Science 8

4. A long, heavy and strong piece of wood is called timber.

5. The timber is used for making furniture, building houses, constructing boats,
making suspension bridges, etc.

6. The plants which bear attractive flowers are called decorative plants.

7. Several species of mammals, birds, reptiles, amphibians, fishes and insects are
found in Nepal.

8. The species of animals which cannot be found in the areas where they once lived,
or in any other habitat are called extinct animals.

9. The species of animals which are declining in the number at very fast rate and
whose existence is threatened by the existing environmental conditions are called
endangered animals.

10. The government of Nepal has established several national parks, wildlife reserves
and wildlife conservation areas for the protection of wildlife.

Exercise

A. Answer these questions in very short.
1. Give any four examples of cereals.
2. What are spices ?
3. Name any two medicinal plants found in the Terai region of Nepal.
4. What is the botanical name of amala?
5. In which geographical region of Nepal is chutro found?
1DPH DQ\ WZR ÁRZHUV ZKLFK DUH XVHG WR PDNH JDUODQGV
7. Which is the smallest national park of Nepal ?
8. Name a national park that is located in the mid-western development
region.
9. Which is the latest declared national park of Nepal ?
10. Where is red panda protected ?
11. What is the average weight of a male tiger ?
12. What is the zoological name of Asiatic elephant?
13. Where is Sagarmatha National Park located ?

B. Give reasons:
1. Wildlife are in danger due to human activities.
2. The trees in the Terai are big and tall.

297 Times' Crucial Science & Environment Book - 8

3. People are not allowed to enter the wildlife reserves.
4. Wildlife are very important to us.

C. Differentiate between:
1. National park and wildlife reserve.
2. Wildlife reserve and hunting reserve.
3. Extinct and endangered animals.

D. Write down short notes on: 2. Medicinal plants
1. Ornamental plants 4. Food giving plants
3. Timber plants

E. Complete the following table:

61 National Park Area Location Wildlife
1. Chitwan National Park
2. Bardiya National Park
3. Shey-Phoksundo National Park
4. Khaptad National Park
5. Shivapuri National Park

F. Answer these questions:
1. Enlist any three medicinal plants of each Terai, Hilly and Himalayan
region.
2. Enlist any three timber plants of each Terai, Hilly and Himalayan
region.
3. Name the major birds and mammals found in Hilly region of Nepal.
4. What are endangered species? Give two examples each of endangered
mammals, birds and reptiles.
5. What are extinct animals? Give example.
6. What are national parks? Enlist the national parks of Nepal.
:ULWH GRZQ DQ\ IRXU FDXVHV IRU WKH H[WLQFWLRQ RI ZLOG ÁRUD DQG
fauna.
8. Write down the importance of forest.
9. Write down the importance of national parks and wildlife reserves.
10. What are the main causes of deforestation?

Times' Crucial Science & Environment Book - 8 298

* %ULHÁ\ LQWURGXFH WKH IROORZLQJ

1. Asiatic elephant 2. Bengal tiger
Giant pied hornbill
3. Rock python 4.

+ 6WXG\ WKH GLDJUDPV DQG DQVZHU WKH TXHVWLRQV WKDW IROORZ

1. Name the above animals.
2. What are the species of these animals called?
3. Why is the number of these animals declining?
4. How can these animals be protected ?
5. What will happen if all of such wildlife disappear from the world?

Write your view.

Visit a protected area which is the nearest to your school. Study habit, habitat
and other conditions of wildlife living there. Are there any threats to the
wildlife of that area (in your view)? Which species are the most threatened?
Prepare a report and show to your teacher.

299 Times' Crucial Science & Environment Book - 8

24CHAPTER Environmental
Degradation and Its
Conservation
Joseph Charles Farman

Joseph Charles Farman was a British geophysicist who
ZRUNHG IRU WKH %ULWLVK $QWDUFWLF 6XUYH\ 7RJHWKHU

with Brian Gardiner and Jon Shanklin, he published the
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Estimated Periods : 12
Objectives: At the end of the chapter, the students will be able to:

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GHILQH JUHHQKRXVH HIIHFW DQG LWV FRQVHTXHQFHV
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H[SODLQ VRPH QDWLRQDO DQG LQWHUQDWLRQDO DJHQFLHV IRU WKH FRQVHUYDWLRQ RI HQYLURQPHQW

What is pollution?
What makes the environment polluted?
What is greenhouse? Why do plants of hot climate grow inside greenhouse?
What is a natural disaster? Which natural disasters have you experienced? Can
natural disasters be prevented? Discuss.

Human activities and their impacts on the environment

Human beings use various components of the environment for survival. They
use air, water, land, forest, etc. They use the components of environment
for carrying out various activities. Human beings use air for breathing, for
EXUQLQJ IXHOV ÀUHZRRGV HWF 7KH\ XVH ZDWHU IRU GULQNLQJ FOHDQLQJ FORWKHV
and utensils, cultivation, etc. The forest products are used for the construction
of buildings, bridges, furniture, etc. Firewoods are also used as fuel. Land is
used for many fold purposes. Human beings build various types of physical
structures such as buildings, roads, bridges, railways, parks, gardens, etc on
the land. Various minerals such as iron, aluminium, copper, marbles, granite,
rocks, etc are extracted from the interior part of the earth. They are used for

Times' Crucial Science & Environment Book - 8 300

the construction of buildings, making utensils etc.
Thus, human beings carry out various activities by using the various components
of the environment. These components should be used in a proper way. But,
human beings are not careful about the use of these components. Therefore,
various problems arise in the environment. It is called environmental pollution.
Mixing of unnecessary things to the environment which causes undesirable
changes in the physical, chemical and biological properties of air, water, land,
etc is called environmental pollution.
Environmental pollution is of four types. They are:
i) Air pollution ii) Water pollution iii) Land pollution iv) Sound pollution

a. Air Pollution

All living things need oxygen to survive. They get oxygen from atmosphere.
No any living thing can survive without oxygen. Therefore, it is called a
life gas. Plants also need oxygen for respiration. They use carbon dioxide
for the preparation of food during photosynthesis. Air is used for burning
fuels too. Thus, air is very important. But air is being polluted due to
different human activities.
Causes of air pollution
6PRNH SURGXFHG IURP YHKLFOHV EXUQLQJ RI ÀUHZRRG NHURVHQH SODVWLF
etc.
2. Smoke and dust produced from factories.
3. Dust produced from running vehicles and construction of roads or
buildings.
4. Bad smell coming from dead and decayed things deposited near house or
roads.
Effects of air pollution
1. Air pollution causes various types of diseases in human beings such as
common cold, pneumonia, bronchitis, lung cancer, etc.
2. Dust and smoke causes warming of the earth. It is called global warming.
It affects the whole climatic activities.
3. Polluted air destroys the cultural heritages like temples, monuments,
monasteries, etc.
4. It causes acid rain.
5. Dust particles collected in the leaves of plants reduce the rate of
photosynthesis.

