Extra Questions for Class 9 Science Chapter 14 Natural Resources

Extra questions for Class 9 Science Chapter 14 Natural Resources with answers is given below. Our subject expert prepared these solutions as per the latest NCERT textbook. These questions will be helpful to revise the all topics and concepts. CBSE Class 9 extra questions are the most simple and conceptual questions that are prepared by subject experts for the students to study well for the final exams. By solving these extra questions, students can be very efficient in their exam preparations.

Natural Resources Class 9 Science Extra Questions and Answers

Very Short Answer Questions

1: What is the role of respiration in oxygen cycle?
Answer: Oxygen enters in the living world through the process of respiration, i.e., it oxidises the food material (glucose molecule) and produces energy and carbon dioxide.

2: Name the gases which cause greenhouse effect.
Answer: Greenhouse effect is caused by carbon dioxide, Chlorofluorocarbons (CFCs) nitrogen oxide and methane.

3: Name some biologically important organic compounds that contain both oxygen and nitrogen.
Answer: Proteins, amino acids and nucleic acids.

4: Name the compound, which is responsible for the depletion of ozone layer in the atmosphere.
Answer: Chlorofluorocarbons (CFCs)

5: Which part of solar radiation is absorbed by ozone layer?
Answer: Ultraviolet radiation

6: What do you mean by biotic component?
Answer: The biotic component means the living organisms, which are present in environment.

7: What do you mean by air pollution?
Answer: An increase in the content of harmful or undesirable substances (pollutants) in the air, is called air pollution.

8: Air is also called “breath of life’. Why?
Answer: Air is called breath of life because it contains oxygen, which is required by all living organisms for respiration.

9: Which winds bring rain in most parts of India?
Answer: The South-West or North-East monsoons.

10: State the harmful effects of ultraviolet rays.
Answer: Ultraviolet rays cause cancer and cataract-like diseases to living organisms.

11: Which non-living component of the Earth determine biodiversity of an area?
Answer: Water is the determinant of biodiversity of an area.

12: State two factors, which are responsible for polluting water.
Answer: Municipal sewage and discharge from industries are responsible for polluting water.

13: What is soil?
Answer: Soil is the outermost layer of our Earth, called the crust, which forms the upper surface of land and supports plant growth.

14: What is top soil? How is it responsible for the biodiversity in an area?
Answer: It is the topmost layer of the soil that contains humus and living organisms in addition to the soil particles. The quality of top soil is an important factor that decides biodiversity in that area.

15: What are the main substances of biogeochemical cycles?
Answer: Its main substances are carbon (C), nitrogen (N), oxygen (O) and water

16: Which group of plants contains nitrogen fixing bacteria in their roots?
Answer: Leguminous plants such as cereals, pea, bean, etc.

17: Name two organisms, which play vital role in nitrogen fixation.

Answer: The organisms, which play vital role in nitrogen fixation are
(i) Rhizobium and blue-green algae, help in fixation of free atmospheric nitrogen.
(ii) Nitrosomonas and Nitrobacter are nitrifying bacteria, which convert ammonia to nitrite and then nitrite to nitrates.

18: Why step farming is common on hills?
Answer: Step farming is common on hills because it slows down the speed of rain water, stops soil erosion and increases water absorption by the soil.

19: Soil formation is done by both biotic and abiotic factors. List the names of these factors by classifying them as biotic and abiotic.
Answer: (i) Abiotic factors of soil formation: Sun, water, wind, etc.
(ii) Biotic factors of soil formation: herbs, lichens, mosses, microorganisms, etc.

20: Write full form of CFCs.
Answer: Chlorofluorocarbons

21: State one use of ozone.
Answer: It protects the Earth from harmful radiations like high energy ultraviolet radiations

22: State the role of symbiotic bacteria in nitrogen cycle of nature.
Answer: Plants are unable to take atmospheric nitrogen directly. Symbiotic bacteria convert the atmospheric nitrogen into water soluble nitrates, which are easily utilised by plants.

23: Name any one method by which water helps in soil formation.
Answer: In physical weathering, water and high temperature cause expansion and contraction of rocks, facilitating their breakdown. As a result forming soil.

24: In which region, the ozone layer is present in the atmosphere?
Answer: Ozone layer is present in stratosphere region of the atmosphere.

