Post on 03-Jun-2018
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Our Environment Introduction
Environment is defined as the surroundings in which the organism lives. The environment may be the physical
environment, the chemical environment or the biological environment. Thus, the environment has two components -
abiotic and biotic.
The abiotic environment includes the air (atmosphere), water (hydrosphere) and land (lithosphere). The biotic
environment includes the plants, animals and the microbes.
Organisms are dependent on the environment to fulfil their needs; man is also constantly interacting with the
environment in order to fulfil his needs. These needs include the basic needs of oxygen, food and shelter in addition
to the social needs like entertainment, medicines, etc. The things that man requires for his survival and comfort are
called the resources. The environment is a reservoir of resources. Maintaining the natural resources of the
environment and their careful use is called conservation. The conservation of environment involves the conservationof the natural resources.
A healthy environment is an absolute necessity for the well-being of all organisms, including man. All our needs, big
and small are being met by the environment. However, man having reached the pinnacle of evolution is trying to bring
about changes in the environment to suit his convenience. Unfortunately, this convenience is temporary. In the long
run, man is losing out on a healthy environment.
How Does Waste Affect the Environment?
Accumulation of wastes due to its improper disposal is a major problem in our country. Population in India has beengrowing at a rapid rate. With this increase, there has also been an increase in the amount of wastes being produced
especially in the cities. Every person, on an average generates about 400 to 500 grams of wastes per day. At this
rate, in a city of about 10 lakh people around 500 tonnes of wastes is being produced every day.
In the absence of proper waste management, this waste lies littered on our streets, road corners and improperly
disposed of in vacant land. All of these are serious health hazards apart from being eyesores. If they are not cleared
regularly at the earliest, they invite host of problems like increasing numbers of insect vectors like flies, mosquitoes,
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etc., scavengers such as stray dogs, pigs and rats which spread dangerous diseases. It also generates bad odour
and causes pollution.
Classification of Wastes
The wastes include kitchen waste, papers, construction materials, old tyres, medical wastes, etc. In order to
understand the severity of the problem and to work towards a solution, one must understand the types of wastes
being generated.
Wastes can be classified into:
Biodegradable Wastes - The biodegradable wastes are those that can be decomposed by the natural
processes and converted into the elemental form. For example, kitchen garbage, animal dung, etc.
Non-biodegradable Wastes - The non-biodegradable wastes are those that cannot be decomposed and
remain as such in the environment. They are persistent and can cause various problems. For example,
plastics, nuclear wastes, glass, etc.
Sources of Wastes- Some of the most common sources of wastes are as follows:
Domestic wastes
Commercial wastes
Ashes
Animal wastes
Biomedical wastes
Construction wastes
Industrial Solid Wastes
Sewer
Biodegradable wastes
Domestic Wastes
It includes the wastes generated in houses. It includes paper, plastic, glass, ceramics, polythene, textiles, vegetable
waste, etc.
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Commercial Wastes
It includes the waste generated in commercial establishments like shops, printers, offices, godowns, etc. It includes
packing materials, spoiled goods, vegetable and meat remnants, polythene, printer paper, etc.
Ashes
They come from the burning of solid fossil fuels like coal, wood and coke. Many houses and road side eateries still
use these fuels. Open burning of wastes also generates ashes.
Animal Wastes
It includes the dung of the animals that are left to find food for themselves on the streets Their reject feed also add to
the wastes.
Biomedical Wastes
These wastes are generated from the hospitals and include expired drugs, plastic syringes, surgical dressings, etc.
They can be very infectious.
Construction Wastes
With booming population, there is also booming construction activity going on in the urban areas. They also generate
garbage like metal rods, bricks, cement, concrete, roofing materials, etc. This type of wastes is also generated by the
digging activities of the various departments like the telephone, electricity, drainage, etc.
Industrial Solid Wastes
Small-scale industries generate some wastes. For example, garment factory would dump textiles of various kinds.
Sewer
The sewer removed from the sewerage during cleaning is often left on the roadside. This poses several health
hazards to the public.
