Question
Question: Algae which form motile colony is A. Volvox B. Nostoc C. Spirogyra D. Chlamydomonas...
Algae which form motile colony is
A. Volvox
B. Nostoc
C. Spirogyra
D. Chlamydomonas
Solution
Hint:- Algae are photosynthetic species with photosynthetic pigments such as chlorophyll in their possession. They miss actual roots, stems and leaves that are typical of vascular plants, though. Some of them are single-celled, while others are multi-cell. They can form colonies as well. The bulk of algae are marine. Others can be found on damp soil, trees and rocks and are terrestrial. With other animals, some algal species form symbiosis.
Complete step-by-step solution:- Volvox consists of spherical or oval hollow colonies containing between 500 and 60,000 cells enclosed in a gelatinous wall, often only visible to the naked eye. Volvox also demonstrates a distinction between somatic (non-sex cells) and reproductive cells, a phenomenon that some biologists consider to be significant in tracing the evolution of microorganisms from higher species. Cytoplasm threads, which facilitate cell-to - cell contact, are often linked together by adjacent cells and the colony travels through water by the flagella's synchronised motion. Photosynthetic colonies are typically arranged such that cells with larger eye spots are clustered on one side to promote photosynthesis by phototaxis (movement towards light), and reproductive cells are clustered on the other side.
Nostoc, a blue-green algae genus, with cells arranged in bead-like chains clustered into gelatinous masses. Masses of Nostoc can be found on the surface and floating in calm water, varying from microscopic to walnut-sized. By fragmentation, replication is. Nostoc contains two pigments, blue phycocyanin and red phycoerythrin, as well as chlorophyll, much like most blue-green algae, and has the capacity to fix nitrogen in specialised cells called heterocysts.
Spirogyra, a member of the free-floating green algae found all over the world in freshwater ecosystems. They can form masses, buoyed by oxygen bubbles produced during photosynthesis, that float near the surface of streams and ponds. Species of Spirogyra can replicate sexually as well as asexually. Asexual, or vegetative, replication happens by simple filament fragmentation. Sexual reproduction happens by a mechanism known as conjugation, in which outgrowths or conjugation tubes are joined by cells with two filaments lying side by side. This helps one cell's contents to fully move through and fuse with the other's contents.
Chlamydomonas, a species of single-celled green biflagellated algae living in soils, rivers, and ditches. The species of Chlamydomonas can become so numerous as to stain the green of fresh water. While photosynthesis occurs, the surface of the cell can also absorb nutrients. Asexual reproduction is carried out by zoospores. Gametes are created by sexual reproduction. The formation of motility, sexual differentiation, and gamete fusion appears to be based on the production of hormone-like regulatory action substances (termones, gamones).
So from these discussions we can conclude that Volvox is the only algae which can form a motile colony. Therefore the correct answer is option (A).
Note:- Algae are significant in their natural environment since they account for half of the organic material's photosynthetic development on earth. They serve as marine animal food. Some of them, such as lichens, survive in symbiosis as well. Lichen is the symbiotic relationship of terrestrial ecosystems between algae and fungi. The appearance of lichen may suggest the environment's pollution level.