Antony van Leeuwenhoek was the first to discover bacteria. He belonged to which country?

Organisms known as methanogens are found in abundance in ............ .

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.

Which of the following is a characteristic feature of the kingdom $Monera$?

What is the primary function of a heterocyst in cyanobacteria?

Bacterial photosynthesis takes place in