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Hazardous Wastes
Hazardous wastes
Some of these wastes are also classified as hazardous wastes. are those that are potentially dangerous and can
cause diseases, fire, etc. The hazardous wastes include toxic wastes. Toxic wastes are those that are poisonous in
nature. Hazardous wastes are those that catch fire easily, react explosively with air or water, corrode other materials,
are toxic or radioactive. The radioactive wastes are particularly dangerous as they cause lasting damage such as
change in the genetic structure of individuals (mutation).
Did U Know?
Cassava, a tuber crop is used to make biodegradable plastics
Components of the Ecosystem
The environment in which the man and other organisms live is called the biosphere. The biosphere is made up of
different regions that have different types of flora (plants) and fauna (animals). The types of organisms in an area are
determined by various factors such as the climate, temperature, rainfall, etc.
An ecosystem is a complete community of living organisms and the non-living materials of their surroundings. Thus,
its components include plants, animals, and microorganisms; soil, rocks, and minerals; as well as surrounding water
sources and the local atmosphere. The size of ecosystems varies tremendously. An ecosystem could be an entire
rain forest, covering a geographical area larger than many nations, or it could be a puddle or a backyard garden.
Even the body of an animal could be considered an ecosystem, since it is home to numerous microorganisms.
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The organisms, in addition to being dependent on the environment for their needs, are also dependent on each other.
This dependency is especially for food. This results in the presence of food chains and food webs.
Food Chains
In an ecosystem, the producer consumer relationship represents the tropic structurewhere each food level is called tropic level. Green plants occupy the producer level and
there are different levels for consumers like primary (example: herbivores or plant
eaters), secondary (example: carnivores feeding on plant eaters), tertiary (secondary
carnivores). Such ecological relationship can be represented graphically by means of
ecological pyramids in which the producers make up the base while the successive
level of consumers constitutes the upper tiers.
Defining pyramid of numbers for food chains
The amount of food flowing through the food chain usually drops with each step up the
chain thus giving the characteristic pyramid shape. The prominent British ecologistCharles Elton was first to recognize in 1927 that such a diagram often forms a pyramid
and there are fewer individuals in each higher tropic level of an ecosystem. The pyramid
of number is therefore often known as Eltonian pyramid.
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Basically there are three types of ecological pyramids (1) pyramid of number (2)
pyramid of biomass and (3) pyramid of energy. As the name suggests, pyramid of
number represents the number of individuals at each tropic level.
Nature of pyramid of numbers for food chains
The shape of pyramid of number varies from ecosystem to ecosystem. The three typesof pyramid of numbers may be upright, partly upright and inverted.
(1) Upright: In general, the pyramid of number is upright when the producer organismsremain in abundance near the base of the food chain and the consumers graduallydecrease in numbers towards the apex. Hence, in such situations, the number ofproducers is always more than that of primary consumers indicating the relationship innumbers between the different tropic levels. The number of consumers decline in thesuccessive levels of pyramids from below upwards.This is true for aquatic andgrassland ecosystem.
(2) Partly upright: The pyramid of number may be partly upright when some parts areupright while some parts are inverted. In forest ecosystem, there are fewer number ofproducers that support greater number of herbivores who in turn support a lesser
number of carnivores.
(3) Inverted: The pyramid of number may be inverted when the producers are least innumber and the predators are greater in number as we move up the food chain..Atypical example is that of parasitic food chain where one primary producer supportsnumerous parasites which again support still more hyperparasites.
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Food Chains and Food Webs
While studying the biotic components in an ecosystem we have realised that food prepared by green plants is
consumed by a series of consumers, both herbivores and carnivores, and finally broken down into their elements and
released back into nature by decomposers in nature. The nutritional sequence in which food is transferred from the
plant (producer) through a series of organisms with repeated eating and being eaten is called a food chain. As food is
being transferred from one organism to another a lot of energy from food is lost. Hence, the biggest food chain has
four or five steps.
Illustrated below are some simple generalised food chains
Food chain in the forest
Food chain in grassland
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Tropic levels in the food chainsBack to Top
The different steps or levels in a food chain form different tropic levels.
The illustration below is self-explanatory. This is the ecosystem that can exist on land.
Tropic levels
Thus a food chain of four levels is built up where green plants fix up the solar energy and prepare the food and make
it, directly or indirectly, available for other consumers.
