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MAN AND HIS ENVIORMENT
Major concepts:
Levels of Ecological Organization
Flow of Materials and Energy In Ecosystem
Interaction in Ecosystem
Ecosystem Balance and Human impact
Pollution; Consequence and Control
Conservation of Nature
Introduction:
Every organism has its specific surrounding or
environment with which it continuously
interacts and remains fully adapted
...
The study of
the interrelationship between organisms and
their environment is called ecology
...
An organism
may be unicellular or multicellular
...
All the
populations that live in a habitat and interact
in various ways with one another are
collectively called a Community
...

Living organisms cannot live isolated from the
non-living part of their environment
...
The self-sufficient unit of an
environment that is formed as a result of
interactions between its biotic community
and the abiotic components is known as an

ecosystem
...
Ecosystems
may also be artificial for example an
aquarium
...
it include all the ecosystems of the
planet earth
...

Biosphere ranges from the floor of oceans to
the tops of the highest mountains
...

|the biosphere makes a thin layer
surrounding the planet earth
...
|
Components of Ecosystem
We have studied in lower classes about the
basic components of an ecosystem
...
e
...

Components
...

The important non-living factors are light air,
water, soil and the basic elements and
compounds
...

Biotic components are further classified as
producer’s consumers and decomposers
...
Producers include plants, algae
and photosynthesis bacteria
...
Producers from the basis of any
ecosystem
...
In aquatic
ecosystems, the main producers are the
floating photosynthetic organisms (mainly
algae) called phytoplankton and shallow
water rooted plants
...
They
cannot synthesize their food and so depend
upon producers for food
...
The animals are the major
consumers of ecosystems
...

Herbivores e
...
cattle, deer, rabbit,
grasshopper etc
...
They are the
primary consumers
...
Carnivores feed
on other animals
...
Secondary
carnivores (tertiary consumers) feed on
primary carnivore’s wolf and owl etc
...
Tertiary carnivores e
...

lion, tiger etc
...

|Recalling:

Omnivores are the consumers that eat animal
flesh as well as plants and plants products
...
|
|tertiary carnivores are not eaten by any
other animals
...
|
Decomposers or reducers break down the
complex organic compounds of dead matter
(of plants and animals) into simple
compounds
...
After
digestion decomposers absorb the products
for their own use
...
Many types of
bacteria and fungi are the principal
decomposers of biosphere
...
The first trophic
level is made of producers; the second of
primary consumers and so on
...

The sun is the primary source of energy for all
ecosystems
...
They store this
energy in their tissues and also transform it
into mechanical and heat energy during their
metabolic activities
...

Herbivores transform it into mechanical and
heat energy during their metabolic activities

and store the rest in their tissues
...
They also use it
for their body activities and store the rest in
their tissues
...

The storage and expenditure of energy in an
ecosystem is in accordance with the basic law
of thermodynamics i
...
energy can neither be
created nor destroyed but can be
transformed from one from into another, in
an ecosystem there is
...

A significant decrease in useful energy during
transfer of energy at each trophic level
...
A food chain is a series of organisms

within ecosystems, in which each organism
feeds on the one before it and is fed by one
after it
...

Grass→ Grasshopper → Sparrow → Hawk
The base of food chain is always formed by a
plant (producer)
...
The secondary
consumer may be eaten by a tertiary
consumer
...
Usually there are 4 or 5 Trophic
levels
...

In nature, food chains are very complex, as
one organism may be the food source of

many other organisms
...
Such interconnected food chains
collectively make ‘food web’ cab be defined
as “a network of food chains which are
interconnected at various trophic levels
...
He noted that the animals present
ate the beginning of food chain are abundant
in number while the animals present at end of
food chain are fewer in number
...
Ecological pyramids

are of three types
...

Pyramids of numbers
It is the graphic representation of the number
of individuals per unit area at various trophic
levels
...
So the producers are of smallest size
but maximum in number, while the tertiary
consumers are large in size but lesser in
number
...
In a terrestrial ecosystem, the
maximum biomass occurs in producers and
there is progressive decrease in biomass from
lower to higher trophic levels
...
|
Biogeochemical Cycles
We know that environment is the source of
materials for all living organisms
...

The materials are continuously recycled
between organisms and environment
...

|since such movement of elements and
inorganic compounds is essential for
maintenance of life they are also called
nutrient cycle
...
Carbon is found
as graphite and diamond in nature
...

|Carbon cycle is a perfect cycle in the sense
that carbon is returned to atmosphere as
soon as it is removed|
...
Fossil fuels like peat, coil, natural gas
and petroleum also contain carbon
...

The major process that brings carbon from
atmosphere or water into living world as
photosynthesis
...
In this way carbon
becomes a part of the body of producers
...


|the balance of carbon cycle has been upset
by human activities such as deforestation and
excessive burning of fossil fuels
...

