The elementary cell body in $Mycoplasma$ performs the function of:

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

Which of the following statements is incorrect regarding $Mycoplasma$?

Select the correct statements from the given statements $(1-4)$ regarding the characteristics of some organisms.
$(1)$ Methanogens are Archaebacteria that produce methane in marshy areas.
$(2)$ $Nostoc$ is a flagellated blue-green alga that fixes atmospheric nitrogen.
$(3)$ Chemosynthetic autotrophic bacteria synthesize cellulose from glucose.
$(4)$ Mycoplasma lacks a cell wall and can survive without oxygen.

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

Select the mismatched pair from the following.