Natural Resources

The difference in the atmosphere of Earth and that on Venus and mars is that the atmosphere of Earth is made of nitrogen 79% and oxygen 20%, small fraction of carbon dioxide and other gases whereas the atmosphere of Venus and Mars is composed mainly of carbon dioxide ranging from 95-97%.

Atmosphere acts as a blanket in the following ways-

• By preventing the harmful rays emitted by the sun from reaching the earth surface. Ozone layer in the stratosphere region of the atmosphere prevents UV rays from reaching the earth and thus protecting life forms from various diseases.
• The Atmosphere also protects us from asteroids and meteor as they brun out due to friction when they enter the atmosphere.

Unequal heating of landmass and water bodies by sun’s heat generate air movement and as a result wind is produced. When the air around landmass gets heated, it becomes lighter and rises up creating a region of low pressure. Air from high pressure region escapes to the low pressure region thus generating wind currents.

• When warm air rises, it expands and cools.
• Cool air can't hold as much water vapor as warm air, so some of the vapor condenses onto tiny pieces of dust that are floating in the air and forms a tiny droplet around each dust particle.
• When billions of these droplets cometogether they become a visible cloud.

Human activities that lead to air pollution are

•Use of automobiles as they use fuels like petrol which release toxic compounds when burned in the engine of the vehicle thus making the air polluted.

•Use of Chloroflourocarbons in refrigerators and air conditioners releases chlorine atoms in the atmosphere which deplete the ozone layer.

•Industries release a lot of harmful gases like sulphur dioxide, oxides of nitrogen, heavy metals which pollute the atmosphere.

Organisms need water for the following reasons-

•Reactions taking place inside the cells occur between substances that are dissolved in water.

•Water also helps in transporting substances in dissolved form in the body.

Hence, organisms need water because it plays a major role in transporting substances and is a vital component in carrying out life processes

Major source of freshwater in the city is underground water reservoirs and Rivers.

Industrial wastes, fertilizers and pesticides from farm runoff are polluting the underground water sources.

• Soil formation happens continuously but takes time.
• Soil is formed because of the gradual breakdown of rocks through the process of weathering.
• Weathering is of three types: physical, chemical and biological.
  
  Physical weathering—the breakdown of rocks from the result of mechanical action. Temperature changes, abrasion (when rocks collide with each other) or frost can cause rocks to break down.
  
  Chemical weathering—the breakdown of rocks through a change in their chemical makeup. This happens when the rock minerals react with water, air or other chemicals and breakdown.
  
  Biological weathering—the breakdown of rocks by living organisms. Burrowing animals help water, and the air gets into rock, and plant roots can grow into cracks in the rock, causing it to split.

Five main interacting factors affect the formation of soil:

• Parent material—what type of rock was the base material.
• Living organisms—iwhether burrowing animals or plant roots caused the weathering.
• Climate—affecting the rate of weathering and decomposition
• Topography—grade of slope affecting drainage, erosion and deposition
• Time—influencing soil properties.

Soil erosion is the wear of top fertile soil by wind or water is known as soil erosion.

Top soil is blown away by high speed wind. Deforestation also losens the soil as the roots that hold the soil together no longer exist. This loosened soil gets eroded away by wind and water easily.

Some methods to prevent soil erosion are-

• Soil should have some vegetations like grass growing in it so that it does not get carried away by rainwater.

•Afforestation or planting of trees, so that roots hold the soil prevent soil erosion.

There are these different states in which water is found during the water cycle.

•Solid state- as ice/snow.

•Liquid state- as water that falls as rain.

•Gaseous state- as water vapour in the atmosphere by evaporation due to sun’s heat. It also exists in clouds in gaseous state.

Deoxyribonucleic acid and ribonucleic acid are two biologically important compounds that contain both oxygen and nitrogen (in their chemical formula).

•Burning of fossil fuels like coal and petroleum releases carbon dioxide in the atmosphere.

•Deforestation also causes increase in carbon dioxide content as the plants that use carbon dioxide are cut down.

•Industries release various harmful gases into the atmosphere. Carbon dioxide is one such gas.

•Overpopulation will also lead to increase in carbon dioxide content as humans release carbon dioxide by respiration.

Greenhouse effect is a phenomenon that heats the earth’s surface. The greenhouse gases prevent infrared diations from escaping the earth which results in heating of the earth’s surface.

Two forms of oxygen found in the atmosphere are diatomic as Oxygen O₂ and triatomic as Ozone O₃.

• The atmosphere is essential for life because it maintains a suitable climate for sustaining life. It does so by:
  
  
• Maintaining proper temperatures throughout day and night. It keeps the average temperature of Earth constant during day and prevents the heat from escaping during the night.
  
  
• The atmosphere contains the gases that we need to stay alive (Eg, oxygen).
  
  
• It acts like a protective blanket. It does not allow harmful UV radiations from reaching us.
  
  
• Without the atmosphere the water cycle would not be possible.

Living organisms depend on soil for food indirectly. Plants need soil for support as well as getting nutrients to prepare their own food.

Herbivore obtains food from plant. Carnivore is directly dependent on the herbivore, the herbivore is directly dependent on the plant and the plant is directly dependent on the soil for the minerals, Thus making them indirectly depending on the soil.

Organisms living in water are not totally independent of soil as a resource. These organisms depend on aquatic plants for food. These aquatic plants, in turn, require nutrients from the soil which carried to the water body by the river or by the wind.

Thus, we get to the conclusion that living organisms are dependent on soil.

Water is essential for life because of the following reasons:

(i) Most biological reactions occur when substances are dissolved in water. Thus, all cellular processes need water as a medium to take place.

(ii) Transportation of biological substances needs water needs water as a medium.

(iii) Organisms need to maintain the level of water within their bodies in order to stay alive.

Weather is predicted by meterological department of the government. The characteristics of weather like temperature, rainfall, humidity are collected in the form of data by using various instruments. Temperature is measured by a thermometer. Rainfall is measured by an instrument known as rian gauge. Various instruments are used to measure humidity.

Yes, isolating these activities to specifid and limited areas would help in reducing pollution. Like if industries are set up in only isolated areas it will reduce the pollution by gas emissions and chemicals.

a) Air- Forest manages the content of CO₂ and O₂ in the atmosphere. Plants take up the CO2 to perform photosynthesis and release oxygen which is inhaled by humans and animals. Humans and animals exhale CO₂ tat is used by plants in photosynthesis.

b) Soil- Roots of plants bind the soil together and prevent the soil from being eroded away by wind or water.

c) Water- Forest means large number of plants. Forest transpire huge amount of water as water vapour which condenses around the dust particles to form clouds. When the clouds get saturated, rainfall occurs and the water flows into water bodies.