transport in vascular plants. adaptations for land the problems: conserve water structure transport...

Download Transport in Vascular Plants. Adaptations for land The problems: Conserve water Structure Transport nutrients and water The solution: Vascular system!!!!!

Post on 24-Dec-2015




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  • Slide 1
  • Transport in Vascular Plants
  • Slide 2
  • Adaptations for land The problems: Conserve water Structure Transport nutrients and water The solution: Vascular system!!!!!
  • Slide 3
  • Transport occurs on three levels Within cell-root hairs Between cells-sugar from mesophyll to seive tube member Long Distance-water from roots to leaves
  • Slide 4
  • Quick Review Diffusion Passive transport Active transport Transport proteins Proton pumps
  • Slide 5
  • Water Potential Animal cells absorb water until they burst Plant cells have a cell wall only absorb water until the pressure inside the cell is greater than the pressure outside the cell. Turgor pressure- pressure against cell wall Water potential( w )=solute potential ( s )+ pressure potential ( p )
  • Slide 6
  • Water moves from high potential to low potential Adding solutes decreases solute potential Adding salt to the water decreases the solute potential, which makes water move out of the cell to the area of lower potential Adding pressure increases pressure potential Cells that are full of water will give up water to empty cells
  • Slide 7
  • How does water get around? Cell walls and Cytoplasm of neighboring cells are connected Plasmodesmata- pores in cell wall that connect cytoplasm
  • Slide 8
  • Plant cell compartments Vacuole Tonoplast =membrane that surrounds C.V. Symplast- connected cytoplasm between cells Apoplast- connected cell walls and extracellular space
  • Slide 9
  • Three ways to move between cells Transmembrane Symplastic Apoplastic- between cell wall and membrane
  • Slide 10
  • Trachieds, vessels, sieve tubes=empty Cytoplasm would slow down bulk flow
  • Slide 11
  • water Root epidermal cells are hydrophilic Water and minerals diffuse into epidermal cells Mycorhizae- symbiosis between root and hyphae
  • Slide 12
  • Endodermis Water and minerals are passed from cell to cell until they reach the Endodermis Surrounds xylem core of root, screens minerals in Apoplast Casparian Strip- suberin cell wall, waterproof Only way into xylem is though symplast
  • Slide 13
  • Endodermal + parenchyma cells actively transport minerals into their cell wall, water follows into xylem
  • Slide 14
  • Why might a crop develop a severe phosphate deficiency after being sprayed with a fungicide? A scientist adds a water soluble inhibitor of photosynthesis to the roots of a plant, However, photosynthesis in not affected by addition of the inhibitor in this manner. Why?
  • Slide 15
  • Bulk Flow Diffusion is too slow for long distance transport Bulk Flow= movement by pressure through trachieds, vessels and sieve tubes Pressure is created by manipulating solute potential (sugar) Tension pulls water from root to leaf
  • Slide 16
  • Long distance transport Water is pushed at night Minerals are pumped into apoplast, creates root pressure Guttation- more water enters leaves than can be transpired
  • Slide 17
  • Water is pulled during the day Transpiration-evaporation from leaves Air outside leaf is drier than air in spongy mesophyll Lower water potential outside, water moves out of leaf Xylem mesophyll environment
  • Slide 18
  • Adhesion and cohesion Cohesion =water molecules stick to each other Adhesion = water molecules stick to hydrophilic surfaces (cellulose) Hydrogen bonds!!!!!
  • Slide 19
  • Unbroken chain of water molecules Tension pulls water molecule chain upwards Pulls vessels in (trunk shrinks on hot days) Decreases water potential, water moves into roots passively
  • Slide 20
  • Broken water molecule chain Cavitation- air bubbles in xylem, caused by freezing Air bubbles expand when sap thaws, become embolisms Water cant get through blockage, cant reform chain
  • Slide 21
  • Fixing embolisms Small, young, nonwoody plants can fix embolisms with root pressure in spring. Trees cant fix embolisms Water can detour around ruined vessel New xylem is added every year, replaces damaged vessels
  • Slide 22
  • Bulk Flow- A review Transpiration-cohesion-tension Water potential is manipulated (by adding solutes at root or losing water to dry air at leaves) Solute concentration allows short distance transport (root hair cortex) Pressure allows long distance transport (root leaf) Plant expends no energy for bulk flow, solar powered
  • Slide 23
  • What would be the effect of fertilizing a plant during a drought? A tip for helping cut flowers last longer without wilting is to cut off the ends of the stems underwater and then transfer the flower to a vase while water droplets are still present on the cut ends of the stems. Explain why this works.
  • Slide 24
  • Stomata Leaves have a large surface area Balance water loss and sugar requirement Closing stomata reduces water loss Plant wilts when cells lose turgor pressure Evaporative cooling prevents denatuation of photosynthetic enzymes
  • Slide 25
  • Stomata density Up to 20,000 stoma/cm (desert, rainforest) Plastic feature Fossil evidence of CO 2 levels More stomata = lower CO 2 Less stomata = higher CO 2 WHY???
  • Slide 26
  • Guard Cells Guard cells gain and lose potassium (K+) Actively move K+ into guard cell open Water enters cell, becomes turgid Guard cells push apart Remove K+ close Water leaves cell, becomes flaccid Guard cells flop together
  • Slide 27
  • Control of guard cells Light stimulates K+ uptake Low CO2 in mesophyll spaces opens stomata Circadian rythms Guard cells lose turgor pressure when plant is dehydrated
  • Slide 28
  • Xerophytes Adapted to dry climates Thick cuticle Less surface area Stomata on bottom of leaf Recessed stoma (crypts, leaf hairs) C 4 and CAM photosynthetic pathways
  • Slide 29
  • Some leaf molds, which are fungi that parasitize plants, secrete a chemical that causes guard cells to accumulate potassium ions. How does this adaptation enable the leaf mold to infect the plant?
  • Slide 30
  • Translocation=movement of sugars Sugar source sugar sink Source=sugar producer Leaves, green stems Sink=sugar consumer Growing stems, flowers, buds Bulb? Tuber? Direction of flow depends on source and sink
  • Slide 31
  • Sugar must be loaded into sieve tubes before it can be delivered to sinks Requires active transport at source (sieve tube sugar concentration is higher than source concentration) Unloaded at sugar sink Passive transport at sink (sugar is always used up by source, concentration is always lower)
  • Slide 32
  • Pressure Flow
  • Slide 33
  • Positive pressure (opposite of transpiration) Sugar loading at source decreases water potential of sieve tube Water moves into phloem cell from adjacent xylem, increases pressure Sugar is removed at sink, releases pressure, water moves back into xylem
  • Slide 34
  • Potatoes break down starch into sugar at low temperatures. (this is a problem for the potatoe chip industry because the sugar in chilled potatoes turns dark brown during processing) What effect would cooling the soil around an expanding potato tuber have on sugar import into the tuber?


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