Significance of food chains
The study of food chains helps in understanding food relationship and interdependence among various
organisms in an ecosystem.
The mechanism of transfer of food, energy and nutrients through various components of nature can also be
studied
The effect of the use of pesticides on the ecosystem can be studied. As several of them are not
biodegradeable it goes on accumulating at every tropic level. Hence consumers at higher tropic levels will
consume more poison along with their food. This phenomena is known as biological magnification.
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Indiscriminate use of DDT and other pesticides has an adverse effect on the food chain and consequently
disturbs the ecosystem.
Tropic Levels
Each link in a food chain is known as a tropic level. For example, in each food chain, plants always form the first
tropic level. The plant eating animals called herbivores like insects, rodents, rabbits, deer, cattle, etc. form the second
tropic level. The animals like frog, small fish, small birds which feed on the second tropic level organism form the third
tropic level. These are eaten by still longer carnivores like lion or tiger, who constitute the fourth tropic level.
Food chain defined as the feeding of one organism upon another in a sequence of food
transfers .Food chain is the chain of transfer of energy ,which typically comes from the
sun, from one organism to another. A simple food chain is like the following:
Green plant -- grasshopper -- rat -- snakehawk--fungus.
In the food chain, the green plant is the primary producer by trapping energy from
sunlight. The grasshopper is the primary consumers because they directly consume the
green plant. The rat is the primary carnivore or secondary consumer because it eats
the grasshopper. The snake, a secondary carnivore or tertiary consumer, eats the rat.
The hawk is the tertiary carnivore because it eats the secondary carnivore, the snake.
The hawk eventually dies and its remains are broken down by decay-causing bacteria
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and fungi.. Each step in a food chain is called tropic level. Tropic level is the feeding
position in a food chain such as primary producers, primary consumers, secondary
consumers, decomposers etc .The producers or green plants form the first tropic level.
Herbivores form the second tropic level, while carnivores form the third and even the
fourth tropic levels.
Different tropic levels
First tropic level: It is represented by Producer. They are organisms like plantsthat produce food from carbon dioxide and water using photosynthesis.Producers can be plant, algae, plankton or bacteria. Primary producers in anaquatic ecosystem are various species like phytoplankton, algae and higherplants. Primary producers in an terrestrial ecosystem are various species likegreen plants.
Second tropic level: Second tropic level is represented by primary consumers.The primary consumers are herbivores that feeds on plants. Eg insects, birdsand mammals in terrestrial ecosystem and mollusc's in aquatic ecosystem.
Third tropic level: This level is represented by secondary consumers.these arePrimary carnivores .The consumers that feed on herbivores are carnivores, arecalled primary carnivores
Fourth tropic level: It is represented by tertiary consumers.They are usually topcarnivore,a consumer at the top of a food chain with no predators.
Diagram showing different tropic levels in terrestrial ecosystem
Back to Top
Diagram showing different tropic levels in marine ecosystem
Examples of organisms for different tropic levels
Examples for different tropic level
First tropic level:Phytoplanktons,algaea,higher plants Second tropic level: zooplankton,cow,grasshopper Third tropic level: Birds,fish,frog,wolf Fourth tropic level:Man, dolphin.lion .hawk. Owl etc
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Significance of Food Chains and Ecosystems
The study of food chains helps in understanding some of the important aspects of the ecosystem in particular and
environment in general.
The food relationship among the different organisms in an ecosystem
The food chains are the living components of the biosphere
These are the vehicles of transfer of energy from one level to another
Through the food chains, transfer of materials and nutrients also takes place
The movement of some toxic substances (like DDT) in the ecosystem, sprayed to kill the pests and insects,
through the various tropic levels, their accumulation at the highest tropic level, etc. can be studied. How
much this affects man can also be known because being an omnivore, man eats food of very type and in the
process receives these poisons at every tropic level. The phenomenon of passing the toxic substances
through different levels is termed as biological magnification.
These functions make the biosphere dynamic. Significance of Ecosystems
From the above, it must be clear that in an ecosystem, energy movement and movement of nutrients occur
continuously.
Energy Flow
Energy from the sun is captured by the green plants and passed on through the various tropic levels. The flow of
energy is unidirectional i.e., non-cyclic. However, some energy is lost at every state in the atmosphere.
