Q. Consider the following statements:
  1. Biological Nitrogen Fixation occurs exclusively in the absence of oxygen.
  2. Atmospheric nitrogen can only be fixed by symbiotic bacteria.
Which of the above statements is / are correct?

Answer: Neither 1 nor 2
Notes: Biological Nitrogen Fixation is not limited to anaerobic (oxygen-absent) conditions; some bacteria such as Azotobacter fix nitrogen aerobically. Additionally, both symbiotic and non-symbiotic (free-living) bacteria are capable of fixing atmospheric nitrogen, making both statements incorrect.