Digital text sem 3
- 1. DIGITAL TEXT BOOK BASIC SCIENCE – STANDARD 8 BENSI B. B.ED NATURAL SCIENCE REG. NO: 18121351006 CSI COLLEGE OF EDUCATION PARASSALA
- 2. STANDARD 8
- 5. Dear students, You were provided with opportunities to observe your surroundings and engage in simple experiments and investigative activities in earlier classes. The classroom experiences undoubtedly might have helped you to record the informations systematically and assimilate ides through discussion and analysis.while understanding the scientific approach, there should also be the attitude to take forward the skills to apply them in day-to-day life. Moreover, an ecofriendly perspective must be adopted too.all the , through direct experiences, enquiry and understanding preferably. This text book presents ideas in accordance with this. There are illustrations, explanatory details, diagrams that enable the comprehension of these ideas. There are opportunities appropriate to the situation to make learning more enjoyable. This book include lesson with biodiversity, levels of biodiversity, importance of biodiversity, rason for biodiversity depletion and methods of biodiversity conservation. We expect the textbook to be helpful in the further learning of science. Go ahead, thinking, asking questions, approaching ideas critically and quizzing with teachers and friends. Make learning a joyful experience. Regards, Textbook development team.
- 6. DR . SAPHIA L. (Assistant Professor, Department of Natural Science CSI College of Education Parassala ) ATHIRA LESKSHMI V.S. (Teacher Trainee, CSI College of Education Parassala) ASWANI V.G. (Teacher Trainee, CSI College of Education Parassala) BENSI B. (Teacher Trainee, CSI College of Education Parassala) SINSHA RAJ R.M. (Teacher Trainee, CSI College of Education Parassala) TEXT BOOK DEVELOPMENT TEAM
- 8. Certain icons are used in this textbook for convenience For further reading Let us assess Extended activities ICT
- 9. Content 1. Biodiversity 1.1 Levels of biodiversity 1.2 Importance of biodiversity. 1.3 Biodiversity loss. 2. Biodiversity conservation. 2.1 Biodiversity Conservation Methods. 2.1.1 In-situ conservation. 2.1.2 Ex-situ conservation. 2.2 Organisations and Conferences for biodiversity conservation
- 10. Observe the illustration. Do you have doubt like these. Do you think it is necessary to conserve our biodiversity? Write your opinion in your science diary. Biodiversity starts in the distant past and it points towards the future. Save our biodiversity Is it necessary to conserve biodiversity? Is it have that much importance on our biosphere?
- 11. 1 | P a g e BASIC SCIENCE VIII In our biosphere immense diversity exists not only at the species level but at all levels of biological organization. Even the common man would find it hard to believe that there are more than 20,000 species of ants, 3,00,000 species of beetles, 28,000 species of fishes and nearly 20,000 species of orchids. Biodiversity is our living wealth. 1.BIODIVERSITY Biodiversity itself is the combination of two words, Bio (life) and Diversity (variety). Biodiversity includes all the diverse organisms that inhabit the earth along with their ecosystems. In simple terms, biodiversity is the number and variety of organisms found within a specified area. It refers to the varieties of plants animals and microorganisms. WALTER G. ROSEN He was a British environmentalist. He coined the term biodiversity in 1985 Biodiversity is not found evenly on earth. It is richer in tropics than polar regions.
- 12. 2 | P a g e BASIC SCIENCE VIII 1.1 Levels of Biodiversity Biodiversity is the term popularized by the sociobiologist Edward Wilson to describe the combined diversity at all the levels of biological organisation. Let’s see what are the levels of biodiversity. Indicators • Genetic diversity • Species diversity • Ecosystem diversity Fig. 1 Genetic diversity : A single species might show high diversity at the genetic level over the distributional range. Genes are the basic building blocks of various life forms. Genetic diversity refers to the variation of genes within the species. Ecosystem diversity : It refers to the variety of ecosystems. India is rich in various ecosystems like desert, rainforest, mangroves, coral reefs, wetlands, estuaries etc. Species diversity : This refers to the variety of species. It relate to the number of species in a defined area. For eg: Western Ghats have greater amphibian species than Eastern Ghats.
- 13. 3 | P a g e BASIC SCIENCE VIII observe the illustration given below and based on the indicators prepare a note on global biodiversity. Illustration 2 Indicators • Which invertebrate group occupy largest and least position in biodiversity? • Why the number of amphibians reduces rapidly day by day? • While considering global biodiversity which group of animal found the most?
