Question

An alga, very rich in protein, is
A. Nostoc
B. Ulothrix
C. Chlorella
D. Spirogyra

Answer 1

Algae is a phylum of the kingdom Plantae. It consists of mostly green-coloured, photosynthetic, oxygenic and thalloid organisms. The bodies of algae are highly variable in shape and they vary from unicellular to filamentous to colonial.

Complete answer: The body of algae is undifferentiated into roots, stems and leaves. Algae are mostly aquatic and some are terrestrial. They have no vascular tissues present in them.
a) Nostoc : Nostoc is a cyanobacterium or a blue-green alga. It is a nitrogen-fixing bacteria. They have heterocyst cells which are specialized cells for the fixation of nitrogen.
b) Ulothrix : Ulothrix is a green alga and it belongs to the class Chlorophyceae. It is an unbranched and filamentous type of algae. Ulothrix has a collar-shaped or girdle-shaped chloroplast.
c) Chlorella : Chlorella is a green alga that belongs to the class Chlorophyceae. It is a unicellular and non-flagellated alga. It has a disc-shaped or discoid chloroplast. Chlorella has a very high protein content due to which it is used as a source of food. They are used as single-celled proteins. Chlorella is also known as the space algae as it is used to release oxygen and is used as a source of food by astronauts. Moreover, it is also used as an experimental material for the laboratory.
d) Spirogyra : Spirogyra is a green alga that belongs to the class Chlorophyceae. It is an unbranched and filamentous type of algae. Spirogyra has a ribbon-shaped chloroplast.
Thus, based on the above information we can conclude that an alga, very rich in protein, is Chlorella.
Hence, the correct answer is option C.

Note: The Chlorophyceae consists of algae that have a haploid body. These algae are mostly present in freshwater but some are marine too. They have photosynthetic pigments like chlorophyll a, chlorophyll b, carotene and xanthophyll.