Reasons for falling IiL

       

   The significance of ‘Health’

We have heard the

word ‘health’ being used

quite frequently. We use it

ourselves as well as for

people around us when we

say things like ‘my grandmother’s health

is not good’. Our teachers use it when they

scold us saying ‘this is not a healthy

attitude’. Now, the question what exactly

does the word ‘health’ mean? If we think

about it, we realise that it always implies

the idea of ‘being well’. We can think of

this well-being as ability for effective

functioning. Incase of our grandmothers,

their being able to go out to the market or

to visit neighbours is ‘being well’, and not

being able to do such things is ‘poor health’.

Being interested in following the

teaching in the classroom so that we can

understand the world would be called a

‘healthy attitude’; while not being interested

would be called the opposite.

 ‘Health’ is therefore a state of being

well enough to function physically,

mentally and socially with optimum

efficiency.

Personal and community issues,

both matter for health:

If health means a state of physical,

mental and social well-being, it cannot be

something that each one of us can achieve

entirely on our own. The health of all

organisms will depend on their

surroundings or environment. The

environment includes the physical

environment. For example every one’s

health is at risk in a cyclone. But even more

importantly, human beings live in societies.

Our social environment, therefore, is an

important factor in our individual health.

We live in villages, towns or cities. In such

places, even our physical environment is

decided by our social environment.

Consider what would happen if no agency

is ensuring that garbage is collected and

disposed. What would happen if no one

takes responsibility for clearing the drains

and ensuring that water does not collect in

the streets or open spaces? So, if there is a

great deal of garbage thrown in our streets,

or if there is open drain water lying stagnant

around where we live, the possibility of ill

health. Therefore, cleanliness of

surroundings is very important for

individual health.

Distinctions between ‘Healthy’

and ‘Disease free’

If this is what we mean by ‘health’,

what do we mean by ‘disease’? The word is

actually self-explanatory – we can think of

it as disturbed ease. Disease, in other

words, literally means being

uncomfortable. However, the word is used

in a more limited meaning. We talk of

disease when we can find a specific and

particular cause for discomfort. This does

not mean that we have to know the absolute

final cause; we can say that someone is

suffering from diarrhoea without knowing

exactly what has caused the loose motions.

We can now easily see that it is possible to

be in poor health without actually suffering from a particular disease. Simply not

being diseased is not the same as being

healthy. ‘Good health’ for a dancer may

mean being able to stretch his/her body into

difficult but graceful positions. On the

other hand, good health for a musician may

mean having enough breathing capacity in

his/her lungs to control the notes from his/

her flute. To have the opportunity to realise

the unique potential in all of us is also necessary for good health. So, we can be in

poor health without there being a simple

cause in the form of an identifiable disease.

This is the reason why, when we think about

health, we think about societies and communities. On the other hand, when we think

about disease, we think about individual

sufferers.

z State any two conditions essential

for good health.

z State any two conditions essential

for being free of disease.

Disease and its causes:

What does disease look like ?

Activity:

Form a group with five students. List

out some diseases and their symptoms. Let

us now think a little more about diseases.

In the first place, how do we know that there

is a disease? In other words, how do we

know that there is something wrong with

the body? There are many tissues in the

body. These tissues make up physiological

systems or organ systems that carry out

body functions. Each of the organ systems

has specific organs as its parts, and it has

particular functions. So, the digestive

system has the stomach and intestines, and

it helps to digest food taken in from outside

the body. The musculoskeletal system,

which is made up of bones and muscles,

holds the body parts together and helps the

body move.

When there is a disease, either the

functioning or the appearance of one or

more systems of the body will change for

the worse.

These changes give rise to symptoms

and signs of disease. Symptoms of disease

are the things we feel as being ‘wrong’. So,

we have headache, cough, loose motions

and wound with pus; these are all symptoms.

These indicate that there may be a

disease, but they do not indicate what the

disease is. For example, a headache may

mean just examination stress or, very

rarely, it may mean meningitis, or any one

of a dozen different diseases.

Signs of disease are what physicians

will look for on the basis of the symptoms.

Signs will give a little more definite

indication of the presence of a particular

disease. Physicians will also get laboratory

tests done to pinpoint the disease further.

Acute and chronic diseases:

The manifestations of disease will be

different depending on a number of factors.

One of the most obvious factors that

determine how we perceive the disease is

its duration. Some diseases last for only

very short periods of time, and these are

called acute diseases. We all know from

experience that the common cold lasts only

a few days. Other ailments can last for a

long time, even as much as a lifetime, and

are called chronic diseases. An example is

the infection causing elephantiasis, which

is very common in some parts of India.

Acute Chronic diseases and poor

health:

As we can imagine, acute and chronic

diseases have different effects on our

health. Any disease that causes poor

functioning of some part of the body will

affect our general health as well. This is

because all functions of the body are

necessary for general health. But an acute

disease, which is terminated very soon, will

not have time to cause major effects on

general health, while a chronic disease will

do so.

As an example, think about a cough

and cold, which all of us have from time to

time. Most of us get better and become well

within a week or so. And there are no bad

effects on our health. We do not lose

weight, we do not become short of breath,

we do not feel tired all the time because of

a few days of cough and cold. But if we get

infected with a chronic disease such as

tuberculosis of the lungs, then being ill

over the years does make us lose weight

and feel tired all the time. We may not go

to school for a few days if we have an acute

disease. But a chronic disease will make it

difficult for us to follow what is being

taught in school and reduce our ability to

learn. In other words, we are likely to have

prolonged ill health if we have a chronic

disease. Chronic diseases therefore, have

very drastic, long-term effects on people’s

health as compared to acute diseases.

