Green-algae
Green algae may be found in marine or freshwater habitats, and some even live on land, growing on soil, trees, or rocks.9,000 and 12,000 species. The photosynthetic pigments (chlorophylls a and b, carotene, and xanthophyll) are within an equivalent proportions as those in higher plants. The typical green algal cell, which can be motile or nonmotile, has a central vacuole, pigments contained in plastids that vary in shape in different species, and a two-layered cellulose and pectin cell wall. Food is stored as starch in pyrenoids (proteinaceous cores within the plastids). Green algae, variable in size and shape, include single-celled (Chlamydomonas, desmids), colonial (Hydrodictyon, Volvox), filamentous (Spirogyra, Cladophora), and tubular (Actebularia, Caulerpa) forms. Sexual reproduction is common, with gametes that have two or four flagella. Asexual reproduction is by cellular division (Protococcus), motile or nonmotile spores (Ulothrix, Oedogonium), and fragmentation. Most green algae occur in fresh water, usually attached to submerged rocks and wood or as scum on stagnant water; there are also terrestrial and marine species. Free-floating microscopic
species function food and oxygen sources for aquatic organisms. Green algae also are important within the
evolutionary study of plants; the single-celled Chlamydomonas is taken into account almost like the ancestral form that probably gave rise to land plants.
High Impact List of Articles
Relevant Topics in General Science