25: Where the hole in ozone layer have recently detected?
Answer: The hole in ozone layer have recently detected over Antarctica.

26: Why the Earth is called as ‘Blue Planet’?
Answer: The Earth is called as ‘Blue Planet’ because it is covered with 75% of water.

27: State the process by which carbon enters in the living system.
Answer: Respiration is the process by which carbon enters in the living system in the form of carbon dioxide.

28: Name the component of air, which is most essential for living organisms.
Answer: Oxygen is the component of air, which is most essential for living organisms.

29: Give two examples where water can be found in the frozen form on the Earth.
Answer: Water is found frozen in the ice-caps at two poles and on snow-covered mountains.

30: Why terrestrial life forms require freshwater?
Answer: Terrestrial life forms require freshwater because their body cannot tolerate high amount of dissolved salts in saline water.

31: Name two fossil fuels, which are responsible for air pollution.
Answer: Coal and petroleum are responsible for air pollution.

32: What do you mean by thermal pollution?
Answer: Thermal pollution is increase in temperature of water-bodies due to addition of hot water or hot effluent into it.

33: Give any two effects of soil erosion.
Answer: Two effects of soil erosion are
(i) Desertification
(ii) Reduction in soil futility

34: What is combustion?
Answer: Combustion is a process of burning of fossil fuels, to provide energy for various needs like cooking, transportation and industrial processes.

35: Name the process by which oxygen is replenished in nature.
Answer: Oxygen is replenished in nature through photosynthesis.

36: What is ozone hole?
Answer: Ozone hole is the depletion of ozone gas in ozone layer, as present over Antarctica.

37: Name two freshwater resources, which provide freshwater for human use.
Answer: The two freshwater resources, which provide fresh water for human use are:
(i) Groundwater
(ii) Surface water (ponds, lakes, streams, etc.)

38: What is the direction of air in coastal areas during the day?
Answer: During the day, the direction of air current or wind is from sea to land.

39: Which particles form the nuclei for condensation of water vapours in the atmosphere?
Answer: Dust and smoke particles.

40: Name the two acids that are present in acid rain.
Answer: Two acids present in acid rain are:
(i) Nitric acid
(ii) Sulphuric acid

Short Answer Type Questions

1: What is lithosphere?
Answer: The outer crust of the Earth is called the lithosphere.

2: What is hydrosphere?
Answer: The water available on the earth’s surface as well as underground water comprise together as hydrosphere. Water covers 75% of the Earth’s surface.

3: What is atmosphere?
Answer: The envelope of air that surrounds the earth is called atmosphere.

4: List the four zones of the atmosphere.
Answer: Four zones of atmosphere are:

Tropospshere
Stratosphere
Mesospshere
Thermospshere

5: What is biosphere?

Answer: This life-supporting zone of the Earth where the atmosphere, the hydrosphere and the lithosphere interact and make life possible, is known as the biosphere. It accommodates several types of living organisms which remain dependent on natural resources. The biosphere ranges between 6km, above sea level and 10kms below sea.

6: How is our atmosphere different from the atmosphere on Venus and Mars?

Answer: Earth’s atmosphere is quite different from the atmosphere present on Venus and Mars. The atmosphere of the earth consists of Nitrogen(79%), Oxygen(20%), small fraction of carbon dioxide and other gases which make it suitable for living. The atmosphere of Venus or Mars has carbon dioxide as the major component (95-97%)

7: How does the atmosphere act as a blanket?

Answer: The atmosphere acts as a blank due to its following functions:

It plays an important role in temperature control. It maintains the average temperature of the earth fairly constant during the course of whole year.
It prevents the sudden increase in temperature during the daylight hours.
During the night, it slows down the escape of heat into outer space.

8: What causes winds?

Answer: Uneven heating of the earth’s surface and water surface causes winds. On heating up the air rises up creating a low pressure region. Air travels from high pressure region to low pressure region forming winds. In addition the rotation of the Earth and the presence of mountain ranges in the paths of the wind also influence to winds.

9: Which gets heated faster land or water?
Answer: Land

10: Define air-pollution?
Answer: An increase in the content of these harmful substances in air is called air pollution.