301 Times' Crucial Science & Environment Book - 8

Control measures of air pollution
1. Tree plantation should be done nearby the houses and roads.
2. The engines of vehicles and factories should be maintained so that they

produce less smoke.
3. The factories and industries should be located far away from human

settlement.
4. Solar heater, electricity, LPG /LTXHÀHG 3HWUROHXP *DV HWF VKRXOG EH

XVHG LQ FRRNLQJ LQVWHDG RI ÀUHZRRG DQG NHURVHQH
5. Legal arrangements should be made to control the air pollution.

b. Water pollution (Degradation of water resources)

Water is one of the important natural resources. It is used by human beings
for drinking, irrigation, industrial works, recreation, transportation,
production of hydroelectricity, etc. Water is used by the plants for the
preparation of foods. Water provides shelter to various types of aquatic
animals. Several types of aquatic plants grow in water.
We get water from rivers, ponds, lakes, streams, rain, underground
source, etc. Nepal is one of the richest countries in water resources.
There are more than 6,000 rivers and rivulets. The volume and speed
of water in rivers and streams depend upon rainfall. Rain water is
the main source of underground water. When rain water is absorbed
through the soil and is collected under the ground, it is considered as
underground water. Water from well, tube well, spring etc are the forms
of underground water.
Various human activities cause the degradation of water resources:
1. Mixing of various wastes and chemicals from industries in the rivers.
2. Mixing sewage (wastes from toilet and kitchen) in the water sources.
3. Bathing and cleaning clothes and utensils near the sources of water.
4. Mixing of excreta of animals in the source of water.
5. Excessive use of insecticides and chemical fertilizers in agriculture.
6. Spilling of petroleum oil while transporting through ocean.
Effects of water pollution
1. Polluted water causes various types of diseases like dysentery, diarrheoa,
jaundice, typhoid, cholera, etc.
2. Polluted water causes various types of disease in aquatic animals.

Times' Crucial Science & Environment Book - 8 302

3. Plants cannot grow well in polluted water.
4. Polluted water causes air pollution.
5. Bad smell coming from polluted water disturbs concentration and

working of people.
Measures to control water pollution

1. Bathing and cleaning clothes and utensils near the source of water
should be avoided.

2. The chemicals and wastes produced from factories and industries should
EH WUHDWHG DQG UHÀQHG EHIRUH PL[LQJ WR WKH ULYHU ODNHV RU RFHDQV

7KH GRPHVWLF GLUW DQG ÀOWKV VKRXOG QRW EH WKURZQ QHDUE\ WKH VRXUFH RI
water.

4. Mixing of sewage and garbage to the source of water should be avoided.
7KH VRLO HURVLRQ ÁRRGV DQG ODQGVOLGHV VKRXOG EH FRQWUROOHG VR WKDW

sources of water will not be polluted.
6. People should be made aware about the bad impacts of water pollution.
7. Excessive use of insecticides and chemical fertilizers should be avoided.

c. Land Pollution

Land is one of the important natural resources. It is the natural habitat
IRU DOO DQLPDOV DQG SODQWV 6RLO À[HV SODQWV DQG SURYLGHV DOO nutrients to
them. Various types of small animals like insects, mice, snake, etc live
under the ground. Human beings carry out construction works on the
land. They make buildings, roads, parks, playground, etc on the land.
It is used for cultivation. Thus, land is very important for plants and
animals. But it is being polluted due to various types of human activities.
Causes of land pollution
1. Mixing of chemicals and wastes from industries and factories on the soil.
2. Excessive use of insecticides and pesticides.
3. Throwing of non-decaying materials like plastic, metal pieces, broken
glasses, etc on the land.
4. Mixing of sewage on the land without proper management.
5. Throwing of cattle excreta, wastes from houses, etc on to the soil.
6. Dumping of wastes from kitchen and houses on the land.
Effects of land pollution
1. Plants cannot grow well in polluted soil.
2. Crops grown in polluted land are poisonous. Such crops make human
beings sick.

303 Times' Crucial Science & Environment Book - 8

3. Animals cannot grow properly in polluted soil.

4. Bad smell coming from the polluted soil affects the surroundings.

3ROOXWHG ODQG DWWUDFWV DQLPDOV OLNH ÁLHV FRFNURDFKHV PLFH HWF 7KH\ FDQ
transmit various types of diseases.

6. The use of chemical fertilizers and insecticides causes an adverse effect
on the health of man, animals and plants.

7. The soil pollution decreases beauty of the environment.

Measures to control land pollution
1. Insecticides and chemical fertilizers should be used properly.

2. Non-biodegradable things like plastic, rubber, metal, glass bottles, etc
should be reused.

3. Biodegradable things like excess food, peels of fruits and vegetables,
cattle dung, etc should be used to prepare compost manure.

4. Chemicals and wastes from factories and industries should be turned
into harmless forms before mixing on the land.

5. Non-biodegradable goods should be recycled and reused.

Greenhouse and greenhouse effect

Have you ever seen plants grown inside the house of glass or plastic? Why is
it done?

When plants are inside the house or glass of
plastic, warm environment is created inside
it even though outside environment is cold.
The glass or plastic allows short waves of
solar heat to pass but do not allow the long
waves to pass through them. When short
waves of the sun enter the greenhouse, they
convert to long waves of infrared radiation
after striking on the land. The long waves
cannot escape out of the glass or plastic of Greenhouse

such houses. Thus, warm environment can be maintained even though the
outside environment is cold. Such house is called greenhouse.

Hence, greenhouse is a house made up of glass or plastic inside which warm
environment suitable for the growth of plants is created even though the
outside environment is cold.

