Gujarat Board GSEB Textbook Solutions Class 9 Science Chapter 14 Natural Resources Textbook Questions and Answers, Notes Pdf.
Gujarat Board Textbook Solutions Class 9 Science Chapter 14 Natural Resources
Gujarat Board Class 9 Science Natural Resources InText Questions and Answers
Page 193
Question 1.
How is our atmosphere different from the atmospheres on Venus and Mars?
Answer:
The atmosphere of the Earth contains a mixture of gases like nitrogen, oxygen, carbon dioxide and water vapour. This helps to support life as the amount of carbon dioxide on the Earth’s atmosphere is low compared to other gases. However, the atmosphere of Venus and Mars consists mainly of carbon dioxide which is not suitable to sustain life in these planets.
Question 2.
How does the atmosphere act as a blanket?
Answer:
The atmosphere acts as a blanket because:
- It keeps the average temperature of the Earth fairly constant.
- It prevents a sudden increase in temperature during the daylight hours.
- It slows down the escape of heat into outer space during the night.
Question 3.
What causes winds?
Answer:
Due to the unequal heating of land and water, the land get heated up faster during the day, the air on land rises up and creates a region of low pressure. As a result, the air over the sea moves towards the region of low pressure formed on the land. This causes winds to flow.
Question 4.
How are clouds formed?
Answer:
Water gets evaporated from water bodies and through biological activities of the organisms. This water goes into the air as water vapour. When the air rises up, it expands and cools which causes the water vapour to condense around the particles suspended in the air to form tiny droplets. This results in the formation of clouds.
Question 5.
List any three human activities that you think would lead to air pollution.
Answer:
The human activities that would lead to air pollution are:
- Burning of coal in thermal power plants to generate electricity.
- Burning of fuels like petrol and diesel in vehicles.
- Large scale deforestation.
Page – 194
Question 1.
Why do organisms need water?
Living organisms need water for:
- Carrying out the various metabolic and biochemical processes taking place in the body.
- Transportation of the various substances from one part of the body to the other in the organisms.
Question 2.
What is the major source of freshwater in the city/town/village where you live?
Answer:
The major source of water is the rivers and underground water resources.
Question 3.
Do you know of any activity which may he pollute this water source?
Answer:
The activity which pollutes the water resource are:
- Excessive use of fertilisers and pesticides which get washed into the water bodies pollute the water resources.
- The sewage water which is directly drained into the rivers.
Page – 196
Question 1.
How is soil formed?
Answer:
Soil is formed due to various physical, chemical and biological processes which result in the breakdown of rocks into fine particles of soil over millions of years. The formation of soil occurs due to factors and processes like Sun, water, wind, living organisms and lichens.
1. Sun: Rocks expand when they get heated by the Sun during the day. During the night, the rocks cool down and contract. This results in the formation of cracks in the rocks as the rate of expansion and contraction are different. The rocks split and break into smaller pieces.
2. Water: Water acts in two ways to break the large rocks into small pieces. Water enters the cracks and crevices in the rocks, gets unevenly heated by the Sun and when it expands during freezing in the winter season, the rocks get broken. Also, the fast running water over the surface of the rocks causes weathering of rocks to form soil.
3. Wind: Winds carry small rocks and sand from one place to another and these strong winds rub against the large rocks to erode them.
4. Living organisms (Lichens): The chemical substances secreted by the living organisms like lichens degrade the rocks and convert them into fine particles of soil.
Question 2.
What is soil erosion?
Answer:
The process by which the fertile topsoil gets removed is called soil erosion.
Question 3.
What are the methods of preventing or reducing soil erosion?
Answer:
The methods to prevent soil erosion are:
- Overgrazing by cattle should be avoided.
- Large scale afforestation should be done as roots of the plants prevent the soil from getting carried away.
- Increasing the vegetation cover on the ground reduces the impact of flowing water on soil and prevents it from getting washed away.
- Contour farming can be done by ploughing the land in furrows across the natural slope of the land to trap water flowing down.
- Step farming is practised in hilly regions which reduce the flow of water and give it more time to percolate into the soil.
