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1. CHAPTER - 14
NATURAL RESOURCES
CLASS :- IX
MADE BY :- ANIKET BISWAS
SCHOOL :- K.V. BARRACKPORE {A.F.S}

2. 1) Resources on the earth :-
The natural resources of the earth are air, water, soil,
minerals and living organisms.
The outer crust of the earth is the lithosphere. The water
on the earth is the hydrosphere. The layer of the air around
the earth is the atmosphere. Living organisms are found
where the atmosphere, hydrosphere and lithosphere interact
and is the biosphere.

3. 2a) Air (Atmosphere) :-
Air is a mixture of gases like nitrogen, oxygen, carbon dioxide, water
vapour and other gases.
During respiration living organisms use oxygen to break down glucose
and get energy for their activities. This results in the release of carbon
dioxide. Burning of fuels also use oxygen and release carbon dioxide.
During photosynthesis green plants convert carbon dioxide into glucose
in the presence of sunlight. This results in the release of oxygen.
These processes help to maintain the oxygen – carbon dioxide balance
in nature.

4. b) The role of atmosphere in climate control :-
The atmosphere covers the earth like a blanket. Air is a bad conductor
of heat. It prevents sudden increase in temperature during the day and
also slows down the escape of heat during the night. So the atmosphere
keeps the average temperature of the earth fairly steady during the day
and throughout the year.
c) The movement of air (Winds) :-
When air gets heated, it rises up and produces low pressure and cool
air moves in to take its place. The movement of air causes winds.
During the day the land gets heated faster than the sea. So the hot air
above the land rises up and cool air from the sea moves towards the land.
During the night sea cools down slowly than the land. So the hot air
above the sea rises up and cool air from the land moves towards the sea.

5. d) Rain :-
When water bodies are heated during the day, a large
amount of water evaporates and rises up. Some water vapour
also get into the atmosphere due to biological activities like
transpiration. As the water vapour rises, it cools and
condenses to form tiny droplets of water. This appears as
clouds. When the tiny droplets of water join together to form
bigger drops of water, they fall down as rain, snow or hail.

6. e) Air pollution :-
The increase in the content of harmful substances in the air is called air
pollution.
Fossil fuels like coal and petroleum contain small amounts of nitrogen
and sulphur. When these fuels are burnt, it release oxides of sulphur and
nitrogen. These oxides dissolve in rain and causes acid rain.
Burning of fossil fuels also release unburnt carbon particles which
reduces visibility. During cold weather along with condensed water it
forms smog.
Regular breathing air containing these harmful substances causes
allergies, cancer, heart diseases etc.

7. 3a) Water : A wonder liquid :-
A very large area of the earth’s surface is covered with water. Water is
also found inside the earth, in the atmosphere as water vapour. The water
in seas and oceans is saline. Fresh water is found in rivers, lakes, ponds
and as ice and snow at the poles and mountains in cold regions.
Water is needed by living organisms because all life processes and
cellular activities need water. So all organisms need water to survive.
The amount of water and other factors like temperature and nature of
soil decides the diversity of species and the number of individuals of
each species in an area.
b) Water pollution :-
The increase in the content of harmful substances in water is called
water pollution.
Water pollution is caused by addition of harmful substances like
fertilisers and pesticides from farms, sewage from towns, cities and
factories, harmful chemicals from factories, disease causing
microorganisms, changes in the amount of oxygen dissolved in water or
changes in the temperature of water.

8. 4 Soil :-
a) Formation of soil :-
Soil is formed by the breaking down of rocks on the surface of the earth
by physical, chemical and biological processess.
- The sun heats the rocks during the day and the rocks expand and at
night the rocks cool and contracts. This causes the rocks to crack and
break into smaller pieces.
- Water enters the cracks in the rocks and when water freezes, it expands
and causes the cracks in the rocks to widen and break into smaller
pieces. The flowing water carries the rock pieces. These pieces rub
against each other and become smaller and smaller particles.
- Strong winds also breaks rocks into smaller particles and carries it from
one place to the other.
- The roots of large trees grow into the cracks in rocks and breaks it into
smaller pieces. Lichens which grow on rocks produce some substance
which cause the rock surface to powder and become soil.

9. b) Composition of soil :-
Soil is a mixture of rock particles, decayed organisms
called humus, living organisms, minerals, air and water. The
amount of minerals, humus, air and water are the factors
which decides the biodiversity in that area.
c) Soil pollution :-
The addition of harmful substances which affects the
fertility of the soil and kills the diversity of organisms living
in it is called soil pollution.
Soil pollution is caused by the excessive use of fertilisers
and pesticides. It kills the organisms like earthworms and
bacteria which makes the soil rich in humus. The removal of
useful components and addition of other harmful substances
reduces the fertility of soil and causes soil pollution.

