Question

Pigment containing membranous extensions in some cyanobacteria are
A. Pneumatophores
B. Chromatophores
C. Heterocysts
D. Basal bodies

Answer 1

Hint: Cyanobacteria word is derived from the word cyano= blue-green. It is also called cyanophyta that can live as both as free living photosynthetic bacteria and as the endosymbiotic plastids that are present in the eukaryotes.

Complete Answer:
A cyanobacterium is also known as blue green algae is a unicellular, colonial or filamentous, marine or terrestrial algae which is currently belonging to eubacteria. It is having chlorophyll similar to green plants and thus acts as photosynthetic autotrophs. The colonies of this bacterium are generally surrounded by gelatinous sheath. A cyanobacterium is having membranous extensions that are containing pigments that are known as chromatophores that are responsible for photosynthesis.

The correct option is B i.e. chromatophores.

Additional information: The presence of chlorophyll a reflects light of wavelength similar to blue green color and reflects blue green color to the cell and also capable of performing photosynthesis. Due to these two reasons, the bacterium is also known as blue-green algae.
- Some of the cyanobacteria are used as a feed supplement like Spirulina. It is used as a dietary supplement as it contains a high amount of protein (51-70%). Besides it acts as a good source of protein, it also acts as a source of vitamin $B_{12}$.
- It is a microbial protein also called a single cell protein because the protein is derived from an edible unicellular microorganism. In animals, it is used as a feed supplement in poultry industry especially in the broiler (meat producing) industry for the growth of chicken within 21 days.

Note: Chlorella and Spirulina are the unicellular blue green algae that are edible in nature. It is rich in proteins and used by an astronaut as their food supplement. It is also rich in calcium, magnesium, potassium, niacin etc.