Causes of diseases:

What are the causes for diarrhoea,

T.B.? How do they spread? When we think

about causes of diseases, we must

remember that there are many levels of

such causes. Let us look at an example. If

there is a baby suffering from loose

motions, we can say that the cause of the

loose motions is an infection with a virus.

So the immediate cause of the disease is a

virus.

But the next question is – where did

the virus come from? Suppose we find that

the virus came through unclean drinking

water. But many babies must have had this

unclean drinking water. So, why is it that

one baby developed loose motions when

the other babies did not?

One reason might be that this baby is

not healthy. As a result, it might be more

likely to have disease when exposed to such

risk, whereas healthier babies would not.

Why is the baby not healthy? Perhaps

because it is not well nourished and does

not get enough food. So, lack of good

nourishment becomes a second level cause

of the disease the baby is suffering from.

Further, why is the baby not well nourished?

Perhaps because it is from a household

which is poor.

It is also possible that the baby has

some genetic difference that makes it more

likely to suffer from loose motions when

exposed to such a virus. Without the virus,

the genetic difference or the poor

nourishment alone would not lead to loose

motions. But they do become contributory

causes of the disease.

Infectious and non-infectious

causes:

As we have seen, it is important to

keep public health and community health

factors in mind when we think about causes

of diseases. We can take that approach a

little further. It is useful to think of the

immediate causes of disease as belonging

to two distinct types. One group of causes

is the infectious agents, mostly microbes

or micro-organisms.

Diseases where microbes are the

immediate causes are called infectious

diseases. This is because the microbes can

spread in the community, and the diseases

they cause will spread with them.

z Do all diseases spread to people

coming in contact with a sick person?

z What are the diseases that are not

spreading?

z How would a person develop those

diseases that do not spread by contact

with a sick person?

On the other hand, there are also

diseases that are not caused by infectious

agents. Their causes vary, but they are not

external causes like microbes that can

spread in the community. Instead, these are

mostly internal, non-infectious causes.

Infectious Diseases

Infectious agents:

We have seen that the entire diversity seen in the living world can be classified into a

few groups. This classification is based on common characteristics between different

organisms. Organisms that can cause disease are found in a wide range of such categories

of classification. Some of them are viruses, some are bacteria, some are fungi, some are

single-celled animals or protozoans. Some diseases are also caused by multicellular

organisms, such as worms and insects of different kinds.

            Earthworms

                   Bugs

Common examples of diseases

caused by viruses are the common cold,

influenza, dengue fever and AIDS. Diseases

like typhoid fever, cholera, tuberculosis and

anthrax are caused by bacteria. Many

common skin infections are caused by

different kinds of fungi. Microorganisms

like protozoan cause diseases like Malaria

(Plasmodium) and Kala-Azar (Leishmania). 

All of us have also come across

intestinal worm infections, as well as

diseases like elephantiasis caused by

different species of worms.

Why is it important that we think of

these categories of infectious agents? The

answer is that these categories are

important factors in deciding what kind of

treatment to use. Members of each one of

these groups – viruses, bacteria, and so on

– have many biological characteristics in

common.

                Bacteria

Organ-specific and Tissue specific manifestations:

The disease-causing microbes enter

the body through these different means.

Where do they go then? The body is very

large when compared to the microbes. So

there are many possible places, organs or

tissues, where they could go. Do all

microbes go to the same tissue or organ,

or do they go to different ones?

Different species of microbes seem

to have evolved to home in on different

parts of the body. In part, this selection is

connected to their point of entry. If they

enter from the air via the nose, they are

likely to go to the lungs. This is seen in the

bacteria causing tuberculosis. If they enter

through the mouth, they can stay in the gut

lining like typhoid causing bacteria. Or they

can go to the liver, like the viruses that

cause jaundice.

The signs and symptoms of a disease

will thus depend on the tissue or organ

which the microbe targets. If the lungs are

the targets, then symptoms will be cough

and breathlessness. If the liver is targeted,

there will be jaundice. If the brain is the

target, we will observe headaches,

vomiting, fits or unconsciousness. We can

imagine what the symptoms and signs of

an infection will be if we know what the

target tissue or organ is, and the functions

that are carried out by this tissue or organ.

It is also important to remember that

the severity of disease manifestations

depend on the number of microbes in the

body. If the number of microbes is very

small, the disease manifestations may be

minor or unnoticed. But if the number of

the same microbe is large, the disease can

be severe enough to be life-threatening.

The immune system is a major factor that

determines the number of microbes

surviving in the body.

Principles of treatment:

What are the steps taken by your

family when you fall sick? Have you ever

thought why you sometimes feel better if

you sleep for some time? When does the

treatment involve medicines?

Based on what we have learnt so far,

it would appear that there are two ways to

treat an infectious disease. One would be

to reduce the effects of (or control) the

disease and the other to kill the cause of

the disease. For the first, we can provide

treatment that will reduce the symptoms.

The symptoms are usually because of

inflammation. For example, we can take

medicines that bring down fever, reduce

pain or loose motions. We can take bed rest

so that we can conserve our energy. which

may be directed to healing.

