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Mr. Jones has run out of dialysis tubing but would like his students to model the permeability of cells. He asks students to design an experiment to test which brand of plastic sandwich bags will allow molecules to pass through. Mr. Jones gives the students a list of available supplies which includes: starch, iodine, water, glassware, and 3 different brands of sandwich bags. What is the independent variable in the experiment?
D. Sandwich bags
I think it is d but i am not 100% sure
From the internet:
"The "dependent variable" represents the output or effect, or is tested to see if it is the effect. The "independent variables" represent the inputs or causes, or are tested to see if they are the cause".
So I would agree, the independent variable will be the sandwich bags, the dependent variable will be the result of passing molecules through the bags.