Photosynthetic bacteria and blue-green algae have molecular components of their light-receptor systems in:

Which of the following statements are incorrect for $Nostoc$ and $Anabaena$?
$(a)$. Possess tissue level organization
$(b)$. Have heterocysts
$(c)$. Can fix atmospheric hydrogen
$(d)$. They are eubacteria

Which of the following is a prokaryotic kingdom?

Assertion $A$: Some bacteria are motile.
Reason $R$: Some bacteria have tubular pili or fimbriae extensions arising from their surface.
Which option is correct for Assertion $A$ and Reason $R$?

Cyanobacteria is a

Atmospheric nitrogen-fixation is carried on by