NATURAL RESOURCES 9TH CBSE NOTES

Natural resources 9th cbse

Earth is the only planet life sustains

Because earth has some important resources

Like light ,air,water,land

All living organisms depends on air light ,water

Portion of land on earth is called lithosphere

Portion of earth where water is present is called hydrosphere

Blanket of air covering earth is called atmosphere

The 3 life sustaining zones lithosphere hydrosphere and atmosphere is called biosphere

Biosphere has so many ecosystems

Ecosystem is place where biotic and abiotic factors interact with each other

Biotic components are plants animals and microorganisms

Abiotic components are air water land light etc

AIR

Air is mixture of gases

Gases in air are major nitrogen78% then oxygen21%

Remaining all are less then 1 percent

Where as in Venus and Mars 95%co2 is present

On earth it is very less because of plants absorb co2 and prepare glucose

Even marine animals consume co2 and prepare their shells

Lofe forms have mkdifies percentages of games in air

Air is insulator

Means bad conductor of heat

So air acts as a blanket on earth and maintains earth temperature steadily

In winter we use blankets because blankets have tiny pores which trap air and acts as a insulator making us feel cozy

As outer air come come inside and inside can't go outside so heat is trapped inside blanket ans we feel warm and cozy in winter with blanket

ATMOSPHERE IN CLIMATE CONTROL

Atmosphere act as blanket and maintains globe temperature

As sun rays fall on earth most of them reflect back

Atmosphere allows some rays to go back and some do not

That is how our earth temperature is regulated

But if pollution increases. Somehow co2 level increase and may trap more heat resulting on global warming that we will study later

Best example of atmosphere controlling temperature is land and sea breeze

Sea breeze

Day time land will become hot

Hot air rises up

Air from sea moves to land

It is called sea breeze

Thats why it will be very sultry and more humidity in coastal areas

Full day they sweat

Land breeze

Water has GREATER HEATING CAPACITY

Means it takes long time for heating or cooling water

By evening wqter becomes hot

Now air on water rises up

Air from land moves towards sea

This is called land breeze

So water takes long time to heat up or become cold as it has greater heating capacity

14.1 activity
Heat sand and water keeping in sunlight and put thermometer
After one hour nite down there temperatures
It will show that sand is more hot then water
Showing that water takes long time to get heated up
Because it has greater heating capacity

14.3 activity
See any smoke or fire
You will see it always goes up
Its because hot air blows up
As on heating
Molecules go far
It becomes lighter
Hence moves up
By conventional current

Movement of air winds

Water vapor is formed due to heating of water bodies

And also due to activities of living organisms

Atmosphere also gets heated up due to radiation of reflected rays

After heating conevctionl air is set up in the air

Always hot air moves up we saw in q4.2 activity

Similarly hot air above land and air rrises up

But land gets heated up faster then wqter

So in coastal areas morning we will see sea breeze

At night we see land breeze

Movement of air is called wind

Movement of wind occurs due to difference in heating of land by sun.

Apart from difference in heating other factors also effect movement of winds

Like
Rotation of earth
Presence of mountains
Eg of Himalayas

RAIN
14.3 activity
When air with very high content of water vapor moves from high pressure reguon to low pressure region or vivmce versa

Water gets heated during day

Lot of water gets converted to water vapor

Water vapor goes into air

Some other vapor is collected due to activities of living organisms

This air also get heated up

Hot air rises up with water vapor

As air rises it expands and cool down

On cooling water vapor becomes into droplets

This water drop will surround some dust or some other particles

Which form as nucleus like dust

Once water droplets are formed

They keep growing by condensation

When they grow heavy and big

They fall down as rain

When the temperature of air is low enough
Precipitation or snow fall may also occur

Rainfall patterns are decided by prevailing wind patterns

In India we may get rains by south west or north east monsoons

We also heard that depression in bay if Bengal

AIR POLLUTION

Fossil fuels contain small amounts of nitrogen and sulphur in them

When they are burnt there oxides enter into atmospheres

And they amy also react with rain and fall on earth as acid rain

When we inhale them also they are dangerous

Fossil fuel burning not only liberates this nitrogen and oxygen they also liberate suspended particles in air

Like carbon unburnt particles ask is formed in air

High levels of there hydrocarbons in air is very dangerous

Visibility decreases and even in cold countries fog smog may form

Accidents may also occur

Regular breathing of this polluted air may increase allergies. Cancer and skin diseases

