Question

An example of colonial alga is
A. Spirogyra
B. Chlorella
C. Volvox
D. Ulothrix

Answer 1

Colonial algae is a kind of algae consisting of cells resembling free swimming unicells making groups. They can be large and interconnected or smaller and relatively simple for example in Synura.

Complete answer:
Let’s start with, Spirogyra is a genus of green algae belonging to the order called Zygnematales. These free-flowing, filamentous algae are featured by ribbon-shaped chloroplasts that are present in a helical manner inside the cells. Hence, the name is derivative of the spiral arrangement of chloroplasts in these algae.
Chlorella is a genus consisting of single-celled green algae which belong to the division Chlorophyta. It is spherical in shape, and without flagella and has the green photosynthetic pigments chlorophyll-a and -b inside chloroplast.
Ulothrix is categorized as a genus of non-branching filamentous green algae, normally found in fresh and marine water. They attach to the surfaces by a modified holdfast cell and its reproduction is normally vegetative. They are classified as Eukaryotic and multicellular because the cells have special functions. The lowermost cell serves as holdfast and it does not consist of chloroplast, and the apical cell is seen as dome-shaped to make them to be seen as multicellular eukaryotic.
Whereas, the Volvox is a polyphyletic genus of chlorophyta green algae categorized in the family Volvocaceae. It makes spherical colonies having up to 50,000 cells. They thrive in a variety of freshwater habitats.
Remember, Volvox is a unicellular green alga which is seen in freshwater bodies. It is photosynthetic in nature and makes colonies of around 50,000 cells which are spherical in shape.

Therefore, the correct answer is option C.

Note:
Keep in mind that around 20 species of Volvox have been identified. As primary producers, the photosynthetic organisms are an extremely important part of many aquatic ecosystems.
Remember, they divide the DNA from any one parent cell and a daughter cell is given off from the parent. Paramecium species of cells may be big predators for a Volvox because a small paramecium can survive inside of a larger Volvox and destroy and consume it from the inside out.