Nutrient Movement
The nutrient movement goes on side by side along with unidirectional flow of energy. The nutrient movement is a
cyclic movement where the nutrients revolve round with an ecosystem, hence cyclic. This cyclic movement of
nutrients is also called as biogeochemical cycle.
Energy Flow in Biosphere
All living beings require a constant supply of energy for the various functions they perform. The energy is obtained
from the sun. This energy is introduced into the biosphere by green plants by a process known as photosynthesis.
Plants are able to trap this light energy and by the process of photosynthesis convert it into chemical energy. Thus
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the initial point of entry of energy in the ecosystem is through the green plants (autotrophs or producers). It has been
estimated that on an average, about one per cent of total sun's energy reaching the earth is trapped by green plants
during the process of food manufacture (i.e., photosynthesis). The energy thus trapped by plants is stored as
carbohydrates. Some of the energy trapped by plants is used by them in performing their metabolic activities like
respiration, growth, etc., and some energy is released in the atmosphere as heat. When the plants are eaten by
herbivorous animals, the energy stored in plants gets transferred to the consumer animals. These animals utilize this
energy for their own metabolic activities. Here again some of the energy is released as heat. When primary
consumers are eaten by secondary consumers, the same process is repeated at every step of the food chain. Here it
must be remembered, that energy released as heat is considered as energy lost.
We can thus conclude the following:
Conversion of energy takes place from one form to another.
The light energy gets converted into chemical energy by plants
during photosynthesis.
Plants act as converters of energy. They do not produce
energy.
The energy lost as heat is quite substantial, if taken together
from various tropic levels
During the transfer of energy through successive tropic levels in
an ecosystem, there is a lost of energy at each tropic level. In
other words, the level following the previous one always
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receives less amount of energy. After studying various food
chains and energy transfers in different ecosystems,
Lindemann in 1942 gave the generalization called "The 10 per
cent law". It shows that about 90% of the energy is used up at
each level and only 10% of it is transferred to the next tropic
level. As a result, at the last tropic level (decomposer), no
energy is left for recycling. This is how the flow of energy is
unidirectional. Fast decreasing energy level at each step sets
the limit of tropic levels only to 4-5 at the maximum. Therefore,
the plants (producers) receive the maximum energy and as you
go further down the tropic levels, the energy in the food goes on
decreasing.
The flow of energy is unidirectional. It enters into the living
system from non-living environment
The energy lost at heat cannot be utilised
Impact of Man's Activities
The addition of certain pollutants like the carbon dioxide gases increases the temperature of the earth. These gases
remain close to the surface of earth, forming an insulating layer. The surface becomes hot due to the solar radiations.
This radiation is normally reflected back into the space. However, due to the presence of the insulating layer the heat
remains within the earth's atmosphere and increases its temperature. The reduction in the forest cover also
contributes to the heating of earth. This is called global warming.
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Global warming results in the melting of polar ice caps. This inturn results in the rise in the level of ocean waters. It is
also called the greenhouse effect. Greenhouses are the covered areas where the temperature is artificially kept
higher than the surrounding cold environment for the growth of plan
Ozone Depletion
Ozone (O3) IS a molecule formed BY three atoms of oxygen WHILE oxygen (O2), IS essential FOR ALL aerobic
forms of life. Ozone IS a deadly poison. However, AT the higher levels of the atmosphere, ozone performs an
essential function. It shields the surface of the earth FROM ultraviolet (UV) radiation FROM the Sun. UV radiation
causes skin cancer, damage TO eyes, immune system. It can also affect GLOBAL rainfall AND cause ecological
disturbances.
Ozone AT the higher levels of the atmosphere IS a product of UV radiation acting ON oxygen (O2) molecule. The
higher energy UV radiations split apart SOME molecular oxygen (O2) INTO free oxygen (O) atoms. These atoms
THEN combine WITH the molecular oxygen TO form ozone AS shown IN the equations below.
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The decline of ozone content IN the atmosphere began IN the 1980s. This decrease has been linked TO synthetic
chemicals LIKE chlorofluorocarbons (CFCs) which are used AS refrigerants AND IN fire extinguishers. IN 1987, the
United Nations Environment Programme (UNEP) succeeded IN forging an agreement TO freeze CFC production AT
1986 levels.
