Question

Blue green algae are:
A. Actinomycetes
B. Eukaryotes
C. Prokaryotes
D. Acellular

Answer 1

Blue green algae are taxonomically classified along with the bacteria and are known as cyanobacteria. They are oxygenic photosynthetic bacteria and are the primary producers in aquatic ecosystems. Blue green algae contain the photosynthetic pigment chlorophyll in the thylakoid membrane. They however lack chloroplasts which are only found in plants which are eukaryotes. This answer can be solved by focusing the cellular structure of Blue green algae.

Complete solution:
In order to get through the answer for this question if we look at the options very carefully we can see that at first based on the level of organization of cellular structure in blue green algae we can odd out options B and D, as blue green algae are prokaryotic just like other bacteria. So, we can follow the below steps to select the appropriate option.
Option A: Blue green Algae are prokaryotes and Actinomycetes as well. However, Actinomycetes are heterotrophic in their mode of nutrition which is not the case with blue green algae (Cyanobacteria).
Thus, Option A is incorrect.
Option B: Blue green algae have cellular structure similar to bacteria (i.e., prokaryotes which are not having a well-defined nucleus and also do not have membrane bound organelles). In contrast, eukaryotes contain a well-defined nucleus as well as membrane-bound organelles. So, this option is not in line with the basic structure of a blue green algal cell.
Thus, Option B is incorrect.
Option C: Prokaryotes are those organisms which do not have a well-defined nucleus and they lack membrane bound organelles. They are the simplest organisms including all bacterial species. Blue green algae are bacteria classified under cyanobacteria, the oxygenic photosynthetic prokaryotes.
Thus, Option C is correct.
Option D: The term acellular means not consisting of, divided into, or containing cells. However, Blue green algae can consist of more than one cell in their colonial or filamentous forms like Anabaena and Nostoc are filamentous blue green algae capable of nitrogen fixation.
Option D is incorrect.

Hence, Option C is the correct answer.

Note:
Blue green algae are so called because of pigments like Anthocyanin and Phycocyanin. They contain a naked genetic material as circular ds DNA and are photoautotrophic prokaryotes. Their cells contain thylakoids where they synthesize their own food by the process of photosynthesis. They are generally found as producers in aquatic habitats. They multiply very rapidly to produce algal blooms. Algal blooms can be harmful for many aquatic organisms due to the toxic products released by them. Examples of blue green algae include Anabaena , Nostoc etc.