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NCERT Exemplar Class 10 Science Chapter 16 Sustainable Management of Natural Resources Solutions

NCERT Exemplar Solutions for Class 10 Science Chapter 16 Sustainable Management of Natural Resources covers all the important questions and answers as well as advanced level questions. It helps in learning about the Ecosystem and its Components, biotic Components include living organisms like Pollution in Ganga, GAP (Ganga Action Plan) 1985, 5 R’s to save the environment, Forests and Wildlife, biodiversity hotspots, conservation of forests, Monoculture and People intervention in forests.

The NCERT Exemplar solutions for class 10 science is very important for board exams. NCERT Exemplar Solutions for Class 10 Science Chapter 16 Sustainable Management of Natural Resources is provided by our experts. They prepared the best solutions which help the students in understanding the solutions in an easy way. This chapters also covers the other topics like Chipko Movement, Water Management, dams, water harvesting systems, Groundwater, Coal, Petroleum and fossil fuels.


Chapter Name

Chapter 16 Sustainable Management of Natural Resources

Book Title

NCERT Exemplar for Class 10 Science

Related Study

  • NCERT Solutions for Class 10 Science Chapter 16 Sustainable Management of Natural Resources
  • Revision Notes for Class 10 Science Chapter 16 Sustainable Management of Natural Resources
  • MCQ for Class 10 Science Chapter 16 Sustainable Management of Natural Resources
  • Important Questions for Class 10 Science Chapter 16 Sustainable Management of Natural Resources

Topics Covered

  • MCQ
  • Short Answers Questions
  • Long Answers Questions

NCERT Exemplar Solutions for Chapter 16 Sustainable Management of Natural Resources Class 10 Science

Multiple Choice Questions

1. From the list given below pick the item that is not a natural resource
(a) Soil
(b) Water
(c) Electricity
(d) Air

Solution
(c) Electricity

Soil, water and air are natural resources whereas electricity is produced by humans.


2. The most rapidly dwindling natural resource in the world is
(a) water
(b) forests
(c) wind
(d) sunlight

Solution
(b) forests

Water, wind and sunlight are non-exhaustible resources. But due to human activities, forests are depleting.


3. The most appropriate definition of a natural resource is that it is a substance/commodity that is
(a) present only on land
(b) a gift of nature which is very useful to mankind
(c) a man-made substance placed in nature
(d) available only in the forest

Solution
(b) a gift of nature which is very useful to mankind

Natural resources are not man made and they are present everywhere on earth.


4. The main cause for abundant coliform bacteria in the river Ganga is
(a) disposal of unburnt corpses into water
(b) discharge of effluents from electroplating industries
(c) washing of clothes
(d) immersion of ashes

Solution
(a) disposal of unburnt corpses into water

Human excreta mainly contain coliforms. Therefore, unburnt corpses are the sources of coliform which pollute Ganga river water.


5. The pH of water sample collected from a river was found to be acidic in the range of 3.5 – 4.5, on the banks of the river were several factories that were discharging effluents into the river. The effluents of which one of the following factories is the most likely cause for lowering the pH of river water? 

(a) Soap and detergent factory
(b) Lead battery manufacturing factory
(c) Plastic cup manufacturing factory
(d) Alcohol distillery

Solution
(d) Alcohol distillery

Acid spillage from lead battery manufacturing factory can lower down the pH.


6. The pH range most conducive for life of fresh water plants and animals is
(a) 6.5 – 7.5
(b) 2.0 – 3.5
(c) 3.5 – 5.0
(d) 9.0 – 10.5

Solution
(a) 6.5 – 7.5

Neutral pH is the most conducive for life of fresh water plants and animals.


7. The three R’s that will help us to conserve natural resources for long term use are
(a) recycle, regenerate, reuse
(b) reduce, regenerate, reuse
(c) reduce, reuse, redistribute
(d) reduce, recycle, reuse

Solution
(d) reduce, recycle, reuse

Reduce, recycle and reuse can conserve the natural resources.


8. Given below are a few statements related to biodiversity. Pick those that correctly describe the concept of biodiversity 

(i) Biodiversity refers to the different species of flora and fauna present in an area
(ii) Biodiversity refers to only the flora of a given area
(iii) Biodiversity is greater in a forest
(iv) Biodiversity refers to the total number of individuals of a particular species living in an area 

(a) (i) and (ii)
(b) (ii) and (iv)
(c) (i) and (iii)
(d) (ii) and (iii)

Solution
(c) (i) and (iii)

Biodiversity includes flora and fauna and it does not describe just one species.


