Question

Study the following statements and select the correct ones.
(i) Methanogens are archaebacteria that produce methane in marshy areas.
(ii) Nostoc is a filamentous blue-green alga which fixes atmospheric nitrogen.
(iii) Many members of the genus Glomus form mycorrhiza.
A. (I) and (ii)
B. (I) and (iii)
C. (ii) and (iii)
D. (i), (ii) and (iii)

Answer 1

Nostoc absorbs nitrogen from the air and converts it into a form that plants and animals can use. Nitrogen fixation is the name for this process. Nitrogen is used by all living species to produce amino acids, proteins, and other essential building blocks.

Complete answer:
Microorganisms known as methanogens create methane as a metabolic byproduct in hypoxic environments. They're prokaryotic and belong to the archaea domain. Methanogenesis, or the biological synthesis of methane in marine sediments, is mainly limited to areas where sulphates are depleted, which is below the top layers.
Nostoc can be found in soil, on moist rocks, at the bottom of lakes and springs (both freshwater and saltwater), and in marine settings on rare occasions. It can also grow symbiotically within plant tissues, supplying nitrogen to its host via heterocysts, which are terminally differentiated cells. To perform photosynthesis, these bacteria have photosynthetic pigments in their cytoplasm.
Glomus is a genus of arbuscular mycorrhizal (AM) fungi that create symbiotic (mycorrhizal) associations with plant roots. Glomus is the biggest genus of AM fungi, having over 85 species, but it is now classified as non-monophyletic.

So, option D is the right answer.

Note: All Glomus species, like other AM fungus, are assumed to be obligate symbionts that rely on mycorrhizal associations with plant roots to complete their life cycle. They can't be cultured in the lab because they don't have a plant host. Glomus species can be found in practically every terrestrial ecosystem, including agricultural areas, grasslands, deserts, tropical forests, and tundras.