But this kind of symptom-directed

treatment by itself may not kill the

infecting microbe go away and the disease

may not be cured. For that, we need to kill

the disease causing microbes.

How do we kill microbes? One way

is to use medicines that kill microbes. We

have seen earlier that microbes can be

classified into different categories. They

are viruses, bacteria, fungi and protozoa.

Each of these groups of organisms will have

some essential biochemical life process

which is peculiar to that group and not

shared with the other groups. These

processes may be pathways for the

synthesis of new substances or medication.

These pathways will not be used by

us either. For example, our cells may make

new substances by a mechanism different

from that used by bacteria. We have to find

a drug that blocks the bacterial synthesis

of pathway without affecting our own. This

is what is achieved by the antibiotics that

we are all familiar with. Similarly, there are

drugs that kill protozoa such as the malarial

parasite.

Principles of prevention:

All of what we have talked about so

far deals with how to get rid of an infection

in someone who has the disease. But there

are three limitations of this approach to

dealing with infectious disease. The first

is that once someone has a disease, their

body functions are damaged and may never

recover completely. The second is that

treatment will take time, which means that

someone suffering from a disease is likely

to be bedridden for some time even if we

can give proper treatment. Over a period

of time the third is that the person suffering

from an infectious disease can serve as the

source from where the infection may

spread to other people. This leads to the

multiplication of the above difficulties. It

is because of such reasons that prevention

of diseases is better than their cure.

How can we prevent diseases? There

are two ways, one general and one specific

to each disease. The general ways of

preventing infections mostly relate to

preventing exposure. How can we prevent

exposure to infectious microbes?

If we look at the means of their

spreading, we can get some easy answers.

For airborne microbes, we can prevent

exposure by providing living conditions that

are not overcrowded. For water-borne

microbes, we can prevent exposure by

providing safe drinking water. This can be

done by treating the water to kill any

microbial contamination. For vector-borne

infections, we can provide clean

environments for example, free of breeding

ground of infectious disease causing

organisms and their vectors. In other words,

public hygiene is one basic key to the

prevention of infectious diseases.

BIO(Production of Food from Animals)

 

            Production of Food from Animals

                    Animal Husbandry:

                

             Farmers adopt different methods of management for getting better yields in agriculture. In the same way, care is also required in the management of rearing animals. Providing food, shelter, protection

and breeding of animals is called ‘Animal husbandry.

Since long time, we have been using animals not only for obtaining food but also for agriculture, transportation etc. We realized their importance and domesticated them.

Cattle Rearing:

People living in rural areas used to

domesticate animals like cows, buffaloes,

bullocks, goats, sheeps, pigs, hens, etc.

Supplying of nutritious food,

accommodating clear and hygienic shelters

for animals are very important issue in

animal husbandry. Generally villagers send

their animal to graze at the places where

grass is easily available.

• Where do people rear their animal in

your village?

           Cattle House

Have a talk with them and collect

information about cattle rearing. For this

you need a questionnaire. Following

questions may be helpful to you. You can

add some more questions as you wish

• What are the cattle here?

• At what places fodder is available?

• What are the places where water is

available?

• What are the necessities of rearing of

cows, buffaloes, goats and sheep?

• What are the major problems that

animal rearers generally face?

Earlier, villagers used to appoint a

person for cattle rearing and was paid by

them. This kind of practice is gradually

disappearing from our villages. Some of

the farmers keep their cattle in the sheds.

They do not take their cattle to the fields.

They supply fodder in those sheds. Rearing

cattle like bulls, cows and buffaloes in large

scale is also the same in sheds. Generally

the farmers in our country are cultivating

the land area of less than one hectare. Even

though mechanization is increasing in

agriculture, farmers use bullocks for

ploughing and other agricultural practices.

• Make a list of agricultural practices by

using bullocks and the buffaloes.

Rearing of goats and sheep is also

related to agriculture. Besides agriculture,

cattle rearing and sheep rearing are

beneficial to farmers. During off season for

cropping cattle rearers make fences in the

fields at off crop seasons. They keep their

sheeps and goats in the fenced enclosures

• Think in which way this practice is

helpful to the farmer as well as field

crops.

Taking care of animal health is equally

important task in animal husbandry. Most

of the times cattle sheds become unclean

because of the remains of fodder, dung and

urine. Dump these wastes away from the

shed. Care should be taken to prevent the

growth of lice and mytes on cattle’s body.

Foot and mouth disease is a common 

and dangerous disease partially in

cows and buffaloes. Sheep and goats suffer

from worm infections.

Milk Production:

Our government treats producing milk

as an industry. We get milk from cattle.

Among cows, traditional species give

2 – 5 liters of milk per day. Murra, species

are reared in most of the districts in our

state. They give up to 8 liters of milk per

day. Haryana, Jaferabad, Nagapuri are the

traditional varieties of cows in our country

which give good quantity of milk. Jersy

(England) and Holstein (Denmark) are the

Foreign varieties. They give 25 liters of

milk per day. These foreign varieties are

cross bred with our native or local varieties.

They give 8 to 20 liters milk per day. Cows

play vital role in total milk production of

our country.

    Holstein Cattle

Out of milk produced in our country

60% is used to prepare cheese, khova, ghee,

curd, milk powder and other milk products.