The atmosphere of the earth acts as the glass of greenhouse. The short waves
from the sun enter the atmosphere and convert to infrared radiations of long

Times' Crucial Science & Environment Book - 8 304

waves after striking on the ground. The long waves cannot escape into the
space. Water vapour, dust particles, greenhouse gases like sulphur dioxide,
FKORURÁXRURFDUERQV, VXOSKXU KH[DÁXRULGH FDUERQ GLR[LGH PHWKDQH HWF
absorb the infrared radiations and make the earth warmer. This effect is
called greenhouse effect.
Greenhouse effect has both advantageous and disadvantageous effects. Due to
it, the heat cannot escape to the space from the earth at night time. Thus, the
suitable temperature is maintained at night and the earth is suitable for the
living things to survive. This is advantageous effect.
VbCyOar2ii,noCduuHssh4t,urwimeasatnearnavdcativpveoihtuiirec,sledcsua.sutTspheaetrhmteicoplrereos,daeumtccto.iuoTnnhtoefsoegf agssauescsehssugacarhseeafsusrpNtrhOees,reNnpOtro2i,dnNuct2heOde,
atmosphere causes the increase in the greenhouse effect. Thus, the earth is
becoming hotter and hotter and is not good for the living things. It is called
global warming.
Some of the disadvantages of greenhouse effect are as follows:
1. Global warming occurs due to greenhouse effect. It may cause melting of

the snow of the mountain and polar region. It reduces the regular supply
of water into rivers. The water level in the coastal region increases.
2. Water cycle is badly affected.
3. Due to increase in temperature, various types of diseases spread on the
earth.
4. It helps in the spreading of harmful insects.
5. Normal ecosystem is disturbed.

Climatic change

Due to various types of human activities, normal climatic phenomena are also
affected. Production of greenhouse gases by the industries and vehicles increases
temperature of the earth’s atmosphere, it is called global warming. Global
warming affects the water cycle. Some of the climatic changes are as follows:
1. Temperature of the earth is increasing every year. In the past 100 years,

the temperature of the earth has been increasing by 0.74°C per year.
2. Floods are occurring in the summer seasons due to unusual melting of

snow in the mountain region.
3. Normal water cycle is disturbed and the season of rainfall changes. It

affects the cultivation and harvesting of the crops.
4. It causes drought in various places of the earth even in the rainy seasons.

305 Times' Crucial Science & Environment Book - 8

Acid rain

Various types of gases asnunitcdrhivcaeoshxicicdaleersb.(oNWnOhd)ei,onnxiittdhreeosg(eCengOa2ps)e,ensstucoloxpmihdeueri(nNdic2oOoxn5i)td,aecett(ScwOaitr2)he,
psurolpdhuucerdtrbiyoxiinddeu(sStrOie3)s,
water of rain, they react with water and form acids. These acids fall along with
the rain water. It is called acid rain. Some acids are formed in the atmosphere
as shown in the following reactions.

2SO2 + O2 ń 623 (Sulphur trioxide)
SO3 + H22 ń +2SO4 (Sulphuric acid)
4NO2 + O2 + 2H22 ń +123 (Nitric acid)
CO2 + H22 ń +2CO3 (Carbonic acid)

Adverse effects of acid rain

1. It increases acidity of the soil. Acidic soil is not good for crops production.

2. It makes the water of pond, river, lakes, etc acidic. It may kill aquatic animals.

3. It corrodes historical monuments like statues, sculptures, etc.

4. It may affect plants and animals.

5. It may cause different types of skin diseases.

Disasters and disaster management

The sudden calamity which has destructive and very unfortunate effects on life
and property is called disaster. The disasters can destroy the lives, property,
cultivable land, habitat of wild animals, sources of water, forest, ecosystem,
etc. The disasters can be divided into two types:

1. Natural disasters: The sudden calamity caused by nature which destroys
life and property and has a long term effect in the social life is called
natural disaster. Flood, landslides, earthquake, volcano, storm, cyclone,
thunderstorm, hailstones, etc are some natural disasters. Some natural
disasters have less severe effects whereas some have devastating effects.

The natural disasters are beyond human control. However, we can reduce
their effects to some extent using certain control and safety measures.

$QWKURSRJHQLF GLVDVWHUV 'LVDVWHUV GXH WR KXPDQ FDXVH The
sudden or unexpected destructive happening that occurs due to human
activities is called anthropogenic disaster. Chemical hazards, road-
WUDIÀF DFFLGHQW FKHPLFDO H[SORVLRQV DFFLGHQW GXULQJ FRQVWUXFWLRQ ZRUNV
GHVHUWLÀFDWLRQ H[SORVLRQ RI QXFOHDU SRZHU SODQW etc are the disasters
due to human cause.

Times' Crucial Science & Environment Book - 8 306

Causes of disasters

The hilly and the Himalayan regions consist of high lands with sharp slopes.
In these areas, disasters mainly occur due to heavy rainfall, deforestation,
IRUHVW ÀUH RYHUÁRZ RI ZDWHU LQ WKH ULYHU HWF 6RPH GLVDVWHUV KDYH EHHQ
reported due to unsafe road construction, construction of canal, XQVFLHQWLÀF
mining, etc. The disasters are also invited due to over population, unplanned
settlement, poor waste management, unmanaged urbanization, unplanned
industrialization, ODFN RI SXEOLF DZDUHQHVV HWF 7KH GLVDVWHUV VXFK DV ÁRRG
ODQGVOLGHV HDUWKTXDNH VWRUP F\FORQH WKXQGHUVWRUP ÀUH IRUHVW ÀUH JODFLHU
explosion of glacial lakes, epidemics, etc are common in Nepal.
Mitigating and management measures of disasters
We can mitigate the risk of disasters if we manage them by being concentrated
on their causes. Some of the mitigating measures of disasters risk are given
below.
1. Pre-planning to face the probable disaster.
2. Creating public awareness about the risks and management of disasters.
3. Rescuing the affected people and taking them to safe place.
4. Providing commodities, rehabilitation and other necessary help to the

affected people.
Earthquake management and mitigating measures of its risks
Earthquake is a destructive natural disaster which involves a sudden shaking
of earth’s surface. In other words, it is the vibration of earth surface due
to the sudden release of stored energy beneath it. There are two types of
earthquakes on the basis of movement: horizontal earthquake and vertical
earthquake. The to and fro or left to right movement of the earth crust is
called horizontal earthquake. The earthquake which involves up and down
movement of the earth is called vertical earthquake. A horizontal earthquake
is more destructive than the vertical earthquake.
A powerful earthquake causes the heavy loss of life and property. Bridges,
building, walls, tall statues and houses collapse due to earthquake. The
earthquakes destroy electric poles and lines, water pipes, telephone lines and
roads which make the life miserable.
We have to adopt the following measures to protect ourselves from earthquake:
Preparedness to minimize loss due to earthquake
)L[LQJ WKH ZDUGUREH IULGJH PLUURU WHOHYLVLRQ HWF ÀUPO\ WR WKH ZDOO RU

support so that they do not fall down.