Carbon dioxide is released back to
environment be respiration of producers and
consumers
...
Burning of wood and
fossil fuels also adds large amount of carbon
dioxide into atmosphere
...
Atmosphere is the reservoir
of free gaseous nitrogen
...
It has to be converted into nitrates

to be utilized by plants
...
Nitrogen Fixation
Conversion of nitrogen gas into nitrates is
called nitrogen fixation
...

Thunderstorm and lightening convert
atmosphere gaseous nitrogen to oxides of
nitrogen
...
The acids in
turn combine with other salts to produce
‘nitrates’
...

Some bacteria also have the ability to
transform gaseous nitrogen into nitrates
...
Some of
these fixation bacteria live as symbionts and
many are free living
...
In
industrial nitrogen fixation, hydrogen is
combined with atmosphere nitrogen under
high pressure and temperature
...

ii
...
) to ammonia
...
After the
formation of ammonia it is converted into
nitrites and nitrates
...
First,
ammonia is converted into nitrates by
bacteria (e
...
Nitrosamines)
...
g
...

b
...
Animals take
nitrogenous compounds from plants
...

C
...
By this process nitrogen
is returned to atmosphere
...
|

INTERACTIONS IN ECOSYSTEMS

In all ecosystems there are many kinds of
interactions among living organisms
...
Some important
interactions among living organism in
ecosystem are given below
...
g
...
are usually in short
supply
...
The competition may be
intraspecific or interspecific
...


Competition helps in maintaining a balance
between the available resources and the
number of individuals of a species
...

Predation
It is an interaction between two animals of
different species or between a plant and an
animal
...
Some examples of
predation are given below
...
There are some example
where a predator is preyed upon by a second
predator and then the second one is preyed
upon by a third predator
...

Certain plants (pitcher plant, sundew Venus
fly trap etc
...
They
feed on insects to fulfill their nitrogen
requirements
...
For example they secrete
sweet nectar that attracts the insects
searching for food
...

Predation keeps the prey population under
check, so as to maintain an ecological
balance
...

In order to control pests in an area, their
predators are released there
...

Symbiosis is of three types
...

|Host can survive without parasite but
parasite cannot survive without host|
...
Only a part of its life cycle is
spent as a parasite
...
In
permanent parasitism, the parasites spend
their whole life cycle as parasites
...

Parasites may also classify as Eco-parasites
and endo-parasites
...
e
...
Mosquito’s leeches’ lice etc
...

Endo-parasites live inside the body of host
and get food and shelter
...
are the examples of endo-parasites
...
g
...

b
...
For example Termites eat
wood but are not able to digest it
...
It secrets
‘cellulose’ enzyme to digest the cellulose of
wood
...

The nitrogen fixer bacteria Rhizobium live in
the root nodules of leguminous plants like
pea, gram etc
...

C
...

Epiphytes are small plants found growing on
other larger plants for space only
...
The larger plants
are neither benefited nor harmed in any way
...
In this way the shark provides
easy transport to the sucker fish to new
feeding grounds
...
It flies around
looking for honeycombs, but it is not strong
enough to open the comb
...
When a
honeyguide bird goes to find honeycomb, it
calls the badger, sometimes the bird has to
stop and wait for the slow-moving badger
...
Traditionally humans have also used
these birds to find honeybee colonies
...

Biogeochemical cycles also maintain the
balance in ecosystems by recycling natural
resources, so that they do not deplete
...
g
...
This has
upset the delicate balance in ecosystems and
nature as well
...

Global Warming
The addition of greenhouse gases (e
...
carbon
dioxide, methane, ozone) in atmosphere
increases the temperature of the earth
...
As a result heat
remains within the Earth’s atmosphere and
increases its temperature
...

Due to Global warming polar ice-caps and
glacier are melting faster than the time taken
for new ice layers to form
...

|in 1990 the United Nations established
intergovernmental panel on climate change
(IPCC)
...
Earth’s surface
temperature has increased = 0
...
These chemicals interact with water
vapors in the presence of sunlight to from
sulphuric acid and nitric acid
...

As temperature falls the acid begin to
condense into liquid form and mix with rain or
snow, on the way down to the earth
...

Some of the significant ill effects of acid are
...
it
also lowers the pH of water
...

Acid rain washes nutrients out of soil
damages the bark and leaves of trees and
harms root hairs
...

Metallic surface exposed to acid rain are
easily corroded
...

Building materials such as limestone
...
Thus, acid rain is dangerous for
historical monuments
...

Deforestation:
Deforestation means clearing of forests by
natural causes or humans
...

Humans cut trees for getting wood (lumber)
which is then used for making structures and
for heat production
...
In this way insect pests
destroy forests by eating the shoots and
spreading diseases
...

Overpopulation
When the industrial revolution started some
250 year ago, the world population was at
600 million- that seems like a lot of people
but knows the world population us almost ten
times at 6 billion and will grow to 8 billion by
2025
...

