Question

A member of class Chlorophyceae is-
a. Chlamydomonas
b. Volvox
c. Ulothrix
d. All of the above

Answer 1

Hint: These algae groups are largely differentiated on the basis of ultra-structural morphology. Typically, they are green because of the superiority of chlorophyll a and chlorophyll b pigments.

Complete answer:
> Option A is incorrect. Chlamydomonas is a unicellular flagellate, green algae genus found in stagnant water and humid soil, in freshwater, seawater, and also as "snow algae" in snow. They used molecular biology as a model organism, in particular studies on flagellar motility and dynamics of chloroplast, biogenesis and genetics. A few of Chlamydomonas many striking features is that it includes channels of ions (channelrhodopsins), which are activated directly by light.

> Option B is incorrect. Within the Volvocaceae family, Volvox is a polyphyletic genus of chlorophyta green algae. It forms spherical colonies that can accommodate up to 50,000 cells. They live in diverse freshwater environments and were first recorded in 1700 by Antonie van Leeuwenhoek. Volvox is a polyphyletic genus in the clade of green volvocine algae. Each mature Volvox colony consists of up to thousands of cells of two distinct types of cells: numerous somatic flagellate cells and fewer soma-deficient germ cells embedded in the layer of a cylindrical shape or coenobium containing an extracellular matrix made of glycoproteins.

> Option C is incorrect. Ulothrix is a Green Algae genus in the Ulotrichaceae family. Ulothrix is a genus of non-branching green filamentous algae, commonly found in both fresh and marine water. Its cells are usually as wide as long, and thrive at low spring and winter temperatures. They get attached by a tweaked holdfast cell to the surfaces. Reproduction is typically of a vegetative nature. They are eukaryotic and multicellular since the cells have unique roles, because the lower cell acts as a holdfast and it has no chloroplast, and the apical cell is dome-shaped.

> Option D is correct. Often classified as Green Algae are chlorophyceae. Chloroplasty in such algae includes pigments such as chlorophyll-a, b, carotene, and xanthophyll. The cell is composed of cellulose. In such algae the reserve food is in the form of starch. Examples include Chlamydomonas, Volvox, Chlorella, Ulothrix etc.

Hence, The correct answer is option (D).

Note: Green algae have chloroplasts containing chlorophyll a and b in lined thylakoids, giving them a vivid green colour, as well as the accessory pigments beta carotene (red-orange) and xanthophyll (yellow). Green algae cell walls normally contain cellulose, and carbohydrate is contained in the form of starch.