There are number of dairy farms in our

state. The milk in dairy farm is collected

from households and pasteurized. Milk is

preserved in packets and transported.

     

          Milk collection

   Is there a milk collecting centre in your

village?

• How do they collect milk and export?

• Do you know how they decide cost of

milk?

• Where is milk chilling center located

in your area? (For this you need to 

observe milk packets which are

available in the market)

There are private and government milk

collecting and chilling centers in our state.

Practices in livestock keeping:

Being high milk yielding varieties, livestock (The animals that are used for milk and agriculture are called livestock) rearing is very important. Traditional livestock are becoming depleted because

of hybrid varieties. Let us read the following case study to know how local breeders conserve their livestock.

Poultry:

Production and rearing of hens on a large scale is generally

called poultry. Billions of hens are reared worldwide

for eggs and chicken. We know that farmers rear

cocks and hens in villages. Most of these are local varieties

We get around 74% chicken and 64% of eggs only 

from poultry farms. Poultry has emerged as one 

of the major industries in last two decades. India

achieved 3rd position in the world by producing 

90 million eggs per annum. And also placed in 

7th position in the production.

• Are the hens reared in the poultry is same as our

 traditional varieties reared by farmers in the villages?

Generally poultry farms are of two types. 

One is for production of eggs and other for meat. 

Broilers are commonly used variety in poultry. 

They are reared for meat. Layer are reared

for the production of eggs.

            Local Varieties   

Natural, wild varieties grow fully in

5 to 6 months. But broilers grow fully in

just 6 to 8 weeks. This happens due to

genetic modification in the hens.

New Hampshire, white Plymouth,

Rhode Island Red, white leg horn, Anoka

are the foreign varieties of meat giving

species.

         Broiler chicken

Some hens reared only for production

of eggs. Some hens are able to lay 300 to

350 eggs in their life span. But, one has to

follow proper management techniques up

to 21 to 72 weeks for getting eggs.

During January to April, egg prices are

high. Do you know what is the reason? This

is because of most of the eggs are used for

hatching. In this period, rate of hatching is

more. Hatchability of eggs is generally

influenced by 37 to 38°C temperature. In

poultry industry hen wastes (litter) is used

as nutritional manure in agriculture.

Egg is a nutritious food. 

Sources of nectar:

Plants which contain nectar and pollen

liked by bees are called bee flora.

The following are some of the more

important plants either wild or cultivated.

Fruit trees like citrus, apple, guava,

tamarind; Cultivated field crops like

mustard, gingelly, wheat, cotton, sunflower;

Vegetable plants like beans, lady's finger,

brinjal; Timber yielding trees like acacia,

neem, sal and bushes, shrubs and natural and

ornamental flower plants are all the sources

of nectar. The bees of a colony sometimes

rob another colony especially during

drought period.

              Bee Hive

Production of honey in large scale is

by providing artificial bee hives. The hive

consists of floor board, brood chamber,

super chamber, top cover, inner cover,

frames and entrance rod. These parts can

easily be separated.

          Artificial bee hive

The hive may be double walled or single

walled. These artificial hives are not similar

to natural hives. Try to find out the

differences between these two hives. To get

more yielding of honey from the colonies

a bee keeper has to follow some

management techniques. Various pests and

predators attack the honey bee colonies.

Wax moths, wasps, robber flies, dragon

flies attack honey bee colonies. King crow,

Bee eater are more harmful during swamp

period. Bee keepers should protect bee

hives from the pests and predators.

Fisheries:

Fish constitute an important and rich sources 

of high quality animal protein. India has a coast

line of about 7500km and the total available area for

fishing both inshore and offshore is nearly

0.48 million square meter. In addition there

are extensive inland water areas comprising

of numerous rivers, fresh water and brackish 

water lakes, reservoirs, tanks, ponds, swamps, etc.

                   Prawns

                    Fish  

                   Crabs

Marine Fisheries:

Marine fish are caught using many kinds of 

fishing nets through fishing boats. With the 

introduction of synthetic fiber nets, there has 

been revolution in fishing gear material. 

Fishermen catch fish by using machines is 

called mechanized fishing. 

They catch tons of fish everyday.

          Mechanized fishing

Inland fisheries:

Fresh water resources include canals,

ponds, reservoirs and rivers. Brackish water

resources, where seawater and fresh water

mix together, such as estuaries and lagoons

are also important fish reservoirs. Fishing

is also done in such inland water bodies,

but the yield is not high.

               Fish pond

Generally farmers rear only one type of fishes or Prawns. 

More intensive fish farming can be done in composite fish 

culture systems. Both local and imported fish species are 

used in such systems. In such a system, a combination of

five or six fish species are used in a single fishpond. 

These species are selected so that they do not compete 

for food among them and have different types of food habits.

As a result, the food available in all the parts of the pond 

is used. As Catlas are surface feeders. Rohus feed in the

middle zone of the pond, Mrigals and common carps are

bottom feeders, and Grass Carps feed on the weeds. 

This species can use all the food in the pond without 

competing with each other. This increases the fish yield 

from the  pond. Even if one species of fishes are

infected with disease it is not spread to others.

One problem with such composite fish culture is that many of these fishes breed only during monsoon. Even if fish seed is

collected from the wild, it can be mixed with that of other species as well. So, a major problem in fish farming is the lack

of availability of good quality seed. To overcome this problem, we have now been worked out to breed these fish in ponds using hormonal stimulation. This has ensured the supply of pure fish seed in desired quantities.

