CO2 causes stomata to close 3. Abscisic acid (ABA) by cells in wilting leaves causes stoma to close 22-22
  23. 23. HOW BIOLOGY IMPACTS OUR LIVES 22B Plants Can Clean Up Toxic Messes Phytoremediation  Use of plants to clean up pollutants 2 basic ways plants clean up sites 1. Organics broken down by plants or microbes, remainder absorbed by plant or left in soil 2. Inorganics absorbed and trapped inside plant, plant then harvested to be disposed of or reclaimed Limitations of phytoremediation  Slow pace, shallow depth (roots)  Will not work on lead and other metals unless other chemicals are added to the soil 22-23
  24. 24. Figure 22B Scientist Gary Bañuelos in a field of canola plantsCanola plants are grown in California’s San JoaquinValley to soak up excess selenium in the soil 22-24
  25. 25. Phloem Function Depends on Membrane Transport 22-25
  26. 26. 22.4 Pressure flow explains phloem transport Plants transport the organic molecules resulting from photosynthesis to the parts of plants that need them Aphids and radioactive 14C tracers are used to follow sugar from source to sink  Aphids are phloem feeders and are used to extract sap from phloem  Sap movement through phloem can be as fast as 60– 100 cm per hour and possibly up to 300 cm per hour 22-26
  27. 27. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 22.4A Aphid acquiring phloem sap Under microscope waste due to feeding on phloem sap An aphid feeding on a plant stem 22-27(top): © Bruce Iverson/SPL/Photo Researchers, Inc.; (bottom):From M.H. Zimmerman "Movement of Organic Substances in Trees" in SCIENCE 133 (13) January 1961
  28. 28. 22.4 Pressure flow explains phloem transport Pressure-flow model  Explanation for the movement of organic materials throughout the plant in phloem  Flow Is from a Source to a Sink  During the growing season, leaves photosynthesize and are a source of sugar  Roots, which are growing, are a sink for sugar  Transport of Sugar  Transport can account for any direction of flow in sieve tubes if we consider that the direction of flow is always from source to sink 22-28
  29. 29. Figure 22.4B Bulk flow due to a pressure gradient Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. pressure flow of solution 2Bulb1: H2O Bulb2:concentrated dilutesucrose sucrosesolution solution 1 H2O H2O 3 differentially permeable membranes 22-29
  30. 30. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 22.4C The pressure-flow model of phloem transport says that sugar is transported in phloem from a source (e.g., water sugar photosynthesizing leaves) to a sink (e.g., palisade mesophyll actively metabolizing roots) cell of leaf Leaf 7 phloem xylem 1 2 sugar water xylem phloem 6 3 4 cortex cell 5 of root 22-30 xylem phloem Root
  31. 31. Plants Require Good Nutrition and Therefore Good Soil 22-31
  32. 32. 22.5 Certain nutrients are essential to plants Approximately 95% of a typical plant’s dry weight is carbon, hydrogen, and oxygen Minerals as Nutrients  Mineral – inorganic substance usually containing two or more elements needed to help build molecules  Essential nutrients  Has an identifiable role  No other nutrient can substitute and fulfill the same roll  A deficiency of this nutrient causes a plant to die or fail to complete its reproductive cycle 22-32
  33. 33. 22.5 Certain nutrients are essential to plants Minerals as Nutrients  Essential nutrients divided into  Macronutrients – needed in large quantity  Micronutrients – needed in trace amounts  Beneficial nutrients either are required for or enhance the growth of a particular plant Hydroponics allows plants to grow in water, instead of soil, if they are supplied with all the nutrients they need 22-33
  34. 34. Figure 22.5A Overview of plant nutrition Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Water evaporatesfrom leaves. H2 O CO2 Macro Micro Carbondioxide O2 enters photo- synthesizing Cu Zn Cl Mo C HOP KNS Ca Fe Mg B Mn leaves.Oxygen escapes from C Hopkins Cafe Managed By Mine Cousin Clyde Mophotosynthesizing leaves. Water enters roots. H2 0 CO2 O2 Minerals enter roots.Oxygen enters and mineralscarbondioxide exitsrespiring roots. 22-34
  35. 35. 22-35
  36. 36. 22-36
  37. 37. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 22.5B Effects of nutrient deficienciessolution lacks nitrogen complete nutrition solutionCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.solution lacks phosphorus complete nutrition solution 22-37 (both): Courtesy Mary E. Doohan
