Q.13. Write an essay on the economic improtance of the algae. (1997, 2000, 2013)
Related Questions -
Q. Describe the economic importance of algae. (2005 06, 10, 12)
Q. Describe in detail the economic importance of algae (2007, 08)
Ans. Economic importance of algae: -
It may be studied in two separate groups :
(i) Beneficial aspects: -
1. Algae as food: - The most important economic products obtained from algae are associated with brown and red seaweeds, which can be utilized as food for human.
Perphyrs, Ulva, chlorells etc are used as food in various forms. Perphyrs is red algae and riches protein (30-35%) and carbohydrates (40-45%). It is good source of vitamin B, C and niacin. Diet of porphyra is called Nori in japan and Korea, Isets ai in China and Sloke in great Britain. Ulva lactus is used as salad and soups. Some products of algae such as galatinous carbohydrates from Gigartina chondrus are used with milk or mixd with fruit.
Chlorella is rich protein and carbohydrates. It is yields about 30% proteins, 15% lipids, 30%, carbohydrates and 5% as when it grow under normal condition it contains about 50% of dry weight of protein.
2. Algae as fodder: - Certain brown algae are used a stock feed for sheep and cattles. There are industries for processing them into commercial feed in Ireland and Scotland. It has been recorded that the milk of cow which are eating such fodder in richer in fat contents. Similarly hens eating this sea weed produce eggs rich in Iodine.
3. Algae in industry: - Some algae provides many products of commercial and pharmaceutical importance.
Diatoms (an algae) prepare diatomaceous earth and is extensively used in sugar refineries and soap manufacture. It is also helpful in cement industry, in the manufacture of dynamite, rubber and blotting paper etc.
Algins extracted by boiling algae in washing soda solution and rollers of type-writers are prepared from it. Japanese prepare artificial wool from Sargassum. Carrageenin, which is produced from algae Chondrus, is used by dairymen to prevent settling of ground chocolate in chocolate milk.
Agar-Agar which is obtained from algae like Gelidium etc. is used in sizing of textile.
Various red algae like Laminaria yields Iodine. Several sea weeds also yield bromine acetic acid and acetone.
(4) Algae in Agriculture: - Blue green algae act as nitrogen fixing agent in the rice fields. Oscillatoria, Nostoc and many other members of cynophyceae have the capability of atmospheric nitrogen. Blue green algae increases 30 percent yield of rice field.
Sewage treatment is done by algae by photosythesis. Algae releases oxygen and oxydized the sewage. Mainly it done by chlamydomonos, chlorella, Euglena etc.
(5) Algae as medicine: - Antibiotics produces by many algae such as chlorella, cladophora, Lyngbya Polysiphonia, Laminaria, Chlorella produces antibiotic chlorellin. Chlorellin inhibits growth of certain bacteria and a few algae. Nitzchia palea is claimed to reduce the growth of bacterian Escherichia coli. Members of the order charales have larvicidal property hence may be usefull in controlling mosquitoes.
(ii) Harmful asects: -
(i) Death of animal: - Some blue green algae such as microcystic, Anabaena, Nodularia produces exotoxin and endotoxin causing death of animals, horses, cattle, shee etc. Besides death, the harmful effects of algae bring about loss of weight, weakness.
(ii) Problem of water purification : - In storage water reservoirs algae put effect separately. One is algae and their decomposition product produce a bad odour and second they causes in terference in water filtration.
(iii) Damage to building by BGA: - In rainy season Blue green algae grow on the wall in all over the world. The common algae causing damage to building are Scytonema, Tolypothris, chroococcum etc.
Q.14. Describe the use of blue-greenalgae. (2007, 10, 12)
Related Question -
Q. Write short note on nitrogen fixation by blue green algae. (2007)
Q. Write a short note on economic importance of blue-reen algae.
Ans. Use of blue-green algae: -
1. As food and medicine: - Some species of blue green algae Nostoc are boiled in soups and utilized as food. Blue-green algae like Spirulina is used as a food by the schebule tribes of Africa and America. It consists of sufficient amount of protein. Due to preasence of sufficient amount of protein, pharmaceutical companies manufacture Spiruline tablets, which are now used as medicine.
2. Usar land reclamation: - The pH value of the most of the usar lands is very high due to which plants are not grown in this type of fields. Blue-green algae are grown in user lands, as a result the high pH value of these fields reduces gradually and now, the cultivation of crops and plants can be possible.
Blue-green algae may also be grow on those usar lands which have pH value about 10. For usar land reclamation, blue-green algae such as Oscillatoria, Formedium, Lyngebia are used.
3. In nitrogen fixation: - Blue green algae are the only organism which are capable of performing ‘oxygenic’ photosynthesis and fix nitrogen also. Blue-green algae absorb the sunlight by the process of hotosynthesis and fix the atomospheric nitrogen in the soil. Since paddy field is always water logged, therefore favourable conditions are present for the growth and development of these algae. Nitrogen fixation occur through a specific structure or cell called heterocyst found in blue-green algae. The bue-green algae that take part in nitrogen fixation are Anabaena, Nostoc, Cytonema Talipothrix, etc.
Q.15. What is water bloom ? Describe in brief.
Ans. Water bloom: - Water bloom also known as water flowers. When the algae are aboundant in a particular body of the water as to give a distinct colour of the entire body of the water such as growth of the algae is known as water blooms. The colour of the water blooms depend upon the colour of the algae. A water bloom is usually formed by a solitary algae.
Water blooms may be temprorary or permanent in nature. It is known that number of temple ponds & few lakes & big ponds in India have permanent water blooms some times algae from a very thick layer of many c.m. water bloms also present in the sea.
Water blooms formation take place by the super abundance of microscopic free floating algae in a pond, tank, lake, rivers etc. The blooms soon develop in such quantities that large areas of waters are covered with thick layer that resembles to green paint or thick pea soup. Many of the algae produce unpleasant smells to the water. These water blooms pollute the water and water become completely useless for man and domestic animals. Water blooms also cause the water poisonsing.
Q.16. Why is it not nacessary to add nitrogenous fertilizers to rice fields? Give reason. (2008)
Ans. Sea weeds are extensively utilized as manures because they are rich in potassium, phosphorous, trace elements and growth substance. These sea weeds are either rotted in fields or composed with organic materials. These manure enrich the fields in mineral nutrients and helps in soil binding, in breaking down clays and promoting good crumb formation. Fucus is used in manure. The dried mud of ponds is usually used as manure in crop fields due to high contents of blue green algae which is used as a good fertilizer. Lithothamion and Lithophyllum are important algae used as sea weeds manure.
Some blue green algae are capable of fixing atmospheric nitrogen. Such forms are commonly found in rice fields. Experiments conducted on Tolypothrix tonius in Japan and Aulosiria fertilissima in India, revealed that production of rice increased by 30% when these algal forms were grown in rice fields. Anabaenopsis and Spirulina are also used as fertilizer in Rajasthan.