A researcher finds that white bread contains more preservatives and has a higher moisture content than wheat bread. She designs a test to determine whether the type of bread, white or wheat, affects the amount of mold growth. What must be done for the researcher to accurately measure the dependent variable?

You are given an electron micrograph of a bacterial cell. in the micrograph you can clearly see three thin layers of different densities surrounding the cell. based on the micrograph, you can infer that this cell is and would appear after application of the gram stain procedure. gram-negative / pink gram-positive / purple gram-positive / pink gram-negative / purple