BIO(Difficult to Breathing and Drinking)

           Not for Breathing Not for Drinking

        

             What is Environmental Pollution ?

The environment is made up of living

and non-living components which are inter

dependent. When everything is working the

way it should be, all the components of the

environment will be functional, healthy and

balanced in the nature.

• What will happen if harmful organisms

or substances enter your body? How

do you feel?

In the same way if something harmful

is introduced into the environment and it

gets disrupted it can cause a chain of

problems affecting all the resources, plant

and animals life. These changes really hurt

the health and well being of living

organisms. Pollution therefore can be

described as the disturbance of

environmental balance caused by human

activities. It can also be caused by chemical

substances, biological species or by

dangerous radiations including sound and

heat.

Pollution is the addition to the

environment (air, water, land) of harmful

substances or energy in quantities that are

harmful to life.

What is Air pollution?

The composition of air in the

atmosphere comprises four major gases

namely nitrogen, oxygen, argon and carbon

dioxide. Other substances are present in a

very little amount and hence, they are

collectively known as trace components.

Air Pollutants:

As we discussed above, air pollutants

arise from both man made and natural

processes. These pollutants are of two

types : Primary and Secondary pollutants.

Pollutants are also defined as primary

pollutants resulting from combustion of

fuels and industrial operations and

secondary pollutants, those which are

produced due to reaction of primary

pollutants in the atmosphere.

 Natural Activities:

• Forest fires release carbon particles

(ash) into the air and pollute the air.

• Volcanic eruption releases various

gases and ash into the atmosphere.

• Decay of organic matter releases

Ammonia gas into the air.

• Decay of organic matter lying under

water releases Methane gas.

• The pollen grains released by plants

remain suspended in the air and pollute

it.

Human activities

 Burning fuels

Burning fuels pollute the air producing

pollutants like carbon monoxide, sulphur

dioxide, smoke, soot and ash.

• Name the fuels burnt in day to day

activities in both rural and urban areas.

Vehicles: Exhaust gases emitted by

motor vehicles pollute air by producing the

harmful pollutants like sulphur dioxide,

nitrogen dioxide, carbon monoxide,

unburnt hydrocarbons, lead compounds and

soot.

Industries: Various industries like

granite, lime, cement etc., pollute air by

releasing pollutants such as sulphur

dioxide, nitrous oxide, chlorine, fly ash ,

dust, asbestos dust etc.

• Name the factories located nearby. How

do they affect the air and water there?

Nuclear power plants: The two

problems of nuclear power are radioactive

waste and the possibility of disasters like

Chernobyl. Nuclear waste is dangerous

because it can cause cancer and other

health problems. The radioactive wastes

possess radio activity for at least one

million years. The other problems are melt

downs. Melt downs are provoked by too

much heat in the power plant. During a melt

down the power plant makes more

Radioactive pollution.

Chernobyl Disaster

The biggest meltdown of Nuclear

power reactor in the world was in

Chernobyl, Soviet Union in 1986. After the

melt down of chernobyl, there was an

explosion and formation of radioactive

cloud. The radiation released during this

disaster directly killed hundreds of people

and affected around 5 million more. About

125,000km2

 of fields were unusable

because of the radioactive clouds. The

forest area was damaged by the radioactive

clouds.

Granite industries are in the most

polluted areas because granite powder,

cement dust, limestone dust is released

into the air causing pollution

are releasing the pollutants like

fly ash, Sulphur dioxide, and radioactive

substances causing the air, water and land

pollution. People are suffering from lung

cancer and skin allergies due to the

pollutionThe people living near the

granite factory have faced several health

problems like respiratory bronchitis and

asthma. Thermal power plants pollute air

by emitting sulphur dioxide, radio-active

substances and fly ash.

Power Generation Plants

There are a number of power generation 

plants in our country. Some produce power

by using water (Hydroelectric power plants),

by using coal and gas (Thermal power plants), 

by using Radioactive elements like Uranium

(Nuclear power plants). Electricity is also

produced from the air and tides of the

oceans. Ash dust and SO2 from the thermal

power plants are polluting the environment.

Deforestation: It is the destruction

of forests and woods. It has resulted in the

reduction of indigenous forests. Forests

now cover only 19% of the earth’s land

surface. Plants use carbon dioxide for the

process of photosynthesis. Due to lack of

forests the consentration of carbon dioxide

is increasing day by day resulting in global

warming. Discuss about the adverse effects

of Global warming?

Fertilizers and Pesticides: Use of

fertilizers and pesticides in agriculture

pollute not only air but also land and water.

You already learnt these issues in the

chapter ‘Production of food from plants’.

Chloro Flouro Carbons (CFC):

CFCs are used in refrigerators, Air

conditioners and aerosol sprays. Use of

CFCs pollutes air by depleting the ozone

layer as a result of which, harmful

ultraviolet rays reach the earth. What ill

effects do we suffer from exposure to UV

rays?

 Mining: Mining of coal and stone

releases coal dust and stone dust that cause

air pollution.

What are the effects of air

pollution?

Air pollution continues to evoke a great

deal of interest worldwide due to its

negative impacts on human health and

welfare. It causes certain diseases including

shortness of breath, sore throat, chest pain,

nausea, asthma, bronchitis and lung cancer.