So
Increase in harmful content in the air is called as air pollution

Increase in air pollution. In atmosphere leads to acid rains and allergies

Even carbon monoxide is also dangerous

As it enter into brain reacting with haemoglobin

Water
Water is present 78 % on land underground also present ,glaciers and even in our bodies

Even some water is in the form of water vapor in the atmosphere

Even though 78 percent is there most of the water is in ocenas and seas which is saline marine and salt water

Fresh water is only present in glaciers,underground and in rivers,lakes and ponds

Availability of fresh wqter differes from place to place

In summers we face acute shortage of water

Especially in rural areas it is rampant

All reactions in all living organisms occur in water medium only

Even transportation and blood all are main composition is wter

So to stay alive water is very important

Terrestrial organisms need fresh water to survive

Because marine water has more salt which we cannot get rid of our body

More the availability of life form more will be the biodiversity in that area

Apart from water which decides life forem
Sunlight
Temeperature
Soil conditions
All decide life

Water pollution

All the pesticides and fertilizers mix with rain water and drain into nearby ponds and lakes

Even sewage is liberated into ponds and lakes

Industrial wastes are dumped and some industries also put how stuff into water to cool it

When water is released from dams cool water water from dams fall into river which is hot at surface

All this temperature fluctuations effect the marine and aquatic life

So this type of addition may effect some life forms and benefit other and thus balance between living forms will be lost

So the contributing factors for wqter pollution is

1.adding undesirable substance effect water
Like mercury enter from paper industries
Some bacteria many cause cholera

2.execsive growth of algae may deplete levels of oxygen causing biological oxygen demand

3.temeparture changes may effect karvas and eggs of organisms

Soil
Mineral riches in the soil

Soil decides the diversity if life in that area

Soil is a part of earths crust which also supplies variety of minerals to living things

From soil only we can take minerals not from rocks

How soil is formed
By weathering of rocks

Huge rocks break and make soil over a period of time

Breaking of rocks factors involved are
Sun
Water
Wind
Living organisms

Sun

Day time rocks expand due to heat
Nights they cool down due to cold
Due to continuation expansion and contraction
Uneven surface and uneven expansion and contraction
Results in cracks in huge rocks
Which eventually breaks up into smaller peices

Water
Wqter settles in between cracks
Freezes
On freezing all substance expand
So continuos contraction and expansion results in widening of cracks

Or

Water flowing causes abrasion
Some rocks break and flow with water
They in turn cause abrasion to another rocks
Which slowly helps in formation of soil

Wind
Wind also erodes rocks
Make them move
Cause abrasion
Resulting in further breaking
Even wind takes soil from from one place to other also like water

Living organisms
Living organisms also influence formation of soil
Lichens grow on rocks
Lichen is symbiotic association of algae and fungi
They release certain chemicals
Which make rocks to break
And form thin layer of soil
Now on small peices mosses will grow
Which breaks them further
Also some time roots of trees Penetrqte into rocks
And makes them to break

Compisition of soul

Soil consists of smaller peices of rock
Bits of decayed living organisms called humus
Microscopic life
Minerals

Type of soil is decided by size of soil particles
Quality if soil is decided by
amount of humus
And
Microscopic life

Humus is major factor in deciding
Soil structure
Because
It makes soil to become more porous
Allows water
Allows air to Pentwater deep

Factors on which plants depend

Minerals depend on rocks from which it is formed
Nutrient content of soil
Amount of humus
Depth of soil

Quality of top soil decides the biodiversity of that particular area

Modern farming techniques
Have resulted in
Excessive use of fertilizers
Pesticides
Insecticides
Which are destroying quality of soil
And killing microorganisms in soil

Microorganusms only recuse nutrients in soil
Earthworms also play major role

Soil pollution is caused
By death of microorganisms
Death of earth worms
Adding undesirable substances
Not following sustainable management
Depletion of desirable substances

Soil we are seeing today is created at some other place
Resulting in soil erosion
By flowing wqter
Overgrazong
Winds
Deforestation
Urbanization
Vegetative covering is important
In deciding soil erosion
Plants bind the soil

Water cycles

We learned earlier water evaporates

And then condenses to form rain

The whole process in which water evaporates
Form water vapor
Condenses to form rain
On the ground
Returning back
Is called as water cycle

