Question

Why Are Algae Green in colour?

Answer 1

Algae is generally an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that consists of species from multiple distinct clades. Organisms included ranges from unicellular microalgae, such as Chlorella, Prototheca and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga.

Complete answer:
Algae are photosynthetic organisms and can be either unicellular or multicellular organisms. They lack a well-defined body, so structures like roots, stems or leaves are absent in them. Algaes are found where there is adequate moisture. Reproduction occurs in both asexual and sexual forms. Asexual reproduction occurs by spore formation.

Algae are green in colour because they are composed of a green-coloured pigment called chlorophyll within their cells. Green algae are examples of algae that have primary chloroplasts which are obtained from endosymbiotic cyanobacteria. They contain chlorophylls A and B.

The largest and most complex marine algae are called seaweeds, while the most complex freshwater forms are the Charophyta, which is a division of green algae that comprises Spirogyra and stoneworts.
Higher organisms use green algae to perform photosynthesis for them. Other species of green algae have a symbiotic relationship with other organisms. Endosymbiotic green algae live close to the surface of some sponges, an example is breadcrumb sponges.

Note: Some unicellular species of green algae, many golden algae, euglenids, dinoflagellates, and other algae have become heterotrophs, sometimes parasitic, relying entirely on external energy sources and have limited or even no photosynthetic apparatus. Trentepohlia is an example of a common green alga genus that can grow on its own or be licensed.