Which of the following statements are wrong for cyanobacteria ?
(i) They are multicellular, colonial or filamentous, freshwater/marine or terrestrial algae,
(ii) The colonies are generally surrounded by gelatinous sheath.
(iii) They often form blooms in polluted water bodies.
(iv) Some of these organisms can fix atmospheric nitrogen in specialised cells called heterocysts.
(v) They have chlorophyll 'a' which is not similar to green plants and are photosynthetic autotrophs.
(vi) Nostoc and Anabaena included in this group