9. Among the statements given below select the ones that correctly describe the concept of sustainable development
(i) Planned growth with minimum damage to the environment
(ii) Growth irrespective of the extent of damage caused to the environment
(iii) Stopping all developmental work to conserve the environment
(iv) Growth that is acceptable to all the stakeholders 

(a) (i) and (iv)
(b) (ii) and (iii)
(c) (ii) and (iv)
(d) (iii) only

Solution
(a) (i) and (iv)

Sustainable development refers to planned growth with minimum damage to the environment while keeping the future of coming generation in mind.


10. In our country, vast tracts of forests are cleared and a single species of plant is cultivated. This practice promotes
(a) biodiversity in the area
(b) monoculture in the area
(c) growth of natural forest
(d) preserves the natural ecosystem in the area

Solution
(b) monoculture in the area

Monoculture is cultivation of a single species of plant.


11. A successful forest conservation strategy should involve
(a) protection of animals at the highest trophic level
(b) protection of only consumers
(c) protection of only herbivores
(d) comprehensive programme to protect all the physical and biological components

Solution
(d) comprehensive programme to protect all the physical and biological components

Balance in the biotic and abiotic community is very essential in the conservation of forests.


12. The important message conveyed by the ‘Chipko Movement’ is
(a) to involve the community in forest conservation efforts
(b) to ignore the community in forest conservation efforts
(c) to cut down forest trees for developmental activities
(d) government agencies have the unquestionable right to order destruction of trees in forests

Solution
(a) to involve the community in forest conservation efforts

'Chipko Movement' represents sacred feelings of community towards the local forest areas.


13. In our country, there are attempts to increase the height of several existing dams like Tehri and Almati, dams across Narmada. Choose the correct statements among the following that are a consequence of raising the height of dams
(i) Terrestrial flora and fauna of the area is destroyed completely
(ii) Dislocation of people and domestic animals living in the area
(iii) Valuable agricultural land may be permanently lost
(iv) It will generate permanent employment for people 

(a) (i) and (ii)
(b) (i), (ii) and (iii)
(c) (ii) and (iv)
(d) (i), (iii) and (iv)

Solution
(d) (i), (iii) and (iv)

Dam construction causes destruction of downstream agricultural land and adversely affects the living organisms present there.


14. Expand the abbreviation GAP
(a) Governmental Agency for Pollution Control
(b) Gross Assimilation by Photosynthesis
(c) Ganga Action Plan
(d) Governmental Agency for Animal Protection

Solution
(c) Ganga Action Plan


15. Select the incorrect statement
(a) Economic development is linked to environmental conservation
(b) Sustainable development encourages development for current generation and conservation of resources for future generations
(c) Sustainable development does not consider the view points of stakeholders
(d) Sustainable development is a long planned and persistent development

Solution
(c) Sustainable development does not consider the view points of stakeholders

Sustainable developments take into consideration both economic growth and ecological conservation simultaneously.


16. Which of the following is not a natural resource?
(a) Mango tree
(b) Snake
(c) Wind
(d) Wooden house

Solution
(d) Wooden house

Resources that occur naturally within environment are called as natural resources.


17. Select the wrong statement
(a) Forests provide variety of products
(b) Forests have greater plant diversity
(c) Forests do not conserve soil
(d) Forests conserve water

Solution
(c) Forests do not conserve soil

Forests prevent soil erosion, add fertility to the soil by adding humus, and thus they conserve the soil and its fertility.


18. Arabari forests of Bengal is dominated by
(a) Teak
(b) Sal
(c) Bamboo
(d) Mangroove

Solution
(b) Sal

Arabari forests of Bengal are dominated by sal trees.


19. Ground water will not be depleted due to
(a) afforestation
(b) thermal power plants
(c) loss of forest, and decreased rainfall
(d) cropping of high water demanding crops

Solution
(b) thermal power plants

The roots of the plants make the soil pervious. Thus, afforestation helps in recharging the ground water.


