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Copyright Notice! This PowerPoint slide set is copyrighted by Ross Koning and is thereby preserved for all to use from plantphys.info for as long as that.

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Presentation on theme: "Copyright Notice! This PowerPoint slide set is copyrighted by Ross Koning and is thereby preserved for all to use from plantphys.info for as long as that."— Presentation transcript:

1 Copyright Notice! This PowerPoint slide set is copyrighted by Ross Koning and is thereby preserved for all to use from plantphys.info for as long as that website is available. Images lacking photo credits are mine and, as long as you are engaged in non-profit educational missions, you have my permission to use my images and slides in your teaching. However, please notice that some of the images in these slides have an associated URL photo credit to provide you with the location of their original source within internet cyberspace. Those images may have separate copyright protection. If you are seeking permission for use of those images, you need to consult the original sources for such permission; they are NOT mine to give you permission.

2 Biology: life study of What is Life? Cellular Structure: the unit of life, one or many Growth: cell enlargement, cell number Evolution: long term adaptation Behavior: short term response to stimuli Reproduction: avoid extinction at death Metabolism: photosynthesis, respiration, fermentation, digestion, gas exchange, secretion, excretion, circulation-- processing materials and energy Movement: intracellular, movement, locomotion Properties of Life

3 Organismal Circulation Unicellular Organisms Autotrophic Multicellular Organisms (Heterotrophic Multicellular Organisms)

4 Cyclosis in Physarum polycephalum, a slime mold The correct taxonomic affiliation is unclear. It has been treated as Fungus and Protist. Further study is needed to resolve its position. This organism consists of one very large cytoplasm (plasmodium) with many nuclei and food vacuoles in the cytosol (coenocytic). Slime molds can weigh up toward kilogram range and moves their blob-like mass around exclusively by cyclosis. Here you can see, in a thin region of cytoplasm, that it moves along pathways that are river-like in appearance. Transport is NOT always unidirectional. http://botit.botany.wisc.edu/courses/img/Botany_ 130/Movies/Slime_mold.mov What is the ATP source?

5 http://www.microscopy-uk.org.uk/mag/imgnov00/cycloa3i.avi Cyclosis: cytoplasmic streaming…intracellular circulation Chloroplasts and other organelles have surface proteins with myosin-like activity. Microfilaments of actin are found just under cell membrane. ATP and Calcium allow myosin to slide along actin filaments, resulting in circulation of organelles within the cell. What is the source of ATP? Can you be more specific? If light intensity were reduced, what would be the prediction on rate of cyclosis based on your hypothesis? Elodea canadensis

6 Figure 36-3 Page 793 Branch Root system Shoot system Stem Apical bud Axillary bud Node Leaves Node Internode Lateral roots Taproot The shoot organ system is photoautotrophic, taking in CO 2 and releasing O 2 in daylight. The root organ system is chemoheterotrophic, taking in O 2 and releasing CO 2 in the darkness of the soil environment. Diffusion is sufficient to exchange gases. But solutes need to be circulated in the large plant body as diffusion is too slow!! O 2 in and CO 2 out CO 2 in and O 2 out O 2 in and CO 2 out

7 Figure 36-3 Page 793 Branch Root system Shoot system Stem Apical bud Axillary bud Node Leaves Node Internode Lateral roots Taproot The shoot system produces carbohydrates (etc.) by photosynthesis. These solutes are transported to the roots in the phloem tissue: Translocation The root system removes water and minerals from the soil environment. These solutes are transported to the shoot in the xylem tissue: Transpiration Water and Minerals Transpiration Carbohydrate etc. Translocation

8 Figure 36-3 Page 793 Branch Root system Shoot system Stem Apical bud Axillary bud Node Leaves Node Internode Lateral roots Taproot Because these pathways involve solutes in water passing in the adjacent tissues of a narrow vascular bundle, this is a circulation system! Transpiration and Translocation The water is moving up the xylem, and down the phloem, making a full circuit! Water and Minerals Transpiration Carbohydrate etc. Translocation

9 Figure 36-18 Page 802 Cortex Cross section of a eudicot stemCross section of a monocot stem Epidermis Pith Ground tissue Vascular bundles Plants occur in two major groups (and some minor ones) They differ, in part, in their circulation systems: Dicots initially have one ring of vascular bundles Monocots rapidly develop multiple, concentric, rings of vascular bundles

10 Monocot stem anatomy Young Monocot Mature Monocot vascular bundles As a monocot plant grows in diameter, new bundles are added toward the outside for increased circulation to the larger plant body.

