what makes fresh water plant cells shrink when put into salt water in terms of osmotic pressure?
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Osmotic pressure refers specifically to the difference in the concentration of elements between two solutions.  If you place a semipermeable barrier between the two solutions, water will flow across that barrier until the concentrations are equal.\n\nIn this way, when you put a freshwater plant into salt water, the fresh water flows out from the plant through the cell membranes, which are semipermeable to water but not salt.\n\nThis osmotic pressure is actually how your kidneys work, to filter fresh water from the fluid you drink and leave a more concentrated solution behind.  See the links below for more details.
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Basically because of a phenomenon called Osmosis, which is the exchange of water or other liquids through a membrane in order to get an equilibrium between dissolved substances and the pressure on the membrane.\n\nThe liquids in the human body have a salt content of roughly 0.9% (aka isotonic solution). Sea water has salt contents up to 3.5% (disregarding the Dead Sea and similar evaporation basins).\n\nLow salt content water (from the body cells) will go through the membranes into the salt water. Effectively, the body dries up even though a person has drunk salt water.\n\nNote, however, that salt water near isotonic values can be drunk in case of emergencies. E.g. before river mouths or in inland seas or bays, freshwater addition can dilute sea water to survivable salt contents.
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Osmosis in potatoes. \nPut pieces of potato in different conc. of glucose solution and look at the changes.
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Osmotic pressure is the pressure necessary to reverse osmosis and return to the initial condition. It would be the difference between the liquid levels at equilibrium and the initial liquid level in our thistle tube example above.
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Plasmolysis: Shrinkage of the protoplasm in a plant or bacterial cell, caused by loo of water through osmosis.
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ok, so generally speaking, in the hypotonic environment, a cell is swell up, and potentially burst. The way to remember this is that hypO (the letter O)tonic is the cell which is normally drawn as a more squarelike shape becomes circular as it takes on water. In an isotonic solution, the environment and the cell have equal solutes so no movement of water occurs. In a hypertonic solution (lots of particles in the environment) so the water leaves the cell and shrivels up. \nHowever, we also have to take into account the type of cell that we are placing into these environments. The above applies to animal cells and paramecium as they don't have rigid cell walls. However, plant cells do have cell walls so it does not apply to them. Plant cells have what we call turgor pressor, so they can withstand the environmental influences, or changes in tonicity, alot better. When the plant takes on water, it has the cell wall to prevent bursting. When the plant cell looses water, the cytoplasm shrinks while the cell wall keeps the cell's shape.\n\nQuestion 2:\nIf you were to place elodea or paramecium from fresh to salt water:\nwhen elodea is placed in salt water, we observe the process of plasmolysis - shrinkage of cell contents due to water loss.\nfor image see:\nhttp://images.apple.com/education/solutions/iwork/lessons/media/RealWorldScienceSample.pdf\n\nWith Paramecium: it has 2 contratile vacuoles that are used to balance salt concentration by expelling water
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Membranes become brittle and fragile when it is frozen. This makes it easier to break up the plasma membrane of the beet root cell. It you constantly heat it and cool it, the membrane will eventually break open.
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Excellent question.  \n\nThis is due to a process called osmosis.  Osmosis is the net movement of water molecules in and out of a partially permeable membrane (a kind of barrier that only allows certain molecules to pass through), from a region of their higher concentration to a region of their lower concentration.\n\nIts pretty self-explanatory here.  Since the concentration of water is higher inside than outside of the plant, water moves out of the plant, resulting in the plant dehydrating and dying.
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A plasmolyzed cell is a "pickeled" plant cell, meaning that it was placed in a hypertonic solution (high salt or sugar solution compared to the cell itself). If the plant has chloroplasts, one can see all the chloroplasts "balling up" and getting crowded in the small cytosol-cytoplasm space during plasmolysis. If the plant cell is put in a 10% solution (and the cell is 0.9% salt itself in the cytoplasm) then there is a net movement of water from high water in the cytoplasm-cytosol of the cell to the area of lower water concentration in the space between the cell mbn and the cell wall until equilibrium is reached.  This is a form of diffusion called osmosis.  \n\nComparable event happens when an animal cell, like an rbc is put in a hypertonic solution.  RBC becomes dehydrated and shrivelled, a process called CRENATION.\n\nBTW, the solutes also move-diffuse from high conc to low as well (aka dialysis, the diffusion of solutes), meaning they move from high solute-low water, to lower solute, higher water until equilibrium is reached.  But the water effects are greater if the solute concentration is not too high, too hypertonic.