Page – 201
Question 1.
What are the different states in which water is found during the water cycle?
Answer:
Water is found in three different states during the water cycle:
- Solid: in the form of ice or snow
- Liquid: in the form of water (Hi)
- Gas: in the form of water vapour.
Question 2.
Name two biologically important compounds that contain both oxygen and nitrogen.
Answer:
Proteins and the nucleic acids (DNA and RNA) are biologically important compounds which contain both oxygen and nitrogen.
Question 3.
List any three human activities which would lead to an increase in the carbon dioxide content of the air.
Answer:
The human activities which would lead to an increase in the carbon dioxide content of the air are:
- Burning of coal in thermal power plants to generate electricity.
- Burning of fuels like petrol and diesel in vehicles.
- Large scale deforestation which results in loss of green plants and trees which utilise carbon dioxide during photosynthesis.
Question 4.
What is the greenhouse effect?
Answer:
The phenomenon in which the incoming sunlight is allowed to pass through the atmosphere but heat radiated back from the planet’s surface is trapped by the gases like carbon dioxide, water vapour and methane present in the atmosphere is called the greenhouse effect.
Question 5.
What are the two forms of oxygen found in the atmosphere?
Answer:
The oxygen is found in the atmosphere in two forms:
- As a diatomic molecule 02, that contains two atoms of oxygen.
- As triatomic molecule 03, that contains three atoms of oxygen. It is called as ozone.
In-Text Activities Solved
(Textbook Page 190)
Activity 14.1
Measure the temperature of the following: Take –
- a beaker full of water
- a beaker full of soil/sand
- a closed bottle containing a thermometer.
Keep them in bright sunlight for three hours. Now measure the temperature of all 3 vessels. Also, take the temperature reading in shade at the same time.
Question 1.
Is the temperature reading more inactivity (i) or (ii)?
Answer:
The temperature reading is more inactivity (ii).
Question 2.
Based on the above finding, which would become hot faster – the land or the sea?
Answer:
The land will become hot faster.
Question 3.
Is the thermometer reading of the temperature of air (in shade) the same as the temperature of sand or water? What do you think is the reason for this? And why does the temperature have to be measured in the shade?
Answer:
The temperature reading of air (in shade) is less than the temperature of sand and water. The reason behind this is that the land and the water directly receive the radiations of the Sun.
Question 4.
Is the temperature of air in the closed glass vessel/bottle the same as the temperature taken in the open air?
- What do you think is the reason for this?
- Do we ever come across this phenomenon in daily life?
Answer:
The temperature of the air in the closed glass vessel/ bottle is more than the temperature taken in the open air.
1. The reason for this is that glass allows radiations of the Sun to enter but does not allow the heat radiations reflected back to escape from it.
2. This phenomenon has been termed as the greenhouse effect. It can be easily observed in a car parked in the Sun with all the windows closed. The temperature inside the car becomes more than the temperature outside it.
(Textbook Page 190)
Activity 14.2
Place a candle in a beaker or wide-mouthed bottle and light it. Light an incense stick and take it to the mouth of the above bottle (Figure is shown below).
Question 1.
Which way does the smoke flow when the incense stick is kept near the edge of the mouth?
Answer:
The smoke flows inwards towards the flame as the hot air around the flame rises up to create a region of low pressure and the air from outside which is at higher pressure rushes in. So, the smoke is carried towards the flame.
Question 2.
Which way does the smoke flow when the incense stick is kept a little above the candle?
Answer:
The hot air rises up and the smoke rises up along with it.
Question 3.
Which way does the smoke flow when the incense stick is kept in other regions?
Answer:
The smoke rises up, spreads and diffuses in the air when incense stick is kept in other regions.
(Textbook Page 191)
Activity 14.3
Take an empty bottle of the sort in which bottled water is sold. Pour about 5-10 mL of water into it and close the bottle tightly. Shake it well or leave it out in the Sun for ten minutes. This causes the air in the bottle to be saturated with water vapour.
