The structure present in cyanobacteria $(BGA)$ that helps in nitrogen fixation is

The class to which mycoplasma belongs is

In $Nostoc$,the heterocysts are:

Refer to the given figures of a bacterial cell and Nostoc and choose the option which shows the correct labels for the structures marked as $A$,$B$,$C$,$D$,and $E$.

The nucleotide sequence in ribosomal $RNA$ provides the best evidence for the phylogeny of Monera. Based on this information,which are the most primitive Monerans?

An example of iron bacteria is