11 ©1996 Norton Presentation Maker, W. W. Norton & Company Monocot stem anatomy Is this slice from a young or a mature part of the corn stem? Lets take a closer look at the vascular tissues

12 ©1996 Norton Presentation Maker, W. W. Norton & Company Monocot stem anatomy: vascular bundle Translocation Transpiration Why must xylem do a lot more transport than phloem?

13 ©1996 Norton Presentation Maker, W. W. Norton & Company Dicot circulation: stem anatomy Dicots start with one ring of bundles… Lets take a closer look at the vascular tissues

14 ©1996 Norton Presentation Maker, W. W. Norton & Company Dicot stem anatomy: vascular bundle phloem fibers functional phloem vascular cambium xylem Translocation Transpiration Support of Stem As a dicot grows, how does it add vascular capacity to become a tree? Cell Divison: More Xylem and Phloem

15 ©1996 Norton Presentation Maker, W. W. Norton & Company Dicot stem anatomy: vascular cambium adds secondary tissues epidermis cortex 1º phloem 2º phloem cambium 2º xylem 1º xylem pith

16 ©1996 Norton Presentation Maker, W. W. Norton & Company Dicot stem anatomy: vascular cambium adds secondary tissues Each year the vascular cambium make a new layer of secondary xylem and secondary phloem

17 ©1996 Norton Presentation Maker, W. W. Norton & Company Dicot stem anatomy: four year-old stem (3 annual growth rings) xylem = wood phloem etc. = bark All of these tissues were added by the vascular cambium!

18 Figure 36.29 Page 810 See also part (a) or less competition in forest? or more competition in forest? cambium phloem

19 Figure 36.0 Page 791 sapwood heartwood periderm phloem cambium = bark pith

20 ©1996 Norton Presentation Maker, W. W. Norton & Company Two Xylem Conducting Cells: tracheid developmental sequence Annular Helical Pitted When flowering plants are young, water needs are limited, tracheids suffice. The walls are strengthened with secondary thickenings including lignin. Protoxylem have stretchable annular or helical thickenings. Metaxylem have reticulate or pitted and fully rigid walls. Tracheids have end walls and flow between cells is through pits.

21 ©1996 Norton Presentation Maker, W. W. Norton & Company plesiomorphicapomorphic Compare Fig. 36.26 Page 806 Two Xylem Conducting Cells: xylem vessel evolution As flowering plants age and grow, water needs increase, and tracheids need to be supplemented. Flowering plants evolved xylem cells with larger cell diameter and perforated end walls to increase water flow. Vessels have perforated end walls or lack end walls, but lateral flow between cells is still through pits.

22 ©1996 Norton Presentation Maker, W. W. Norton & Company Dicot stem anatomy: xylem parenchyma, vessels, and tracheids The huge vessel transports lots of water longitudinally, and shows lots of pits for lateral transport

23 ©1996 Norton Presentation Maker, W. W. Norton & Company Dicot stem anatomy: xylem parenchyma, vessels, and tracheids The huge vessel transports lots of water longitudinally, and shows lots of pits for lateral transport

24 ©1996 Norton Presentation Maker, W. W. Norton & Company Secondary xylem: cross sections of three different species Vessels, Tracheids have different distribution patterns. Some produce big vessels only in spring wood Others produce vessels year-round.

25 ©1996 Norton Presentation Maker, W. W. Norton & Company Dicot stem anatomy: woody stem circulation O 2 in and CO 2 out This sketch is showing the importance of lateral transport. In both transpiration and translocation materials must move radially to the interior and to the exterior as well as up and down the plant.