Biological Magnification
Extensive usage of several pesticides and other chemicals to protect our crops from diseases and pests has resulted
in the entry of these harmful chemicals into our bodies through the food chain. These chemicals are either washed
down into the soil or into the water bodies. From the soil, these are absorbed by the plants along with water and
minerals, and from the water bodies these are taken up by aquatic plants and animals. This is one of the ways in
which they enter the food chain. As these chemicals are not degradable, they get accumulated progressively at each
tropic level. As human beings occupy the top level in any food chain, the maximum concentration of these chemicals
gets accumulated in our bodies. This phenomenon is known as biological magnification. This is the reason why our
food grains such as wheat and rice, vegetables and fruits, and even meat, contain varying amounts of pesticide
residues. They cannot always be removed by washing or other means.
Did U Know?
PERSISTENT ORGANIC POLLUTANTS [POP] OR PESTICIDES enter our food chain through various methods.
DDT, a very harmful pesticide has been banned from use. Almost all ready made foods contain two or more
pesticides. Among fruits and vegetables peaches, apples, spinach and lettuce have the highest amount of pesticide
content. Onions have the least followed by papaya. Dieldrin and DDE are the most commonly used pesticides. DDE
is a break down product of DDT. Dieldrin is an organochlorine pesticide. Use of organically grown food items is one
way of reducing pesticide intake.
Waste Management
We are an integral part of the environment. Our activities change the environment around us.Changes in the environment affect us.
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Environmental problems like depletion of the ozone layer and waste disposal are issues that have
to be dealt with serious concern.
In our daily activities, we generate a lot of materials that are thrown away. These accumulated
wastes can be classified as biodegradable and non-biodegradable. Substances that are broken
down by biological processes are said to be biodegradable. Substances that are not broken downby biological processes are said to be non-biodegradable.
The huge amount of municipal refuse generated daily demands a highly efficient system tomanage its collection and disposal. Waste management has been a serious issue in urban areas.
Disposing garbage at the outskirts of a city is a common sight. Empty cans, food wrappers etc.
which are non-biodegradable are littered in crowded places and tourist centres. It is necessary tohave awareness regarding methods of disposing different types of waste.
Improvements in our life-style have resulted in greater amounts of waste material generation.
Changes in attitude also have a role to play, with more and more things we use becomingdisposable. Changes in packaging have resulted in much of our waste becoming non-
biodegradable.
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The disposal of the waste we generate is causing serious environmental problems. There are anumber of concepts about waste management, which vary in their usage between countries or
regions. The waste hierarchy refers to the "3 Rs" reduce, reuse and recycle, which classify waste
management strategies according to their desirability in terms of waste minimization.
E-waste
What contributes to e-waste? Discarded electronic devices like televisions, personal computers, floppies,
audio-video CDs, batteries, electric switches, telephones, air conditioners, cellphones, electronic toys,
refrigerators, washing machines, dryers, kitchen utensils and even aircraft contribute to the growing pile
of e-waste in the city. At least, 30,000 personal computers are sent for dismantling evey year in the city.
How is it hazardous? These products contain components that contain toxic substances like lead,
cadmium, mercury, hexavalent chromium, plastic, PVC, BFRs, barium, beryllium, and carcinogens like
carbon black and heavy metals. The deadly mix can cause severe health problems for those handling the
waste. It could even prove fatal.
Sewage Treatment
Sewage Treatment
The ultimate return of used water to the environment is done by treating sewage. Typically, sewage
treatment involves three stages. They are primary, secondary and tertiary.
The solids are first separated from the waste water. The dissolved biological matter is gradually
converted into a solid mass by using water-borne bacteria. Finally the biological solids are
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neutralized and then disposed off or reused. The treated water is disinfected chemically. The final
effluent is usually discharged into a stream or water body or used for irrigation.
Our Environment Summary
Environment is defined as the surroundings in which the organism lives. It has two components - abiotic and
biotic.
The abiotic environment includes the air (atmosphere), water (hydrosphere) and land (lithosphere). The
biotic environment includes the plants, animals and the microbes.
