Class 10 Science Objective Test Solutions

1 0 B 0 5 + 1 0 B 0 6 C ombined test - Our E nv t. + Mg mt of Natural R es - Answ ers & Solutions - Set A Tes t Code: X-S-15-16 Q No. Ans wer Level S kill C hapter 1. C E asy 2. C Medium Concept Knowledge Our E nv ironment 3. C Hard 4. A E asy Problem Solving Our E nv ironment 5. A Medium 6. C Medium Recall Our E nv ironment 7. A Medium 8. B Medium Problem Solving Our E nv ironment 9. B Medium 10. C Medium Concept Knowledge Our E nv ironment 11. A E asy 12. D E asy Concept Knowledge Our E nv ironment 13. C E asy 14. C E asy Concept Knowledge Our E nv ironment 15. C E asy 16. A Hard Concept Knowledge Our E nv ironment 17. B Hard 18. A E asy Concept Knowledge Our E nv ironment 19. D E asy 20. B E asy Concept Knowledge Our E nv ironment Concept Knowledge Management of Natural Resources Recall Management of Natural Resources Recall Management of Natural Resources Recall Management of Natural Resources Recall Management of Natural Resources Critical T hinking Management of Natural Resources Concept Knowledge Management of Natural Resources Concept Knowledge Management of Natural Resources Recall Management of Natural Resources Recall Management of Natural Resources Solutions Q1. (C) B iod eg rad able w aste is d efined as substanc es that are broken d ow n by biolog ic al proc esses. T his type of waste has low shelf life and are decayed or degraded using biological process by d ec omposers like bac teria and fung i. B iog eoc hemic al c y c le is a c y c lic flow w hic h inv olv es transfer of matter and energy among different components of the biosphere. Since degradation of non biodegradable waste is very slow and toxic, they do not enter biogeochemical cycle whereas biodegradable waste undergo degradation process in which complex organic molecule are converted into simpler form such that these compounds are released into the nutrient pool and these nutrients are reutilised by the plants from the soil. T hus, biodegradable waste degrades in a short span of time and does not require centuries to degrade. T hus, the correct answer is option C. Avanti Learning Centres Pvt Ltd. All rights reserved. Page - 1 / 4

1 0 B 0 5 + 1 0 B 0 6 C ombined test - Our E nv t. + Mg mt of Natural R es - Answ ers & Solutions - Set A Q2. (C) T he energy flows from the sun which is the only continuous source of energy for Earth. G reen plants trap a part of solar energ y reac hing E arth. Suppose the solar energ y trapped or rec eiv ed by E arth is , then in that case, the green plant trap only i. e of the energy as biomass. T his energy as plant matter is available to the herbivore. Out of this, energy is available and is lost as heat by the herbivore and only i. e of energy is available to the carnivore. Since the energy obtained is lesser when it passes from higher trophic level, the organism has to rely on more than one organism for energy. T hus, the correct sequence is option C. Q3. (C) Chlorine, hydrogen peroxide and chlorofluorcarbon are the gases which are responsible for the d epletion of oz one lay er w hereas nitrog en d iox id e d oes not affec t the lev el of oz one. T hus, the correct answer is option C. Q4. (A) T he energy flows from the sun which is the only continuous source of energy for the earth. G reen plants trap a part of solar energ y reac hing the E arth. T he solar energy the earth is Plant will get % of the energy of sunlight ( ) ∴ of G rasshopper will get % of energy of plant (100 ) of Frogs will get % of energy of snakes of = Q5. (A) T he longer the food chain, larger will be the energy loss. Since chain- 1 and 4 are direct and smaller, energy conservation and utilisation will be most efficient. Q6. (C) B iolog ic al mag nific ation refers to prog ressiv e inc rease in c onc entration of the tox ic substanc es at each successive trophic level. Non biodegradable pesticides buildup in the fat tissues of the body are passed onto the organisms that feed on it. T his happens because a toxic substance accumulated by an organism cannot be metabolised or excreted and is thus passed onto the next higher trophic level. Q7. (A) T he energy decreases as the trophic level goes higher because most of the energy is utilized in the life process and rest of the energy is passed on to the next trophic level. Spraying an insecticide in water to control mosquitoes will cause trace amounts of D D T to accumulate in the c ells of mic rosc opic aq uatic org anisms, the z ooplankton, in the w ater. When 1 0 - 20 suc h tox ic zooplanktons are consumed by small fish, they harvest D D T as well as food. (Concentrations of D D T greater than those in the plankton have been measured in small fish).T he process of concentration goes right on up the food chain from one trophic level to the next. Large fish, which feed on 5- 6 such small fishes, may accumulate D D T to 40 or more times the concentration in their prey. Further, when the bird eats such preys, it shows a high fold increase in concentration of insecticide along the length of this short food chain. Q8. (B) D uring bright sunlight, photos ynthes is takes place in plants and it us es up the carbon d ioxid e dissolved in the water. T his dissolved forms a weak carbonic acid with a about to , if it is removed , of the pond water ris es . Where as during night only res piration takes place in green plants, it prod uces g as which dissolves in the water to prod uce carbonic acid . So the of the water in the pond may fall. Q9. (B) Aquarium is an artificial ecosystem that does not contain soil and decomposing bacteria which helps in degrading complex organic substance into simple inorganic substance and act as c leaners. B ut pond s and lakes hav e this fac ility. In natural ec osy stem, uneaten food or fish w aste turns into ammonia, decomposers convert these pollutant into non toxic nitrates. T hus, if aquarium water is not cleaned, then wastes could accumulate to large extent which could lead to the death of the fishes. Low oxygen levels are rarely a problem if an aquarium is well aerated and not overstocked. Avanti Learning Centres Pvt Ltd. All rights reserved. Page - 2 / 4

