NCERT Class 9 Science Chapter 14 Natural Resources Question Answer to each chapter is provided in the list so that you can easily browse throughout different chapters Class 9 Science Chapter 14 Natural Resources and select need one.
NCERT Class 9 Science Chapter 14 Natural Resources
Also, you can read the SCERT book online in these sections Solutions by Expert Teachers as per SCERT (CBSE) Book guidelines. These solutions are part of SCERT All Subject Solutions. Here we have given SCERT Class 9 Science Chapter 14 Natural Resources Solutions for All Subjects, You can practice these here.
Natural Resources
Chapter – 14
GENERAL SCIENCE
TEXTUAL QUESTIONS AND ANSWERS
INTEX QUESTIONS AND ANSWERS
Textbook Page No. 193
1. How is our atmosphere different from the atmospheres on Venus and Mars?
Ans. The atmosphere of the earth is a mixture of many gases like nitrogen, oxygen, carbon dioxide and water vapour along with other gases and these composition of air help life to exist on the earth. But on planets like Venus and Mars, the atmosphere does not support life since major component of their atmosphere consists of carbon dioxide (95% -97%).
2. How does the atmosphere act as a blanket?
Ans. Air is a bad conductor of heat and hence the atmosphere keeps the average temperature of the earth fairly steady during the day and even during the whole year. It prevents the sudden increase in temperature during the daylight hours and during night, it slows down the escape of heat into outer space. Thus, the atmosphere covers the earth like a blanket.
3. What causes winds?
Ans. There are three types of wind:
(i) Pressure Systems. In our desert example, the hot air moved upward, and the cool air flowed in to replace it.
(ii) Elevation.
(iii) Special Kinds of Wind Storms.
4. How are clouds formed?
Ans. A large amount of water evaporates due to heating of water bodies during daytime and goes into the air. This phenomenon is known as evaporation. Evaporation also occurs due to some biological activities. As a result, the air near the surface of water gets heated and the hot air rises up carrying water vapour with it. As the air rises, it expands and cools. Cool air in the atmosphere sinks towards the ground. Due to further cooling, water vapours present in the air take the shape of small droplets. These tiny droplets become bigger and bigger due to condensation and thereby, formation of clouds take place.
5. List any three human activities that you think would lead to air pollution.
Ans. Following three human activities would lead to air pollution:
(i) Burning of wood and coal in household activities and factories.
(ii) Deforestation which reduces absorption of carbon dioxide (CO₂) from air.
(iii) Heavy emission of carbon monoxide (CO) from vehicles.
Textbook Page No. 194
1. Why do organisms need water?
Ans. Living organisms need water due to the following reasons:
(i) War is the main constituent of protoplasm.
(ii) In case of plant, water is the solvent through which mineral salts are transported from one part of the plant to other.
(iii) Water acts as a reactant in numerous metabolic reactions.
2. What is the major source of fresh water in the city /town /village where you live?
Ans. The major source of fresh water in the city/ town /village where I live are river, well and tube- well.
3. Do you know of any activity which may be polluting this water source?
Ans. Discharge of sewage into the rivers mainly pollutes water along with bathing and washing activities.
Textbook Page No. 196
1. How is soil formed?
Ans. Over long periods of time, the rocks at or near the surface of the earth are broken down by various physical, chemical and some biological processes. The end product of this breaking down is the fine particles of soil. There are four important factors which have immense effect on this changing process of rock into soil.
These factors are:
(i) Sun: During daytime due to the intensity of heat of sunlight, rocks get expanded and at night these rocks cool down and contract. As a result of uneven expansion and contraction, rocks crack and break up into small pieces. These gradually get converted to soil.
(ii) Water: Water has two different effects. Firstly, water could get into the cracks in the rocks and on freezing, it helps to widen the cracks. Secondly, flowing water often carries big and small particles of rock downstream and these rocks rub against other rocks which result into wear down of rocks into small particles of soil.
(iii) Wind: Strong wind erodes rocks slowly and carries sand or small rock particles from one place to another, thus leading to formation of soil.
(iv) Living organisms: Living organisms like lichen grows on rock surface and releases certain chemical substances which cause rock surface to powder down and form thin layers of soil. Other small plants like moss grow on this surface and they further influence.
The rock to break down into soil. The roots of big trees also sometimes go into cracks in the rocks and as they grow bigger, force the crack to break.
2. What is soil erosion?
Ans. In simple term, soil erosion means wearing away of soil. Broadly speaking, it is the movement of soil components, especially top soil from one place to another, Soil erosion results in the loss of fertility because it is the top soil layer which is fertile.
Normal soil erosion keeps on taking place as a natural process. Climatic agents such as rainfall and wind cause such erosion. A natural balance between soil erosion and its renewal is maintained. But due to certain man-made activities the rate of soil erosion becomes much faster than the rate of formation of soil and thus cause land degradation.
Some of such activities are:
(i) Deforestation without reforestation.
(ii) Overgrazing by cattle.
(iii) Surface mining without land reclamation.
(iv) Irrigation techniques that lead to salt build-up.
(v) water-logged soil.
(vi) farming on land with unsuitable terrain, etc.
3. What are the methods of preventing or reducing soil erosion?
Ans. Some methods of preventing or reducing soil erosion are mentioned below:
(i) Reducing the rate of overgrazing.
(ii) keeping minimum vegetation cover over top soil.