Extreme effects of air pollution include

high blood pressure and cardiovascular

problems.

The World Health Organization states

that 2.4 million people die each year from

causes directly attributable to air pollution

(WHO, 2007).

In addition to its negative health

impacts, air pollution is known to cause

injuries to animals, forests and vegetation,

and aquatic ecosystems.

Various harmful effects of

pollutants

Particulate Matter: Dust and smoke

spoil our cloths, reduce visibility and

affect the buildings; dust and smoke

get deposited on the leaves of the

plants. Thus affects the rate of

photosynthesis and transpiration. They

also cause Bronchitis, Asthma in

human beings. Particles of lead oxide

present in automobile exhaust can

cause Anaemia, Brain damage and even

death. Particles of mercury cause

Minimata disease which affect the

nervous system and can cause death.

Hydrogen Sulphide: Tarnishes silver

objects and blackens lead paints and

painting. It has a smell like Rotten

Eggs. It causes head ache in humans

when inhaled in a large quantity.

Carbon monoxide: It is a poisonous

gas. If it combines with haemoglobin

in our blood, it forms a stable

compound called carboxy

haemoglobin. Due to the formation of

this compound haemoglobin is unable

to carry oxygen to various parts of our

body. This leads to respiratory

problems. It causes suffocation and

may cause even death.

What can we do to reduce air

pollution?

Air pollution cannot be totally

eliminated, it can however be controlled.

Some of the methods for controlling air

pollutions are:

• Tall chimneys should be installed in 

all factories to reduce air pollution

at the ground level.

• The 'Fuel burning equipment' which

burns the fuel completely should be

used in homes and industries.

• Install electrostatic precipitators in

the chimneys of industries.

• Reduce vehicular emissions by using

non polluting fuels like CNG.

• Use LPG for domestic use.

• Improve the quality of fuel in

automobiles and use catalytic

converters in them.

• Make use of Renewable alternative

source of energy like Solar Energy,

Wind Energy and Hydro Energy.

 All motor vehicles should be

maintained properly so that they

comply with pollution norms.

Use unleaded petrol

Plant and grow more and more trees in

your surroundings.

Where is all of this pollution

coming from?

There are two main sources of water

pollution; definite and non-definite

sources.

Definite source pollution is due to

discharges from a single source, such as

an industrial site. It includes factories,

wastewater treatment facilities, septic

systems, and other sources that are clearly

discharging pollutants into water sources.

Non definite-source pollution involves

many small sources that combine to cause

significant pollution. For instance, the

movement of rain or irrigation water over

land picks up pollutants such as fertilizers,

herbicides and insecticides carries them

into rivers, lakes, reservoirs, coastal

waters, or groundwater. Non-definite

sources are more difficult to identify, as

they cannot be traced back to a particular

location. Landfills can also be a nondefinite source of pollution, if substances

leach from the landfill into water supplies.

Biodegradable waste: This consists

mainly of human and animal waste. The

biodegradable waste enters the water supply

and thus pollute the water. The waste

provides an energy source (organic carbon)

for bacteria. Organic carbon is converted

to carbon dioxide and water, which can

cause atmospheric pollution and acid rain;

this form of pollution is far more

widespread and problematic than other

forms of pollutants as a large supply of

organic matter in the water provides an

opportunity for oxygen-consuming

(aerobic) bacteria to multiply quickly,

consume all available oxygen, and kill all

aquatic life.

Sediment: It is one of the most

common sources of water pollution.

Sediment consists of mineral or organic

solid matter that is washed from land into

water sources. Sediment pollution is

difficult to identify, because it comes from

non-definite sources such as

constructional, agricultural, logging,

flooding, and city runoff. Sediment can

cause large problems, as it can clog

municipal water systems, smoother aquatic

life, and cause water to become

increasingly turbid. Turbid water can cause

thermal pollution, because it absorbs more

solar radiation.

Prevention And Controlling of

Water Pollution

Water pollution can be prevented or

minimized by adopting following

measures.

• Toxic industrial wastes should be treated

chemically to neutralize the harmful

substances present in it before

discharging into rivers and lakes.

• The sewage should not be dumped in to

the rivers directly. It should first be

treated at the sewage treatment plant to

remove the organic matter from it in the

form of manure.

• The use of excessive fertilizers and

pesticides should be avoided.

• The use of synthetic detergent should be

minimized or biodegradable detergents

should be used.

• Dead bodies of human beings and

animals should not be thrown in to rivers.

• The excreta and other garbage should be

treated in a biogas plant to get fuel as

well as manure.

• The water of rivers, streams, ponds and

lakes should be purified or cleaned. This

can be done both by the industries and

the govt. For example Ganga action plan

launched by the Indian Government.

• Trees and shrubs should be planted along

the banks of the rivers.

• There should be general awareness

among the masses regarding the harmful

effects of water pollution and the ways

of prevention. Waste paper, plastics,

waste food materials and rotten food and

vegetables should not be thrown in to

open drains.

BIO(Bio-geo-chemical cycles)

                 Bio-geo-chemical cycles

            Bio-geo-chemical cycles

A constant interaction, between the

biotic and abiotic components of the

biosphere, makes it a dynamic, but stable

system. These interactions consist of

transfer of matter and energy between the

different components of the biosphere.

Bio-geo-chemical pathways determine the

path of transfer of matter on earth. Let us

look at some of the major biogeochemical

cycles.

