Question

Cyanobacteria are also referred to as
A. Protists
B. Golden algae
C. Slime moulds
D. Blue green algae

Answer 1

Hint: Eubacteria or true bacteria includes several subgroups. Cyanobacteria is a subgroup classified under eubacteria. Cyanobacteria are autotrophic, gram-negative bacteria.

Complete answer: Cyanobacteria are the most primitive organisms to have oxygenic photosynthesis. They added oxygen to the atmosphere. Mostly they are found in marine water bodies. The red sea is named because of the abundant occurrence of the cyanobacterium Trichodesmium erythraeum, which imparts red colouration to water. They occur in a symbiotic association with almost every group of eukaryotes, i.e. green algae, fungi, bryophytes like mosses and Anthoceros, ferns, gymnosperms, angiosperms, sponges, shrimps, mammals, etc. Cyanobacteria are commonly referred to as blue-green algae because they perform photosynthesis. There is no relation between Cyanobacteria and the colour, i.e. blue-green, but due to its ability to perform oxygenic photosynthesis, Cyanobacteria refer to blue-green algae.
So the correct answer is option is D.

Additional Information: Cyanobacteria has not well-defined nucleus and the chromatin material is centrally located, resembling the bacterial chromosome. The cell wall is four-layered and is inversely covered by a mucilaginous sheath, composed largely of muropeptides. The protoplasm can be distinctly divided into two parts; the centroplasm and chromoplasm. The central colourless centroplasm contains the chromatin material.

Note: Cyanobacteria may be colonial, filamentous and unicellular. The filamentous form consists of one or more cellular strands, called trichomes surrounded by a mucilaginous sheath. Cyanobacteria are characterized by the absence of flagellum throughout their life cycle.