307 Times' Crucial Science & Environment Book - 8

2. Placing the brittle things such as mirror, bottle, glass, etc. in low lying
safe places.

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bag and keeping it at safe place.

5HSDLULQJ DQ\ GDPDJH LQ WKH ZDOO ÁRRU FHLOLQJ RU IRXQGDWLRQ RI WKH
house.

5. Identifying safe places inside and outside the house so that we can remain
safe there during emergency.

Safety measures during the earthquake
1. Leave the house and gather in wide open place if you are near the door.

But do not rush down from a multi-storeyed building, do not jump out of
window.
2. Do not get out of house if there are narrow streets in dense settlement.
3. If you are outside the house, stay in open place. Do not rush toward your
house.
4. Sit under the table or bed to protect your head.

5. Stand under the frame of inner door but not near the external wall or
window.

6. Keep yourself away from wardrobe, cupboard or glasses.
7. Turn off gas, electric supply and water supply if possible.
Safety measures after the earthquake
1. As soon as the earthquake stops, rush out from the house and gather in

a wide open place.
2. Do not return to the house immediately. There are more chances of strong

aftershocks within 72 hours of the main earthquake.
3. Don't stay near the wall, electric pole, etc even in the open place.
,I \RX KDYH JRW DQ\ NLQG RI ZRXQG VWRS EOHHGLQJ DW ÀUVW DQG WKHQ JR IRU

ÀUVW DLG

Times' Crucial Science & Environment Book - 8 308

,I \RX ÀQG VRPHERG\ WUDSSHG LQVLGH WKH EURNHQ KRXVH WU\ WR UHVFXH WKHP ,I
you can't do this, inform the rescue team or police.

6. Do not enter the house immediately after the earthquake stops. Strong
aftershocks can continue after the main earthquake and cause further
damages.

7. Do not believe on the hearsay of people because many people share wrong
information during such time.

8. Listen to the emergency information broadcast from radio and television
and follow the directives.

9. Ensure your safety before rescuing others.
10. Observe the conditions of pillars, walls window, etc before entering the

house.
Flood and landslide management and mitigating measures of their risks
Flood LV D QDWXUDO GLVDVWHU ZKLFK RFFXUV GXH WR DQ RYHUÁRZ RI PXGG\ ZDWHU
from river, stream or other sources of water. It may occur due to heavy
rainfall, sudden burst of a lake at high altitude, excessive melting of snow
from Himalayas, burst of dams, etc. A landslide is a natural disaster in which
a soaked part of land gets collapsed and slides down due to the effect of gravity.
Landslide usually occurs in hills, slope lands and mountainous regions of our
country. It occurs most frequently during rainy seasons.

Flood Landslides

Heavy or incessant rainfall for a long period of time increases hydraulic pressure
along the slope of land and results in landslides. It is because the rainwater is
absorbed by the land which gets collected in the soil. The shaking of earth’s surface
due to earthquake can cause landslides. Similarly, the deep cutting of land on the
EDQN GXH WR IDVW ÁRZLQJ ULYHUV RU VWUHDPV FDXVHV ODQGVOLGHV

:H VKRXOG DGRSW WKH IROORZLQJ PHDVXUHV WR PLWLJDWH WKH ULVNV RI ÁRRG DQG
landslides:

$YRLGLQJ WKH FURVVLQJ RI ÁRRGHG VWUHDPV ULYHUV HWF

,QIRUPLQJ WKH VHQLRUV LPPHGLDWHO\ LI VRPHERG\ LV VHHQ LQ WKH ÁRRG RU
landslide.

309 Times' Crucial Science & Environment Book - 8

3. Providing sirens and emergency signals for the communication RI ÁRRGLQJ
or landslides.

0DQDJLQJ IRRG GULQNLQJ ZDWHU DQG UHVLGHQFH WR ÁRRG DIIHFWHG SHRSOH

3URYLGLQJ ÀUVW DLG RU WDNLQJ WKH LQMXUHG WR WKH KRVSLWDO LQ FDVH RI QHHG

0DQDJHPHQW RU FRQWURO PHDVXUHV RI ÁRRG DQG ODQGVOLGHV

1. Constructing embankment, check dam, spur, channel wall, etc to control
WKH ÁRZ RI ZDWHU LQ ULYHU DQG VWUHDP

2. Avoiding the constructions of houses, temples, buildings, etc near the
banks of streams and rivers.

3. Planting the richly rooted plants such as bamboo, Sajiwan, Ajambari,
Asuro, etc in the banks of rivers and streams.

4. Adopting VFLHQWLÀF DJULFXOWXUDO V\VWHP, i.e. terrace farming in hilly
region.

5. Controlling the overgrazing by cattle and random cutting down of trees.

6. Shifting the human settlement to safer places in case of possibility of
ÁRRGLQJ

Fire management and mitigating measures of its risks

Fire is the disaster mainly due to human &ŽƌĞƐƚ ĮƌĞ
activities. It can spread in factories, industries
RU HYHQ LQ WKH KRXVHV RI SHRSOH 6XFK ÀUH FDQ
burn and destroy everything. It can also destroy
the crops and forest. 7KH IRUHVW ÀUH EXUQV VHHGV
and saplings of plants and causes deforestation.
It also kills the nestlings of birds and babies of
wild animals.

:H VKRXOG DGRSW WKH IROORZLQJ PHDVXUHV WR VDYH RXUVHOYHV IURP ÀUH

.HHSLQJ WKH ÀUH PDNLQJ GHYLFHV VXFK DV PDWFKER[ OLJKWHU HWF DZD\
from the reach of children.

$YRLGLQJ VPRNLQJ 7KH VPRNHUV VKRXOG SXW RXW ÀUH RI cigarette butts
before throwing.

0DLQWDLQLQJ VDIH ZLULQJ LQ WKH KRXVH VR WKDW ÀUH GXH WR VKRUW FLUFXLW LV
avoided.

