This PSEB 9th Class Science Notes Chapter 14 Natural Resources will help you in revision during exams.
PSEB 9th Class Science Notes Chapter 14 Natural Resources
→ Earth is the only planet on which life exists.
→ Life on earth depends upon ambient temperature, water, and food.
→ The resources on earth are equally important.
→ The most important requirement is solar energy.
→ The environment is the surroundings of an organism and influences its life.
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The environment is the sum total of all the components both from living and non-living ones.
→ The living or biotic components include plants, animals, and microorganisms whereas non-living or abiotic or physical components consists of air, water, soil, light, and temperature.
→ The habitat of plants and animals greatly varies.
→ Natural resources. It is the stock of nature such as air, water, soil, coal, minerals, animals, and plants that are useful to mankind in many ways.
→ Life on earth depends upon resources like soil, water, air, and energy from the sun. Inexhaustible resources are present in plenty and cannot be exhausted by man’s consumption.
→ The stock of exhaustible natural resources in nature is limited and will finish sooner or later.
→ Air is an important form of inexhaustible natural resource which is essential for our survival.
→ Composition of Air:
- Nitrogen (N2) – 78%
- Oxygen (O2) – 21%
- Carbon dioxide (CO2) – 0.03%
- Argon – 0.93%
- Helium, Neon, Ozone, Ammonia – 0.04%
→ Helium, Argon, and Neon are noble gases.
→ Lithosphere: It is the outer crust of our planet, the Earth.
→ Hydrosphere: It is the portion of the earth’s surface covered with water which is about 75 percent—comprising of seas, oceans, rivers, streams, lakes, ponds, etc.
→ Atmosphere: It is the multilayered gaseous envelope of air that covers the whole of our planet Earth like a blanket.
→ Atmosphere plays important role in the control of climate, movement of air (winds), and rain.
→ Biosphere: It is the life-supporting zone of the Earth where the atmosphere, the hydrosphere, and the lithosphere interact and make life possible.
→ It occupies the highest position or level in the hierarchy of organisation on the earth.
→ Water is an important medium for all the life processes and acts as a universal solvent and is termed ‘wonder liquid’.
→ Water covers 75% of the earth’s surface.
→ The oceans, rivers, streams, lakes, ponds, pools, polar ice caps, water vapours constitute the hydrosphere.
→ Soil is another main natural resource essential for our survival and development.
→ Soil forms the upper surface of the land and supports plant growth.
→ Soil is an important resource that decides the diversity of life in an area.
→ The outermost layer of Earth is called the crust and the minerals found in this layer supply a variety of nutrients to life forms.
→ Causes of Soil Erosion:
- Wind causes soil erosion by carrying away the top loose soil particles.
- Rain causes soil erosion on unprotected topsoil by washing it down.
- Improper farming or tilling and leaving the field fallow for a long time causes soil erosion.
- Frequent flooding of rivers causes soil erosion by removing the fertile topsoil of the fields near the river banks.
- Deforestation also leads to soil erosion.
→ The underground reservoir of the earth of metals and minerals is limited.
→ Renewable sources of energy are regenerated naturally within a short span of time e.g. plants, animals, sunlight, etc.
→ Non-renewable sources of energy take millions of years to form like coal, lignite, petroleum, and natural gas.
→ The substances like water, oxygen, carbon, and nitrogen move from one stage to another say from biotic to abiotic and again to biotic components in a cyclic manner.
→ Air Pollution: It is an undesirable change in the physical, chemical, or biological characteristics of air. It is caused due to an increase in the content of harmful substances (air pollutants) in the air such as oxides of nitrogen and sulphur, etc.
→ The major sources of air pollution are the burning of fossil fuels like coal and petroleum, automobiles, thermal power plants, and industries.
→ Pollution of air, water, and soil affects the quality of life and harms biodiversity.
→ Water Pollution is the contamination of the water of rivers and lakes with unwanted and harmful substances.
→ Water is said to be polluted when there is any physical, biological, or chemical change in its quality that adversely affects living organisms and makes it unfit for use.
→ The balance in the environment including the flow of energy and matters is also supported by various living beings by acting as producers and consumers.
→ Forests provide timber for building and furniture along with raw materials for the paper industry.
→ Ozone layer: Ozone is a triatomic gas with a molecular formula O3 which is present in the upper reaches of the atmosphere (in the stratosphere region).
→ The ozone layer prevents the harmful radiations of the sun from reaching the surface of the earth, where they may damage many forms of life.
→ Role of ozone: Unlike oxygen, ozone is poisonous but it performs a very important role for us.
→ It forms a thick layer in the upper regions of the atmosphere and absorbs harmful radiation from the sun.
→ This prevents those harmful radiations from reaching the surface of the Earth where they may damage many forms of life.
→ CO2 forms 95-97% of the atmosphere on Venus and Mars.
→ On the moon, the temperature ranges from -190°C to 110°C.
→ Smog formed by smoke and fog is a visible indication of air pollution.
→ Exhaustible Resources: These resources are limited in nature and will finish sooner or later.
→ Inexhaustible resources: These resources are unlimited and cannot be exhausted by man’s consumption.
→ Renewable resources: These resources are naturally replenished after man’s consumption.
→ Non-Renewable Resources: These resources cannot be replaced after they are used.
→ Underground Water: The water present below the soil is called underground water.
→ Crust: Topmost surface of the earth is called the crust.
→ Mineral resources: These resources are present on earth and are non-renewable.
→ Atmosphere: It is a transparent gaseous envelope surrounding the earth.
→ Pollution: It is an undesirable change in physical, chemical, or biological characteristics of the water and soil.
→ Acid rain: When gases like SO2 and SO3 react with water to form sulphuric acid and sulphurous acid and precipitate as rain is called acid rain.
→ Smoke: It is a secondary pollutant produced as a result of reactions of products of incomplete combustion.
→ Smog: Combination of smoke and fog forms smog (Smoke + fog = Smog).
→ Aerosoles: Certain chemicals are released in the air with force in the form of mist or vapour.
→ Soil: The topmost fertile layer of the earth capable of supporting plant growth is called soil.
→ Fertility of soil: The capacity of the soil to sustain plant life with required nutrients is called the fertility of the soil.
→ Water covers 75% of the earth’s surface.
→ NGO: Non-Governmental Organisation.
→ IUCN: International Union For Conservation of Nature and Natural Resources.