Also when a cell is hypertonic to its environment does that mean the environment is hypotonic to the cell?
If the tube shrinks, water must be going out of the tube, and this must be occurring because there is a concentration gradient across the tubing. However, both sides start with distilled water, so the water on both sides should have the same (low) amount of dissolved substances. Presumably the shrinkage is occurring over a period of hours or days? My guess would be that something is getting into the water in the cup - this could be dissolved matter from floating dust or bacteria, but more likely are gases from the air. Distilling water would degas it - oxygen, nitrogen, and CO2 would be removed. However, these gases, most significantly CO2, will redissolve in the water if it is left in air (carbon dioxide dissolves to make a solution of carbonic acid). In addition, any contaminants that persisted through the distillation would be concentrated when the cup water evaporates, though this is likely to be a small change due to the high purity of distilled water. You are correct about your second question.
