Which one of the following can fix atmospheric nitrogen directly?

What is the function of leghemoglobin?

Legume plants are important because they

Bacteria found in root nodules of legumes are

We find that $Rhizobium$ forms nodules on the roots of leguminous plants. Also,$Frankia$,another microbe,forms nitrogen-fixing nodules on the roots of the non-leguminous plant $Alnus$. Is it necessary for a microbe to be in close association with a plant to provide mineral nutrition? Explain with the help of one example.

The pigment leghaemoglobin is present in the roots of