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Potato Lab

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Brandon Buu

on 17 September 2013

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Transcript of Potato Lab

Potato Lab
Brandon Buu
Johnny Pham
Alishan Boyadjian

Our hypothesis was correct, there was a higher concentration of sucrose in the sweet potato than the white potatoes.
Judging from the data table given, ranking the % changes it looks like Blue is 0M, Orange is .2M, purple is .4M, red is .6M, green is .8M, and yellow is 1 M. According to the data, the sweet potato had lower %changes in general compared to the white potato suggesting that since the sweet potato had an already high concentration less water would flow in and out of the cells. In effect, the sweet potato had a higher sucrose solution.
Experimental difficulties included measuring the data accurately. Water droplets were dropped and lost through moving the samples to the balance.
A further exerperiment would be to test whether a sweet potato would pull more water than a white potato inside the same sample tube.
In onclusion, now we know that water moves from a high concentration to a low concentration, just like how in the ocean water would move into your cells.. To improve this eperiment we could have measured and documented the weight of a tube before and used tongs to directly transfer the potato sample to weigh..
This lab shows how osmosis works and how water potential measures the degree to which a water moves and to which direction it moves.
Conclusion/Analysis
Hypothesis
Our hypothesis is that the sweet potatoes will contain more concentration of sucrose than the white potatoes because it contains more starch. White potatoes will have a higher % change in context to the sweet potatoes when put in varying sucrose solutions.
Procedure
1, set up 14 25 ml beakers. 2 of the beakers contained water, as that was the control, while the other 12 beakers contained solutions of varying sucrose molarity that are colored: orange, yellow, purple, blue, green, and red.
2, use a cork borker to cut out 7 pieces of sweet potato and 7 pieces of white potato, all roughly the same length (5 cm).
3. weigh each piece and recorded it as the initial weight.
4. The potato pieces are then put into the beakers and left there for 24 hours.
5.After that amount of time, the potatoes were taken out of the beakers and weighted.
6.Once the weights were recorded, the percent change was calculated using the formula: weight change divided by initial weight divided by 100. The percent change was recorded and conclude our experiment.
Background
Osmosis is a form of diffusion in which water diffuses through a selectively permeable membrane from a high concentrated region to a lower concentrated region. In a hypotonic solution, the concentration of a substance is larger is larger within the cell and the cell gains water to dilute this concentration. In a hypertonic solution, the concentration of a substance is larger in the solution than within the cell; the cell will lose water to increase the concentration of the substance.
Water Potential is explained in terms of [solutes] in a system and the likelihood of said system to lose water. The more positive the water potential, the fewer solutes in the system and the more likely it is to lose water. The more negative, the system becomes less likely to lose water.

Materials
1. 7 25 ml beakers
2. 7 test tubes
3. 1 White potato
4. 1 Sweet potato
5. 1 corker
6. 1 weight balance
7. Sucrose solutions of varying molarities

Data Table
Line Graphs
Regular Potato
Sweet Potato
Calculations
Water Potential of Solution
Beaker 1 (orange): psi = (-1.0)(0.2)(0.0831)(301) = -5.0 bars
Beaker 2(yellow): psi = (-1.0)(1.0)(0.0831)(301) = -25.0 bars
Beaker 3(purple): psi = (-1.0)(0.4)(0.0831)(301) = -10.0 bars
Beaker 4(blue): psi = (-1.0)(0)(0.0831)(301) = 0 bars
Beaker 5(green): psi = (-1.0)(0.8)(0.0831)(301) = -20.0 bars
Beaker 6(red): psi = (-1.0)(0.6)(0.0831)(301) = -15.0 bars

Molarity of Potatoes
Regular Potato = 0.41 M
Sweet Potato = 0.41 M
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