Explanation:
Experimental variables offer valuable information about the results and feasibility of the experiment; they are usually performed under the same circumstances as the other studies except generally the independent variable is modified.
Positive controls in experiments use treatments whose expected results are known (e.g. varying the solute or solute concentration), while negative controls in e.g. both solutions inside and outside the tubing are isotonic, or the same)experiments use treatments that should not produce results under the correct experimental conditions.
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