The ozone layer keeps harmful rays from the sun also the atmosphere burns up small deburey from rockets, space trash ex. Also small rocks and particles can get burned before hitting the earth. One of the greatest things is it keeps spefic gasses needed for life like oxygen in the world.
If the question is referring to an osmosis experiment, the high test concentration of sugar in at the beginning will be INSIDE the visking tubing.
To digest means your body reacts to what u consume