20. Opposition to the construction of large dams is due to
(a) social reasons
(b) economic reasons
(c) environmental reasons
(d) all the above

Solution
(d) all the above

The ecosystem near the dam is destroyed. This is an environmental reason. Relocation of people is a social reason. Agricultural land and employment are economic reasons.


21. Khadins, Bundhis, Ahars and Kattas are ancient structures that are examples for
(a) grain storage
(b) wood storage
(c) water harvesting
(d) soil conservation

Solution
(c) water harvesting


22. Pick the right combination of terms which has no fossil fuel.
(a) Wind, ocean and coal
(b) Kerosene, wind and tide
(c) Wind, wood, sun
(d) Petroleum, wood, sun

Solution
(c) Wind, wood, sun

Coal, kerosene and petroleum are fossil fuels.


23. Select the eco-friendly activity among the following
(a) Using car for transportation
(b) Using polybags for shopping
(c) Using dyes for colouring clothes
(d) Using windmills to generate power for irrigation

Solution
(d) Using windmills to generate power for irrigation

Using car for transportation, using polybags and dyes for coloring clothes increases the environmental pollution.


24. It is important to make small check dams across the flooded gullies because they
(i) hold water for irrigation
(ii) hold water and prevent soil erosion
(iii) recharge ground water
(iv) hold water permanently 

(a) (i) and (iv)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (ii) and (iv)

Solution
(b) (ii) and (iii)

Check dams prevent soil erosion. Check dams also help in improvement of groundwater level by holding the water.


Short Answer Questions 

25. Prepare a list of five items that you use daily in the school. Identify from the list such items that can be recycled.

Solution
The following items are used in our daily life in schools: paper, rexin bag, blade, pen, plastic box, scale, eraser, compass and dividers (metallic), steel lunch box, steel spoon.

Paper, blade, plastic box, eraser, compass, steel lunch box and steel spoon can be recycled.


26. List two advantages associated with water harvesting at the community level.

Solution
Two advantages associated with water harvesting at the community level are:

  • Due to recharging of wells the ground water level increases.
  • Ground water keeps the layers of soil above it moist and prevents loss of water by evaporation.


27. In a village in Karnataka, people started cultivating crops all around a lake which was always filled with water. They added fertilisers to their field in order to enhance the yield. Soon they discovered that the waterbody was completely covered with green floating plants and fishes started dying in large numbers.
Analyse the situation and give reasons for excessive growth of plants and death of fish in the lake.

Solution
Excessive use of fertilisers in the fields carried the chemicals down to the lake during rains. Many fertilisers contain phosphates and nitrates. The surface of water gets completely covered with plants as these chemicals promote excessive growth of aquatic plants. This process is known as eutrophication. This in turn depletes the availability of light, dissolved oxygen and nutrients in water, thereby resulting in the death of fishes.


28. What measures would you take to conserve electricity in your house?

Solution

The measures taken to conserve electricity in our houses are as follows:

  • Put off the fans and lights when they are not in use.
  • Maximum use of solar radiation.
  • During winters, use solar water heating system.
  • Use of fluorescent tubes or CFL.


29. Although coal and petroleum are produced by degradatioin of bio- mass, yet we need to conserve them. Why?

Solution
Both the energy sources take millions of years for their formation. These resources are being utilised at a much faster rate than their formation rate, hence they will be exhausted in the near future. This is the reason why they need to be conserved.


30. Suggest a few measures for controlling carbon dioxide levels in the atmosphere.

Solution

A few measures for controlling carbon dioxide levels in the atmosphere are as follows:
  • Reduce the consumption of petrol in the automobiles.
  • Use CNG or a clean fuel.
  • Instead of burning litter prepare manure out of it.
  • Plant more trees.


31. (a) Locate and name the water reservoirs in Figures16.1 (a) and (b).
(b) Which has an advantage over the other and why?

Solution

(a) The water reservoir is a pond in Figure 16.1 (a) and underground water body in the Figure 16.1 (b).

(b) Figure 16.1 (b) has more advantage than Figure 16.1 (a), because of the following reasons:

  • Water does not evaporate.
  • Water is spread out to recharge wells.
  • Water provides moisture for vegetation over a wide area.
  • Water is protected from contamination by animal and human wastes.
  • Water prevents breeding of insects


Long Answer Questions 

32. In the context of conservation of natural resources, explain the terms reduce, recycle and reuse. From among the materials that we use in daily life, identify two materials for each category. 