The things that man requires for his survival and comfort are called the resources. So, the environment, with
respect to man, is a reservoir of his resources.
The wastes can be classified into:
Biodegradable: The biodegradable wastes are those that can be decomposed. For example, kitchen
garbage, animal dung, etc.
Non-biodegradable: The non-biodegradable wastes are those that cannot be decomposed and remain as
such in the environment. For example, plastics, nuclear wastes, glass, etc.
Some of these wastes are also classified as hazardous wastes. Hazardous wastes are those that catch fire
easily, react explosively with air or water, corrode other materials, are toxic or radioactive.
Waste management involves collection, storage, transportation, recycling and disposal
Our Environment - Test Questions
Question 1
Question: Define environment.
Answer: Environment is defined as the surroundings in which the organism lives.
Question 2
Question: How is the environment classified into three types?
Answer: The environment may be classified into three types based on the nature of its components.
The physical environment that includes the physical features of the environment, the chemical
environment that includes the chemical substances that make up the environment and the biological
environment that includes the living organisms.
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Question 3
Question: What are the two components of the environment?
Answer: The two components of the environment are the biotic (plants, animals and microbes) and the
abiotic (non-living component).
Question 4
Question: Define conservation of environment.
Answer: Maintaining and judiciously using the environment is called conservation.
Question 5
Question: Name any four environmental problems faced by today's world.
Answer: Four environmental problems being faced by today's world are:
1) Population explosion
2) Pollution
3) Global warming
4) Soil erosion
Question 6
Question: Why is ozone layer important?
Answer: Ozone layer is important for us as it protects us from the harmful ultraviolet rays.
Question 7
Question: How does municipal waste contribute to air pollution?
Answer: Municipal waste consists of organic matter. The decomposition of this under anaerobic
conditions produces methane. Methane produces carbon monoxide on oxidation. The municipal wastes
also contribute to air pollution by producing foul smelling gases on decomposition.
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Question 8
Question: What is greenhouse effect?
Answer: Earth is surrounded by an envelope of gases. Most of the solar radiation that reaches the
earth is reflected back. However, some of the heat is absorbed by the gases like carbon dioxide that form
an insulating layer around the earth. This heating of earth by the insulating effect of the gases is called
greenhouse effect.
Question 9
Question: What is ozone? How is it beneficial to us?
Answer: Ozone (O3) is a gas present in the stratosphere of the atmosphere. Ozone is known to absorb
the ultraviolet (UV) rays present in the sun's radiation. The UV rays are believed to cause skin cancer and
mutations. Thus, the ozone protects us from the harmful effects of the UV rays.
Question 10
Question: What is oxygen depletion?
Answer: The sewage contains the organic matter that encourages the growth of
microorganisms. These organisms consume the oxygen present in water. This reduces the oxygen
content of the water. This is called oxygen depletion. The aquatic organisms like the fish cannot then
survive in such waters.
Effects on Environment - Test Questions
Question 11
Question: Why are most industries situated along the riverbanks?
Answer: Most industries are situated along the riverbanks for easy availability of water and disposal of wastes.
Question 12
Question: What are the two harmful effects of sewage?
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Answer: The two harmful effects of sewage are:
1) spread of diseases like cholera, gastroenteritis, amoebiasis, etc.
2) depletion of oxygen which is harmful for the fishes and aquatic organisms living in the waters.
Question 13
Question: How does a pesticide like DDT reach human body?
Answer: Pesticides like DDT can reach human body through the food chains of the ecosystem. There are two
ways:
1) The DDT enters the grass which is eaten by the cows. It can reach the human body through the milk of the cows.
2) The DDT, flows along the rain waters into the water bodies where they accumulate in the bodies of the fish. It can
then reach the bodies of the persons eating these fish.
Question 14
Question: Mention the main steps of sewage treatment.
Answer: The main steps of sewage treatment are:
1) Primary treatment - the suspended particles are removed.
2) Secondary treatment - the organic wastes are degraded.
3) Tertiary treatment - the inorganic pollutants are removed.
Question 15
Question: What is effluent treatment?
Answer: Effluent treatment involves the removing of the harmful chemicals discharged from the industries into the
water bodies or at least, rendering them harmless.