- 14. 4 | P a g e BASIC SCIENCE VIII 1.2 Importance of Biodiversity. What are the benefits of conserving biodiversity? In order to understand it, we must identify the importance of biodiversity on earth. Observe the illustration given below. On the basis of the illustration, prepare a note on need for conserving biodiversity. Illustration 3 Importance of biodiversity Tourism Boost ecosystem productivity Food Medicine Recreation Ecological services Auxiliary services There are 12 mega diversity countries in the world. India is one of them.
- 15. 5 | P a g e BASIC SCIENCE VIII Fig 2 Biodiversity then Fig. 3 Biodiversity now What is the condition of biodiversity around us? What happens to the biodiversity? Discuss the indicators. Indicators • Are all organisms that once existed in your locality still exist? • Are changes in the agricultural field affect biodiversity? • Are the changes in lifestyle leads to biodiversity depletion? • What is the role of humans in biodiversity loss? Along with the inferences formulated through discussion, collect relevant supplementary materials and prepare a scientific article. Exhibit it on the wall magazine. How do you understand the changes in biodiversity? • Through observation • Bird watching
- 16. 6 | P a g e BASIC SCIENCE VIII Observe the fig. 3 and list out the reasons for biodiversity depletion. • • • 1.3 Biodiversity Loss While it is doubtful if any new species are being added into the earth’s treasury of species, there is no doubt about their continuing losses. The biological wealth of our planet has been declining rapidly and the accusing finger is clearly pointing to human activities. Illustration 4 Causes of biodiversity loss Alien species invasion. Climate change. Habitat loss and fragmentation Over exploitation Co- extinction.
- 17. 7 | P a g e BASIC SCIENCE VIII Try to find other causes of biodiversity loss? ▪ Pollution. ▪ Deforestation. ▪ ▪ IUCN (International Union for Conservation of Nature) is an organization for environmental protection, operating in different countries. Under the auspices of IUCN, a list of endangered plants and animals is prepared every year. This is known as Red Data Book. Some countries prepare Red Data Book on their own. This information in Red Data Book is helpful to identify the extent of biodiversity depletion and to plan out appropriate conservation methods. RED DATA BOOK
- 18. 8 | P a g e BASIC SCIENCE VIII 2. BIODIVERSITY CONSERVATION Do you think conservation of biodiversity is necessary? Is it necessary to protect organisms at the verge of extinction? What are the precautions we should adopt to conserve biodiversity? Discuss and write your inferences. 2.1Biodiversity Conservation Methods The enormous value of biodiversity due to their genetic, commercial, medical and aesthetic importance emphasizes the need to conserve biodiversity. There are many national and international organizations and legal systems working for the conservation of biodiversity. The Government conserves bio-rich areas declaring them as protected areas. Two conservation methods are prevalent. They are: 1. In-situ conservation. 2. Ex-situ conservation. 1. In-situ conservation : Conservation methods in which organisms are protected in their natural habitats. 2. Ex-situ conservation : Conservation method in which organisms are protected outside their natural habitats.
