An organism is discovered that thrives in both the presence and absence of oxygen. Interestingly, as oxygen is removed from the organism's environment, the rate of sugar consumption increases while the growth rate decreases. What do these observations suggest about the likely identity of this organism?
A) It is an unremarkable eukaryotic organism.
B) It is a photosynthetic organism.
C) It is an obligate anaerobic organism.
D) It is a facultative anaerobic organism.

Question

Quizplus · Accepted Answer

The observations of this organism thriving in both the presence and absence of oxygen, and the increase in sugar consumption and decrease in growth rate as oxygen is removed from the environment, suggest that the organism is able to perform both aerobic respiration and fermentation. This is a characteristic of facultative anaerobic organisms. Option A is unlikely since eukaryotic organisms generally require oxygen for metabolic processes. Option B is unlikely since photosynthetic organisms require a source of light for energy, and there is no mention of light in the scenario. Option C is also unlikely since obligate anaerobic organisms cannot survive in the presence of oxygen.

An Organism Is Discovered That Thrives in Both the Presence