26 ©1996 Norton Presentation Maker, W. W. Norton & Company Dicot stem anatomy: 2-year old stem showing ray and periderm Rays transport sugar from the phloem toward the interior… …to keep pith and xylem parenchyma fueled. Rays transport water and minerals from the xylem to the exterior… …to keep the periderm, cortex, and phloem parenchyma hydrated. phloem

27 ©1996 Norton Presentation Maker, W. W. Norton & Company Xylem and Phloem: tissues with many cell types but conduction function main transpiration flow main translocation flow radial transport toward pith toward cortex

28 Mendocino Tree (Coastal Redwood) Sequoia sempervirens Ukiah, California 112 m tall (367.5 feet)! This tree is more than ten times taller than is theoretically possible based solely upon the length of the column of uncavitated water. How could this be achieved? http://www.nearctica.com/trees/conifer/tsuga/Ssemp10.jpg

29 Transpiration in a tall tree has at least 3 critical components: Evaporation: pulling up water from above Capillarity: climbing up of water within xylem Root Pressure: pushing up water from below

30 ©1996 Norton Presentation Maker, W. W. Norton & Company Transpiration: root pressure (osmotic push) guttation Solutes from translocation of sugars accumulate in roots. Water from the soil moves in by osmosis. Accumulating water in the root rises in the xylem. Water escapes from hydathodes. This is not dew condensing!

31 Transpiration: root pressure (osmotic push) http://img.fotocommunity.com/photos/8489473.jpg The veins (coarse and fine) show that no cell in a leaf is far from xylem and phloem (i.e.water and food!). The xylem of the veins leaks at the leaf margin in a modified stoma called the hydathode. These droplets are xylem sap. Root pressure accounts for maybe a half-meter of push up a tree trunk.

32 Capillarity: maximum height of unbroken water column The small diameter of vessels and tracheids and the surface tension of water provide capillary (climb). Cohesion of water, caused by hydrogen bonds, helps avoid cavitation. A tree taller than 10.4 m would need some adaptations to avoid cavitation atmospheric pressure keeps water in tube gravity pulls water down vacuum created 10.4m glass tube water

33 ©1996 Norton Presentation Maker, W. W. Norton & Company Conifer stem anatomy: pine xylem tracheids with pits, xylem rays tracheids with pits ray parenchyma vascular cambium In spite of the limitations of tracheids-only xylem, conifers are among the tallest of trees!

34 ©1996 Norton Presentation Maker, W. W. Norton & Company Conifer stem anatomy: bordered pits as check-valve for flow These pit features allow conifers to be very tall and still avoid cavitation in their xylem cells. As pressures change between adjacent cells, the torus movement blocks catastrophic flow that would result in cavitation. P low P high

35 Transpiration: evaporation (pull) 76 cm vacuum mercury water mercury Water evaporating from a porous clay cap also lifts the mercury! Transpiration can lift the mercury above its normal cavitation height!

36 ©1996 Norton Presentation Maker, W. W. Norton & Company Grown in 32 PO 4 (radioactive phosphorus) 1 hour Cold medium 6 hoursCold medium 90 hours Is phosphate uptake from soil: transpiration or translocation? In xylem or phloem? Is phosphate mobilization from lower leaf: transpiration or translocation? In xylem or phloem? note: fading new growth black

37 Modified from: ©1996 Norton Presentation Maker, W. W. Norton & Company Translocation: How solutes move in phloem plasmodesmata active transport Leaf Root High Pressure Low Pressure

38 Modified from: ©1996 Norton Presentation Maker, W. W. Norton & Company Translocation: How solutes move bidirectionally in phloem Leaf sugars amino acids Developing leaves, apical bud, flowers fruits Lateral buds, stems, roots, root tip High Pressure Low Pressure

39 Figure 36-3 Page 793 Branch Root system Shoot system Stem Apical bud Axillary bud Node Leaves Node Internode Lateral roots Taproot Root Pressure: Water moves into the root because of solutes from phloem. Pressure pushes the water up the stem. Water and Minerals Transpiration Carbohydrate etc. Translocation Transpiration Capillarity: Water climbs in the xylem cell walls by adhesion. Water molecules follow by cohesion. Evaporation: Water evaporates from mesophyll into atmosphere. Water molecules are pulled up the xylem by virtue of cohesion.

40 Figure 36-3 Page 793 Branch Root system Shoot system Stem Apical bud Axillary bud Node Leaves Node Internode Lateral roots Taproot Pressure = Bulk Flow The pressure gradient forces phloem sap away from leaves to all sinks (bidirectionally). Water and Minerals Transpiration Carbohydrate etc. Translocation Root (etc.) = Sinks Solutes removed from phloem by active transport. Water follows by osmosis, reducing pressure. Leaf = Source Photosynthesis produces solutes. Solutes loaded into phloem by active transport. Water follows by osmosis, increasing pressure.


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