Select the correct combination of the statements (1–4) regarding the characteristics of certain organisms. (1) Methanogens are Archaebacteria which produce methane in marshy areas. (2) Nostoc is filamentous blue-green alga which fixes atmospheric nitrogen. (3) Chemosynthetic autotrophic bacteria synthesise cellulose from glucose. (4) Mycoplasma lack a cell wall and can survive without oxygen.