Why is $Mycoplasma$ pleomorphic?

Which group includes microorganisms that lack a defined nucleus but contain genetic material (nucleoid)?

The smallest living cells with a cell wall are:

An akinete is a structure associated with ........

The cell wall of $Nostoc$ is made up of:

Which of the following are concerned with eubacteria?
$(1)$ Methanogens $(2)$ Anabaena $(3)$ $N_2$ fixation $(4)$ Thermoacidophiles $(5)$ Eukaryotes $(6)$ Diatoms $(7)$ Gelatinous sheath $(8)$ Heterocyst