Question

The classification of group algae is based on
A. Nature of sex organ
B. Nature of pigments
C. Nature of spores
D. None of the above

Answer 1

Algae belong to the large group of eukaryotic organisms and they are polyphyletic groups.

Complete answer:
Algae is the chlorophyll bearing, simple, thalloid, autotrophic and largely aquatic organisms. They are found in various habitats such as moist stone, soils and wood. Some of them also occur in the association with fungi and bear. The algae reproduce by vegetative, asexual and sexual means. Vegetative reproduction takes place by fragmentation and each fragment develops into a thallus. Asexual reproduction is by the production of different types of spores. Sexual reproduction takes place by the fusion of two gametes. The algae are classified based on pigments and they are Chlorophyceae Phaeophyceae and Rhodophyceae.
Chlorophyceae are the algae that may be generally unicellular, colonial or filamentous. They usually contain pigments chlorophyll-a and chlorophyll-b and the pigments are located in particular chloroplasts. Eg: Volvox, Chara etc. Phaeophyceae are also known as brown algae and are found primarily in marine habitats. They contain the pigments chlorophyll a, c, carotenoids and xanthophylls. Their brown colour is due to the presence of xanthophyll pigment known as fucoxanthin. Rhodophyceae algae are commonly known as red algae because they have an abundance of red pigments known as r-phycoerythrin. The majority of red algae are found in the marine habitats. They stored food as floridean starch which has a similar structure like amylopectin and glycogen.
So, the classification of a group of algae is based on the nature of pigments.
Hence, the correct answer is, ‘b. Nature of pigments’.

Note: The form and size of algae are highly variable. More than $70\%$ of marine algae are used as food. The Chlorella is a unicellular alga rich in proteins and is used as a food supplement by space travellers.