4. Keeping the ÀUH EULJDGH DQG ÀUH ÀJKWHUV LQ prompt position.

5. Managing a permanent source of water near the settlement area.

$WWHPSWLQJ WR SXW RXW ÀUH LQ FDVH LW VSUHDGV

Times' Crucial Science & Environment Book - 8 310

5HVFXLQJ WKH DIIHFWHG SHRSOH GXH WR ÀUH DQG HQVXULQJ WKHLU ÀUVW DLG

$GRSWLQJ PHDVXUHV WR VWRS WKH VSUHDG RI ÀUH IURP WKH DIIHFWHG DUHD

Epidemics management and mitigating measures of its risks

The widespread outbreak of an infectious disease which infects many people
at the same time and kills them is called epidemics. Several epidemics have
occurred in the past in Nepal. We should adopt the following measures to save
ourselves from epidemics:

1. Educating people about the causes of outbreak of diseases.

2. Drinking boiled water only and avoiding the intake of stale food.

3. Educating people about personal cleanliness and community sanitation.

4. Maintaining cleanliness at the source of water and ensuring its conservation.

5. Knowing the causes, effects and preventive measures of the disease and
acting according to it.

6. In case of epidemics, managing treatment for the affected people.

Conservation of environment

All organisms including human beings get all essential things from the
environment. Air, water, land, forest, minerals, heat, etc are such things which
are used by organisms. In addition to those things, human beings use other
animals too. It is the responsibility of human beings to use these things properly
and conserve them. Different activities such as public awareness programme,
afforestation, conservation of land, management of wastes, pollution control,
etc are done to conserve environment. Conservation of environment includes
those activities which are done to preserve the various components of the
environment. Some of the activities which are done for the conservation of the
environment are as follows:

1) Conservation of forest 2) Land conservation

3) Management of wastes 4) Pollution control

5) Public awareness 6) Management of drainage

7) Management of watershed

1. Conservation of forest: Conservation of forest plays important role for
the environmental conservation. Forest provides shelter to wild animals
and fresh air to the environment. It helps to maintain water cycle and
temperature of the environment. Moreover, it prevents various natural
GLVDVWHUV OLNH ÁRRGV ODQGVOLGHV HURVLRQ HWF )RUHVW FRQVHUYDWLRQ VKRXOG
be done through participation of local people. They should be made
aware. Tree plantation program should be launched. Subject matter of

311 Times' Crucial Science & Environment Book - 8

forest conservation should be kept in school level curriculum also. Strict
rules should be made against deforestation.
2. Conservation of land: Land is an important component of environment.
Land provides shelter to various types of animals. Plants grow on
the land. Human beings make infrastructure of development such as
buildings, parks, roads, bridges, etc on the land. Hence, the land is to be
preserved. Planting trees in naked hills, terrace farming in sloppy land,
reduction in the use of chemical fertilizers, etc are some of the ways of
land conservation. The content about the land conservation should be
kept in the curriculum of school.
3. Management of waste: Solid wastes such as animal excreta, solid waste
from kitchen, chemical fertilizers, pesticides, wastes from factories, etc
make the environment polluted. They should be properly managed.
Latrine should be made in every house. Public latrine should be made at
several places in town areas. Human and other animals’ excreta should
be disposed properly. The wastes from kitchen should be used to make
manure. The wastes from factories should be treated well before mixing
to the land. Public should be made aware about the management of
waste.
4. Pollution control: Dust and smoke from factories and vehicles,
chemicals and wastes from factories and hospitals, liquid waste from
kitchen, toilet and factories, etc are the main agents for pollution. It
is the responsibility of human beings to control those pollutants for
environmental conservation.
5. Public awareness: People should be made aware about the negative
impacts of environmental degradation. Unless people are conscious about
the environmental conservation, government and other agencies cannot
do anything for environmental conservation. Public campaign, informal
education, street drama keeping the education about environmental
conservation in curriculum of school and colleges are some of the activities
for public awareness.
6. Management of drainage: In town area, management of drainage is
an important task. The wastes from kitchen and latrines are discharged
through drainage. The drainage should be covered and supplied away
from drinking water supply. The leakage should be controlled by timely
repairing. The wastes from drainage should be collected in a big pit and
treated with chemicals to prevent the spread of diseases.
7. Watershed management: Watershed is the basis for the survival
of various types of aquatic animals and plants. Water is needed for
industries and agriculture. It is an important basis for tourism. It is also

Times' Crucial Science & Environment Book - 8 312

the source of drinking water. Therefore, it is to be conserved carefully.
Tree plantation in the surrounding of watershed, conservation of water
in the watershed, etc are some of the activities to be done for watershed
management.
National and International Organizations for the Conservation and
Promotion of Environment
9DULRXV QDWLRQDO DQG LQWHUQDWLRQDO DJHQFLHV DUH ZRUNLQJ LQ WKH ÀHOG RI
conservation and promotion of environment. Those organizations have
VLJQLÀFDQW UROH IRU WKH IRUPXODWLRQ RI SROLFLHV DQG SURJUDPPHV LQ WKH ÀHOG
of conservation. Nepal Trust for Nature Conservation (NTNC), Ministry of
(GXFDWLRQ HWF DUH VRPH QDWLRQDO RUJDQL]DWLRQV ZRUNLQJ LQ WKLV ÀHOG 6LPLODUO\
United Nations Environment Programs (UNEP), World Wide Fund for Nature
(WWF), International Centre for Integrated Mountain Development (ICIMOD),
HWF DUH VRPH LQWHUQDWLRQDO DJHQFLHV ZRUNLQJ LQ WKH ÀHOG RI FRQVHUYDWLRQ

1. Nepal Trust for Nature Conservation (NTNC)

It is a non-government organization established
in 2039 BS. It has been established with the aim
of conservation of the nature along with project of
development. It conducts national and international
seminars in association with environmental agencies.
Its chief functions are as follows:
1. To conduct research for the conservation of environment.
2. To carry out conservation work of land and watersheds.
3. To conserve endangered wild life and vegetation.
4. To conduct afforestation program.
5. To make local people participate for the conservation of the nature.
6. To conserve and promote national parks, wildlife reserves, temples,

stupas, etc.

