5. Write a note on economic importance of algae and gymnosperms.
Economic importance of algae
1. Green algae such as Ulva, Caulerpa, Enteromorpha, Chlorella etc are used as food rich in lipid, protein, vitamins, minerals etc.
2. Chlorella and Caulerpa are used to obtain antibiotics also.
3. A number of green algae such as Chlamydomonas, Chlorella, Scenedesmus etc are used in sewage oxidation tanks.
Economic importance of Gymnosperms
1. The seeds of Pinus gerardiana are roasted and eaten.
2. The softwood of gymnosperms is used in the construction of furniture, plywood, packing cases, match sticks, railway sleepers etc.
3. The wood from Picea, Pinus, Larix and Abies is used in the manufacture of paper.
4. Pine needles are used to make fibre boards.
5. Resins containing terpenes, resin acids and esters can be obtained from gymnosperms. Resins are used in waterproofing, sealing joints etc.
6. A drug called ephedrine is extracted from Ephedra which is a gymnosperm. This drug is useful in respiratory ailments such as asthma.