Solution

Reduce: Reduce means to use a material/commodity in lesser quantity. For example: electricity and water.

Recycle: Recycle means a used material is collected and sent back to a manufacturer so that the manufacturer can make some other useful material from it. For example: plastic cups and buckets, glass tumbler, paper, metal objects.

Reuse: Reuse means using a thing over and over again instead of throwing it away. For example: used envelopes, plastic carry bags, bottles of jam.


33. Prepare a list of five activities that you perform daily in which natural resources can be conserved or energy utilisation can be minimised.

Solution
A list of activities which we can perform daily to conserve the natural resources or minimize the energy utilisation is:

  1. Unused water in the water bottle can be used to water the plants.
  2. Avoid using a hose pipe for watering plants.
  3. Wash vehicles only when they are dirty.
  4. Use fan and light only when required.
  5. Use CFL in place of conventional bulbs/tubes.


34. Is water conservation necessary? Give reasons. 

Solution
The total amount of fresh water is more than enough to meet the needs of human beings. But because of its uneven distribution, wide seasonal as well as yearly fluctuation in rainfalls and wastage water shortage, there is a need to conserve water.


35. Suggest a few useful ways of utilising waste water.

Solution
Waste water can be used for:

  • Replenishing the ground water.
  • Irrigation
  • Washing cars and watering the gardens.


36. What is the importance of forest as a resource?

Solution
Forests are renewable resources which provide:

  • Habitat, food, protection to wild life.
  • Help in balancing CO2 and O2 of atmosphere.
  • Improve the water holding capacity of soil.
  • Regulate water cycle.
  • Provide useful products like fruits, resins, gums, essential oils, bidi wrapper etc.


37. Why are the Arabari forests of Bengal known to be a good example of conserved forest?

Solution
The forest department developed a strategy in which the villagers were involved in the protection of the forest. The villagers were paid in turn for the labour and they also had some benefit in harvesting operations. The villagers were allowed to collect wood and fodder on nominal fee. Therefore, in this way, by the active and willing participation of the local people, the sal forests of Arabari were conserved.

NCERT Exemplar Chapter 16 Sustainable Management of Natural Resources Class 10 Science Solutions

NCERT Exemplar Class 10 Science Chapter 16 Sustainable Management of Natural Resources Solutions

NCERT Exemplar Solutions for Class 10 Science Chapter 16 Sustainable Management of Natural Resources covers all the important questions and answers as well as advanced level questions. It helps in learning about the Ecosystem and its Components, biotic Components include living organisms like Pollution in Ganga, GAP (Ganga Action Plan) 1985, 5 R’s to save the environment, Forests and Wildlife, biodiversity hotspots, conservation of forests, Monoculture and People intervention in forests.

The NCERT Exemplar solutions for class 10 science is very important for board exams. NCERT Exemplar Solutions for Class 10 Science Chapter 16 Sustainable Management of Natural Resources is provided by our experts. They prepared the best solutions which help the students in understanding the solutions in an easy way. This chapters also covers the other topics like Chipko Movement, Water Management, dams, water harvesting systems, Groundwater, Coal, Petroleum and fossil fuels.


Chapter Name

Chapter 16 Sustainable Management of Natural Resources

Book Title

NCERT Exemplar for Class 10 Science

Related Study

  • NCERT Solutions for Class 10 Science Chapter 16 Sustainable Management of Natural Resources
  • Revision Notes for Class 10 Science Chapter 16 Sustainable Management of Natural Resources
  • MCQ for Class 10 Science Chapter 16 Sustainable Management of Natural Resources
  • Important Questions for Class 10 Science Chapter 16 Sustainable Management of Natural Resources

Topics Covered

  • MCQ
  • Short Answers Questions
  • Long Answers Questions

NCERT Exemplar Solutions for Chapter 16 Sustainable Management of Natural Resources Class 10 Science

Multiple Choice Questions

1. From the list given below pick the item that is not a natural resource
(a) Soil
(b) Water
(c) Electricity
(d) Air

Solution
(c) Electricity

Soil, water and air are natural resources whereas electricity is produced by humans.


2. The most rapidly dwindling natural resource in the world is
(a) water
(b) forests
(c) wind
(d) sunlight

Solution
(b) forests

Water, wind and sunlight are non-exhaustible resources. But due to human activities, forests are depleting.


