Essay on IB Biology SL IA

2194 Words Dec 18th, 2013 9 Pages
AP/IB Biology Lab Assessment
The effect of various fruit and vegetable cell membranes on their water potential

Independent variable: Type of fruit or vegetable. (Produce used: Russet potatoes, Pascal celery, Gala apple, Navel orange, and Imperator carrot). The fruit or vegetable will be placed in six 56.7 gram cups, ranging with sucrose molarities of 0 (distilled water), 0.2, 0.4, 0.6, 0.8, 1.0, with 5 trials, leading to 30 cups for each produce variable.
Dependent variable: The water potential of the produce, found by placing the produce in different molarities of sucrose and finding the isotonic state of the produce with a plotted line graph.
Controlled variables: The controlled variables include:
The type of produce used:
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Procedure:
1. Obtain all materials and wash hands
2. Cut 30 pieces of each type of fruit or vegetable, small enough to fit in a 56.7 gram plastic cup (6 pieces for each trial).
3. Weigh the initial mass of each sample of produce with the digital gram scale and record on a table.
4. Place the recorded samples of produce in their designated cups using tweezers, fill the six cups of each trial with 24 ml distilled water, 0.2-molarity sucrose, 0.4-molarity sucrose, 0.6-molarity sucrose, 0.8-molarity sucrose, and 1.0-molarity sucrose.
5. Cover each plastic cup with a substantial amount of aluminum foil to prevent the evaporation of the solution.
6. Let the 30 cups for each of the 5 types of produce sit for two days.
7. After two days, remove the aluminum foil, and record the final mass of each sample of produce using the digital gram scale, and transporting the fruit or vegetable with tweezers. Remove excess liquids of the sample by dabbing it on a paper towel.
8. Record the final masses on a table
9. Record the percent change in mass for each cup, find the averages and standard deviation for the 6 solutions for each fruit or vegetable variable.
10. Plot the averages for each fruit or vegetable with a line graph and record where the percent change in mass intercepts the x-axis (molarity of sucrose)- where the graph intercepts the x-axis represents the molar concentration of sucrose with a water potential that

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