We never see sea or ocean drying up

Its because of water cycle

Rain water won't return back so easily

Some of them percolate into ground

We may bring them up using tube well or bore

Other forms springs or glaciers

Some water is used by plants and animals

In different ways all the water again return back

Wtaer when returning brings so many minerals

Which will be used up eventually by marine organisms
Or enter into animals or humans when we drink

This is how complex is biogeochemical cycle water cycle is

Pls draw diagram given on text book
Always good diagram only shows
That u understood the subject

Nitrogen cycle

Nitorgen is present 78 %in atmosphere

Nitrogen also important constituent if many essential molecules like DNA rns vitamins mainly proteins
Alkaloid urea also

Nitrugen is very important but these organisms can't use them directly

Except few bacteria none of the organisms can use them directly

These bacteria are rhizobium bacteria which live in root nodules of legumes pulses plants

Other then this bacterial remaining all organisms get their nitrogen in different ways

During lightning and thunderstorms
Nitrogen in atmosphere reacts with oxygen and forms nitrogen dioxide

They react with water and fall on ground as acid rain
N2 + O2 gives N2O3 or N2O5
N2O3 or N2O5 with water forms HNO3 or HNO2
And fall on ground as acid rain

These rae then utilized by various life forms

Plants take nitrates or nitrites and convert them into amino acids

Amino acids form proteins

When animals eat these plants or animals which eat them
That amino acids enter into their bodies

Once this animal or plant dies the amino acids in them are converted back into nitrites or nitrates

Then different types of bacteria convert it back into elemental bacteria

Thus nitrogen enters back into atmosphere

So whole process can be easily studies as

Nitorgen fixation
Done by lighting and acid rain
Or symbiotic bacteria like
Rhizobium or azatobacter

Nitrification

Ammonia is coverted to nitrites or nitrates by nitrifying bacteria
Like
Nitrosomonas ,nitrococcus

Ammonifying bacteria

After plants and and animals die
Nitrites or nitrates are converted to ammonia by ammonifying bacteria
Eg.
Bacillus bacteria

Denitrification
Denitrifyring bacteria converts ammonia to nitrogen
Pseudomonas
Bacillus
And also some fungus also does this

Carbon cycle

Carbon is constituent of all organic matter on the earth

In diamonds graphite coal coke it is found in elemental form

In co2 co carbonates bicarbonate its in compound form

All life forms are based on proteins carbohydrates fats nucleic acids and vitamins

[ ] The endoskeletom and exoskeleton of many life forms also formed from caco3

Carbon is coming mainly from plants which are taking co2 in photosynthesis

Then co2 is concerted to carbohydrates

Then glucose is used for various other metabolic activities

Then glucose is used in respiration and in respiration oxygen is liberated into atmosphere

Then oxygen is used in respiration and co2 is liberated back into atmosphere

Co2 also comes from various methods like combustion.vehicles heating etc

Green house effect

Its same like heat is trapped in glass

Suppose u put ur car in hot sunny day .once you get into car it will be very hot.

Its because glass trap.

How it traps means
Light goes inside
Looses its velocity
Cannot come out
Trapped inside
So becomes hot

In the same way it co2 level in atmosphere increases it causes green house effect

Results in global warming

Some of the gree house gases are co2 and ch4 methane

Which if increases in atmosphere

Results in trapping of sunlight such effect is called green house effect

Oxygen cycle

After. Nitrogen

Oxygen is 21 % in atmosphere

In air oxygen is also int the form of co2 and on earth in various compounds its present

Elemental oxygen from atmosphere is taken in 3 cases
Combustion
Respiration
Nitrogen oxides formation

But oxygen returns only in the form of photosynthesis

Ozone layer

Oxugen is present as o2 in the atmosphere

Oxygen combines to form ozone during lighting and thunderstorms

Even though its poisonous gas

It prevents reaching of us rays to earth

But cfc chloro flouri carbon can deplete ozone layer

So avoiding using of cfcs are taken seriously

Because if ozone depletes it make up rays reach earth

Which is very dangerous

May cause skin cancer.crops cannot go and even dangerous for every life form

Cfcs are mainly released from aerosols.rocket fuels.sparays .perfumes.jet planes

All these usage are banned with declaration of UNEP in 1986

Which proposed immediate freezing of cfs all over the world

For the sake of mankind