3. The most appropriate definition of a natural resource is that it is a substance/commodity that is
(a) present only on land
(b) a gift of nature which is very useful to mankind
(c) a man-made substance placed in nature
(d) available only in the forest

Solution
(b) a gift of nature which is very useful to mankind

Natural resources are not man made and they are present everywhere on earth.


4. The main cause for abundant coliform bacteria in the river Ganga is
(a) disposal of unburnt corpses into water
(b) discharge of effluents from electroplating industries
(c) washing of clothes
(d) immersion of ashes

Solution
(a) disposal of unburnt corpses into water

Human excreta mainly contain coliforms. Therefore, unburnt corpses are the sources of coliform which pollute Ganga river water.


5. The pH of water sample collected from a river was found to be acidic in the range of 3.5 – 4.5, on the banks of the river were several factories that were discharging effluents into the river. The effluents of which one of the following factories is the most likely cause for lowering the pH of river water? 

(a) Soap and detergent factory
(b) Lead battery manufacturing factory
(c) Plastic cup manufacturing factory
(d) Alcohol distillery

Solution
(d) Alcohol distillery

Acid spillage from lead battery manufacturing factory can lower down the pH.


6. The pH range most conducive for life of fresh water plants and animals is
(a) 6.5 – 7.5
(b) 2.0 – 3.5
(c) 3.5 – 5.0
(d) 9.0 – 10.5

Solution
(a) 6.5 – 7.5

Neutral pH is the most conducive for life of fresh water plants and animals.


7. The three R’s that will help us to conserve natural resources for long term use are
(a) recycle, regenerate, reuse
(b) reduce, regenerate, reuse
(c) reduce, reuse, redistribute
(d) reduce, recycle, reuse

Solution
(d) reduce, recycle, reuse

Reduce, recycle and reuse can conserve the natural resources.


8. Given below are a few statements related to biodiversity. Pick those that correctly describe the concept of biodiversity 

(i) Biodiversity refers to the different species of flora and fauna present in an area
(ii) Biodiversity refers to only the flora of a given area
(iii) Biodiversity is greater in a forest
(iv) Biodiversity refers to the total number of individuals of a particular species living in an area 

(a) (i) and (ii)
(b) (ii) and (iv)
(c) (i) and (iii)
(d) (ii) and (iii)

Solution
(c) (i) and (iii)

Biodiversity includes flora and fauna and it does not describe just one species.


9. Among the statements given below select the ones that correctly describe the concept of sustainable development
(i) Planned growth with minimum damage to the environment
(ii) Growth irrespective of the extent of damage caused to the environment
(iii) Stopping all developmental work to conserve the environment
(iv) Growth that is acceptable to all the stakeholders 

(a) (i) and (iv)
(b) (ii) and (iii)
(c) (ii) and (iv)
(d) (iii) only

Solution
(a) (i) and (iv)

Sustainable development refers to planned growth with minimum damage to the environment while keeping the future of coming generation in mind.


10. In our country, vast tracts of forests are cleared and a single species of plant is cultivated. This practice promotes
(a) biodiversity in the area
(b) monoculture in the area
(c) growth of natural forest
(d) preserves the natural ecosystem in the area

Solution
(b) monoculture in the area

Monoculture is cultivation of a single species of plant.


11. A successful forest conservation strategy should involve
(a) protection of animals at the highest trophic level
(b) protection of only consumers
(c) protection of only herbivores
(d) comprehensive programme to protect all the physical and biological components

Solution
(d) comprehensive programme to protect all the physical and biological components

Balance in the biotic and abiotic community is very essential in the conservation of forests.


12. The important message conveyed by the ‘Chipko Movement’ is
(a) to involve the community in forest conservation efforts
(b) to ignore the community in forest conservation efforts
(c) to cut down forest trees for developmental activities
(d) government agencies have the unquestionable right to order destruction of trees in forests

Solution
(a) to involve the community in forest conservation efforts

'Chipko Movement' represents sacred feelings of community towards the local forest areas.


