DAV sample question papers with Marking Scheme class - VIII (Term - I & II) 2017-18 In order to enable the teachers and students to prepare well for the Annual Examination at the end of the academic session 2017-18, the DAV Centre for Academic Excellence provides Sample Question Papers. It is hoped that these sample question papers will certainly improve the classroom transaction of the subject matter in our schools. These Sample Question Papers have been prepared by practicing teachers of DAV Public Schools under the guidance of experienced resource persons in workshops conducted by the DAV Centre for Academic Excellence.
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Force and Pressure Class 8 Living Science Solution
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A. 1. b 2. a 3. d 4. b 5.d 6. a 7. c 8. b B. 1. Biodiversity means the variety of plants, animals and microorganisms generally found in an area. 2. `Flora' refers to plants. 3. Yes - I agree 4. False 5. Erosion 6. Overgrazing 7. True 8. renewable 9. extinct 10. forest 11.True 12. trees 13. endemic 14. endangered C.1. Biodiversity is the variety of plants, animals and microorganisms generally found in an area. 2. Flora: Species of all plants found in a particular area is known as flora of that area. Fauna: Species of all animals found in a particular area is known as fauna of that area. 3. Cutting down forests and using the land for other purposes is known as deforestation. 4. Some animals cannot adjust to the environmental changes and begin to die. These animal species become endangered as their population becomes very small. 5. A biosphere reserve is a large protected area set aside for conservation of wildlife, plant, animal and microorganism resources, and the traditional life of the tribals living in that area. 6. Endemic species are those species of plants and animals that are found exclusively in a particular area and are not naturally found anywhere else. For example, the Indian giant squirrel and flying squirrel are endemic to the Pachmarhi Biosphere Reserve area. 7. IUCN prepared Red Data Book to highlight those animals who are threatened with extinction, with the aim of promoting their conservation. Those threatened with extinction. 8th Conservation of plants_animal science solution Download File 8th chemical effect of electric current living science solution
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1. No. All microbes are not harmful. some are useful as well. 2. a. Algae b. Viruses 3. They cannot reproduce on their own but are to reproduce by using the energy of the host cells. 4. Algae, in the sense that they are capable of producing their own food. 5. In a pond, P. 32 Oral Questions For Formative Assessment 1. That substance is the carbon dioxide_ Carbon dioxide, a gas. as it escapes it causes dough to rise. 2. This is ensured by using dead or weakened microbes. The process is called vaccination. 3. Certain bacteria and protozoa living in animals like cows, goats and sheep help these animals in digesting grass and plants by breaking down cellulose. 4. No. Pasteurization of milk consists of heating milk to a high temperature of around 70 '2C for about half a minute and then cooling it quickly, P. 33 For Formative and Summative Assessment A.1.c 2.d 3.a 4.a 5.d. 6. b 7.c 8.a 9.d 10.c B. 1. Microbiology 2. False 3. False 4. Cyst 5. Cocci 6. False 7. False 8. Desirable 9. Antibiotics 10. Bacterium 11. dengue 12, virus 13. True 14. Pasteurization 15. True C. 1. An organism that is so small that it can only be seen through a microscope, is called a microorganism 2. Bacteria, Algae, Protozoa, Fungi and Viruses. Among these, Bacteria and Protozoa are unicellular organisms.. 3. a. Cocci b. Bacilli c. Spirilla 4. Simple plant like organisms that have cell walls and chlorophyll within the cells are classified under algae. They make their own food by photosynthesis. Some examples of algae are spirogyra, chlamydomonas and focus. 5. Viruses cannot reproduce by themselves. However, when a virus enters the living cell of an organism, it Is able to reproduce. It uses the energy of the host cells for this purpose. After the formation of thousands of viruses, the host cell often dies. 6. Algae are used as food because they are a rich source of vitamins A, C, D and E, 7. Cooling helps in food preservation, It stops microbes growing and reproducing, and hence preserves food. 8. Microorganisms growing art food sometimes produce toxic substances. These make the food poisonous. Consuming such food can cause a serious illness called food poisoning. 9. Pasteurization of milk consists of heating it to a high temperature of 70 "C for about half a minute and then cooling it quickly. This kills most of the bacteria without affecting the flavor, C. 1. Mosquitoes act as carriers of germs. For example, when houseflies sit on dirt, germs stick to their bodies. When they sit on food, they transfer the germs to the food. 2. Most micro-organisms are hardy and can be found even in places where no other life forms can exist. They are so hardy because they form a hard outer covering called a cyst around themselves, specifically during unfavorable conditions_ They survive by remaining inactive within the cyst till the conditions are favourable again. 3. Yeast is used to make bread soft and fluffy. The yeast uses sugar for food. the process of breaking down sugar. alcohol is formed and carbon dioxide is given off. This process is known as fermentation. The bubbles of carbon dioxide given off cause the dough to rise. This dough can be used to make bread. When this dough is baked, more bubbles of gas are formed due to heat. As the gas escapes, the bread rises and becomes soft and fluffy. The heat during the baking process also evaporates the alcohol. 4. The process of breaking down of sugar by yeast into alcohol and carbon dioxide is known as fermentation. The process of fermentation of sugar by yeast is used in the manufacture of alcohol and alcoholic drink such as beer and wine. Wine is prepared by fermentation of sugar in grapes and beer by fermentation of sugar in germinating barley. 5. Viruses cause diseases by invading hosts body. They can enter in the following ways:
7. Salt prevents food spoilage by checking the growth of bacteria_ Safi forces microorganisms wafer by a process called osmosis. 8. Dehydration of food consists of removing water from it. This stops microorganisms from growing as they cannot grow without water, Cereals, pulses, spices and dry fruits are preserved by this method. 9. Microorganisms such as bacteria, fungi and protozoa. act as decomposers. By decomposing the tissues of dead organisms they break down plant and animal tissues into Simple substances and sent back nutrients to the soil_ Without this piles of dead organisms would cover the earth. Some bacteria decompose sewage and other wastes in water. This is nature's method of keeping the environment free from pollution. E. 1. Viruses are considered to be on the borderline of living and non-living due to the following reasons: (i) They do riot have cell body and other structures like other microbes. ii) They cannot reproduce by themselves. (iii) They are able to reproduce only when they enter in a host cell. Since reproduction is a very important characteristic of life, viruses are regarded as a risk extreme living and non-living. 2. Useful activities of bacteria:
1. (a) Because the higher temperature in summers favours the growth of Lactobacillus bacteria. (b) Because the higher temperature in summers favours the growth of Lactobacillus bacteria, 2. Nitrogen is used to inhibit growth of bacteria, which keeps the chips fresh for a longer time. 3. To prevent contamination of disease-causing microbes of our rood we should always wash our hands before handling food and after going to toilet. 4. The life span of bacteria is very short and they reproduce very quickly. Because of this thousands of generations pass within a few years. Therefore evolution, such as becoming resistant to antibiotics, occurs in bacteria within our own lifetime. Living science class8 microorganism solution pdf download Download File Living science class 8:Microorganism solution extra score Download |
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