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, 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? Use only those that apply.
1) nutrient recycler
2) mutualist
3) commensal
4) parasite
5) primary producer
A)1, 3, 4
B)2, 3, 4
C)2, 4, 1
D)1, 2, 5
E)1, 2, 3

Question

Quizplus · Accepted Answer

The bacterium acts as a mutualist by inhibiting plant pathogens (2), becomes a parasite when it causes disease inside the leaf (4), and finally acts as a nutrient recycler by decomposing the dead plant (1).

In a Hypothetical Situation, a Bacterium Lives on the Surface