13. In our country, there are attempts to increase the height of several existing dams like Tehri and Almati, dams across Narmada. Choose the correct statements among the following that are a consequence of raising the height of dams
(i) Terrestrial flora and fauna of the area is destroyed completely
(ii) Dislocation of people and domestic animals living in the area
(iii) Valuable agricultural land may be permanently lost
(iv) It will generate permanent employment for people 

(a) (i) and (ii)
(b) (i), (ii) and (iii)
(c) (ii) and (iv)
(d) (i), (iii) and (iv)

Solution
(d) (i), (iii) and (iv)

Dam construction causes destruction of downstream agricultural land and adversely affects the living organisms present there.


14. Expand the abbreviation GAP
(a) Governmental Agency for Pollution Control
(b) Gross Assimilation by Photosynthesis
(c) Ganga Action Plan
(d) Governmental Agency for Animal Protection

Solution
(c) Ganga Action Plan


15. Select the incorrect statement
(a) Economic development is linked to environmental conservation
(b) Sustainable development encourages development for current generation and conservation of resources for future generations
(c) Sustainable development does not consider the view points of stakeholders
(d) Sustainable development is a long planned and persistent development

Solution
(c) Sustainable development does not consider the view points of stakeholders

Sustainable developments take into consideration both economic growth and ecological conservation simultaneously.


16. Which of the following is not a natural resource?
(a) Mango tree
(b) Snake
(c) Wind
(d) Wooden house

Solution
(d) Wooden house

Resources that occur naturally within environment are called as natural resources.


17. Select the wrong statement
(a) Forests provide variety of products
(b) Forests have greater plant diversity
(c) Forests do not conserve soil
(d) Forests conserve water

Solution
(c) Forests do not conserve soil

Forests prevent soil erosion, add fertility to the soil by adding humus, and thus they conserve the soil and its fertility.


18. Arabari forests of Bengal is dominated by
(a) Teak
(b) Sal
(c) Bamboo
(d) Mangroove

Solution
(b) Sal

Arabari forests of Bengal are dominated by sal trees.


19. Ground water will not be depleted due to
(a) afforestation
(b) thermal power plants
(c) loss of forest, and decreased rainfall
(d) cropping of high water demanding crops

Solution
(b) thermal power plants

The roots of the plants make the soil pervious. Thus, afforestation helps in recharging the ground water.


20. Opposition to the construction of large dams is due to
(a) social reasons
(b) economic reasons
(c) environmental reasons
(d) all the above

Solution
(d) all the above

The ecosystem near the dam is destroyed. This is an environmental reason. Relocation of people is a social reason. Agricultural land and employment are economic reasons.


21. Khadins, Bundhis, Ahars and Kattas are ancient structures that are examples for
(a) grain storage
(b) wood storage
(c) water harvesting
(d) soil conservation

Solution
(c) water harvesting


22. Pick the right combination of terms which has no fossil fuel.
(a) Wind, ocean and coal
(b) Kerosene, wind and tide
(c) Wind, wood, sun
(d) Petroleum, wood, sun

Solution
(c) Wind, wood, sun

Coal, kerosene and petroleum are fossil fuels.


23. Select the eco-friendly activity among the following
(a) Using car for transportation
(b) Using polybags for shopping
(c) Using dyes for colouring clothes
(d) Using windmills to generate power for irrigation

Solution
(d) Using windmills to generate power for irrigation

Using car for transportation, using polybags and dyes for coloring clothes increases the environmental pollution.


24. It is important to make small check dams across the flooded gullies because they
(i) hold water for irrigation
(ii) hold water and prevent soil erosion
(iii) recharge ground water
(iv) hold water permanently 

(a) (i) and (iv)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (ii) and (iv)

Solution
(b) (ii) and (iii)

Check dams prevent soil erosion. Check dams also help in improvement of groundwater level by holding the water.


Short Answer Questions 

25. Prepare a list of five items that you use daily in the school. Identify from the list such items that can be recycled.

Solution
The following items are used in our daily life in schools: paper, rexin bag, blade, pen, plastic box, scale, eraser, compass and dividers (metallic), steel lunch box, steel spoon.

Paper, blade, plastic box, eraser, compass, steel lunch box and steel spoon can be recycled.


26. List two advantages associated with water harvesting at the community level.

Solution
Two advantages associated with water harvesting at the community level are:

  • Due to recharging of wells the ground water level increases.
  • Ground water keeps the layers of soil above it moist and prevents loss of water by evaporation.


