Question

In which of the following, all listed genera belong to the same class of algae?
A. Chara, Fucus, Polysiphonia
B. Volvox, Spirogyra, Chlamydomonas
C. Porphyra, Ectocarpus, Ulothrix
D. Sargassum, Laminaria, Gracillaria

Answer 1

Algae(Thallophyta) is the most primitive group of kingdom Plantae. Algae are classified mainly into three classes namely, Chlorophyceae (green algae), Rhodophyceae (red algae), and Phaeophyceae (brown algae).

Complete answer: Algae lack a well-developed stem, root and leaves are usually aquatic. They lack vascular systems. Water uptake is carried out by simple diffusion. Based on the pigment present in algae, food storage and type of flagella present on gametes are broadly classified as below-

Class	Common Name	Pigments Found	Food Storage	Flagella	Examples
Chlorophyceae	Green Algae	Chlorophyll-a, chlorophyll-b.	Food is stored in form of Starch, Fat	Simple, whiplash, iso-kont.	Chlamydomonas, Volvox, Spirogyra, Chara, Ulvothrix
Phaeophyceae	Brown Algae	Chlorophyll-a, Chlorophyll-c, carotenoids, xanthophyll.	Food is stored in form of Laminarin, mannitol, Fucosan	Hetro-kont type of flagella	Laminaria, Dictyota, Sargassum, Fucus
Rhodophyceae	Red Algae	Chlorophyll-a, Chlorophyll-d, phycocyanin, allophycocyanin, phycoerythrin.	Food is stored in the form of Floriden starch.	Absent	Porphyra, Gracilaria, Gelidium, Polysiphonia

So, the correct answer to the given question is option B. Volvox, Spirogyra, Chlamydomonas which belongs to the same class of Chlorophyceae. They have Chlorophyll-a, Chlorophyll-b. in common.

Note: The study of algae is called Phycology. Father of Phycology William Henry Harvey. The majority of the earth's oxygen is produced by algae. During sexual reproduction, flagella play an important role in the fusion of gametes. GM Smith, later on, classified algae into seven divisions. Seven different divisions are Euglenophyta, Chrysophyata, Chlorophyta, Rhodophyta, Pyrrophyta, Phaeophyta, and Xanthophyta.