Write a note on economic importance of algae and gymnosperms.
Economic importance of algae - Algae have diverse economic uses.
(a) Food source: Many species of marine algae such as Porphyra, Sargassum, and Laminaria are edible and used as food.
(b) Food supplements: Chlorella and Spirulina are rich in proteins and are used as food supplements.
(c) Commercial importance: It is used for the production of Agar which is obtained from Gelidium and Gracilaria. Agar is used for growing microbes in laboratories and in ice creams and jellies.
(d) Production of hydrocolloids: Certain brown (align) and red algae (carrageen) are used for the production of hydrocolloids.
Economic importance of gymnosperms – Gymnosperms are of great economic value. They are used in the following ways.
(a) Construction purposes: Many conifers such as pine, cedar, etc., are sources of the soft wood used in construction and packing.
(b) Medicinal uses: An anticancer drug Taxol is obtained from Taxus a gymnosperm. Many species of Ephedra produce ephedrine, which can be used in the treatment of asthma and bronchitis.
(c) Food source: The seeds of Pinus are edible and used as food.
(d) Source of resins: Conifers such as Pinus australis is an excellent producers of resins. Resins are used in various industries such as varnishes, plasters and enamel paint because they are resistant to decay.
When and where does reduction division take place in the life cycle of a liverwort, a moss, a fern, a gymnosperm and an angiosperm?
Mention the ploidy of the following: protonemal cell of a moss; primary endosperm nucleus in dicot, leaf cell of a moss; prothallus cell of a ferm; gemma cell in Marchantia; meristem cell of monocot, ovum of a liverwort, and zygote of a fern.
What is the basis of classification of algae?
Name three groups of plants that bear archegonia. Briefly describe the life cycle of any one of them.
