Question

Select the mismatch

• A. Rhizobium – Alfalfa
• B. Rhodospirillum – Mycorrhiza
• C. Frankia – Alnus
• D. Anabaena – Nitrogen fixer

Answer 1

The correct option is B Rhodospirillum – Mycorrhiza

Rhodospirillum is anaerobic and free-living. It is a nitrogen fixer, which helps in the conversion of atmospheric nitrogen to ammonia. It is not associated with roots of the vascular plant as mycorrhiza (association of the fungus with the root).

A number of cyanobacteria such as Anabaena and Nostoc are also free-living nitrogen-fixers.

Species of rod-shaped Rhizobium has such relationship with the roots of several legumes such as alfalfa, sweet clover, sweet pea etc.
The microbe, Frankia, also produces nitrogen-fixing nodules on the roots of non-leguminous plants (e.g., Alnus).