2.03 Cell Membranes and Homeostasis

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Title: Ms. K
Cell Membrane and Homeostasis Experiment
Objective(s): The reason for this experiment is to see how starch and iodine affect each other and how a plastic bag works similar to a membrane in certain situations.
Introduction: I know prior to doing this experiment that iodine mixed with starch creates a dark color and that most objects, organic and inorganic, naturally experience isotonic reactions.
Hypothesis: I think that the potato will absorb more starch than the sweet potato and they will both absorb relatively similar amounts of water.
Procedure: Variables: Controlled- water and size of potatoes. Manipulated variables- potatoes growth based on contents of solution.
Data:
Data and Observations
Bag Content Initial color of water/iodine solution in the cup Final color of the solution in the cup
Starch and Water Dark blue, purple Blackish Blue
Water Orangey Orange
Analysis Questions
Part 1
1. Restate your hypothesis and discuss if the observed results supported the hypothesis.
- Based off what I observed, my hypothesis, stating that the potato will absorb more starch than the sweet potato, was correct.
2. Identify the control and variables in your experiment.
- Variables: Controlled- water and size of potatoes. Manipulated variables- potatoes growth based on contents of solution.
3. Why do we observe the color of the solution before adding the sandwich bags to each cup?
- To make sure that the solutions contain the necessary contents.
4. Based on your observations, is the sandwich bag permeable to starch? To iodine?
- Iodine is permeable to the sandwich bag, while starch is not.
5. Look up the molecular structures of starch and iodine, and use those structures to explain your observations.
- Starch is a more complex compound than iodine, making it easier for iodine to pass through objects.
6. If a balance was available, describe how you could use it in this experiment and what the purpose would be.
- The balance could be

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