A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Faecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan.
-Which of the following statements about the cell wall is most probable?
A) Its innermost layer is composed of a phospholipid bilayer.
B) After it has been subjected to Gram staining, the cell should remain purple.
C) It has an outer membrane of lipopolysaccharide.
D) It is mostly composed of a complex, cross-linked polysaccharide.

Question

Quizplus · Accepted Answer

The mention of lipopolysaccharide in the paragraph suggests that the bacterium has an outer membrane of lipopolysaccharide, which is common in Gram-negative bacteria. This also matches with the fact that the cell is not susceptible to the penicillin family of antibiotics, which target the peptidoglycan layer of Gram-positive bacteria. Options A, B, and D are not supported by the information in the paragraph.

A Hypothetical Bacterium Swims Among Human Intestinal Contents Until It