(iii) Reducing deforestation to maintain flow of running water through the roots of trees which check soil erosion.
(iv) Crop rotation in cropland to maintain fertility of soil, etc.
Textbook Page No. 201
1. What are the different states in which water is found during the water cycle?
Ans. During the water cycle, water is found in three different stateS are:
(i) Solid (ice or snow).
(ii) Liquid.
(iii) Vapour.
2. Name two biologically important compounds that contain both oxygen and nitrogen.
Ans. Two biological compounds that contain both oxygen and nitrogen are mentioned below:
(i) Proteins in different compositions.
(ii) Nucleic acids (DNA and RNA)
3. List any three human activities which would lead to an increase in the carbon dioxide content of air.
(i) Burning of fossil fuel during transportation and industrial activities.
(ii) Burning of wood and coal in household and factory purposes.
(iii) De restation, which reduces the rate of CO₂ utilisation by green plants during photosynthesis.
4. What is the greenhouse effect?
Ans. The greenhouse effect is a process that occurs when gases in Earth’s atmosphere trap the Sun’s heat. This process makes Earth much warmer than it would be without an atmosphere. The greenhouse effect is one of the things that makes Earth a comfortable place to live. Carbon dioxide (CO₂) has the ability to absorb the infra-red radiations reflect by the earth’s surface. As a result, the temperature of the atmosphere rises. Thus, the presence of excess carbon dioxide (in excess of 0.033%) will lead to further rise in temperature of the atmosphere.
This phenomenon of increase in temperature of the atmosphere due to the presence of excess carbon dioxide is called the greenhouse effect.
5. What are the two forms of oxygen found in the atmosphere?
Ans. Oxygen is found in the atmosphere in two forms:
(i) in a di-atomic molecular form (O₂) called oxygen, and
(ii) in a triatomic molecular form (O₃) called ozone.
EXERCISE
Textbook Page No. 205
1. Why is the atmosphere essential for life?
Ans. The atmosphere contains various gases essential for living organisms to survive. These gases mainly include nitrogen, oxygen and carbon dioxide. The atmosphere also keeps the average temperature of the earth fairly steady by preventing sudden increase and slow down in temperature during the day and at night respectively. Therefore, atmosphere is essential for life.
2. Why is water essential for life?
Ans. Living organisms need water due to the following reasons are mentioned:
(i) War is the main constituent of protoplasm.
(ii) In case of plant, water is the solvent through which mineral salts are transport from one part of the plant to other.
(iii) Water acts as a reactant in numerous metabolic reactions.
(iv) Water releases oxygen during photosynthesis.
(v) The growth of cells during elongation on phase is mainly dependent on absorption of water.
(vi) Water acts as the temperature buffer for living organisms.
(vii) All organisms have to maintain the water level of their body for their survival.
3. How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resource?
Ans. The living organism dependent omn the the soil are mentioned below:
(i) For food, animals are dependent on plants which grow on soil.
(ii) Carnivores depend on animals for food which eat plants grown on.
(iii) Plants prepare their own food with the water taken from soil.
(iv) Plants absorb minerals for their survival from soil.
(v) Plants also need soil for mechanical support.
Thus, all living organisms are directly or indirectly dependent on soil.
Organisms that live in water are not independent of soil as a resource. They depend on green plants for food and energy which absorb minerals from water or from soil at the bottom of sea. But water bodies get minerals from soil through river, rainwater flowing through soil, etc. Continuous supply of minerals from soil to water ultimately fulfill the mineral requirements of organisms living in water. Therefore, they are not totally independent of soil as a resource.
4. You have seen weather reports on television and on newspapers. How do you think soil we are able to predict the weather?
Ans. To predict weather one must study wind pattern which decides rainfall pattern. Wind pattern is dependent on areas of low and high air pressure or air depressions. Study of all these can help us in weather prediction.
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?
Ans. Isolating the polluting activities to specific and limited areas would not help in reducing pollution. Air, water and soil are interrelated and pollution activities in limited areas would not only have pollution effects on that particular area, but also other nearby areas would be adversely affected. Air pollution in a limited area will cause harm in many directions as air gets pollutants which can spread to nearby areas easily. Pollution of water bodies will affect aquatic plants and animals which drastically disturbs the entire food chain of the whole ecosystem. Soil pollution has also widespread affect on all plants growing in that area and organisms which directly or indirectly feed on such plants. Therefore, we should reduce the rate of pollution as a whole.
6. Write a note on how forests influence the quality of our air, soil and water resources.
Ans. The quality of our air , soil, and water resource are mentioned below:
(i) Maintenance of air quality: Forests maintain oxygen-carbon dioxide ratio in the atmosphere. Oxygen is consumed during respiration by all organisms which is replenished by the green plants of forests by releasing oxygen and consuming CO₂ during photosynthesis.
(ii) Prevention of soil erosion: Forest trees check the force of running water during flood and heavy wind and thereby prevent soil erosion. The roots of forest trees also bind top soil and falling leaves make humus for top soil which prevent soil erosion.
(iii) Maintenance of humidity in atmosphere: Large amount of water is released to atmosphere during transpiration, but the water vapours on precipitation form clouds. As a result rain occurs which maintains water requirement of atmosphere as well as of soil.
(iv) Reduction of pollution: Many forest plants have the capacity to absorb heavy metals, which are mainly soil and water pollutants and hence reduce soil and water pollution to a great extent.
