In $Aulosira$,$Tolypothrix$ and $Nostoc$, . . . . . . are the sites for Nitrogen fixation.

Match the organisms in Column-$I$ with habitats in Column-$II$.

Column-$I$	Column-$II$
$(a)$ Halophiles	$(i)$ Hot springs
$(b)$ Thermoacidophiles	$(ii)$ Aquatic environment
$(c)$ Methanogens	$(iii)$ Guts of ruminants
$(d)$ Cyanobacteria	$(iv)$ Salty area

Select the correct answer from the options given below:

In the five-kingdom classification of Whittaker,kingdom $Monera$ is the group of microorganisms. Among the following statements,find out the incorrect statement for bacteria.

Identify the microorganisms shown in the image.
$P$ and $Q$

Which of the following cells does not contain a nuclear membrane?

In which of the following are gas vacuoles found?