Question

Which of the following statements about cyanobacteria is incorrect?

• A. Cyanobacteria like Nostoc and Anabaena are chemosynthetic autotrophs.
• B. Cyanobacterial colonies are generally surrounded by a gelatinous sheath.
• C. They are unicellular, filamentous and terrestrial/marine organisms.
• D. Some of these organisms can fix nitrogen in specialized cells called heterocysts.

Answer 1

Answer: (A)

The cyanobacteria (blue-green algae) have chlorophyll a, similar to green plants, and are photosynthetic autotrophs. The cyanobacteria are unicellular, colonial or filamentous, freshwater/marine or terrestrial algae. The colonies are generally surrounded by a gelatinous sheath. They often form blooms in polluted water bodies. Some of these organisms can fix atmospheric nitrogen in specialised cells called heterocysts, e.g., Nostoc and Anabaena.