Questions:
The goal of this experiment was to model how a cell membrane functions. This includes what types of substances are able to pass through the membrane, and how the membrane passes them through to the inside of the cell.
Procedure:
For this experiment, dialysis tubing was used to model a cell membrane. The tubing was filled with a glucose and starch solution, then tied at each end. The mixture was used to model the inside of the cell. The "cell" was then placed in a beaker that was filled with a iodine/water mixture. After 24 hours, the solutions in the beaker and dialysis tubing were tested for the presence of glucose and starch. The presence of glucose will be tested using indicator strips; the presence of starch will be tested based off of the chemical reaction indicators between the starch and iodine. Starch forms a blueish black complex with iodine whereas glucose does not react.
Claims:
Based off of the results from the procedure, it can be determined that the starch remained inside the dialysis tubing, and the iodine diffused into the dialysis tubing. While some glucose diffused into the beaker, the inside the tubing also tested positive for containing traces of glucose. The water diffused into the tubing until it could not contain any more. The results of the experiment proved that molecules move from regions of higher concentration to lower concentration during diffusion.
Evidence:
The following table displays the results drawn from the experiment that support the previous claim.
"+" represents a positive test, "-" represents a negative test
Solution Color
Initial Contents Initial Final Initial Final
Bag 15% glucose, 1% starch milky white black + +
Beaker H2O+IKI yellow/brown yellowish - +
It can be concluded from the evidence in the chart that the glucose diffused into the beaker and the iodine diffused into the dialysis tube.
Research:
When compared to results drawn from similar experiments, online information resources, and notes taken during class lectures, it can be confirmed that molecules move from regions of higher concentration during diffusion.
Reflection:
Reflecting on this experiment, the ideas and data constantly supported the results. I believe it could be improved by tracking the motion of the water to observe if it diffused.
Pictures:
Pictures:
Glucose strip before the experiment
Glucose strip after experiment
Dialysis tubing with starch and glucose before the experiment
Dialysis tubing with starch and iodine after the experiment
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