(N/A) Algae have diverse economic uses. They perform half of the total carbon dioxide fixation on earth by photosynthesis,acting as primary producers in aquatic habitats.
Economic importance of algae:
$(a)$ Food source: Many species of marine algae such as Porphyra,Sargassum,and Laminaria are edible. Chlorella and Spirulina are rich in proteins and are used as food supplements.
$(b)$ Commercial importance: Agar is used in the preparation of jellies and ice cream. It is obtained from Gelidium and Gracilaria. Carrageenin is used as an emulsifier in chocolates,paints,and toothpastes,obtained from red algae.
$(c)$ Medicines: Many red algae such as Corallina are used in treating worm infections.
Economic importance of gymnosperms:
$(a)$ Construction purposes: Many conifers such as pine and cedar are sources of softwood used in construction and packing.
$(b)$ Medicinal uses: An anticancer drug,Taxol,is obtained from Taxus. Many species of Ephedra produce ephedrine,which is used in the treatment of asthma and bronchitis.
$(c)$ Food source: The seeds of Pinus gerardiana (known as chilgoza) are edible.
$(d)$ Source of resins: Resins are used commercially for manufacturing sealing waxes and waterproof paints. $A$ type of resin known as turpentine is obtained from various species of Pinus.