UPSC General Studies Sample Paper General Studies Sample Paper-5

  • question_answer
    Consider the following statements about Rhizobium.
    1. Rhizobium lives in the roots of gram, peas, moong beans and other legumes and provides them with nitrogen.
    2. It converts atmospheric nitrogen into plant soluble ammonium.
    3. It can make its own food.
    Which of the statement(s) given above is/are correct?

    A)  1 and 2

    B)         1 and 3            

    C)  2 and 3

    D)  Only 3

    Correct Answer: A

    Solution :

    [a] Rhizobium cannot make its own food, so it lives symbiotically with legumes. The first two statements are correct. Rhizobia are soil bacteria that fixes nitrogen (diazotrophs) after becoming established inside root nodules of legumes (Fabaceae). Rhizobia require, a plant host they cannot independently fix nitrogen. Rhizobium can fix nitrogen from the atmospheric, elemental N3 into a plant-usable form, ammonium, using the enzyme nitrogenase.


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