Question

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 bacteriophages and dehydration. Fecal 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. This bacterium derives nutrition by digesting human intestinal contents (in other words, food). Humans lacking this bacterium have no measurable reproductive advantage or disadvantage relative to humans who harbor this bacterium. Consequently, the bacterium can be properly described as which of the following?

1. symbiont
2. endotoxin
3. mutualist
4. commensal

Answer 1

1. symbiont

Step-by-step explanation:

Symbionts are organisms interacting in a biological relationship that can be of the type mutualistic, commensalistic, or parasitic

In this case, there is a relationship of commensalism between two organisms: the human and the bacterium.

Commensalism is a relationship between two symbionts where one benefits and the other is not harmed or helped. Commensalism it is derived from the word commensal (old french), used for human social interaction. Sometimes the word commensal is used in biology, however, the term symbiont is used more frequently to refer biological relationships.