Question 16
Question: Mention three problems that have resulted due to population explosion.
Answer: Three problems that have resulted due to population explosion are:
1) Strain on resources-both renewable and non-renewable.
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2) Depletion of forests resulting in climatic change.
3) Increased levels of pollution due to more industrial activity.
Question 17
Question: What are the problems associated with accumulation of wastes?
Answer: Accumulation of wastes increases the number of insect vectors like flies, mosquitoes, etc., scavengers
such as stray dogs, pigs and rats. These spread dangerous diseases. It also generates bad odour and causes
pollution.
Question 18
Question: What are the two types of wastes?
Answer: Two types of wastes are: Biodegradable The biodegradable wastes are those that can be decomposed by
the natural processes and converted into the elemental form. For example, kitchen garbage, animal dung, etc.
Non-biodegradable The non-biodegradable wastes are those that cannot be decomposed and remain as such in the
environment. They are persistent and can cause various problems. For example, plastics, nuclear wastes, glass, etc.
Question 19
Question: What are the sources of wastes being generated in the cities?
Answer: Most of the garbage in the cities come from the following sources: Domestic wastes, commercial wastes,
ashes, animal wastes, biomedical wastes, construction wastes, industrial solid wastes and sewer.
Question 20
Question: What are the important aspects of waste management?
Answer: The important aspects of waste management are: Collection - collection of garbage such that it is not
spread through out the city, Storage - facility for temporary storage to keep the stray dogs and other animals away,
Transportation - proper transportation to the disposal sites, Recycling - reusing the non-biodegradable wastes so that
pollution is minimised Disposal - Safe disposal so that the wastes do not cause any harm in the future.
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Protection of the Environment - Test Questions
Question 21
Question: What does the concept of sustainable development expect every generation to do?
Answer: According to the concept of sustainable development, every generation will leave clean air, water and soil
resources for the future generations.
Question 22
Question: Give the interrelationship of population, environment and development.
Answer: As the population increases, their strain on the environmental resources also increases. The development
of man is dependent on the resources that man gets from the environment. Thus, man has to pay attention to the
conservation of the environment if he needs development. This is called sustainable development.
Question 23
Question: How does the government ensure conservation and protection of the environment?
Answer: The government ensures conservation and protection of the environment by enacting laws within the
framework of the constitution of the country. Laws are necessary to ensure that the environment is being conserved
Our Environment - Multiple Choice Test
Question 1
Question: A natural phenomenon that becomes harmful due to pollution is _____________.
1.global warming
2.ecological balance
3.greenhouse effect
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4.desertification
Answer: 3
Question 2
Question: The pollutant responsible for ozone holes is ____________.
1.CO2
2.SO2
3.CO
4.CFC
Answer: 4
Question 3
Question: One of the best solutions to get rid of non-biodegradable wastes is _________________.
1.burning
2.dumping
3.burying
4.recycling
Answer: 4
Question 4
Question: Animal dung is _________________ waste.
1.biodegradable
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2.non-biodegradable
3.hazardous
4.toxic
Answer: 1
Question 5
Question: Which of the following is biodegradable?
1.iron nails
2.plastic mugs
3.leather belts
4.silver foil
Answer: 3
Question 6
Question: Which of the following is non-biodegradable?
1.animal bones
2.nylon
3.tea leaves
4.wool
Answer: 2
Question 7
Question: Name one non-biodegradable waste which may pollute the earth to dangerous levels of toxicity, if not
handled properly.
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1.DDT
2.CFC
3.Radioactive substances
4.PAN
Answer: 3
Question 8
Question: In a lake polluted with pesticides, which one of the following will contain the maximum amount of
pesticides?
1.small fish
2.microscopic animals
3.big fish
4.water birds
Answer: 4
Question 9
Question: Name the substance whose accumulation in pelicans of Lake Michigan led to the formation of thin shells
of their eggs.
1.CFC
2.PAN
3.DDT
4.PAC
Answer: 3
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Question 10
Question: Name the process in which a harmful chemical enters the food chain and gets concentrated at each level
in the food chain.
1.concentration
2.biomagnification
3.expansion
4.pollution
Answer: 2