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because in osmosis/ diffusion, solvent / solute moves across a barier to balance the concentration. since the water is saltier than normal, either water has to come out of the cells to dilute it, or salt has to go into the cells to make them more concentrated. either one is bad for cells, but in terms of osmosis, it is the water that does the moving, leaving the cells dehydrated.
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Osmotic pressure is the hydrostatic pressure produced by a solution in a space divided by a differentially permeable membrane due to a differential in the concentrations of solute.\n\nOsmotic potential is the opposite of water potential with the former meaning the degree to which a solvent (usually water) would want to stay in a liquid.\n\nWhen a biological cell is in a hypotonic environment (the cell interior contains a lower concentration of water than its exterior), water flows across the cell membrane into the cell, causing it to expand due to osmotic pressure. In plant cells, the cell wall restricts the expansion, resulting in pressure on the cell wall from within called turgor pressure. The osmotic pressure π of a dilute solution can be calculated using the formula\n\n\nwhere\ni is the van 't Hoff factor\nM is the molarity\nR is the gas constant, where R = 0.08206 L atm/mol K\nT is the thermodynamic temperature (formerly called absolute temperature)\n\nNote the similarity of the above formula to the ideal gas law and also that osmotic pressure is not dependent on particle charge.\n\n[edit]\nApplications\n\nOsmotic pressure is the basis of reverse osmosis, a process commonly used to purify water. The water to be purified is placed in a chamber and put under an amount of pressure greater than the osmotic pressure exerted by the water and the solutes dissolved in it. Part of the chamber opens to a differentially permeable membrane that lets water molecules through, but not the solute particles. The osmotic pressure of ocean water is about 27 atm. Reverse osmosis desalinators use pressures around 50 atm to produce fresh water from ocean salt water.\n\nOsmotic pressure is necessary for most plants. It is the resulting turgor pressure on the cell wall that allows herbaceous plants to stand upright, and how plants regulate the aperture of their stomata. In animal cells which lack a cell wall however, excessive osmotic pressure can result in cytolysis.
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The amobea will shrivel and die.  Osmosis causes solutions to find equalibriam by moving from places of high concentration to low conetration.  Because the solution of saline in the water is high there is a lower concentration of free H2O that that in the cytoplasm of the amobea; thus the H20 from within the amobea will move, throgh the membranous cell wall trying to create a balance where both bodies (saline solution and cytoplasm) have equal parts sodium and H2O\n\nleave the kid be...if you had this stuff when you were in school you would have used the hell out of it.   Don't pretend you wouldn't...Besides...it is a valid research tool...qualitative research.
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Uncut vegetables are able to resist water loss because of their thick skin (cuticle) and axy coating.\n\nIf you cut vegetables, they will rapidly dry out in the air. If you place them in water, then they are coated with water and no evaporataion takes place.\n\nBecause plant cells have a cell wall and cellulose unless the cell wall is damaged they will remain isolated from the water and only small amounts of water will shift. Ionically the internal salt content of the cells in most vegetables will be at balance with the source water.If you added salt  you would notice an osmotic change as they vegetables would loose water to balance this ionic difference.\nBut plain old tap water is about what the osmality of the typical plant cell is at and it can remain that way safely for some time.
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Hard question to answer.  i seem to remember a professor talking on this very subject so i will try and do him justice.\n\n1) surface tension of the phosopholipid bilayer cannot remain bound together once a cell reaches a certain size. another factor is genetic. the genome (depending on the cell type) has a pre determined size. once it is reache a phenominon called apoptosis or cellular suicide is activated bringing a wierd meaning to the welfare of the many outways the welfare of the one. anther aspect is environment.  depending on the cell and the environment it finds itself in, it must compete for for food.  larger cells need more food.  If the food source of the environment is scarce then it wil die as a result of starvation.  in biologic systems immune resppnse may play a significant factor in making the environment too hostile for life.  However lare single cell organisms do exsist.  I will not hand you the answer but I will give you a hint.  Look to Marine life..  good question!
