Cyanobacteria and heterotrophic bacteria have been clubbed together in eubacteria of kingdom-Monera as per the 'five kingdom classification' even though the two are vastly different from each other. Is this grouping of the two types of taxa in the same kingdom justified? If so,why? Discuss the cellular composition of cyanobacteria and heterotrophic bacteria that make them introduced in eubacteria.

(N/A) Yes,the grouping is justified because both cyanobacteria and heterotrophic bacteria are prokaryotic organisms.
$1$. Both lack a well-defined nucleus and membrane-bound organelles.
$2$. Both possess a rigid cell wall made of peptidoglycan (murein).
$3$. Both contain $70S$ ribosomes.
$4$. Cyanobacteria are photosynthetic autotrophs containing chlorophyll $a$ (similar to green plants),while heterotrophic bacteria obtain nutrients from organic matter.
$5$. Despite their metabolic differences,their fundamental cellular organization (prokaryotic nature) is identical,which is the primary criterion for their placement in the kingdom-Monera under the 'five kingdom classification'.