The cell/plasma membrane of a bacterium living in a salty aquatic environment contains a membrane channel protein called MelB. When this bacterium is placed in a hypertonic solution that models/mimics its natural habitat, MelB facilitates the uptake of the sugar melibiose along with sodium ions (Na+).

The hypothetical scenario has the major drawback in that it will only provide qualitative data, as opposed to the quantitative data, that the original method allows.

In reference to the hypothetical scenario above, outline how you would prepare an appropriate positive and negative control (100 words).

In reference to the hypothetical scenario, the independent variable (IV) would be