2. The World Conservation Union (IUCN)

It is an international organization established
in 1948 AD. It was established as International
Union for the Conservation of Nature and Natural
resources, but later its name was changed as ‘IUCN’
WKH :RUOG &RQVHUYDWLRQ 8QLRQ ,WV KHDG RIÀFH LV LQ
Gland city of Switzerland.
Many Nepalese agencies like National Park and
Wildlife Conservation Department, Nepal Trust for

313 Times' Crucial Science & Environment Book - 8

Nature Conservation fund, Nepal Environment Journalists Group, etc
have taken the membership of IUCN.
Main objectives of IUCN
1. To protect natural solidarity of nature and its diversities.
2. To conserve natural resources and utilize them in a sustainable basis.
3. To inspire, encourage and co-ordinate with the different countries,

societies and organizations.
Important functions of IUCN
1. It helps government and non-government organizations to develop

training program package, books and other materials.
,W LGHQWLÀHV WKH LPSDFWV RI GHYHORSPHQW DFWLYLWLHV RQ WKH HQYLURQPHQW DQG

provides guidelines to minimize the adverse impacts.
3. It protects and conserves the cultural and natural heritages.
4. It encourages the conservation of bio-diversity.
5. It provides leadership to the local agencies to develop environmental

code of conduct.
,8&1 KDV HVWDEOLVKHG DQ RIÀFH LQ RXU FRXQWU\ 1HSDO LQ ,W KDV
been conducting many programmes with other agencies such as
National Planning Commission, Swiss Development Federation, etc. It
FRQGXFWHG YDULRXV SURJUDPV LQ WKH ÀHOG RI FRQVHUYDWLRQ RI ELR GLYHUVLW\
environmental law, environmental planning, conservation of natural
and cultural heritage, conservation of wetland, etc.

3. World Wide Fund for Nature (WWF)

WWF is an international organization for the
conservation of nature. It was established in 1961.
Its headquarters is in Switzerland. In Nepal, it is
called World Wildlife Fund (WWF).
It has been established with the following
objectives:
1. To protect and conserve the gene pool, races

of the organisms and the diversity of geo-
spatial system.
2. To ensure sustainable utilization of natural resources.
3. To conduct various programmes to reduce consumption of natural
resources and production of toxic pollutants.

Times' Crucial Science & Environment Book - 8 314

Programs
WWF has conducted hundreds of projects for the conservation of nature
in 130 countries. It helps in the protection and conservation of rare
wild animals and vegetation. It helps to conduct programmes such
as preserving water resources, protection of endangered plants and
animals, discouraging illegal trading of endangered animals and plants.
It encourages different countries to establish ministry for environment
and nature conservation.

4. United Nations Environment Programme (UNEP)

United Nations Environment Programme
(UNEP) is an organization established by
8QLWHG 1DWLRQV LQ WR ZRUN LQ WKH ÀHOG RI
FRQVHUYDWLRQ RI HQYLURQPHQW ,WV KHDG RIÀFH
is in Nairobi of Kenya ,WV UHJLRQDO RIÀFH IRU
Asia is situated at Bangkok, the capital city of
Thailand.
The UNEP has been conducting various
programmes for the conservation of
environment of the world. It is working
for maintaining balance between environment and development. It
organizes many world conferences in ɇ(QYLURQPHQW DQG 'HYHORSPHQW·.
The discussions are mostly related to the conservation of bio-diversity,
reduction of greenhouse effect, reduction in the production of greenhouse
gases, protection of ozone layer, etc. It works as a co-ordinator to the
various environmental programmes conducted by the different agencies
of United Nations.

5. International Centre for Integrated Mountain Development
(ICIMOD)

ICIMOD is a non-governmental
organization established with the help
of UNESCO in 1983. Its main objective
LV WR ZRUN LQ WKH ÀHOG RI GHYHORSPHQW
of natural resources, hilly region and community development.
Objectives
1. To exchange knowledge of policy, programs and projects for

integrated development of hilly region.
2. To conduct trainings and programs for integrated development of

hilly regions.

315 Times' Crucial Science & Environment Book - 8

7R LQFUHDVH WKH FDSDFLW\ RI WKH SHRSOH RI KLOO\ UHJLRQ WR ÀJKW ZLWK
problems of hilly region.

Activities of ICIMOD
ICIMOD has conducted various programs for environmental conservation.
It has organized various conferences in collaboration with national and
international agencies about the development of hilly region. It has
done research work of district level energy project, management of
mountainous watershed area, employment opportunity in hilly region,
hilly agriculture and generology, horticulture, bee farming, hill disasters,
etc. It has been trying to solve various problems of hilly region.

ĐƵůƟǀĂƟŽŶ ͗ ĂĐƟŽŶ ŽĨ ŐƌŽǁŝŶŐ ĐƌŽƉƐ͕ ǀĞŐĞƚĂďůĞƐ͕ ĞƚĐ

monuments ͗ Ă ƐƚĂƚƵĞ͕ ďƵŝůĚŝŶŐ ŽĨ ŚŝƐƚŽƌŝĐ ŝŵƉŽƌƚĂŶĐĞ

ŝƌƌŝŐĂƟŽŶ : suply of water to land or crops

ŝŶƐĞĐƟĐŝĚĞ : a chemical used to kill insects

ƉĞƐƟĐŝĚĞ : a chemical used to kill insects that damage crops

coastal region : a region near to ocean

ƌĞŚĂďŝůŝƚĂƟŽŶ ͗ ĂĐƟŽŶ ŽĨ ƌĞƐƚŽƌŝŶŐ ƐŽŵĞŽŶĞ ƚŽ ŶŽƌŵĂů ůŝĨĞ

1. Mixing of unnecessary things to the environment which causes undesirable change
in the physical, chemical and biological properties of air, water, land, etc. is called
environmental pollution.

2. Mixing of various types of harmful gases, dusts, bad smells, etc to the air is called
air pollution.

3. Mixing of sewage, liquid wastes from factories, chemicals from hospitals, etc. to
the water source is called water pollution.

4. Mixing of waste from kitchen, industries, hospitals, etc to the land is called land
pollution.

5. Greenhouse is a house made up of glass or plastic inside which warm environment
suitable for the growth of plants is created.

6. Due to presence of gases like SO2, CO2, CFCs, dust particles, water vapour, etc the
atmosphere acts as glass of greenhouse. Thus, the earth is getting hotter every
year. It is called greenhouse effect.

7. Change in global temperature, floods occurring in summer seasons, disturbance in
water cycle, etc are some climatic changes.

8. The falling of the acid along with the rain is called acid rain.

9. Conservation of environment includes those activities which are done to preserve
the various components of environment such as water, air, land, forest, etc.

Times' Crucial Science & Environment Book - 8 316

10. Conservation of forest, land conservation, management of wastes, pollution control,
management of drainage, watershed management, etc are some activities done for
the conservation of environment.

