2) In “Chardakov method for water potential measurement” experiment, you find that M solution has not been changed by water loss or absorption by the. Chardakov Technique. Plant Physiology. UNI. Incubating tissue in solution. Pre- incubation. Incubation. Post-incubation. Save for later measurement. Did solution change concentration? Solutes stay the same If water left or entered tissue –Water also entered or left solution –Solution becomes more dilute or.
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Repeat for all solutions. Which method do you think will be more accurate? OK Any substance that can change shape or flow easily. Water potential values determined by this method may be slightly more negative than those obtained by the Chardokov method.
No change in density, concentration No net water movement Tissue and solution were at the same WP If we can find this solution concentration —We can find the tissue WP. A measure of how much material is packed into a unit volume of the material The fewer. An alternate method to determine his point requires performing a regression analysis of the best fit line of your data.
Be sure to use a different pipet for each dye stock.
Mix the tubes thoroughly with a vortex mixer. Weigh the cores to the nearest mmethod. Then remove the tissues, gently blot on paper towels and reweigh. Immerse the pipette in the water that previously had tissue sections in it until the tip is approximately at the center of the tube.
Density changes can be observed by watching whether a drop of the original solution floats or sinks in the test solution after tissue incubation. The water potential of the tissue is considered to be equal the osmotic potential of the incubating nethod at which there is no change in tissue weight i.
Cut them to the same length ca. Draw the best fit line for your data.
Be sure not to include any fragments of the skin. Incubate the cores for 1.
What is the water potential calculated by this method? Incubate the cores for at least 1. A “kink” may be observed in the graph below the x-axis.
Cytology Osmosis and Water relations. Then, the percent change in weight of the tissue is plotted versus solution concentration or osmotic potential. Use methid cork borer to prepare at least 27 uniform tissue samples from the potato. From the graph, determine the concentration metho the sucrose solution in which there was no net weight gain i.
Incubating tissue in solution Pre-incubationIncubation Post-incubation Save for later measurement.
Alternately, for a more accurate measurement of changes in the solution density, a refractometer can be used. In contrast to the Chardakov method which analyzes changes in solution density after incubation, this technique monitors tissue weight changes.
This method meyhod on the change in density in a solution that occurs after a tissue has been immersed in it. The solution gains or looses water depending on the water potential of the tissue.
If the density of a solution does not change no net movement of water then this solution has the same water potential as the tissues that were incubated in it. Record the temperature of charddakov solutions Table 1 Using a Pasteur pipet, remove a small amount of water dyed with methylene blue to dye the sucrose solution, dip a dry probe into methylene blue powder and then mix. Two ways chradakov move water Bulk flow Osmosis Both move water from high energy to low Differences —Source of energy difference.
Use the following equation to calculate the percent change in weight for each tissue by the following equation: Osmosis diffusion of water through a selectively permeable membrane Membrane X is permeable to water but not to protein Which side has the highest concentration.
Pour off the solutions into a set of empty, correspondingly labeled tubes.
Investigating osmosis: measuring the water potential of a potato cell
Does a gas differ from other fluids? Does it correspond to the value obtained by the Chardakov technique? It is assumed that solute movement between tissue and solution is negligible.
Put two or preferably three potato cores in each solution water or sucrose.
Examine the cores as you weigh them. Periodically swirl the containers. Use a cork borer to prepare at least 27 uniform tissue samples from the potato. Hypertonic Concentration with higher solute concentration and less water concentration Hypotonic lower solute concentration and more water concentration.
This technique for measuring water potential is similar in theory to the Chardakov method and shares the advantage of being simple to perform and doesn’t require expensive equipment.
Work quickly to minimize evaporation and keep the tissue wrapped in a moist towel. Dispense 10 mL of water or a sucrose solution 0. Metyod Water Potential by the Gravimetric Technique.