Today we are going to discuss a question about whether an Organism is controlled by the biological clock or by other external factors. In order to answer this question, researchers have conducted an experiment with flying squirrels. Flying squirrels normally have 24-hour cycle. To discover whether they are affected by the biological clock or external factors, the researchers placed these squirrels in dark surroundings for 7 days to see if they still have 24-hour cycles, regardless of their environment. Although the squirrels were very active in the dark, it turned out that when they were kept in darkness simulating night. For a long duration of time, they only had 23 and a half hour cycles, which means that their cycle was 30 minutes. Master then these flying squirrels were placed back to their original environment with sunlight after being kept in the dark for a long time and then seeing the light the squirrels returned to their original cycle. This demonstrates a case in which an Organism is controlled by external factors, not by the biological clock.