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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
(a) List two bacteria which bring about nitrification. (b) List one denitrifying bacteria. (c) List any two bacteria which play a role in biological nitrogen fixation. |
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Answer» (a) Nitrobacter, Nitrocystis. (b) Pseudomonas (c) Azobacter, blue green algae (Anabaena), Rhizobium leguminosarum (lives as symbiont in nodules of roots of leguminous plants such as pea). |
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| 2. |
When we breathe in air, nitrogen also goes inside along with oxygen. What is the fate of this nitrogen?A. it moves along with oxygen into the cellsB. It comes out with the `CO_(2)` during exhalationC. It is absorbed only by the nasal cellsD. Nitrogen concentration is already more in the cells so it not at all absorbed. |
| Answer» Correct Answer - B | |
| 3. |
Rainfall patterns depend onA. the underground water tableB. the number of water bodies in an areaC. the density pattern of human popultion in an areaD. the prevailing season in an area |
| Answer» Correct Answer - B | |
| 4. |
The process of nitrogen-fixation by bacteria does not take place in the presence ofA. molecular form of hydrogenB. elemental form of oxygenC. waterD. elemental form nitrogen |
| Answer» Correct Answer - B | |
| 5. |
How is our atmosphere different from the atmospheres on Venus and Mars? |
| Answer» Earth’s atmosphere is different from those of Venus and Mars. This difference lies essentially in their compositions. Earth’s atmosphere is a mixture of nitrogen `(79%)`, oxygen `(20%)`, and a small fraction of carbon dioxide, water vapours and other gases. This makes the existence of life possible on Earth. However, the atmospheres on Venus and Mars mainly consist of carbon dioxide. The amount of carbon dioxide on these planets can range from `95% "to" 97%.` | |
| 6. |
The two forms of oxygen found in the atmosphere areA. water and ozoneB. water and oxygenC. ozone and oxygenD. water and carbon dioxide |
| Answer» Correct Answer - C | |
| 7. |
How is our atmosphere different from the atmospheres on Venus and Mars ? |
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Answer» Correct Answer - On planets Venus and Mars, carbon dioxide the major component constituting upto 95-97% of the atmosphere. Nitrogen gas and oxygen gas are absent. Also, their respective atospheres do not have water vapour. No life is known to exist there. On the contraty, on earth, air form the blanket earth having nitrogen (78.08%), oxygen (20.94%), carbon dioxide (0.03%), argon (0.91%) and trece components (0.04%) It has life on it. |
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| 8. |
The atmosphere of the earth is heated by resiations which are mainlyA. radiated by the sumB. re-radiated by landC. re-radiated by waterD. re-radiated by land and water |
| Answer» Correct Answer - D | |
| 9. |
An increase in carbondioxide content in the atmosphere would not causeA. more heat to be retained by the environmentB. increase in photosynthesis in plantsC. Global warmingD. abundance of desert plants |
| Answer» Correct Answer - D | |
| 10. |
What is paedogenesis? |
| Answer» Paedogenesis is the process of formation of soil from upper rocky crust of Earth. | |
| 11. |
The presence of water in the human body regulatesA. body temperatureB. blood pressureC. respirationD. perspiration |
| Answer» Correct Answer - A | |
| 12. |
The amount of which salt in the sea is the highest ?A. Calcium fluorideB. Calcium chlorideC. Sodium chlorideD. Sodium fluoride |
| Answer» Correct Answer - C | |
| 13. |
Which of the following substances is a (are) greenhouse gas(es) ?A. Carbon dioxideB. AmmoniaC. MethaneD. Sulphur dioxide |
| Answer» Correct Answer - A::C | |
| 14. |
The region of water on the surface of the earth is called theA. lithosphereB. hydrosphereC. oceanD. stratosphere |
| Answer» Correct Answer - B | |
| 15. |
What is the greenhouse effect? |
| Answer» Some gases like carbon dioxide, methane, nitro us oxide prevent the escape of heat from the Earth’s surface by trapping it. This increases the average temperature of the Earth. This is called the greenhouse effect. An increase in the content of such gases would lead to a situation of global warming. | |
| 16. |
The excess of carbon dioxide in air causesA. fogB. smogC. pollutionD. acid rain |
| Answer» Correct Answer - C | |
| 17. |
List any three human activities which would lead to an increase in the carbon dioxide content of air. |
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Answer» (i) Burning of fossil fuels (coal and petroleum products) in homes, industries and automobiles. (ii) Burning assocated with agricultural practices. (iii) Deforestation. |
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| 18. |
Name two planets other than Earth which also have an atmosphere. |
| Answer» Venus and Mars also possess atmosphere. | |
| 19. |
In coastal areas, wind current moves from sea towards the land during day but during night it moves from land to the sea. Discuss th reason. |
| Answer» See text Air Movement in Coastal Areas. | |
| 20. |
Where is the major part of fresh water bound up? |
| Answer» In the form of ice caps and glaciers (1.9% out of 2.5% of fresh water). | |
| 21. |
Name two fresh water sources which provide fresh water for human use. |
| Answer» 1. Ground water, 2. Surface water (ponds, lakes, streams, rivers, etc.). | |
| 22. |
Give two ways in which carbon dioxide is fixed. |
