Question

An obligate anaerobe bacterium was grown in two test tubes filled with media rich in glucose. One tube was sealed to produce anaerobic conditions, and the other was not. An uninoculated, unsealed tube was used as a control. Glucose utilization by this bacterium causes acid production, which is indicated by a lightening of the media color. If the bacterium is able to produce ATP only by fermentation, which result do you expect to receive?
A. lightening of media in the sealed tube only
B. lightening of media in the unsealed tube only
C. lightening of media in the sealed and unsealed tubes only
D. lightening of media in the control tube only

Answer 1

The answer is A. 

Glucose in the sealed tube will be used up by the obligate anaerobe bacterium. This is because it is the only environment that satisfies the condition of having no air or oxygen for the organism to survive. The unsealed tube will obviously have air entering and exiting inside and therefore will not be a suitable environment for the organism. The control tube will have no change in color since it is uninoculated or in other words, no organism was put inside of it.