11: List any three human activities that you think would lead to air pollution.

Answer: Three human activities leading to air pollution are:

Rapid urbanization and industrialization.
Deforestation
Burning of fuels like coal and petroleum.
Burning of coal in thermal power plants.

12: Name two diseases caused due to an increased content of pollutants in the air produced due to the burning of fossil fuels.
Answer: Bronchitis, asthma, lung cancer.

13: What is smog?

Answer: Smoke + Fog = Smog. The presence of unburnt hydrocarbons in air when mixed with condensed water vapours forms a thick layer called smog. It lowers the visibility during winter season and is an indication of air pollution.

14: How do fossil fuel cause air pollution?

Answer: The fossil fuels like coal and petroleum contain traces of nitrogen and sulphur. When these fuels are burnt, nitrogen and sulphur too are burnt and this produces different oxides of nitrogen and sulphur. These oxides of nitrogen and sulphur are poisonous and can cause respiratory problems. These oxides when mix with rain water give rise to acid water due to formation of nitric and sulphuric acids.

15: What are the effects of acid rain?

Answer: Effects of acid rain are:

Acidification of soil reduces fertility of soil.
Destroys aquatic life and pollutes water resources.
Causes irritation to eyes and skins of human beings and cattle.
Causes corrosion to buildings, bridges, statues etc.

16: What are biogeochemical cycles? Names two examples.

Answer: Biogeochemical cycles are the cyclic pathways through which chemical substances move through biotic environment (biosphere) and abiotic environment (lithosphere, atmosphere and hydrosphere) components of the earth.
A few example of biogeochemical cycles are:

Water Cycle
Nitrogen Cycle
Carbon Cycle
Oxygen cycle

17: In which regions is soil erosion very difficult to revert?
Answer: The regions with bare vegetation, mountains and hilly regions, soil erosion is very difficult to reverse.

Long answer Type Questions

1: How are clouds formed?

Answer: Due to various weather phenomena (e.g. uneven heating of land and water bodies on the earth surface), warm and cold convection of air currents generate. Water vapours which are also present in air due to evaporation also rise up. Since air cools down on rising, it leads to condensation of water vapours present in it. Thus vapours condense onto a tiny salt particles called condensation nuclei which form clouds.

Broadly clouds formed are of four types:

Nimbostratus: (Nimbus means rain). These clouds carry thick precipitation or rains.
Altostratus: These clouds form a foggy, gray and dull weather look.
Cirrostratus: these clouds form fluffy cotton like pattern.
Cirrus: These are high-level clouds seen during fair weather.

2: Meenakshi saw reduction in greenish layer of lichens at the bark of trees at the biology garden of the school. The garden was few metres away from diesel generator placed for electricity backup. She immediately informed the school authorities to check the pollution level of diesel and kerosene used in the generator.

(a) How reduction in Lichens layer is related to pollution?
(b) What measures should be taken by school authorities to check the reduction?
(c) What qualities are shown by Meenakshi by informing school about the Lichens?

Answer:
(a) Lichens are found to be very sensitive to the levels of contaminants like sulphur dioxide in
the air. Diesel and Kerosene contain traces of nitrogen and sulphur which for deadly oxides when mixed in air.

(b) School authorities should check the pollution level and quality of fuel used in diesel generator. They should also replace the generator with a better which does not pollute the environment. The generator should be place away from the school premises to avoid inhalation of smoke from it.

(c) She is concerned about air pollution and showed her social responsibility to keep the environment clean and pollution free.

3: Why do organisms need water?
OR
Why is water essential for life?
OR
Water is known as ‘A Wonder Liquid’. Justify this statement by giving any two reasons.

Answer: Water is an essential part for living organisms:

Most of the biochemical processes involve water e.g. photosynthesis takes water as one of the raw material to prepare food.
The major component of blood is water (plasma) which helps in transportation of food and excretory substances.
Water is used as part of food as a source of energy.
Water in sweat cools down the body temperature. Similarly water as transpiration loss in plants controls temperature of the plant as well as it helps in ascent of sap.
Water is used in many activities like drinking, food preparation, irrigation, power generation and industries.
Water is an essential medium for aquatic life. Amphibians also need water to carry out reproduction.
Water is a universal solvent hence it is used in medicines and a many chemical reactions takes place when dissolved in water.
Water makes up 70% of body weight of human beings and it carries out various metabolic activities in all animals.