  38. 38. Figure 22.5B Effects of nutrient deficiencies (cont.) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.solution lacks calcium complete nutrition solution Courtesy Mary E. Doohan 22-38
  39. 39. 22.6 Roots are specialized for the uptake of water and minerals Soil is a mixture of mineral particles (sand, silt, and clay), decaying organic material, living organisms, air, and water, which together support the growth of plants Soil that contains a high percentage of decomposing organic material is called humus A soil profile is a vertical section of soil, from the ground surface to the unaltered rock below. Usually, a soil profile has parallel layers known as horizons 22-39
  40. 40. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. negatively charged soil particle cortex K+ Soil horizonsTopsoil :humus K+ K+ A Ca2+plus livingorganisms root hair Ca2+Zone of leaching: K+ Ca2+removal of nutrientsSubsoil: B K+accumulation Ca2+of minerals andorganic materials Ca2+ K+ film of waterParent material:weathered rock C epidermis of root air spacea.Simplified soil profile b. Minerals in soil Figure 22.6A Simplified soil profile and minerals in soil 22-40
  41. 41. 22.6 Roots are specialized for the uptake of water and minerals In order for water to reach the xylem of a root, it must pass through the cortex in one of two ways  Apoplast route – between cells  Symplast route – through cells using plasmodesmata Regardless of pathway, water enters root cells by aquaporins Minerals are actively taken up by plant cells  Astonishing ability to concentrate minerals  Ions need to be actively transported into plant cells 22-41
  42. 42. Figure 22.6B Apoplast and symplast routes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. endodermis pericycle phloem xylem cortex 50 µm vascular cylinder pericycle endodermis andCasparian strip cortex epidermis apoplast route of water and symplast route minerals of water and a. root hair minerals (Top left): © CABISCO/Phototake 22-42
  43. 43. Figure 22.6B Apoplast and symplast route of uptake (cont.) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 An ATP-driven 2 The electrochemical Endodermal Cell pump transports gradient causes K+ H+ outofcell. to enter by way of a H+ I– I– channel protein. K+ H+ K + I– I–ATP H+ ADP + P K+ H+ K + I– K + H+ I– K+ H+ H+ H+ 3 Negatively charged ions (I–) are transported Water Outside Endodermal Cell along with H+ into cellb. 22-43
  44. 44. 22.7 Adaptations of plants help them acquire nutrients Root Nodules  Some plants, such as legumes, soybeans, and alfalfa, have roots colonized by Rhizobium bacteria  Rhizobium can reduce atmospheric nitrogen (N2) to NH4+ for incorporation into organic compounds Mycorrhizae  Involves fungi and almost any type of plant root  Fungus increases the surface area available for mineral and water uptake and breaks down organic matter in soil 22-44
  45. 45. Figure 22.7A Root nodules Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. root nodule bacteria Portion of infected cell (root nodules): © Dwight Kuhn; (cell): © E.H. Newcomb & S.R. Tardon/Biological Photo Service 22-45
  46. 46. Figure 22.7B Mycorrhizae result in better growth Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Mycorrhizae present Mycorrhizae not present mycorrhizae (plants, top): © Runk/Schoenberger/Grant Heilman Photography; (mycorrhizae, circle): © Dana Richter/Visuals Unlimited 22-46
  47. 47. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 22.7C Dodder twists around host  Parasitic plants, such as dodders, broomrapes, and pinedrops, send out rootlike dodder projections called (brown) haustoria that tap into the xylem and phloem of the host stem © Kevin Schafer/Corbis 22-47
  48. 48. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. bulbs release digestive enzymes Figure 22.7D Sundews are carnivorous  Carnivorous plants, such as the Venus Sundew leaf flytrap and enfolds prey the sundew, sticky digest insects hairs narrow as a source leafform of nitrogen  By-pass need for nitrates from soil which may be lacking (sundew leaf, prey): © Dr. Jeremy Burgess/Photo Researchers, Inc . 22-48
  49. 49. Connecting the Concepts: Chapter 22 The evolution of a transport system was critical, however, in order for plants to make full use of advantages of land environment Presence of a transport system allows materials to be distributed to those parts of the plant body that are growing most rapidly Another benefit of a transport system is distribution of hormones that regulate plant responses to the environment 22-49

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