- 19. 9 | P a g e BASIC SCIENCE VIII 2.1.1 In-Situ Conservation Biosphere reserve These are vast regions designed with an aim to protect world’s important ecosystems, biodiversity and genetic resources. Biosphere reserves in India State Biosphere reserve Uttar Pradesh Nanda devi Meghalaya Nokrek Assam Manas West Bengal Sundarbans Kerala Nilgiri, Agastyarkoodam Odissa Great Nicobar and Similipal Fig 4
- 20. 10 | P a g e BASIC SCIENCE VIII National park National parks are designed to protect wild lives along with the protection of historical monuments, natural resources and geographical features of an area. National parks in India National Park State Important wildlife Kaziranga Assam One horned Rhino Gir national park Gujarat Indian lion Bandipur Karnataka Elephant Eravikulam Kerala Nilgiri tahr Fig. 5
- 21. 11 | P a g e BASIC SCIENCE VIII Wild life sanctuary These are forest areas declared as protected areas to prevent the extinction of wild lives by protecting the ecosystems. Wild life sanctuaries in India Wildlife Sanctuary State Ghana bird sanctuary Rajasthan Vedanthangal bird sanctuary Tamil nadu Peppara Kerala Periyar Kerala Wayanadu Kerala Abohar wildlife sanctuary Punjab Fig 6
- 22. 12 | P a g e BASIC SCIENCE VIII Sacred grooves These are small areas of biodiversity protected in regions inhabited by human beings. Due to change in life style many of these highly bio-rich areas have been destroyed. Only a few are remaining now. Sacred groves play an important role in conservation of water also. Fig 8 ▪ Largest national park in India – Hemis National Park,jammu& Kashmir. ▪ Smallest national park in India – South Button Island national park, Andaman and Nicobar Islands. ▪ Largest wild life sanctuary in india – Rann of Kutch, Gujarat. ▪ Smallest wild life sanctuary in India – Bor tiger reserve, Maharashtra. Community reserves Community reserves are areas protected with the participation of the public. These are ecologically important places located in populated areas. The Kadalundi community reserve spread over the Fig 7 district of Malappuram and Kozhikode is an example. Fig 7
- 23. 13 | P a g e BASIC SCIENCE VIII Complete the illustration Illustration 5 In-situ conservation National park --------------- ---- Biosphere reserve --------- Community reserve ------------ Wildlife sanctuary ----------------- -
- 24. 14 | P a g e BASIC SCIENCE VIII 2.1.2 Ex-Situ Conservation see ‘vanyajeevisamrakshanam’ in school resouces in IT @ School, Edubundu Zoological gardens In zoological gardens different varieties of animals are protected and housed separately and necessary arrangements are made available for their reproduction. Eg: zoological gardens at Thiruvananthapuram and Thrissur in kerala. Fig 9 Botanical gardens These are wide research centres where rare and important plants of diverse species are protected. Eg: Jawahalal Nehru Tropicl Botanical Garden and Reseach Institute (JNTBGRI) at Palode & Malabar Botanical Garden (MBG) at Olavanna. Fig 10 Gene banks These are research centres with facilities to collect seeds and gametes to preserve them for a long time. Organisms canbe recreated whenever required. Eg: Rajiv Gandhi Centre For Biotechnology at Thiruvananthapuram. Fig 11 Fig 11
- 25. 15 | P a g e BASIC SCIENCE VIII Indicators ▪ What is the scope for ex-situ conservation? ▪ What is the significance of gene bank? 2.2 Organizations and Conferences for Biodiversity Conservation Many government and non-government organizations design and coordinate environment protection activities. Let us familiarize ourselves with some of the organisations and institutions at the national and international levels. 2.2.1 Organisations IUCN (International Union for Conservation of Nature) IUCN is a Switzerland based independent organization working for the protection of biodiversity. WWF (World Wide Fund for nature) Biodiversity conservation, prevention of exploitation and pollution of natural resources are the objectives of WWF. Its headquarters is also in Switzerland.
- 26. 16 | P a g e BASIC SCIENCE VIII 2.2.2 Conferences The government of India along with 155 nations have signed the convention of Biodiversity at Earth Summit held at Rio De Janeiro, Brazil in 1992. The world conservation strategy has suggested the following steps for biodiversity conservation: ✓ Effort should be made to preserve the species that are endangered. ✓ Prevention of extinction requires proper planning and management. ✓ Varieties of food crops, forage plants, timber trees, livestock, animals and their wild relatives should be preserved. ✓ Each country should identify habitats of wild relatives and ensure their protection. ✓ Habitats where species feed, breed, rest and nurse their young should be safeguarded and protected. ✓ International trade in wild plants and animals be regulated. RIO EARTH SUMMIT, 1992
- 27. 17 | P a g e BASIC SCIENCE VIII Significant learning outcomes ▪ Explain biodiversity ▪ Find out the causes of biodiversity loss. ▪ Engage in conservation activities realizing the importance of conservation of biodiversity. Let us assess 1. Find the odd one out; a. Botanical garden, zoological gardens, sacred groves, gene bank. b. Species diversity, forest diversity, genetic diversity, ecosystem diversity. 2. Examine the statements given below and rewrite if there are errors. a. Eravikulam is an example of community reserve. b. In ex-situ conservation organisms are protected outside their natural habitat. c. Animals are reared and protected in botanical gardens. 3. What we can do for the protection of biodiversity? Extended activities ▪ Prepare a poster that emphasize biodiversity depletion and its consequences. ▪ Conduct a seminar that emphasizes biodiversity and importance of biodiversity conservation.