Now, take a lighted incense stick. Open the cap of the bottle and allow some of the smoke from the incense stick to enter the bottle. Quickly close the bottle once more. Make sure that the cap is fitting tightly. Press the bottle hard between your hands and crush it as much as possible. Wait for a few seconds and release the bottle. Again press the bottle as hard as you can.
Question 1.
When did you observe that the air inside seemed to become ‘foggy’?
Answer:
When we stop pressing and crushing the bottle and the pressure inside the bottle is released, the air inside seems to become “foggy”.
Question 2.
When does this fog disappear?
Answer:
The fog disappears when the bottle is pressed again.
Question 3.
When is the pressure inside the bottle higher?
Answer:
The pressure inside the bottle is higher when we press or crush the bottle.
Question 4.
Is the ‘fog* observed when the pressure in the bottle is high or when it is low?
Answer:
The fog is observed when the pressure inside the bottle is low.
Question 5.
What is the need for smoke particles inside the bottle for this experiment?
Answer:
The smoke particles act as a nucleus around which the water vapour gets condensed to form tiny droplets.
Question 6.
What might happen if you do the experiment without the smoke from the incense stick? Now try it and check if the prediction was correct. What might be happening in the above experiment in the absence of smoke particles?
Answer:
The fog formation does not occur without the smoke. The tiny droplets are not formed as nothing is available to act as a nucleus for the condensation of water vapour.
(Textbook Page 192)
Activity 14.4
Collect information from newspapers or weather reports on television about rainfall patterns across the country.
Also, find out how to construct a rain gauge and make one. What precautions are necessary in order to get reliable data from this rain-gauge? Now answer the following questions:
Question 1.
In which month did your city/town/village get the maximum rainfall?
Answer:
The maximum rainfall in our city/town/village occurred in the month of July and August due to the Southwest monsoon.
Question 2.
In which month did your state/union territory get the maximum rainfall?
Answer:
The maximum rainfall in our state/union territory also occurs in the month of July and August due to the Southwest monsoon.
Question 3.
Is rain always accompanied by thunder and lightning? If not, in which season do you get more of thunder and lightning with the rain?
Answer:
No, rain is not always accompanied by thunder and lightning. Thunder and lightning occur more during the rains which occur in the rainy season.
(Textbook Page 192)
Activity 14.5
Question 1.
Find out more about monsoons and cyclones from the library. Try and find out the rainfall pattern of any other country. Is the monsoon responsible for rains the world over?
Answer:
- The student can find this from the internet and other resources. Do it yourself.
- The rainfall pattern is decided by the prevailing wind patterns in the region.
- Yes, monsoon is responsible for the rains in most parts of the world.
(Textbook Page 193)
Activity 14.6
Question 1.
Organisms called lichens are found to be very sensitive to the levels of contaminants like sulphur dioxide in the air. As discussed earlier in section 7.3.3, lichens can be commonly found growing on the barks of trees as a thin greenish-white crust. See if you can find lichen growing on the trees in your locality.
Answer:
The lichens can be found on the bark of trees in hilly areas or unpolluted areas. They are not found in polluted areas.
Question 2.
Compare the lichen on trees near busy roads and trees some distance away.
Answer:
The lichens on trees near busy roads are blackish compared to the lichens found on trees some distance away.
Question 3.
On the trees near roads, compare the incidence of lichen on the side facing the road and on the side away from the road.
Answer:
The lichens on the side facing the road are more blackish compared to the side away from the road. Also, more lichens are there on side facing away from the road.
(Textbook Page 193)
Activity 14.7
Many municipal corporations are trying water-harvesting techniques to improve the availability of water.
Question 1.
Find out what these techniques are and how they would increase the water that is available for use.
Answer:
The techniques of rainwater harvesting are:
- The water is taken underground by the roadside drains. The underground water can be utilised by making wells or installing tubewells.
- The rooftop rainwater harvesting technique can be used to collect the rainwater from the rooftop in a storage tank or recharge the underground water level by allowing it to flow underground through a deep pit in the ground.
(Textbook Page 193)
Activity 14.8
Question 1.
