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

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

Cyclosis in Physarum polycephalum, a slime mold 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 move their blob-like mass around exclusively by cyclosis. http: //botit. botany. wisc. edu/courses/img/Botany_ 130/Movies/Slime_mold. mov The correct taxonomic Here you can see, in a thin region affiliation is unclear. of cytoplasm, that it moves along It has been treated as pathways that are river-like in Fungus and Protist. appearance. Further study is needed to resolve its position. Transport is NOT always What is the ATP source? unidirectional.

Cyclosis: cytoplasmic streaming…intracellular circulation Chloroplasts and other organelles have surface proteins with myosin-like activity. Elodea canadensis Microfilaments of actin are found just under cell http: //www. microscopy-uk. org. uk/mag/imgnov 00/cycloa 3 i. avi membrane. What is the source of ATP? ATP and Calcium allow myosin to slide along actin filaments, resulting in circulation of organelles within the cell. Can you be more specific? If light intensity were reduced, what would be the prediction based on your hypothesis?

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

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

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

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

Monocot circulation: transpiration and translocation © 1996 Norton Presentation Maker, W. W. Norton & Company

Monocot stem anatomy Mature Monocot Young 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.

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

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

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

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

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

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

Figure 36. 29 Page 810 See also part (a) or less competition in forest? cambium phloem or more competition in forest?

Figure 36. 0 Page 791 sapw ood periderm phloem cambium = bark heartwood pith

Dicot stem anatomy: 2 -year old stem showing ray and periderm © 1996 Norton Presentation Maker, W. W. Norton & Company

Dicot stem anatomy: periderm dying epidermis maturing cork cells periderm cork cambium phelloderm cortical collenchyma cortical parenchyma © 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. © 1996 Norton Presentation Maker, W. W. Norton & Company

Dicot stem anatomy: xylem vessel evolution plesiomorphic apomorphic 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. © 1996 Norton Presentation Maker, W. W. Norton & Company

Dicot stem anatomy: xylem parenchyma, vessels, and tracheids © 1996 Norton Presentation Maker, W. W. Norton & Company

© 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

Dicot stem anatomy: woody stem circulation 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. O 2 in and CO 2 out © 1996 Norton Presentation Maker, W. W. Norton & Company

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

Xylem and Phloem: tissues with many cell types but conduction function © 1996 Norton Presentation Maker, W. W. Norton & Company

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/Ssemp 10. jpg

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

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

Transpiration: root pressure (osmotic “push”) 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. http: //img. fotocommunity. com/photos/8489473. jpg

Capillarity: maximum height of unbroken water column glass tube vacuum created gravity pulls water down atmospheric pressure keeps water in tube water 10. 4 m 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”

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

Conifer stem anatomy: bordered pits as “check-valve” for flow secondary wall primary wall middle lamella pit aperture pit membrane pit border torus pit chamber P low P high 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.

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

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

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

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

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

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