Final answer:
The organism that produces bubbles upon the addition of hydrogen peroxide and causes the medium to become very acidic is most likely an acidophilic 1. bacteria, due to the presence of catalase and its preferential growth in acidic environments.
Step-by-step explanation:
The student's question asks about an organism that produces bubbles upon addition of hydrogen peroxide and causes the pH of the medium to become very acidic. Based on the information given, this organism is likely to be bacteria. The production of bubbles indicates the presence of the enzyme catalase, which breaks down hydrogen peroxide into water and oxygen. This reaction is a characteristic of many bacteria, especially those that live in aerobic conditions and are capable of aerobic respiration.
Furthermore, the fact that the medium becomes very acidic suggests that the organism is an acidophile, which thrives in acidic environments. Bacteria are known to be versatile in their pH range, with acidophilic bacteria growing optimally at a pH near 3.0, making them capable of creating very acidic conditions through their metabolic processes. Therefore, given the two observations, the presence of catalase and the resulting acidic pH, we can conclude that the most likely organism in question is bacteria.