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Plants growing in saline environments usually take one of three major adaptive tacts. Some, like tamarisk trees, accumulate salt in their leaves and drop the leaves, or secrete salt out like iceplants. Others, including iceplants, have succulent leaves to sequester water and salt. Still others "hide" either in time or space, growing only when rains counteract high soil salinity or keeping low to avoid dessication and preserve what water they do have.
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The turgid pressure of the water in the vascular tissues pushes against the cell wall, makeing the plant more rigid
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http://www.biologyreference.com/Ve-Z/Water-Movement-in-Plants.html\n\nThe Cohesion-Tension Theory\nThe major mechanism for long-distance water transport is described by the cohesion-tension theory, whereby the driving force of transport is transpiration, that is, the evaporation of water from the leaf surfaces. Water molecules cohere (stick together), and are pulled up the plant by the tension, or pulling force, exerted by evaporation at the leaf surface.\n\nWater will always move toward a site with lower water potential, which is a measure of the chemical free energy of water. By definition, pure water has a water potential of 0 MegaPascals (MPa). In contrast, at 20 percent relative humidity, the water potential of the atmosphere is -500 MPa. This difference signifies that water will tend to evaporate into the atmosphere. The water within plants also has a negative potential, indicating water will tend to evaporate into the air from the leaf. The leaves of crop plants often function at -1 MPa, and some desert plants can tolerate leaf water potentials as low as -10 MPa. The water in plants can exist at such low water potentials due to the cohesive forces of water molecules. The chemical structure of water molecules is such that they cohere very strongly. By the cohesion-tension theory, when sunlight strikes a leaf, the resultant evaporation first causes a drop in leaf water potential. This causes water to move from stem to leaf, lowering the water potential in the stem, which in turn causes water to move from root to stem, and soil to root. This serves to pull water up through the xylem tissue of the plant.\nFrom Root to Leaf\nPlants have root hairs and often mycorrhizal fungi at the root surface, both of which serve to filter the soil water as it enters the plant. Mycorrhizae are symbiotic associations between plant roots and fungi. The root cells and mycorrhizal fungi both actively uptake certain mineral nutrients. Mycorrhizae can be particularly important for the uptake of phosphate. The active uptake of minerals by living cells of the root and the subsequent transfer of minerals to the xylem can result in positive root pressures, with water potentials above 0 MPa. This occurs only under certain conditions, such as at night or during rainstorms, when water loss from the leaves is minimal. Such positive root pressures disappear with the onset of leaf transpiration.\n\nWater molecules move from the soil into living cells of the root, and eventually into the transport cells of the xylem, known as tracheids and vessels. These xylem cells are dead and hollow, allowing rapid water transport. They also have hardened cell walls to help them resist the tendency to collapse as water is sucked through them. Both tracheids and vessels \n\n \nA drop of guttation, water extruded by a plant's root pressure, on a blade of grass. have pits on the sides of their walls, which include porous areas for side-to-side transport. Unlike tracheids, a vessel is composed of many cells stacked end to end, with perforations between cells, allowing for more efficient transport.\n\nThe long-distance transport of the water molecule occurs first within the xylem cells of the root, then the xylem of the stem and branch, and then into the xylem of a leaf midrib and vein. Driven by transpiration, the water molecule is pulled from the nonliving tracheids and vessels of the xylem in the living cells of the leaf mesophyll (middle layer) and to the surface of mesophyll cell walls. The water molecule then evaporates into a leaf inter-cellular air space and finally out of a stomatal pore and into the atmosphere. Though photosynthetic action consumes some water, only a small fraction of the water that travels through the plant is used directly for the photo-synthetic reaction, which occurs in leaf mesophyll cells. Instead, most water is lost by transpiration through the stomates.\nThe Role of Stomates\nLeaves of land plants are covered with a waxy cuticle that pr