Question

Cyanobacteria are classified under which of the following kingdoms?
(a)Monera
(b)Protista
(c)Algae
(d)Plantae

Answer 1

Hint: Cyanobacteria do not have a well-defined nucleus and well-organized chromosomes. In that place, they have a single circular DNA. Also, the cell organelles like mitochondria, chloroplasts, Golgi complex, etc. are not found in these bacteria.

Complete answer:
In the five-kingdom system classification given by R. H. Whittaker, all the prokaryotic organisms were included in the kingdom Monera while all the eukaryotes were included in the other four kingdoms Protista, Fungi, Plantae, and Animalia. Since cyanobacteria are prokaryotes, they are classified with the other bacteria under the kingdom Monera. The kingdom includes small, microscopic, and primitive organisms with the simplest organization in the living word. A diagram of cyanobacteria has been given below –

Additional Information: Cyanobacteria are also known as Blue-Green Algae because it can perform oxygenic photosynthesis as other plants do and thus they constitute a phylum of bacteria consisting of the free-living photosynthetic forms called Cyanophyta. Upon studying the pieces of evidence of evolution, these have been thought to be evolved either in water or on land. These are gram-negative prokaryotes considered to be the first organisms that made the earth atmosphere aerobic. They can be unicellular, filamentous, or colonial with heterocyst in the filamentous forms.

So, the correct answer is ‘Monera’.

Note: -Any organism which are bacteria, archaebacteria, cyanobacteria, mycobacteria, etc., will always be included in the kingdom Monera because all such organisms are prokaryotic organisms and Monera is the kingdom of prokaryotes only.
-Algae are included under the plant kingdom because they bear chlorophylls and are photosynthetic just like the other plants and also, they are eukaryotes.