10. d) Soil erosion :-
The carrying away of soil from one place to the other by flowing water
and wind is called soil pollution. Large scale deforestation also causes
soil erosion.
Soil erosion can reduced or prevented by vegetative cover on the
ground, afforestation, construction of bunds, terraces, dams etc.
Activity :- Effect of flowing water on top soil.
Take two trays of the same size and fill them with soil. Plant mustard or
green gram in one of the trays. Water both the trays for a few days till the
first tray is covered by plant growth. The tilt both the trays at the sane
angle. Pour equal amount of water gently on both the trays. More soil is
carried out of the tray which did not have plant growth. This shows that
vegetative cover reduces soil erosion.

11. 5) Biogeochemical cycles :-
Biogeochemical cycles are the transfer of matter and energy between
the biotic and abiotic components of the biosphere.
The common biogeochemical cycles are :-
i) Water cycle,
ii) Nitrogen cycle,
iii) Carbon cycle
iv) Oxygen cycle.
a) Water cycle :-
When water bodies are heated during the day, a large amount of water
evaporates and rises up. Some water vapour also get into the atmosphere
due to biological activities like transpiration and respiration. As the water
vapour rises, it cools and condenses to form tiny droplets of water. This
appears as clouds. When the tiny droplets of water join together to form
bigger drops of water, they fall down as rain, snow or hail. Some of this
water enters the ground and forms ground water. When water flows from
the land to the seas it carries many nutrients and minerals which are used
by marine organisms.

12. b) Nitrogen cycle :-
The nitrogen in the atmosphere is fixed into nitrogen compounds in the
soil by nitrogen fixing bacteria in the root nodules of leguminous plants
and also during lightning. These nitrogen compounds are taken by plants
and used to make proteins. When animals eat plants they also get
proteins. When plants and animals die, bacteria convert the proteins into
nitrogen compounds like nitrites and nitrates. Other bacteria convert
these nitrogen compounds back into nitrogen in the atmosphere.
Nitrogen is an essential component of biological molecules like
proteins, nucleic acids and some vitamins.
WATER CYCLE

13. NITROGEN CYCLE
Nitrogen in
atmosphere
Nitrogen
fixation
Protoplasm
In plants
Protoplasm
in animals
Ammonia
Nitrification
Ammonification
Atmospheric fixation
Nitrification
Nitrates
Nitrites
Dentrification

14. c) Carbon cycle :-
Carbon in the form of carbon dioxide is used by plants to
prepare glucose by the process of photosynthesis. The
glucose is used to provide energy and to convert into other
organic compounds When animals eat plants it enters the
body of animals. During respiration energy and carbon
dioxide are produced. The carbon dioxide goes back into the
atmosphere. Another process which adds carbon dioxide
back into the atmosphere is the combustion of fuels like coal
and petroleum. The organic compound in plants and animals
are also converted into carbonates, limestone, coal,
petroleum, exoskeletons (shells) of some animals.
Carbon is an essential component of biological molecules
like carbohydrates, fats, proteins, vitamins, nucleic acids etc.

15. CARBON CYCLE
0011
Organic compounds
In animals
CoalPetroleum
Carbonates
in water
Limestone
Inorganic carbonates
shells
CO2 in atmosphere
Organic compounds
In plants
Respiration and
decomposition
Combustion

16. d) Oxygen cycle :-
Oxygen in the atmosphere is used for respiration,
combustion and formation of oxide of elements. Oxygen is
sent back into the atmosphere during photosynthesis.
Oxygen is an essential component of biological molecules
like carbohydrates, fats, and proteins.
Atmospheric oxygen
O2
Organic molecules
Glucose C6H1206
Photosynthesis Respiration
Carbon dioxide
CO2
Water
H2O

17. 6) The greenhouse effect :-
Gases like carbon dioxide, methane, chlorofluro carbon(CFCs) traps
the heat radiated by the earth and prevents the escape of heat from the
earth. The increase in the presence of these gases in the atmosphere
causes increase in the temperature of the atmosphere. This is called the
greenhouse effect.
Greenhouse effect can cause melting of polar ice, increase in sea
levels, flooding of coastal areas and submerging of islands.
7) Ozone layer :-
Ozone molecule contains three atoms of oxygen (O3). It is present in
the upper layers of the atmosphere. It is poisonous gas. It protects the
earth from the harmful ultra-violet radiations from the sun which is
harmful for living organisms.
The ozone layer is being damaged by carbon compounds like chloro
fluoro carbons (CFSs). To prevent the damage to the ozone layer, the use
of (CFSs) is being reduced.

19. NATURAL RESOURCES:
VITAL AND INVALUABLE

20. FOREST
A forest is any area withA forest is any area with
a lot of trees. There area lot of trees. There are
forests all over theforests all over the
world. The type of forestworld. The type of forest
varies depending on thevaries depending on the
location of the forest:location of the forest:
for example, there arefor example, there are
tropical rain forests,tropical rain forests,
coniferous forests, andconiferous forests, and
deciduous forests.deciduous forests.