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Answer» (i) Green plants, through photosynthesis, convert carbon dioxide `(CO_(2))` to glucose in the presence of sunlight. (ii) Many marine animals use carbonates dissolved in sea water to form their shells. |
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| 23. |
Define eutrophication. What is ill effect of eutrophication? |
| Answer» Eutrophication is nutrient enrichment (i.e., addition of nitrates and phosphates) of water body that results in the growth of aquatic plants, especially algae causing colouration of water known as algal bloom. It leads to depletion of dissolved oxygen in water resulting in killing of aquatic organisms (e.g., fish). | |
| 24. |
Name the articles which act as nucleus for water droplets to form around in the atmosphere. |
| Answer» Dust, smoke and other suspended particles of air. | |
| 25. |
Environment biologists have recently reported that (i) Carbon dioxide concentration in the atmosphere has reached more than 390 ppm. (ii) The antarctic and arctic waters are becoming acidic causing thinning of animals shells. (iii) Polar ice is melting (iv) some low lying islands have submerged in sea. (a) What are the reasons behind all these changes occurring on earth? (b) Suggest a mechanism to control the same and if possible to reverse the trend. |
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Answer» (a) Reason for these global ecological changes is faulty recycling of carbon dioxide. More of carbon dioxide is being produce than its conumption in photosynthesis due to following curses of urbanisations (i) Excess combustion of fossil fuels in industries, power houses, automobiles, homes and other place. (ii) Reduced in take of `CO_(2)` by plants due to deforestation (Forests serves as sinks of carbon dioxide utilization) (iii) Higher amounts of `CO_(2)`entering the atmosphere not only increases its atmospheric concentratiion but also the concentration of dissolved `CO_(2)` in water especialy in colder seas. The acidity tends to do thinning of hte shells of many marine animals. (iv). `CO_(2)` is a green house gas which is causing global warming. Rise in global temperature is melting snow over poles. This is raising the level of sea water slowly. It has already submerged some low lying islands. (b) Suggestions for checking global warming. (i) Large scale tree plantation in all vacant area. (ii) Reduced felling of forest trees. (iii) Reducing consumption of fossil fuels by reducing dependence on thermal power plants, increasing efficiency of automobiles and switching over to alternate technologies that do not consume fossil fuels (e.g., Solar power systems, small hydroelectric power plants, windmills, etc). |
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| 26. |
Name the fertilizers whose excessive presence in water bodis results in algal growth. What is the consequency of eutrophication. |
| Answer» Inorgaic fertiliers containing phosphates and nitrates releasesd into water bodies give out a lot of nutrition to phytoplankton. It causes eutrophication. Algal growth occurs tremendously. Decomposition of these algae makes the aerobc decomposers highly active which in turn causes depletion of dissolved oxygen in water bodies. Lack of dissolved oxygen in water leads to death of aquatic animals, especially fishes, due to suffocation. | |
| 27. |
What is the major source of fresh water in the city/town village where you live? |
| Answer» Major sources of fresh water in the city/town/village where we live is underground water. | |
| 28. |
There is a mass mortality of fish in a pond. What may be the reason? |
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Answer» In a pond, a mass mortality of fish may occur due to following seasons. (i) Passage of pesticide rich water from crop fields. (ii) Release of toxic industrial waste. (ii) Pouring of hot water froman industry or thermal power plant. (iv) Release of waste rich in heavy metals and mercury. (v) Blockage of gills of fish by some suspended pollutant such as oil. |
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| 29. |
You have seen seather reposts on television and in neqapapers. How do you think are able to predict the weather? |
| Answer» The meteorological department of the government collects data on the elememt of weather such as maximum and minimum temperatures, maximum and minimum humidity, rainfall , wind speed, etc. they are able to study these elements using various instruments. The maximum and minimum temperature of a day is meausred by a thermometer known as the maximum thermometer. Rain fall is meausred by an instrument know as the gauge. Wind speed is meausred by anemometers . There are various instruments used to measure humidity | |
| 30. |
(i) Razia saw excessive growth of blue -green algae in nearby pond of her village. (ii) Fish which was previously in pletny were no where to be seen. (iii)The pond is started go give a stink. Water of the pond changes its colour and is found to be not suitable for cattle. Some of the cattle who visited the pond for drinking and bathing have faled sick. (iv) What expianatient will Razia give for these anomalies to the paniced villagers. |
