Our Environment Introduction 0

8/11/2019 Our Environment Introduction 0

1/27

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,


2/27

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.


3/27

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.


4/27

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.


5/27

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.


6/27

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.


7/27

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


8/27

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.
http://www.tutorvista.com/content/science/science-ii/environment/food-chain.php#tophttp://www.tutorvista.com/content/science/science-ii/environment/food-chain.php#tophttp://www.tutorvista.com/content/science/science-ii/environment/food-chain.php#top


9/27

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


10/27

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
http://www.tutorvista.com/content/science/science-ii/environment/trophic-levels.php#tophttp://www.tutorvista.com/content/science/science-ii/environment/trophic-levels.php#tophttp://www.tutorvista.com/content/science/science-ii/environment/trophic-levels.php#top


11/27

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


12/27

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


13/27

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.


14/27

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.


15/27

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.


16/27

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.


17/27

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


18/27

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.


19/27

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.


20/27

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?


21/27

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.


22/27

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.


23/27

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


24/27

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


25/27

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.


26/27

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


27/27

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

Our Environment Introduction 0

Documents

Transcript of Our Environment Introduction 0