You have isolated a bacterium that grows in a medium containing an organic substrate and nitrate in the absence of oxygen. The nitrate is reduced to nitrogen gas. You can be sure that this bacterium is
A) gram- positive.
B) a photoheterotroph.
C) using anaerobic respiration.
D) a photoautotroph.
E) a chemoautotroph.

Question

Quizplus · Accepted Answer

The fact that the bacterium is growing in the absence of oxygen and utilizing nitrate as an electron acceptor suggests that it is using anaerobic respiration. This rules out options B, D, and E. The information given does not provide any indication of the bacterium's Gram status, so option A cannot be definitively chosen.

You Have Isolated a Bacterium That Grows in a Medium