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Answer» (i) Bloom forming algea occur in a pond only when the quality of pond water has crumbled due to pollution. Blue-green algae secrete toxins that are harmful to animals and humans. (ii) Fish of the polluted pond must have died due to deficiency of oxygen in pond water. Oxygen deficiency occurs when there is excess of organic matter (called organic lodaing). The aerobic decomposers consume the dissolve oxygen. This is followed by anaerobic decomposition of organic matter. It produces sulphide and other sludge producing substances. Blue-green algae cna grow under such circumstances. (ii) Stink from the eutrophic pond comes from anaerobic breakdown products of organic matter. The toxins released by blue-green algae further decline the quality of water causing sickness and skin rashes in animals and human beings. (iv) Razia could explain the villagers that deterioration of pond has been due to excess of chemica fertilizers used by them in their crop fields. Rain wash brought these fertilizers into the pond. This is called eutrophication. There was initial spurt in the growth of aquatic plants due to this. Excess plant matter slowly caused organic loading of water that reduced its oxygen content killing the fish and other aquatic animals. So fertilizers should be used very judiciously in the fields. Pond should also not be used as garbage bin or septic tanks of village community. |
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| 31. |
Lichens are called pioneer colonisers of bare rock. How can they help in formation of soil? |
| Answer» Lichens release small quantity of acids which corrode the surface of rock creating minute pores and releasing minerals. With the passage,of time these minerals deposit on rock to form a thin layer of soil. | |
| 32. |
Soil formation is done by both abiotic and biotic factors. List the name of these factors by classifying them as abiotic and biotic. |
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Answer» (i) Abiotic factors of soil formation: Sun, water, wind. (ii) Biotic factors of soil formation: Lichens, mosses, herbs, shrubs, trees and animals (earthworms). |
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| 33. |
A motor car, with its glass totally closed, is parked directly under the sun. The inside temperature of the car rises very high. Explain why? |
| Answer» Glass is transparent to sunlight allowing it to pass into the interior of the car. It heats up the intetior. But heat waves do not escape from the car due to glass being opaque to the same. As a result, the interior of the car placed in the sun will become very hot. It is similar to glass house effect. | |
| 34. |
It has been made mandatory to install rain water harvesting system and solar water heater in all buildings in urban areas.(i) What is the rational when rain water already passes into drains? (ii) Why are solar water heaters are being installed when electric geysers are available? |
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Answer» (i) Rain water passed into drain does not enter the ground but is taken out of the urban area and poured into a water body at quite a distance with or without treatment. However, ground water is being withdrawn everywhere for drinking, industrial and irrigation purposes. As a result, the level of ground water is going down and arid conditions are being faced in many areas. In rain water harvesting, rain water from a building is passed directly into ground dug-wells or water pumps. This recharges ground water. (ii) Installation of solar water heaters is a method of saving electricity which is always in short supply due to rapid urbanisation, industrialization and intensive agriculture. Coal/gas based power plants are polluting units they add carbon dioxide to the atmosphere causing global warming. Saving electricity is now valued social resonsibility. |
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| 35. |
Name the component present in marble which reacts with acids present in acid rain. |
| Answer» Calcium carbonate. | |
| 36. |
(a) Name two acids that are usually present in rain water. (b) How these acids affect our hearitage monuments such as Taj Mahal ? |
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Answer» (a) Sulphuric acid `(H_(2)SO_(4))` and Nitric acid `(HNO_(3))` (b) The acids present in acid rain react with marble of Taj Mahal of Agra (U.P.) and corrode it. Chemical reactions involved are: `underset(("Marble")) underset("Calcium carbonate") (CaCO_(3))+underset("Sulphuric acid")(H_(2)SO_(4))to underset("Calcium sulphate")(CaSO_(4))+underset("Carbon dioxide")(CO_(2))+underset("Water")(H_(2)O)` `underset("Marble")(CaCO_(3))+underset("NItric acid")(HNO_(3))to underset("Calcium nitrate")(Ca(NO_(3))_(2))+CO_(2)+H_(2)O` |
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| 37. |
Explain carbon monoxide poisoning. |
| Answer» Carbon monoxide (CO) is a toxic air pollutant. It is exhaled from motor vehicles as on eof the exhaust gases, and also from cigarette smoke. Our blood hs respiratiory pigment, haemoglobin (Hb) in the erythrocytes (RBCs) and it has high affinity for oxygen. As a result, oxygen combines with haemoglobin in the lungs and is carried by blood to various body tissues body tissues as oxyhaemoglobin (OHb). Carbon monoxide (CO), a poisonous as, has 200 times more affinity for haemoglobin than oxygen. When the polluted air containing large amount of CO in inhaled, the CO then combines with haemoglobin to form a stable poisonous compound called carboxyhaemoglobin (COHb). This drastrically reduces the availability of oxygen to the body tissues and leads to suffocation and finally death. | |
| 38. |