21. Forests occur naturally, but they can be affected positivelyForests occur naturally, but they can be affected positively
and negatively by human behavior. If a forest is carefullyand negatively by human behavior. If a forest is carefully
replanted and allowed to grow, it can exist in balance. If thereplanted and allowed to grow, it can exist in balance. If the
forest is cut down faster than it can grow back, then it willforest is cut down faster than it can grow back, then it will
be used up quickly.be used up quickly.

22. Forests serve as home toForests serve as home to
many of the organisms thatmany of the organisms that
live on the land. Forests arelive on the land. Forests are
also very importantalso very important
because they are majorbecause they are major
contributors to recyclingcontributors to recycling
and cleaning the worldand cleaning the world
supply of oxygen. Forestssupply of oxygen. Forests
also provide wood, whichalso provide wood, which
is useful both as ais useful both as a
construction material andconstruction material and
as a fuel source.as a fuel source.

23. FOSSIL FUELS
Fossil fuels take millions ofFossil fuels take millions of
years to form. They are theyears to form. They are the
product of the fossilizedproduct of the fossilized
remains of dead plantsremains of dead plants
and animals that haveand animals that have
been exposed to the heatbeen exposed to the heat
and pressure deep withinand pressure deep within
the earth’s crust. There arethe earth’s crust. There are
many types of fossil fuels,many types of fossil fuels,
such as petroleumsuch as petroleum
(gasoline), natural gas, and(gasoline), natural gas, and
coalcoal..

24. Fossil fuels are arguably one ofFossil fuels are arguably one of
the most valuable naturalthe most valuable natural
resources in modern times. It isresources in modern times. It is
estimated that 86 percent of theestimated that 86 percent of the
world’s energy comes directlyworld’s energy comes directly
from burning fossil fuels. Fossilfrom burning fossil fuels. Fossil
fuels are the source of energyfuels are the source of energy
for almost every machine,for almost every machine,
including the generators thatincluding the generators that
produce electric energy.produce electric energy.

25. Because fossil fuels take soBecause fossil fuels take so
long to form, they are beinglong to form, they are being
consumed faster than theyconsumed faster than they
can be produced. Fossil fuelscan be produced. Fossil fuels
are a major contributor to airare a major contributor to air
pollution because when theypollution because when they
are burned they release manyare burned they release many
dangerous gases such asdangerous gases such as
nitrogen dioxide, methane,nitrogen dioxide, methane,
and carbon dioxide.and carbon dioxide.

26. SOLAR ENERGY
The sun is the closestThe sun is the closest
star to Earth. Itstar to Earth. It
brings heat and lightbrings heat and light
to the world. Someto the world. Some
areas of the world,areas of the world,
such as those closestsuch as those closest
to the equator, haveto the equator, have
more sun thanmore sun than
others.others.

27. The sun shines naturallyThe sun shines naturally
but it is not affected bybut it is not affected by
human activity. Ithuman activity. It
cannot be used up.cannot be used up.
However, its intensityHowever, its intensity
varies with the seasons,varies with the seasons,
and it is not available atand it is not available at
night.night.

28. The sun’s rays are usedThe sun’s rays are used
for energy by organismsfor energy by organisms
that undergothat undergo
photosynthesis. Nearlyphotosynthesis. Nearly
every organism on theevery organism on the
planet gets energyplanet gets energy
through photosynthesis,through photosynthesis,
directly or indirectly.directly or indirectly.
There are also ways thatThere are also ways that
people can utilize thepeople can utilize the
energy that the sunenergy that the sun
provides.provides.

29. We can use solarWe can use solar
power in simplepower in simple
(facing the sun to(facing the sun to
get warm, usingget warm, using
greenhouses togreenhouses to
grow food, etc.) andgrow food, etc.) and
more complex (solarmore complex (solar
panels for heating)panels for heating)
ways.ways.

30. WIND
Wind is caused by the uneven heating of theWind is caused by the uneven heating of the
atmosphere. Some areas of the world, such as costalatmosphere. Some areas of the world, such as costal
regions, have more wind than others because theregions, have more wind than others because the
terrain of the area is relatively flat and has fewterrain of the area is relatively flat and has few
obstacles to block the wind from blowing.obstacles to block the wind from blowing.

31. The wind blowsThe wind blows
naturally – it is notnaturally – it is not
caused by humancaused by human
activity, and it cannotactivity, and it cannot
be used up.be used up. The power of the wind drivesThe power of the wind drives
sailboats. It has been used tosailboats. It has been used to
power windmills that grindpower windmills that grind
grain. Windmills can also usegrain. Windmills can also use
the circular movement of thethe circular movement of the
blades to turn a turbine. This isblades to turn a turbine. This is
increasingly used as a means ofincreasingly used as a means of
generating electricity.generating electricity.

32. Wind power does notWind power does not
make greenhouse gasmake greenhouse gas
emissions. It does notemissions. It does not
directly cause pollution.directly cause pollution.
However, critics of windHowever, critics of wind
power say a large numberpower say a large number
of windmills could causeof windmills could cause
problems for animals,problems for animals,
especially migratory birds.especially migratory birds.
Some people think theSome people think the
windmills arewindmills are
unattractive.unattractive.

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