Select a small area (say, 1 m2) near a water-body, it may be a river, stream, lake or pond. Count the number of different animals and plants in this area. Also, check the number of individuals of each type or species.
Answer:
Count the number of different animals and plants in the area and tabulate your results. You will find a large number of plants and animals near a waterbody.
Question 2.
Compare this with the number of individuals (both animals and plants) found in an area of the same size in a dry, rocky region.
Answer:
Count the number of different animals and plants in the area and tabulate your results. You will find a limited number of plants and animals near a dry, rocky region.
Question 3.
Is the variety of plant and animal life the same in both these areas?
Answer:
No, variety of plant and animal life is different in both areas. The area near a water body has a greater diversity than the dry, rocky region.
(Textbook Pages 193-194)
Activity 14.9
- Select and mark out a small area (about 1 m2) in some unused land in or near your school.
- As in the above activity, count the number of different animals and plants in this area and the number of individuals of each species.
- Remember to do this in the same place twice in a year, once during summer or the dry season and once after it has rained.
Question 1.
Were the numbers similar both times?
Answer:
No
Question 2.
In which season did you find more variety of plants and animals?
Answer:
In the rainy season.
Question 3.
In which season did you find more number of individuals of each variety?
Answer:
In the rainy season.
(Textbook Page 195)
Activity 14.10
Take some soil and put it into a beaker containing water. The water should be at least five times the amount of soil taken. Stir the soil and water vigorously and allow the soil to settle down. Observe after some time.
Question 1.
Is the soil at the bottom of the beaker homogeneous or have layers formed?
Answer:
The soil is not homogeneous. The soil gets arranged in layers.
Question 2.
If layers have formed, how is one layer different from another?
Answer:
Yes, the layers are different in respect of the particle size, colour and composition.
Question 3.
Is there anything floating on the surface of the water?
Answer:
Yes, the dead and partially decomposed parts of plants are seen floating on the water surface.
Question 4.
Do you think some substances would have dissolved in the water? How would you check?
Answer:
Yes, some substances would have dissolved in the water. It can be checked by first leaving the water undisturbed for soil to settle down, decant the water in a porcelain dish and then evaporate the water from solution by heating. A powdered substance can be observed in the dish after the water gets evaporated fully. The powdered substance is the substances dissolved in water.
(Textbook Page 196)
Activity 14.11
- Take two identical trays and fill them with soil. Plant mustard or green gram or paddy in one of the trays and water both the trays regularly for a few days, till the first tray is covered by plant growth. Now, tilt both the trays and fix them in that position. Make sure that both the trays are tilted at the same angle. Pour an equal amount of water gently on both trays such that the water flows out of the trays as shown in the figure below.
- Study the amount of soil that is carried out of the trays. Is the amount the same in both the trays?
Answer:
No, the amount of soil carried away is slightly more in the tray without plants. - Now pour equal amounts of water on both the trays from a height. Pour three or four times the amount that you poured earlier.
- Study the amount of soil that is carried out of the trays now. Is the amount the same in both the trays?
Answer:
No, the amount of soil carried away is far more in the tray that does not have plants as compared to the
one with plants. - Is the amount of soil that is carried out more or less or equal to the amount washed out earlier?
Answer:
Earlier the amount of soil washed out was less.
(Textbook Page 199)
Activity 14.12
Question 1.
Find out what the consequences of global warming would be.
Answer:
The consequences of global warming would be:
- The snow of the mountains will melt at a faster rate which will increase the amount of water in the rivers. This will result in floods and huge damage to human life and vegetation.
- Polar ice caps will melt at a faster rate, the sea level will rise and many coastal areas may get submerged.
- Many animals that are not able to survive the variation of temperature would become extinct.
- The wildlife would get affected adversely.
Question 2.
Also, find out the names of some other greenhouse gases.
Answer:
Apart from carbon dioxide, the other greenhouse gases are methane, CFCs and water vapour.
(Textbook Page 201)
Activity 14.13
Question 1.
Find out which other molecules are thought to damage the ozone layer.
