Root nodules contain

Which bacteria are present in the structure shown below?

Identify the following process from the diagram.

Which of the following are the part or example of symbiotic mutualistic association?
$I.$ Yeast
$II.$ Rhizobium
$III.$ Mycorrhiza
$IV.$ Oscillatoria

What are the steps involved in the formation of a root nodule?

Mark the correct sequence of steps for the development of root nodules in legumes:
$a.$ Formation of infection thread.
$b.$ Division of cortical and pericyclic cells.
$c.$ Curling of root hairs.
$d.$ Leghaemoglobin synthesis.