In a hypothetical situation, a bacterium lives on the surface of a leaf, where it obtains nutrition from the leaf's nonliving, waxy covering while inhibiting the growth of other microbes that are plant pathogens. If this bacterium gains access to the inside of a leaf, however, it causes a fatal disease in the plant. Once the plant dies, the bacterium and its offspring decompose the plant. What is the correct sequence of ecological roles played by the bacterium in the situation described here?
A) nutrient recycler, commensal, pathogen
B) mutualist, commensal, pathogen
C) mutualist, pathogen, nutrient recycler
D) nutrient recycler, mutualist, primary producer

Question

Quizplus · Accepted Answer

The bacterium first plays a mutualistic role by inhibiting the growth of other plant pathogens. However, when it gains access to the inside of the leaf, it becomes a pathogen and causes fatal disease in the plant. Once the plant dies, the bacterium and its offspring decompose the plant, making it a nutrient recycler. Therefore, the correct sequence of ecological roles played by the bacterium is mutualist, pathogen, nutrient recycler. Choice A is incorrect because it lists commensal instead of mutualist as the first role played by the bacterium, and the sequence of roles is incorrect. Choice B is incorrect because it lists commensal instead of mutualist as the first role played by the bacterium. Choice D is incorrect because it includes primary producer, which is not applicable to the bacterium in this scenario.

In a Hypothetical Situation, a Bacterium Lives on the Surface