An unknown microscopic prokaryote isolated from fresh water is observed to perform oxygenic photosynthesis using phycobilin accessory pigments and chlorophyll distributed along unstacked internal membranes, but completely lacks membrane-bound plastids. Which of the following correctly classifies this organism and describes its cellular organization?
- It is a cyanobacterium with photosynthetic thylakoid membranes lying free within the cytoplasm.Answer
- BIt is a unicellular plant possessing a rigid cell wall composed exclusively of cellulose.
- CIt is a photosynthetic virus possessing cytoplasm enclosed by a protein capsid.
- DIt is a photosynthetic bacterium belonging to the genus spirulina with a cellulosic envelope.
Answer
The organism is a cyanobacterium with photosynthetic thylakoid membranes lying free within the cytoplasm.
Cyanobacteria are prokaryotic members of Kingdom Monera that perform oxygenic photosynthesis. Unlike eukaryotic algae or plants, their photosynthetic pigments (chlorophyll and phycobilins) and thylakoid membranes are located directly within the cytoplasm rather than compartmentalized inside chloroplasts.
Step-by-Step Solution
Key Concept
Structural features and photosynthetic organization of Kingdom Monera (Cyanobacteria)