It is called an indicator because after a few minutes of diffusion, it changed the starch from white to a purple like color.
Water is a negative control
Explanation:
plants deprived of light will lose their color and die . The shoots exposed to "limited / no " sunlight had a yellow / white color due to the fact that photosynthesis could not occur . The lack of sunlight stunted photosynthesis and therefore the sprouts where not able to produce chlorophyll needed to create green color
If you change more than one variable at a time, then you will have a harder time trying to figure out why the certain change occurred.
