Which statement best describes the process that takes place in these
nodules?
o
a. bacteria in the plant nodules convert water from the soil into
molecules the plants can use.
o
b. bacteria in the plant nodules convert oxygen from the soil into
molecules the plants can use
o
c. bacteria in the plant nodules convert nitrogen from the soil into
molecules the plants can use.
o
d. bacteria in the plant nodules convert carbon from the soil into
molecules the plants can use.

C. Bacteria in the plant nodules convert nitrogen from the soil into

molecules the plants can use

Explanation:

Free nitrogen in the soil is fixed into ammonia by symbiotic bacteria, called Rhizobium which are found in the root nodules of leguminous plants. Rhizobia infects the roots of legumes producing nodules where they fix nitrogen gas (N2) from the atmosphere into a more readily useful form of nitrogen. The ammonia is taken up directly by the plant and used to form amino acids and subsequently proteins.

The ammonia are converted into nitrites by the nitrifying bacteria e.g., Nitrosomonas and Nitrococcus. The nitrifying bacteria of the genus Nitrobacter convert nitrites to nitrates which are absorbed by plants.