$Azotobacter$ and $Bacillus \text{ } polymyxa$ are:

Categorize the following nitrogen-fixing microorganisms into symbiotic and free-living types:
$I-$ Rhizobium
$II-$ Azotobacter
$III-$ Beijerinckia
$IV-$ Rhodospirillum
$V-$ Frankia
$VI-$ Bacillus
$VII-$ Anabaena (free-living)
$VIII-$ Nostoc (symbiotic)
Select the correct grouping for (Symbiotic) and (Free-living) respectively.

$A -$ The enzyme nitrogenase is highly sensitive to molecular oxygen.
$R -$ To protect nitrogenase enzymes,the nodule contains an oxygen scavenger called leghaemoglobin.

Which of the following bacteria are free-living nitrogen fixers?

How many of the following organisms are capable of nitrogen fixation?
Azospirillum, Glomus, Nostoc, Monascus purpureus, Yeast, Anabaena, Oscillatoria, Azotobacter, Trichoderma

Identify the odd one out in the context of nutrition.