11. Natural disasters like earthquake, floods, landslides, volcanoes, tsunami, hurricane,
etc cause the loss or damage of life and property.

12. Shaking or vibration of the surface of the earth is earthquake.

13. Sliding down of a piece of land, soil or rocks in the hills or slopy land due to gravity
of the earth is landslide.

14. Flood is defined as inundation of normally dry land due to overflowing of water
sources.

15. IUCN, WWF, UNEP, ICIMOD, etc are some national and international agencies
working for the conservation of environment.

Exercise

A. Fill in the blanks.
1. SO2, CO2, dust particles, water vapour, etc are…………
2. ……………causes the corrosion of historical monuments like
statues, sculptures, etc.
/DQGVOLGH HDUWKTXDNH ÁRRG YROFDQR HWF DUH«««««
4. …………….is used to measure magnitude of the earthquake.
5. …………..is located in Gland city of Switzerland.
6. …………was established in 1961 A. D.

B. Write down the full form of:

i. NTNC ii. IUCN iii. WWF

iv. UNEP v. ICIMOD

C. Answer these questions in short.
1. What is pollution?
2. What is greenhouse? Is it necessary in hot places?
3. What is greenhouse effect? Name some greenhouse gases.
4. What is climatic change? Give some examples.
5. What is acid rain? What are the gases responsible for acid rain?
6. What is natural disaster? Give some examples.
7. What is landslide? What are its causes?

317 Times' Crucial Science & Environment Book - 8

:KDW LV ÁRRG" 0HQWLRQ LWV SUHYHQWLYH PHDVXUHV
9. What is volcano? What are the causes of volcano?

' 'HÀQH ii. Epicentre iii. Richter scale
i. Hypocentre

E. Answer these questions.
1. Write down the causes, effects and preventive measures of air
pollution.
2. How does greenhouse work? Explain the positive impacts of
greenhouse effect.
3. Explain the negative impacts of greenhouse effect.
4. What are adverse effects of acid rain?
5. Explain the various activities to be done for the conservation of
environment.
6. Explain the causes of earthquake.
7. Explain preventive measures of landslide.

F. Write short notes on

i. IUCN ii. WWF iii. ICIMOD

What activities are done in your community for the conservation of
environment? Explain such activities. Which organizations are involved for
carrying out such activities? Prepare a report and show it to your teacher.

Times' Crucial Science & Environment Book - 8 318

25CHAPTER Environment and
Sustainable
Development
Gro Harlem Brundtland

*UR +DUOHP %UXQGWODQG LV D 1RUZHJLDQ SROLWLFLDQ ZKR VHUYHG WKUHH
WHUPV DV 3ULPH 0LQLVWHU RI 1RUZD\ 6KH ZDV WKH FKDLUPDQ RI WKH
%UXQGWODQG &RPPLVVLRQ IRUPHG E\ WKH 81 WKDW LQWURGXFHG WKH

FRQFHSW RI VXVWDLQDEOH GHYHORSPHQW E\ SXEOLVKLQJ D UHSRUW LQ

Estimated Periods : 7
Objectives: At the end of the chapter, the students will be able to:

LQWURGXFH WKH ELR GLYHUVLW\
H[SODLQ WKH SULQFLSOHV RI VXVWDLQDEOH GHYHORSPHQW
H[SODLQ WKH DWWHPSWV UHJDUGLQJ VXVWDLQDEOH GHYHORSPHQW LQ WKH ZRUOG

What is biodiversity?
What is the effect of development in biodiversity?
Can developmental activities be carried out without harming the natural
environment? Discuss.

Biodiversity

The word ‘biodiversity’ is the short form of ‘biological diversity’. The term
ELRORJLFDO GLYHUVLW\ ZDV ÀUVW XVHG E\ ZLOGOLIH VFLHQWLVW ) 'DVPDQQ LQ ,WV
contracted form ‘biodiversity’ might have been coined by W.G. Rogen in 1985
for the study of variety and prevalence of species of plants and animals. Thus,
the term biodiversity denotes the existing number of living organisms in a
particular area and the differences between them. For example, we see plants
around us. Most of the plants are green and they prepare their own food. It is
the common feature of plants. But, there are differences among the different
species of plants: some are tall trees, some are shrubs while some are soft and
small herbs. Similarly, some plants grow on common land, some in water and
some in desert. It means there is diversity among the plants.
Hence, ELRGLYHUVLW\ PD\ EH GHÀQHG DV WKH PHDVXUH RI YDULHW\ RI HDUWK·V
animals, plants and microbes having genetic differences within the species
and in ecosystems. It means that biodiversity refers to the total number of
genes, species and ecosystems in a region and the variations between them.
The biodiversity can be categorized into three classes-species diversity, genetic
diversity and ecosystem diversity.

319 Times' Crucial Science & Environment Book - 8

Ecosystem diversity

An ecosystem is a dynamic structural and functional system of biotic community
and its non-living environment, which interact together. An ecosystem may
be natural or man-made, small or large, short lived or long-lived, etc. For
H[DPSOH D ZDWHU ÀOOHG SRQG LQ UDLQ\ VHDVRQ ZKLFK EHFRPHV GU\ LQ ZLQWHU LV
an example of small, short lived and natural environment. On the other hand,
river, forest, lake, sea, etc are large, long-lived and natural ecosystems. An
aquarium is a small man-made ecosystem.
Ecosystem diversity refers to the variety and number of distinct ecosystems
in a particular geographical area. It includes different types of habitats, biotic
communities and their composition.

Aquarium WŽŶĚ ĞĐŽƐLJƐƚĞŵ

There are different types of ecosystems in Nepal according to the geographical
regions. It is divided into three regions the Terai, hilly and Himalayan region,
which have different physical features. The variation in climate and structure
of land has caused the diversity in ecosystem. Nepal is rich in ecosystem
diversity. It has been recorded that Nepal has a total of 118 types of ecosystems,
75 types of vegetation and 35 types of forests. Different ecosystems exist in the
forests, wetlands, mountains, lakes, rivers, agricultural lands, etc. In each
ecosystem, particular creatures form a community interacting with other
living and non-living components. Thus, there is diversity in ecosystem.

Genetic diversity

No two individuals on the earth are exactly similar to one another. They differ
from one another even if they belong to the same species. It is due to the
variation of genes present in different individuals.

