The enzyme responsible for the reduction of molecular nitrogen to the level of ammonia in leguminous root nodule is

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

The enzyme nitrogenase is:

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.

Name one non-symbiotic nitrogen-fixing prokaryote.

The function of leghaemoglobin in the root nodules of legumes is