4: What is meant by depletion of ozone layer? Mention one important feature of ozone in atmosphere. Identify the factors responsible for the formation of ozone hole.

Answer: The part of atmosphere, at height 320 km above sea level, there is a 5km thick ozone layer. This layer acts as a shield/blanket which absorbs UV radiations from sunlight. Thus it saves biotic life on the earth from the harmful effects UV radiation.

Over Antarctica, there is declining of ozone layer thickness and hole is seen. If depletion of ozone layer dwindles further, it would have severe consequences on the lives of living beings.

Following are the main chemicals responsible for the destruction of ozone layer:
1. chlorofluorocarbons (CFCs)
2. halogens (used in fire extinguishers)
3. methane and nitrous oxide

CFCs used as propellants in aeroplanes and coolant in refrigeration are the most damaging, which catalytically destroy ozone and convert it into oxygen.

Value Based Questions

1. 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 rationale when rain water already passes into drains?
(ii) Why are solar water heaters being installed when electric geezers are available?

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, Industrialisation and intensive agriculture. Coal/gas based power plants are adding CO₂ to the atmosphere causing global warming. Saving electricity is now an important social responsibility.

2. (i) Sheela saw blue-green algae forming bloom in the village pond,
(ii) Fish, which was previously abundant was no-where to be seen.
(iii) The pond is giving a stink. Water of the pond is not even fit for cattle. Some of the cattle who were taken to the pond for drinking and bathing have fallen sick,
(iv) What explanation will Sheela give for this to the villagers.

Answer: (i) Bloom forming algae occur in a pond only when the quality of pond water has deteriorated due to pollution. Blue-green algae secrete toxins that are harmful to animals and humans,

(ii) Fish must have died due to deficiency of oxygen in pond water. Oxygen deficiency occurs when there is excess of organic matter (organic loading). The aerobic decomposers consume the dissolved oxygen. This is followed by anaerobic decomposition of organic matter. It produces sulphides and other sludge producing substances. Blue-green algae can grow under such circumstances.

(iii) Stink comes from anaerobic breakdown products of organic matter. The toxins released by blue-green algae further deteriorate the quality of water causing sickness and skin rashes in animals and humans.

(iv) Sheela could explain to the villagers that deterioration of pond has been due to excess fertilizers used by them in their fields. Rain wash brought these fertilizers into the pond. There was initial spurt in the growth of plants due to this. The phenomenon is called eutrophication. 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.

3. (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 animal 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.

Answer: (a) The reason for these global changes is faulty recycling of carbon dioxide. More of carbon dioxide is being produced than its consumption in photosynthesis due to

Excess combustion of fossil fuels in industries, power houses, automobiles, homes and other places,
Reduced intake of CO₂ by plants due to deforestation,
Higher amounts of CO₂ entering the atmosphere not only increases its atmospheric concentration but also the concentration of dissolved CO₂ in water, especially in colder seas. This is making colder waters acidic. The acidity is thinning the shells of many marine animals.
CO₂ 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 was already submerged some low lying islands.

(b) Suggestions:

Large scale tree plantation in all vacant areas,
Reduced felling of forest trees.
Reducing consumption of fossil fuel by reducing dependence on thermal power plants, increasing efficiency of automobiles and switching over to alternate technologies that do not consume fossil fuels.

4. On a school trip to an industrial estate, students found that the marble used in the office buildings of most factories has lost its shine and become pitted.

(i) What is the reason of marble pitting
(ii) Can this factor cause harm to vegetation as well ?
(iii) Suggest way to prevent this.

Answer: (i) Pitting and discolouring of marble is due to corrosive action of dry or wet acid rain, comprising sulphur dioxide and nitrogen oxides, emitted during combustion of fossil fuels in industries. The acid reacts with insoluble calcium carbonate of marble and converts it into soluble calcium sulphate and calcium nitrate.

(ii) Yes, Acid rain can also cause harm to vegetation by
(a) Direct action of acid over plants causing death of leaves,
(b) Solubilisation of essential minerals and their leaching leaving only toxic minerals in the soil.