Bio-geo-chemical cycles as we may

see from the name itself includes both

biological, geological and chemical or

physicochemical pathways. This means the

reservoir or pool of nutrients on earth may

contain some chemicals of biological

origin while others may be purely inorganic

in nature also may be geochemical

(obtained from rocks and soil) in origin.

Water though not considered as a biogeo-chemical cycle by most ecologists

actually is the precursor of the major

elements Hydrogen and Oxygen as some

living organisms use them for making the

basic food molecules for several

organisms in nature.

Water is also a universal solvent and

essential for various reactions to take place

within a living cell. Thus we shall also take

up water cycle briefly in this chapter.

Though the nutrient pool involves several

elements of nature but, we shall study just

the cycling of some major elements like

Oxygen, Nitrogen and Carbon.

The water cycle

All the water that is on the earth has

always been here? Earth never gets water

added to it nor does water disappear from

the earth. Water is constantly recycled in a

process known as the Hydrological or

Water cycle.

Fresh water is more scarce than you

might think.Nearly 97% of all the water on

the earth is in the oceans, and so only about

3% is fresh water. About 2% of this fresh

water is permanently frozen in Glaciers and

at the Polar Ice caps.

Thus only about 1% is available fresh

water. Again about 1/4 of this 1% is present

as groundwater. Only about 0.009% of

water on earth is in the rivers and lakes.

Rest is present in the bodies of living

organisms, as soil moisture, as humidity of

atmosphere etc. Water is the most essential,

abundant substance in living things.

The human body for example, is

composed of about 70% water (remember

all living organisms together constitute

only 0.005% of water on earth). Water

participates in many biochemical

mechanisms, including photosynthesis,

digestion and cellular respiration. It is also

the habitat for many species of plants,

animals and microorganisms, and it

participates in the cycling of the materials

used by living things. So, it is important

that we protect our water

resources.

The Nitrogen cycle

Nitrogen is both the most abundant

element in the atmosphere and, a building

block of proteins and nucleic acids. The

Nitrogen cycle is a complex

biogeochemical cycle in which Nitrogen

is converted from its inert atmospheric

molecular form (N2

) into a form that is

useful in biological processes.

The element Nitrogen is constantly

moving in a giant circle from the air,

through the soil, into the bodies of plants

and animals, and eventually back to the air

by the process of Nitrogen cycle. All living

things need nitrogen mainly for growth,

repair and development (Nitrogen being

essential for protein formation). Even

though the Earth’s atmosphere is made up

of 78% nitrogen, plants and animals cannot

use it in this form.

The atmospheric nitrogen is thus

converted into certain compounds which

plants may take up from the soil by some

biochemical process (caused by certain

bacteria like Rhizobium, Nitrosomonas etc)

and physicochemical processes (caused by

lightning). Animals get the required amount

of nitrogen from plants either directly

(herbivores) or indirectly (carnivores).

The nitrogen cycle contains several

stages:

1. Nitrogen fixation:

Atmospheric nitrogen occurs primarily

in inert form (N2) or non reactive form that

few organisms can use; therefore it must

be converted into a compound - or fixed -

 form in a process called nitrogen fixation.

Most atmospheric nitrogen is ‘fixed’

through biological processes. A number of

bacteria and blue green algae are known to

be able to fix atmospheric nitrogen into

compounds in their own body. These may

be symbiotic (Rhizobium) or freeliving

(Nitrosomonas) respectively. These

organisms convert atmospheric nitrogen

into the organic nitrogen for their own

cells. As they die rapidly( they grow rapidly

as well), this nitrogen, now present in the

soil as compounds become available to

plants. In leguminous plants like pea, beans

etc there is a symbiotic relationship of the

nitrogen fixing bacteria with the plant.

2. Nitrification:

Nitrates can also be converted to

Ammonia by the de Nitrifying Bacteria in

the soil (especially in waterlogged soils).

The nitrifying bacteria may then use this

ammonia to synthesize compounds for

their own cell and eventually convert to

Proteins, Nucleic acids, Nitrites and

Nitrates. Nitrites are produced mainly by

Nitrosomonas, while nitrates by

Nitrobacters that are also capable of

utilizing nitrites and converting them to

nitrates. Death of these microorganisms

add the nitrogenous compounds to the soil.

Plants take up nitrate as well as ammonium

ions from the soil to convert them to

proteins and nucleic acids.

3. Assimilation:

Nitrogen compounds mainly as nitrates

or ammonium ions(NH4+) are taken up

from soil by plants which are then used in

the formation of plant proteins and as

animals eat these plants, animal proteins

are synthesised.

4.Ammonification:

Production of Ammonia (NH3

) from

Nitrates and other Nitrogenous compounds

in called Ammonification.

Describe a path of ammonification

discussed in the above section.

Ammonification also occurs when

plants and animals die, or when animals

emit wastes, the nitrogen in the organic

matter reenters the soil and water

bodies where it is broken down by

other microorganisms, known as

decomposers. This decomposition

produces ammonia which is then

available for other biological

processes.

5.Denitrification:

Nitrogen makes its way back into

the atmosphere through a process

called denitrification, in which

solid nitrate (NO3) is converted back to

gaseous nitrogen (N2). Denitrification

occurs primarily in wet soils where water

makes it difficult for microorganisms to

get oxygen. Under these conditions, certain

organisms - known as denitrifiying bacteria

- will process nitrate to gain oxygen,

leaving free nitrogen gas as a byproduct.