27. In a village in Karnataka, people started cultivating crops all around a lake which was always filled with water. They added fertilisers to their field in order to enhance the yield. Soon they discovered that the waterbody was completely covered with green floating plants and fishes started dying in large numbers.
Analyse the situation and give reasons for excessive growth of plants and death of fish in the lake.

Solution
Excessive use of fertilisers in the fields carried the chemicals down to the lake during rains. Many fertilisers contain phosphates and nitrates. The surface of water gets completely covered with plants as these chemicals promote excessive growth of aquatic plants. This process is known as eutrophication. This in turn depletes the availability of light, dissolved oxygen and nutrients in water, thereby resulting in the death of fishes.


28. What measures would you take to conserve electricity in your house?

Solution

The measures taken to conserve electricity in our houses are as follows:

  • Put off the fans and lights when they are not in use.
  • Maximum use of solar radiation.
  • During winters, use solar water heating system.
  • Use of fluorescent tubes or CFL.


29. Although coal and petroleum are produced by degradatioin of bio- mass, yet we need to conserve them. Why?

Solution
Both the energy sources take millions of years for their formation. These resources are being utilised at a much faster rate than their formation rate, hence they will be exhausted in the near future. This is the reason why they need to be conserved.


30. Suggest a few measures for controlling carbon dioxide levels in the atmosphere.

Solution

A few measures for controlling carbon dioxide levels in the atmosphere are as follows:
  • Reduce the consumption of petrol in the automobiles.
  • Use CNG or a clean fuel.
  • Instead of burning litter prepare manure out of it.
  • Plant more trees.


31. (a) Locate and name the water reservoirs in Figures16.1 (a) and (b).
(b) Which has an advantage over the other and why?

Solution

(a) The water reservoir is a pond in Figure 16.1 (a) and underground water body in the Figure 16.1 (b).

(b) Figure 16.1 (b) has more advantage than Figure 16.1 (a), because of the following reasons:

  • Water does not evaporate.
  • Water is spread out to recharge wells.
  • Water provides moisture for vegetation over a wide area.
  • Water is protected from contamination by animal and human wastes.
  • Water prevents breeding of insects


Long Answer Questions 

32. In the context of conservation of natural resources, explain the terms reduce, recycle and reuse. From among the materials that we use in daily life, identify two materials for each category. 

Solution

Reduce: Reduce means to use a material/commodity in lesser quantity. For example: electricity and water.

Recycle: Recycle means a used material is collected and sent back to a manufacturer so that the manufacturer can make some other useful material from it. For example: plastic cups and buckets, glass tumbler, paper, metal objects.

Reuse: Reuse means using a thing over and over again instead of throwing it away. For example: used envelopes, plastic carry bags, bottles of jam.


33. Prepare a list of five activities that you perform daily in which natural resources can be conserved or energy utilisation can be minimised.

Solution
A list of activities which we can perform daily to conserve the natural resources or minimize the energy utilisation is:

  1. Unused water in the water bottle can be used to water the plants.
  2. Avoid using a hose pipe for watering plants.
  3. Wash vehicles only when they are dirty.
  4. Use fan and light only when required.
  5. Use CFL in place of conventional bulbs/tubes.


34. Is water conservation necessary? Give reasons. 

Solution
The total amount of fresh water is more than enough to meet the needs of human beings. But because of its uneven distribution, wide seasonal as well as yearly fluctuation in rainfalls and wastage water shortage, there is a need to conserve water.


35. Suggest a few useful ways of utilising waste water.

Solution
Waste water can be used for:

  • Replenishing the ground water.
  • Irrigation
  • Washing cars and watering the gardens.


36. What is the importance of forest as a resource?

Solution
Forests are renewable resources which provide:

  • Habitat, food, protection to wild life.
  • Help in balancing CO2 and O2 of atmosphere.
  • Improve the water holding capacity of soil.
  • Regulate water cycle.
  • Provide useful products like fruits, resins, gums, essential oils, bidi wrapper etc.


37. Why are the Arabari forests of Bengal known to be a good example of conserved forest?

Solution
The forest department developed a strategy in which the villagers were involved in the protection of the forest. The villagers were paid in turn for the labour and they also had some benefit in harvesting operations. The villagers were allowed to collect wood and fodder on nominal fee. Therefore, in this way, by the active and willing participation of the local people, the sal forests of Arabari were conserved.

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