Answer:
The other molecules which damage the ozone layer are:
- Many hydrocarbons
- Bromochloromethane
- Pesticides like methyl bromide
Question 2.
Newspaper reports often talk about the hole in the ozone layer.
Answer:
Newspaper reports talk about the hole in the ozone layer which was first discovered over Antarctica in 1985. The ozone hole refers to the thinning of the ozone layer which has been caused due to the excessive use of ozone-depleting substances like the CFCs.
The ozone layer absorbs the harmful ultraviolet radiations of the Sun which can cause cataract, cancers, skin diseases and damage animal and plant life. Montreal Protocol was signed by nations in 1987 and in 1994, the United Nations declared that 16th September will be celebrated as ‘World Ozone Day’.
Question 3.
Find out whether the size of this hole is changing and in what manner scientists think this would affect life on Earth (figure is given below).
Satellite picture showing the hole (magenta colour) in the ozone layer over Antarctica
Answer:
Loss of ozone layer was around 3% during 1981. By 2005, the ozone hole increased to about 24 million sq km which is approximately equal to North America in size.
Gujarat Board Class 9 Science Natural Resources Textbook Questions and Answers
Question 1.
Why is the atmosphere essential for life?
Answer:
The atmosphere is essential for life because
- It keeps the average temperature of the Earth fairly constant.
- It prevents a sudden increase in temperature during the daylight hours.
- It slows down the escape of heat into outer space during the night.
- The gases like oxygen, carbon dioxide and nitrogen present in the air help in sustaining life on Earth.
Question 2.
Why is water essential for life?
Answer:
Water is essential for life because it helps in
- Carrying out various metabolic and biochemical processes taking place in the body of living organisms.
- Transportation of various substances from one part of the body to the other in living organisms.
Question 3.
How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resource?
Answer:
Living organisms are dependent on the soil as soil provides
- Habitat for the living organisms.
- Provides nourishment, food and nutrients to various organisms.
- Burrowing animals live in the burrows made in the soil, e.g., rabbit, rats.
- The minerals and water present in the soil support the growth of plants which provide food for animals.
No, the organisms that live in water are not totally independent of soil as a resource as the decomposers present in the soil beds inside water help in recycling various nutrients dissolved in water, which support the life of these organisms. The nutrients released from the soiled are present in a dissolved state in the water used by the aquatic organisms.
Question 4.
You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?
Answer:
The weather can be predicted by analysing the wind patterns prevailing in an area as these wind patterns decide the pattern of the rainfall there. The regions of high pressure and low pressure can be ascertained by studying the direction of flow of air. The rain in India is caused due to South-west monsoon and North-east monsoon. Most rains occur during the South-west monsoon as it covers a large part of the country.
Question 5.
We know that many human activities lead to increasing levels of pollution of the air, water¬bodies and soil. Do you think that isolating these activities to specific and limited areas would help in reducing pollution?
Answer:
Yes, if human activities that lead to increasing levels of pollution of the air, water-bodies and soil are isolated to specific and limited areas, it would help in reducing pollution.
- Proper waste management practices can reduce water and land pollution.
- The water released from the homes and industries can be treated to remove harmful impurities before discharging them into the water bodies.
- The heated water released from the industries harms the aquatic organisms. It can be allowed to cool down before discharging it into water bodies.
- The industries and factories can be shifted away from residential areas to reduce the menace of noise pollution and air pollution.
- The harmful gases released from the vehicles, power plants and industries can be treated to make them free of poisonous gases and particulate matter, before being released.
Question 6.
Write a note on how forests influence the quality of our air, soil and water resources.
Answer:
Forests play an important role and influence the quality of air, soil and water resources as they:
- Maintain the balance of oxygen and carbon dioxide in nature by fixing carbon dioxide and releasing oxygen during photosynthesis.
- The roots of the trees in the forests bind the soil tightly and prevent soil erosion.
- The forests help to maintain the water cycle in nature.
- Forests play an important role in the biogeochemical cycles.
- The roots of the tress and the plants help to trap the flowing water and increase its percolation into the ground.
- The forests help in maintaining the temperature of the surrounding environment.