1 0 B 0 5 + 1 0 B 0 6 C ombined test - Our E nv t. + Mg mt of Natural R es - Answ ers & Solutions - Set A Q10. (C) Q11. Food chain is unidirectional and energy flows from one trophic level to the next. If all the Q12. Q13. organisms of one trophic level are killed, the flow of energy will be ceased. Higher trophic level Q14. predates the lower trophic level population. If all the organisms in one trophic level are killed Q15. Q16. then their prey (lower trophic level) will increase in population and their predators (higher Q17. trophic level) will be deprived of food. If all the organisms of one trophic level are killed, it will Q18. Q19. create an imbalance in the ecosystem. For example, in a food chain, G rass D eer Lion . If all lions are killed , then the population of d eer w ill inc rease w hic h w ill c ause ov er-g raz ing . (A) In the year , a non violent movement was aimed at protection and conservation of trees and forests from being destroyed. T his movement is named as Chipko Movement. T he name of the Chipko moment originated from the word 'embrace' as the villagers used to hug the trees and protect them from wood cutters from cutting them. (D ) T he full form of 3 R's are Reduce, Reuse and Recycle. (C) B iod iv ersity is d efined as the v ariation of flora and fauna in the w orld or in a partic ular habitat. Forests are known as 'biodiversity hot spots' because of the presence of a large number of species of plants and animals. (C) D isadvantages of building dams are as follows: It leads to displacement of large number of peasants, tribals and domestic animals without enough compensation and rehabilitation. Since, a large area is required to build up a dam, many trees and forest are destroyed thereby affecting the shelter of the animals. Valuable agricultural land may be permanently lost as that land would be used up in building dam. T his displacement will greatly affect the employment of the villagers. (C) Khadins and bundhis are the traditional rain water harvesting systems used in Rajasthan and Madhya Pradesh respectively. (A) A- Petroleum, also know n as c rud e oil, is a thic k and blac k liq uid found beneath the E arth's surface and is refined into various types of fuels. B - C oal is a flammable blac k hard roc k used as a solid fossil fuel. T he products on combustion of coal and petroleum are carbon dioxide, sulphur dioxide, nitrogen oxides C- Acid rain is formed high in the clouds where sulphur and nitrogen oxides react with water, oxygen and oxidants. E - F- (B) Low in the river is due to the presence of excess amount of acid. T hus, the waste that is released into the river must be in acidic in nature. In the given options, baking soda and sodium carbonate are base, alcohol is neutral, plastic does not affect . Vinegar is acidic in nature and its ranges from . T hus, the correct answer is option B. (A) T he name of the device is solar cooker. A solar cooker is a device which uses solar energy to heat, cook or pasteurise drink. T hey are relatively inexpensive, low-tech devices and also it takes time for cooking. (D ) A person with an interest or concern with something is known as stakeholder. When it is concerned with a forest, we find that there are four stakeholders: 1. T he people who live in and around the forest and are dependent on forest products. 2. T he Forest D epartment of the G overnment which owns the forest land and control the resources of forest. 3. T he industrialists who use various forests products for their factories. 4. T he forest and wildlife activists who want to see their forests in their original form. Since people living in urban areas have no connection with forest or forest management, it is not a direct stakeholder in the management (or conservation) of forests? Avanti Learning Centres Pvt Ltd. All rights reserved. Page - 3 / 4

1 0 B 0 5 + 1 0 B 0 6 C ombined test - Our E nv t. + Mg mt of Natural R es - Answ ers & Solutions - Set A Q20. (B) When combustion of coal and petroleum takes place in insufficient air (oxygen), then carbon monoxide is formed instead of carbon dioxide. Avanti Learning Centres Pvt Ltd. All rights reserved. Page - 4 / 4