What kind of pollution is produced when some undesirable materials are added to water bodies or some desirable materials are taken away from them ?A. Air pollutionB. Water pollutionC. Soil pollutionD. Noise pollution |
| Answer» Correct Answer - B | |
| 39. |
List any three human activies that you think lead to air pollution. |
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Answer» 1. Burning of fossil fuel (coal, petroleum products) in automobiles, generators, thermal power plants. 2. Smoke from industries (e.g. brick -kiln, crashers, etc). 3. Burning of fuel wood and dung cakes in household cooking. |
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| 40. |
What is detritus? |
| Answer» Dead remains of plants and animals are called detritus. | |
| 41. |
(a) Fill in the blanks marked 1-5 in figure of nitrogen cycle. (b) What will happen if the step of ammonification does not take place? (c) What will happen if the step of denitrification does not take place? |
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Answer» (a) 1. Animal nutrition, 2. Ammonia in soil 3. Ammonification. 4. Nitrates in soil, 5. Denitrification. (b) If ammonification does not take place the conversion of complex organic compounds such as proteins and nucleic acids of decaying organisms into ammonia will not take place. (c) If denitrification does not take place, conversion of nitrate salts present in soil and water intofree molecular nitrogen will not occur. |
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| 42. |
How is soil formed? |
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Answer» Soil is formed by breaking down of rocks at or near the surface of the Earth through various physical, chemical, and biological processes by various factors such as the sun, water, wind and living organisms. (i) Sun: During day time, the rocks are heated. This causes the rocks to expand. During night time, these rocks cool down and contract. Since all parts of the rock do not undergo expansion and contraction at the same rate, this causes the formation of cracks in these rocks. These cracks lead to the breaking up of huge rocks into smaller pieces. (ii) Water: Water catalyses the process of formation of soil in two ways. (a) Water goes into the cracks and crevices formed in the rocks. When this water freezes, its volume increases. As a result, the size of the cracks also increases. This helps in the weathering of rocks. (b) Running water wears away hard rocks over long periods of time. Water moving in fast speed carries big and small particles of rock downstream. These rocks rub against each other, resulting in breaking down of rocks. These smaller particles are carried away by running water and deposited down its path. (iii) Wind: Strong winds carry away rocks, which causes rubbing of rocks. This results in the breaking down of rocks into smaller and smaller particles. (iv) Living organisms: Some living organisms like lichens help in the formation of soil. Lichens also grow on rocks. During their growth, lichens release certain substances, which cause the rock surface to powder down forming a thin layer of soil. On this thin layer of soil, some small plants like moss also grow. They further cause the breaking down of the rock particles |
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| 43. |
(a) Identify the biogeochemical cycle given below: (b) Fill in the blanks marked 1-4. |
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Answer» (a) Fill in the blanks A-Food/organic molecules/ Glucose , `C_(6) H_(12)O_(6)`, B-Photosynthesis, C-Resiration. (b) Identication Oxygen cycle. |
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| 44. |
(a) Identify the biogeochemical cycle given below: (b) Fill in the blanks marked 1-4. |
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Answer» (a) The figure indicates the biogeochemical cycle of oxygen. (b) 1. Photosynthesis by green plants, 2. Fossil fuels, 3. Dead plants and animals, 4. Carbon dioxide. |
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| 45. |
(a) Identify the biogeochemical (b) Fill in the blanks, A,B,C and D. (c) What will happen if the step E does not occur. |
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Answer» (a) Identification: Nitrogen cycle. (b) Fill in the blanks: A-Amonification , B-Ammonia, C-Nitrite, D-Nitrates. (c) In the absence of step E there will be no replenishment of atmospheric nitrogen. |
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| 46. |
What are detritivores? Name any one of them. |
| Answer» The orgnaisms which consume detritus are called detritivores, e.g., Earthworm. | |
| 47. |
What is methane burp? |
| Answer» Methane burp is a process of periodical release or belching or methane in huge quantities. This is caused by the melting of the methane hydrates existing in permafrost and sea floor. Methane is a GHG, one of the main culprit of global warming. | |
| 48. |
What are biogeochemical cycles? |
| Answer» Biogeochemical cycles are repeated circulation of biogeochemicals of the environment abiotic and biotic components of the environment which result in their repeated withdrawal and replacement of their pool. | |
| 49. |
What are the methods of preventing or reducing soil erosion? |
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Answer» The methods of preventing or reducing soil erosion are: (i) Prevention of deforestation (ii) Plantation of trees |
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| 50. |
Name two measures which prevent the soil erosion. |
| Answer» (i) Intensive cropping and reforestation, (ii) Terrace farming. | |