Question

25. A mutualistic relationship exists between plants called_____________which harbour the bacterium ______________in their roots in special structures called root_______________. Here the bacteria take _____________from the air and fix it so the plants can use it.

A. Legumes rhizobium leghaemoglobins phosphorous

B. Legumes rhizobium nodules phosphorous

C. Legumes rhizobium nodules nitrogen

D. Beans rhizopus leghaemoglobins nitrogen

Answer 1

Answer - C. Legumes, rhizobium, nodules, nitrogen

Rhizobium is a bacterial symbiont of papilionaceous roots like legumes that can fix nitrogen. This bacteria is normally found in soil but can't fix nitrogen. One entering the legume roots they first develop a number of nodules. these nodules are normally pinkish in colour due to the presence of leghaemoglobin - a pigment, this pigment acts as oxygen scavenger and protects the nitrogenase present within bacteroids. hence by a mutualistic relationship with the legume, they can successfully fix the nitrogen by taking them from the air. As these bacteria not only restricted to beans, and special structures are not leghaemoglobin and also they fixes nitrogen not phosphorous all except C are wrong.