Question

What is required for nitrogen fixation by Rhizobium?
(A) Potassium
(B) Phosphorus
(C) Molybdate
(D) Sodium

Answer 1

Hint: Nitrogen fixation is considered as a chemical process in which the dinitrogen which is present in air is converted into ammonia or other nitrogenous compounds in the soil or aquatic system. In this process, Dinitrogen which is inert in nature, is made to react with other chemicals present in surroundings to form more reactive nitrogenous compounds.

Complete answer:
Nitrogen fixation is considered as a chemical process in which the dinitrogen which is present in air is converted into ammonia or other nitrogenous compounds in the soil or aquatic system. In this process, Dinitrogen which is inert in nature, is made to react with other chemicals present in surroundings to form more reactive nitrogenous compounds.
This process takes place with the help of enzymes like Rhizobium, Azotobacter and so on. Nitrogenous is a complex enzyme which helps in reducing atmospheric nitrogen to ammonia. Phosphorus is an important part of the ATP unit which is called the energy unit and hence, it helps in the development and growth of the plant. It plays an important role in nitrogen fixation by nodule formation and provides energy for this process.
Therefore, phosphorus is required for nitrogen fixation by Rhizobium.
Hence, the correct option is (B) Phosphorus.

Note:
Rhizobium is a bacteria found in the soil which helps in fixing nitrogen in the leguminous plants. It attaches itself to the roots of the plant and produces nodules. These nodules convert atmospheric nitrogen into ammonia. There are some diseases which are caused by Rhizobium bacteria which are Rhizobium rhizogenes (responsible for infectious hairy roots in dicotyledonous plants) and Rhizobium radiobacter (responsible for crown gall disease).