Question

legumes, a type of plant, require rhizobia, a type of soil bacteria, to survive since these organisms fix nitrogen. rhizobia use the legumes for food. what would most likely happen to the legume population if rhizobia suddenly became extinct?
○ become extinct
○ learn to fix nitrogen
○ benefit in the long run
○ stay the same

Explanation:

Legumes depend on Rhizobia for nitrogen fixation to survive, and Rhizobia depend on legumes for food (a mutualistic relationship). If Rhizobia go extinct, legumes lose their nitrogen - fixing partner. Plants can't quickly "learn" to fix nitrogen (a complex biological process), and without nitrogen fixation, legumes can't get enough nitrogen to survive. So their population would likely become extinct. The other options are illogical: "learn to fix nitrogen" is not a rapid or likely process for legumes, "benefit in the long run" is wrong as they lose a vital partner, and "stay the same" is impossible as the mutualistic relationship is broken.

Answer:

A. become extinct