Economic importance of Algae:
Algae are useful to man in a variety of ways. At least a half of the total carbon dioxide fixation on earth is carried out by algae through photosynthesis. Being photosynthetic they increase the level of dissolved oxygen in their immediate environment. They are of paramount importance as primary producers of energy-rich compounds which form the basis of the food cycles of all aquatic animals.
Many species of Porphyra, Laminaria and Sargassum are among the 70 species of marine algae used as food. Certain marine brown and red algae produce large amounts of hydrocolloids (water-holding substances), e.g., algin (brown algae) and carrageen (red algae) are used commercially. Agar, one of the commercial products obtained from Gelidium and Gracilaria are used to grow microbes and in preparations of ice-creams and jellies. Chlorella and Spirullina are unicellular algae, rich in proteins and are used as food supplements even by space travellers.
Economic Importance of Gymnosperms:
Gymnosperm plants are widely used as ornamental. Conifers are often featured informal gardens and are used for bonsai. Yews and junipers are often low-growing plants cultivated for ground cover. Confiers are effective windbreaks, especially those that are evergreen. Turpentine and resin are derived from conifer resins. Copal, a hardened form of resin from a kauri is used to manufacture paints and Varnishes. Balsam and dammer resin are used in the preparation of mounting media for microscope slides. Resines have medicinal uses.
Fossilized resin of conifers are used to manufacture amber. Commercially useful oils are derived from such conifers as junipers, pines, hemlock, fir, spruces and aborvitae. These oils serve as air freshness, disinfectants, and smell in soaps and cosmetics. Seeds are often food sources. Pine seeds are a delicacy eaten plain or used as a garnish on bakery produces Seeds of Ginkgo and cycads may be poisonous unless detoxified. “Berries” of juniper are used as flavouring. Most plywood is gymnosperms.
