Final answer:
Without hydrogen peroxide, placing a disk soaked in catalase solution in distilled water results in no reaction, as catalase requires hydrogen peroxide as a substrate to function.
Step-by-step explanation:
If a disk soaked in catalase solution was placed in a beaker with distilled water (with no hydrogen peroxide), one would not expect any observable reaction such as bubbling. This is because catalase is an enzyme that specifically catalyzes the decomposition of hydrogen peroxide into water and oxygen gas. In distilled water, without hydrogen peroxide present, catalase has no substrate to act upon, and hence, there will be no reaction. Catalase increases the decomposition rate of hydrogen peroxide by providing an alternative reaction pathway with a lower activation energy, but in its absence, the catalase remains inactive.