Transport systems in plants.pptx
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This document discusses the transport systems in dicotyledonous plants. It describes the three main tissue types - dermal, vascular, and ground tissues. The dermal tissue provides an outer protective covering. The vascular tissue, made up of xylem and phloem, transports water, minerals and organic nutrients throughout the plant. The ground tissue fills the internal space. Secondary growth in woody plants is driven by the vascular cambium, which produces secondary xylem and phloem. Water and minerals enter the roots through three pathways - transmembrane, symplastic, and apoplastic. They are then transported through the xylem to the leaves. In the leaves, transpiration creates a pulling force that draws
Transport systems in plants.pptx
- 1. UNIT 5: SUPPORT AND TRANSPORT SYSTEMS IN PLANTS
- 4. Dermal, Vascular, and Ground Tissues Each plant organ has: DERMAL TISSUE: OUTER PROTECTIVE COVERING VASCULAR TISSUE: TRANSPORT AND SUPPORT GROUND TISSUE: SPACE FILLERS
- 5. Dermal, Vascular, & Ground Tissues
- 7. Dermal tissue Non-woody plants dermal tissue system consists of epidermis waxy coating called cuticle helps prevent water loss from epidermis Woody plants protective tissues called periderm replace epidermis in older regions of stems & roots Trichomes outgrowths of shoot epidermis & can help with insect defence.
- 8. Vascular Tissues Vascular tissue system carries out long-distance transport of materials between roots & shoots Two vascular tissues are xylem & phloem Xylem conveys water & dissolved minerals upward from roots into shoots Phloem transports organic nutrients from where they are made to where they are needed
- 9. Ground Tissues Tissues that are neither dermal nor vascular are ground tissue system Ground tissue internal to the vascular tissue is pith; ground tissue external to the vascular tissue is cortex Ground tissue includes cells specialized for storage, photosynthesis, & support
- 11. CROSS SECTION THROUGH A DICOT STEM
- 14. 2. SECONDARY GROWTH Secondary growth occurs in stems & roots of woody plants rarely in leaves Secondary plant body consists of tissues produced by vascular cambium & cork cambium
- 18. a. The Vascular Cambium and Secondary Vascular Tissue The vascular cambium is cylinder of meristematic cells 1 cell layer thick develops from undifferentiated parenchyma cells Secondary xylem accumulates as wood (consists of tracheids, vessel elements & fibers. Early wood formed in spring has thin cell walls to maximize water delivery. Late wood formed in late summer has thick-walled cells & contributes more to stem support.
- 19. Tree rings visible where late & early wood meet can be used to estimate a trees age Dendrochronology analysis of tree ring growth patterns can be used to study past climate change. As a tree or woody shrub ages older layers of secondary xylem (heartwood) no longer transport water & minerals. Outer layers (sapwood) still transport materials through xylem.
- 21. 3. UPTAKE OF WATER AND MINERALS INTO THE ROOTS The plasma membrane directly controls the traffic of molecules into and out of the cell. In most plant tissues, the cell wall and cytosol are continuous from cell to cell. The cytoplasmic continuum is called the symplast. The cytoplasm of neighbouring cells is connected by channels called plasmodesmata. The apoplast is the continuum of cell walls and extracellular spaces.
- 22. Water and minerals can travel through a plant by three routes: Transmembrane route: out of one cell, across a cell wall, and into another cell. Symplastic route: via the continuum of cytosol. Apoplastic route: via the cell walls and extracellular spaces.
- 23. Water and minerals can travel through a plant by three routes:
- 24. Pathway 1: Transmembrane route Water and minerals move from soil (high WP) through cell wall, plasmamembra ne & into cytoplasm of roothair. 01 Through cell wall, plasma membrane & into cytoplasm of cortex cells. 02 Through cell wall, plasma membrane & into cytoplasm of endodermis 03 Through cell wall, plasma membrane & into cytoplasm of pericycle. 04 Through cell wall, plasma membrane & into xylem of plant. 05
- 26. Pathway 2: symplastic route Water and minerals flow from high WP in soil, through cell wall, plasma membrane & into cytoplasm of roothair. Through plasmodesmata linking cytoplasm of cells into cytoplasm of the cortex cells. Flowing through plasmodesmata into cytoplasm of endodermis cells & pericycle & into xylem.
- 27. Pathway 3: Apoplastic route During Apoplastic route water & minerals travel along cell walls of roothairs, cortical cells, and endodermis, Endodermis has Casparian strips that prevent further movement of water, therefore water enter cytoplasm of endodermal cells and then take: symplastic route (through cytoplasm & plasmodesmata that link cytoplasm of cells) into xylem of root.
- 29. Transport of minerals across an endodermal plasma membrane Minerals follow same routes as water when it moves through roothair & cortex cells. But when it moves through the endodermal plasma membrane it does it in the following way: An ATP driven pump removes hydrogen ions from cell. This establishes an electrochemical gradient that allows potassium ions & other positively charged ions to cross the membrane via a channel protein. Negatively charged mineral ions can cross the membrane by bonding to a carrier (hydrogen ions) which are diffusing down their concentration gradient.
- 30. CELLS THROUGH WHICH WATER MOVE ROOTHAIR. CORTEX CELLS. ENDODERMIS PERICYCLE. XYLEM ATP driven pump
- 31. Transport of minerals across an endodermal plasma membrane
- 32. 3. TRANSPORT OF WATER AND MINERALS TO THE LEAVES What makes upward movement of water in xylem of stems & leaves possible? Root pressure Cohesion-adhesion-tension Transpiration
- 33. I) Root pressure Water entering root cells creates positive pressure called root pressure. It occurs at night & push xylem sap upwards.
- 34. II) Cohesion- adhesion- tension model Upward movement of water requiring no energy. Cohesion- Tendency of water molecules cling together & form continuous water column. Adhesion- Tendency of water molecules to cling to the sides of the container (xylem) they are in. It gives water column extra strength & prevents it from slipping back
- 35. III) Transpiration Transpiration is loss of water vapour through stomata of leaf. Water molecules that evaporate from cells into intercellular airspaces are replaced by other water molecules from leaf xylem. Because water molecules are cohesive, transpiration exerts a pulling force / tension, that draws water column through xylem to replace water lost by stomata. This is also a mechanism by which minerals are transported throughout plant body.
- 36. Environmental factors that influence the speed of transpiration High temperature faster transpiration High light intensity faster transpiration Windy faster transpiration High humidity slower transpiration
- 37. What is guttation and what causes it? Root pressure is responsible for guttation. Guttation is when drops of water are forced out of the vein endings along the edges of leaves called hydathodes.
- 38. 4. TRANSLOCATION OF SUBSTANCES FROM THE LEAVES TO THE REST OF THE PLANT Phloem sap is an aqueous solution (high in sucrose) travels from sugar source to sugar sink Products of photosynthesis are transported through phloem by process of translocation.
- 39. Sugar source (organ producing sugar (mature leaves) Sugar Sugar sink (organ that stores sugar (net consumer ) Sugar Sugar loaded into sieve-tube elements of phloem. Sugar moves by symplastic or both (symplastic and apoplastic) pathways. Sugar At the sink, sugar molecules diffuse from phloem to sink tissues & are followed by water. Sugar
- 40. TRANSLOCATION OF SUBSTANCES FROM THE LEAVES TO THE REST OF THE PLANT