Urbanization
Urbanization means growing of cities people
move from rural areas to cities in search of
better job, education opportunities and
higher standards of living
...
most of the migrants in cities do not find

good jobs and become the part of urban poor
...
the slum areas increase in number and
people living there are at greater risk of
diseases
...

The current level of urbanization in Pakistan is
about 32% which is not high by global
standards
...
The cities should have thick green
belts in their surroundings to control
pollution
...
the
urban spread-out should also be controlled
utilization of public transport instead of
individual transports also proves effective
way to manage urbanization
...
Technology and industry are
making life easier and convenient for humans
but are also contributing towards the
pollution of environment
...

|the substances that actually cause pollution
are called the pollutants
...
pollutants are of two types i
...

biodegradable and non-biodegradable|
...
It is defined as
the change of composition of air by the
addition of harmful substances (e
...
industrial

and automobile gases and particulate
matter)
...
Burning of coil
produces a lot of smoke and dust whereas
burning of petroleum produces Sulphur
dioxides, hydrocarbons particulate matter
and traces of metals
...

Fertilizer industries release oxides of Sulphur
and nitrogen
...
Thermal industries are
coal based and their pollutants are fly ash,
soot and Sulphur dioxide
...
Steel industries
release carbon mono oxide carbon dioxide
Sulphur dioxide phenol fluorine cyanide
particulate matter etc
...
Noise is also considered
as a form of pollution
...

Effects Of Air Pollution
We have studied that global warming is one
of the consequences of air pollution
...

|according to estimates at the current rate of
increase the average global temperature will
go up by 3 Celsius to 8 Celsius in the next 100
years
...
This is a mixture of
gases
...
It also causes many respiratory

disorders and allergies as it contains polluting
gases
...

Ozone depletion
The upper layer (stratosphere) of the
atmosphere has ozone which absorbs
ultraviolet (UV) rays present in the sun’s
radiation
...

Ozone holes are created with permit UV rays
to reach the Earth’s surface
...

|the harmful effects of the UV rays are visible
in the countries such as Australia and New

Zealand where the rate of skin cancer is
higher than the other regions of the world
...
Air pollution can
be controlled by the following ways:
Afforestation
It means the establishment of new forests by
planting on non-forest areas
...

Modification of industrial effluents
The air pollutants coming from industries
should be passed through filters and other
devices, so that the particulate matter is
removed before the wastes gases are

released out
...
Industries should also
invest for solar cookers or for producing bio
gas
...
Similarly Sulphur-free fuel
should be used in coal-based industry to
reduce pollution by Sulphur dioxide
...
Water
pollution severely affects the health of
people
...
It contains organic matter and the
excreta of human and other animals
...
The wastes
of industries (acids alkalis dyes and other
chemicals) are disposed in nearby water
bodies
...
Certain industries release a lot of
hot water from their cooling plants
...
Fertilizers and pesticides enter into water
bodies with the rain water flow and the
ground water by seepage
...
They cause a number of diseases
in animals
...
Oil floats on the water surface and
prevents atmospheric oxygen from mixing in
water
...


Some heavy metals e
...
lead, mercury, arsenic
and cadmium also make the water polluted
...
If
water with such heavy metals is given to
plants, the metals enter the vegetables that
grow on these plants
...

Heavy metals reduce growth and
development and cause cancer and nervous
system damage
...

Effects of water Pollution
The following are major effects of water
pollution
...
The sewage and fertilizers
contain large amount of inorganic materials
(nutrients)
...

There rich algal growth leads to increase in
the number of the decomposers
...
Algal
bloom also reduces the light reaching the
lower layers in water
...
From water, they
enter into small organisms which are fed
upon by fish
...


Epidemics
Organic pollutants in water facilitate the growth
of germs
...


Control of water Pollution
Public should be made aware of the dangers
of water pollution
...

Industrial wastes should also be treated
before they are released into water bodies
...
In the
recent times, soil has been subjected to
pollution
...
The

acid rains change the pH of soil making it
unsuitable for cultivation
...

Materials like polythene block the passage of
water into soil and so decrease the water
holding capacity of soil
...

Improper disposal of nuclear wastes also
causes radioactive substances to remain in
soil for a long time
...

Control Of Land Pollution
There should be suitable and safe disposal of
wastes including nuclear wastes
...
should be recovered and recycled
...

Conservation Of Nature
Conservation of nature means the
conservation of natural resources
...
g
...

is obtained from natural resources
...
g
...
g
...
We
have to conserve the non-renewable
resources because their reserves are limited,
and humans are heavily dependent on them
for daily needs
...
To ensure
sustainable use of resources in our
environment, we should act upon the
principle of the ‘The 3R’ i
...
Reduce, Reuse
and recycle
...
We should use this
principle at different places, in our daily lives
...
we should turn off the tap when not in
use
...
The lights and fans should be off,
when we are not in room
...
We
should not wastes food and should give
unused food to poor people

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