Thus, the nitrogen content of the earth

and its atmosphere remains in a perfect

balance.

Human intervention and nitrogen

cycle

Unfortunately, humans are interfering

with the natural balance when they overuse

artificially produced nitrates as agricultural

fertilizers that are often washed into water

bodies by rain as well as by releasing

exponential amounts of untreated domestic

sewage into water bodies. Before these

nitrates can be converted into atmospheric

nitrogen, they are often carried off by rain

or irrigation to streams and rivers and even

seep down to groundwater.

In some parts of the world, water for

humans and animals contains such high

concentrations of nitrates that it is unsafe

for consumption. These excessive amount

of nitrates and other nitrogenous

compounds, when they reach rivers and

lakes, cause too much algal growth. This

over-abundance of algae uses up too much

of the oxygen in the water. When oxygen

level falls, other forms of life in the water

bodies die off.

The Carbon cycle

Carbon is found in various forms on the

Earth. It occurs in the elemental form as

say Soot, Diamond and Graphite. In the

combined state, it is found as gases, Carbon

dioxide and Carbon monoxide in the

atmosphere, as carbonate and hydrogen

carbonate salts in various minerals, while

all life-forms are composed of carbon

containing molecules like Proteins,

Carbohydrates, Fats, Nucleic acids and

Vitamins. The endoskeletons and

exoskeletons of various animals are also

formed from carbonate salts.

Carbon dioxide is also responsible for

maintaining the Earth as a Green house with

temperature conditions suitable for life.

Thus, Carbon exists in the biosphere as the

central element of life. Carbon Dioxide or

CO2

, now makes up about 0.04% by volume

of air.

Have you ever thought how this level

of Carbon is being maintained in the

nature?

Carbon is incorporated into life

through various processes. The main

reservoirs of carbon are sedimentary rocks,

fossilized organic carbon including the

fossil fuels, the oceans, and the biosphere.

Photosynthesis:

The first step in the biological

carbon cycle is the conversion of

inorganic atmospheric carbon into a

biological form. This ‘fixing’ of

carbon in biological form takes place

within plants and other organisms -

 known as producers - in a process

called photosynthesis, by which

energy from sunlight is converted into

chemical form.

In photosynthesis, light energy

helps to combine carbon dioxide and

water to create the simplest of sugars,

the carbohydrate molecules known as

Glucose (C6H12O6). In oceans,

photosynthesis is carried out by

microscopic aquatic plants called

phytoplankton. The carbohydrates

then become the source of chemical

energy to cells in all plants and

animals. In plants, some carbon

remains as simple glucose for short-term 

energy use, while some are converted

to large complex molecules such as starch

for long term energy storage.

The Green house effect:

A greenhouse is a small house made of

glass that is used to grow plants. It traps

the sun’s rays and keeps the heat from

escaping. It is warm inside. In the same way

that the glass traps heat in a greenhouse,

some gases present in the atmosphere such

as Carbon di Oxide, Carbon monoxide,

Methane and Water vapour trap heat from

radiating back to the space. The natural

greenhouse gases act like a big blanket

around the earth, keeping it warm and

making life possible without which

temperatures would have fallen to sub zero

values. This phenomenon of naturally

warming up is called ‘‘Greenhouse effect”.

But the extent of this natural warming

up process have been grossly affected now.

Due to various human activities like burning

of fossil fuels, deforestation and

industrialization, an excessive amount of

carbon dioxide and other green house gases

has been emitted to the environment. As a

result more heat gets trapped. This causes

the temperature of the earth to rise, which

results in Global Warming. 

Oxygen cycle:

Oxygen is an abundant element,

next to Nitrogen, on our Earth. It is

found in the elemental form in the

Atmosphere to the extent of nearly 21%.

It also occurs extensively in the combined

form in the Earth’s Crust as well as in the

air in the form of carbon dioxide. In the

crust, it is found as the oxides of most

metals. It is also present as carbonate,

sulphate, nitrate and other compounds. It

is also an essential component of most

biological molecules like carbohydrates,

proteins, nucleic acids and fats (or lipids).

The cycle and storage:

 Oxygen from the atmosphere is used

up mainly by the processes, combustion,

respiration and in the formation of oxides

of elements like Nitrogen, Iron etc. Oxygen

is returned to the atmosphere in only one

major process, that is, Photosynthesis.

Ozone layer:

The Earth’s atmosphere is divided into

several layers. The lowest region, the

Troposphere, extends from the Earth’s

surface up to about 10 kilometers (km) in

altitude. Virtually all human activities occur

in the Troposphere. Mount, Everest, the

tallest mountain on the planet, is only about

9 km high. The next layer, the Stratosphere,

continues from 10 km to about 50 km.

Most commercial airline traffic occurs in

the lower part of the Stratosphere. most

atmospheric ozone is concentrated in a

layer in the stratosphere, about 15-30

kilometers above the Earth’s surface.

Ozone is a molecule containing three

Oxygen atoms. It is blue in colour and has

a strong odour.

Normal oxygen, which we breathe, has

two oxygen atoms and is colourless and

odourless. Ozone is much less common

than normal oxygen. Out of each 10 million

air molecules, about 2 million are normal

Oxygen, but only 3 out of 10 millions are

Ozone.