Chlorophyceae (Green Algae) – Class 11 | Chapter – 3 | Short Notes Series PDF

Chlorophyceae (Green Algae): Green Algae are eukaryotic organisms characterized by the presence of chlorophylls a and b in them, and these chlorophylls act as major photosynthetic pigments. The photosynthetic pigments of green algae are usually colorless, and heterotrophic taxa are also present in them, such as Hyalogonium, Polytomella, and Polytoma. Green Algae are associated with Cyanobacteria (which is also known as Blue-green Algae), and they are also found in freshwater habitats. Green Algae is also known as Freshwater Algae, and they play a very important in ecological successions (both primary and secondary).

The bright green color of green algae is because of chloroplasts that contain both chlorophylls a and b. In addition, green algae also have accessory pigments, i.e., xanthophylls (yellow) and beta carotene (red-orange), in their stacked thylakoids. Green algae store carbohydrates in the form of starch, and their cell walls usually contain cellulose. Chlorophyceae (Green Algae) are anchored by fibrous strands and a cross-shaped system of microtubules, and only motile male gametes of charophytes have flagella in them. The flagella are also present in the motile male gametes of Ginkgo, cycads, pteridophytes, and bryophytes but these flagella are absent from the gametes of flowering plants and pinophyta.

Reproduction of Chlorophyceae (Green Algae)

The reproduction pattern in green algae is very diverse, and it is also a very interesting field to study. Many different species of algae follow different reproduction pattern and some of them shares a common pattern too. First, Ulva, the diplobiontic species, species of green algae, follows a unique reproduction cycle which is known as Alternation of generation. In this reproduction pattern, the two multicellular forms of species, i.e., diploid and haploid alternate and these alternate forms may or may not be having the same morphology (isomorphic to each other).

The fertilized egg cell of the diploid zygote undergoes the meiosis process of cell division, which gives rise to haploid cells, which give rise to the haploid generation of species, and later these haploid cells of these species will become new gametophytes. Now, the haplobiontic generation from the species is the only haploid generation, and they will be multicellular, and later they form the diploid generation of them.

Thus, a diploid form of the species evolved from the haploid ancestors’ generation has both a multicellular haploid generation and multicellular diploid generation. All diploid generation of these species is considered to have evolved independently from Ulvophyceae more than once. Studies have also found that all land plants have a common diploid ancestor. The same process is also found in many species of brown & red algae.


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By Team Learning Mantras