Science Do as directed; [1 M ]

1. Ozone layer is present in Stratosphere of the atmosphere. It protects earth from harmful Ultraviolet radiations coming from the sun.
2. Troposphere has most of the atmospheric gases. All the weather phenomenons take place in this region of atmosphere.

Detritivores are animals that feed on dead organic material like plant detritus. Earthworms, fungus are detritivore that feed on dead and decomposing organic matter.

All the living organisms along with their surroundings constitute biosphere. The physical division of biosphere is abiotic factors like water, air, soil, heat and light energy from sun.

The amount of rainfall that earth receives determines the density and richness of biota because plants need water to grow; it is one of major requirements of biota.

Alternative sources of energy used can be:

1. Solar energy.
2. Wind energy harnessed by windmills.
3. Geothermal or tidal energy which uses the waves of water.

Mars, venus and Pluto are planets that have atmosphere. They are gas giants.

Rhizobia are soil bacteria that fix themselves in root nodules of legumes and then carry out nitrogen fixation.

The resources available on earth like air, water, food, shelter and energy from sun are major basic requirements to sustain life on earth.

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Cholera, typhoid and diarrhea are diseases caused by drinking water polluted with infectious agents like bacteria, viruses and protozoans.

Ozone depleting substances are responsible for ozonedepletion. Chlorofluorocarbons are such air pollutants that have chlorine atoms. 1 chlorine atom.

Environment is defined as surroundings where animals, plants and human beings function.

All the living organisms on the planet constitute the biosphere. The physical division of biosphere are the abiotic factors like air, soil, water, heat and light energy from the sun.

Arid areas like Rajasthan and part of Jaisalmer, Thar dessert are areas with very poor vegetation.

Ozone layer blocks Ultraviolet radiations coming from sun to reach earth’s surface and thus protects us from various diseases like cataract etc.

In coastal areas, sea breeze blows during daytime. The sea breeze has ideal speed for kite flying. Hence, people love to fly kites near the seashore.

The process by which bacteria convert organic nitrogen to ammonia is known as ammonification. After ammonification has occurred, ammonium is converted into nitrite and nitrate. Ammonification is also known as mineralization.

Water is called the universal solvent because it can dissolve most substances in loarge amounts. Because of this, water is rarely found in its pure form. (Precipitation absorbs carbon dioxide and other gases, as well as traces of organic and inorganic material from the atmosphere. Because water reacts with minerals in the soil and rocks, surface and groundwater may contain many different dissolved substances. Surface waters may also contain domestic sewage and industrial wastes. Groundwater from shallow wells may contain nitrogen compounds and chlorides, but water from deep wells generally contains only dissolved minerals. Seawater contains many soluble compounds in addition to salt).

Carbon dioxide concentration in atmosphere is rising primarily because of two reasons:

• Deforestation.
• Increased combustion of fossil fuels.

As trees take in carbon dioxide from air and release oxygen back into the air, it helps in maintaining the desired levels of oxygen and carbon dioxide in the atmosphere. But due to deforestation, trees are being cut down and this is leading to the increase in carbon dioxide levels. The increased combustion of fossil fuels also leads to the release of enormous amounts of carbon dioxide in the atmosphere.

Energy from sun, air are examples of inexhaustible natural resources. They will not ever get exhausted.

Bacteria like Bacillus, Clostridium and Streptomyces acause ammonification. Bacillus ramosus is one such ammonifying bacteria.

When water laden air cools down it causes water to return back to its liquid state and fall on earth in the form of rainfall. So, the chief source of precipitation is water laden air.

Nucleic acids and proteins are two biologically important compounds that contain both oxygen & nitrogen.