The genes are the basic structural units present in the chromosome of a cell.
The arrangement of genes in chromosomes determines the characteristics of
an individual. The genes carry hereditary information that is transmitted
from one generation to the next.

The genetic composition of a species is different from that of another species.
For example, the goats are different from sheep in many respects although
there are differences among the goats.

Times' Crucial Science & Environment Book - 8 320

Species diversity

Species diversity refers to the variety of living beings. A species is a group or
population of similar organisms that reproduce by interbreeding within the
group. The members of a species cannot breed with those of another species.
A large number of plant and animal species are found in Nepal. Hence, there
is species diversity.

Sustainable development and its principles

Sustainable development means those developmental activities that meet the
needs of present people without compromising the ability of future generations
to meet their own needs. Actually, it is a system of using resources in which
the present human needs are met while preserving the environment. Thus,
WKH QHHGV DUH IXOÀOOHG QRW RQO\ IRU WKH SUHVHQW SHRSOH EXW DOVR IRU WKH IXWXUH
generations.
It is clear that sustainable development is a must for environmental
conservation. The principles of the sustainable development include the
environment friendly activities. These principles can be explained as follows:
1. Conservation of ecosystem

Sustainable development is based on the principle of maintaining
a balance between biotic and abiotic components of an ecosystem.
Hence, biodiversity and natural resources are preserved in sustainable
development .
2. Conservation of biodiversity
Every species of plant and animal has a role in the balance of nature.
Similarly, every non-living component is equally important. If any of
these components are destroyed while carrying developmental activities,
the natural balance will be disturbed. The unbalance in natural cycles
has dangerous consequences on human as well as other lives. Hence,
sustainable development emphasizes on the developmental activities
based on biodiversity conservation.
3. Control of population growth
The uncontrolled population growth is the main cause of environmental
degradation. It is because the large population means the rapid
consumption of natural resources. Hence, the population must be
controlled in order to meet the objectives of sustainable development.
4. Emphasis on public participation
People play major role for the continuous improvement of environmental
resources. They are both the consumers and the conservers of the

321 Times' Crucial Science & Environment Book - 8

environmental resources. Hence, public participation is a must for
sustainable development.
5. Development of human resource
Human beings are the rational creatures, hence, they must be conscious for
the proper use of natural resources. They should have essential knowledge
and skill for the proper mobilization of developmental activities.
6. Conservation of cultural heritages
Sustainable development emphasizes on the conservation of social
traditions, customs, religious places and cultural activities of people.
It is because our present civilization and advancement leads the future
generations to live comfortable life.
7. Limit of development activities
Our earth has certain carrying capacity for every kind of developmental
activity, Hence, the sustainable development aims at carrying out the
development activities taking care of the capacity of the earth. It also
teaches people to use the natural resources within limits.

Global efforts on sustainable development

The idea of sustainable development grew from numerous environmental
movements in earlier decades. The summits such as the Earth Summit in
Rio, Brazil, 1992, were major international meetings to bring sustainable
development to the mainstream.
The main global attempts on the sustainable development are:
1. Addressing biodiversity loss

The Convention of Biological Diversity (CBD) was born in the “Earth
Summit”, 1992. Now, 192 countries and the EU are the parties to that
convention. In April, 2002, the Parties to the Convention committed to
VLJQLÀFDQWO\ UHGXFH WKH ORVV RI ELRGLYHUVLW\ E\
2. Rio+20 UN conference on sustainable development:
Twenty years after the Earth Summit (1992), a conference was held
by UN on sustainable development. The conference aimed to get bold
agreements to address things like poverty, sustainable development,
decent jobs, etc.
3. Non-governmental organizations
Some of the NGOs have come up with the objectives to become more
participatory, grass root- oriented to help empower the people, to save
the nature, etc.

Times' Crucial Science & Environment Book - 8 322

4. Foreign aid for development assistance
In 1970, the world’s rich counties agreed to give 0.7% of their gross
national income DV RIÀFLDO LQWHUQDWLRQDO GHYHORSPHQW DLG WR WKH SRRU
countries.

5. Water and development
The concept has arisen to use water resource for the country’s development.

6. Energy security
This concept focuses on access to clean, reliable and affordable energy
services for cooking, heating, lighting, communication, etc.

7. World summit on sustainable development:
The world summit on sustainable development (2002) discussed various
issues such as privatization of water resources, energy security, etc for
the sustainable development.

Importance of Sustainable Development

Sustainable development is essential for the environmental conservation. If
we carry out development activities in sustainable way, the present natural
resources of the earth can be used for a long time. Thus, the resources will be
useful for other animals and the future human generations.
The importance of sustainable development can be summarized in the following
points:
1. It stresses on the proper use and management of natural resources.
2. It helps to make adequate food available for wildlife.
3. It helps to improve living standard and lifestyle of human beings.
4. It also helps to maintain the limit of consuming natural resources.
5. It helps to aware people about their responsibility to preserve the environment.
6. It helps to save the natural resources for the next generation.
7. It develops the concept of conservation of natural resources and

environment in the people.

chromosomes : thread like structure of nucleic acids found in nucleus of cells
sustainable ͗ ĂďůĞ ƚŽ ŵĞĞƚ ƉƌĞƐĞŶƚ ŶĞĞĚƐ ǁŝƚŚŽƵƚ ĚŝƐƚƵƌďŝŶŐ ĨƵƚƵƌĞ ŐĞŶĞƌĂƟŽŶƐ

323 Times' Crucial Science & Environment Book - 8

1. Biodiversity may be defined as the measure of variety of earth’s animals, plants
and microbes having genetic differences within the species and in the ecosystem.

2. An ecosystem is a dynamic structural and functional system of biotic community
and its non-living environment, which interact together.

3. Ecosystem diversity refers to the variety and number of distinct ecosystems in a
particular geographical area.

4. Genetic diversity includes genetic differences within each species.

5. Species diversity refers to the variety of living beings.

6. Sustainable development means those developmental activities that meet the needs
of present generation without compromising the ability of future generations to
meet their own needs.

7. The principles of sustainable development are as follows:

a. Conservation of ecosystems b. Conservation of biodiversity

c. Control of population growth d. Emphasis on public participation.

e. Development of human resource. f. Limit of development activities.

g. Conservation of cultural heritages

Exercise
A. Answer these questions in very short.

:KR XVHG WKH WHUP ELRORJLFDO GLYHUVLW\ IRU WKH ÀUVW WLPH"

2. What was the term ’biodiversity’ used for?

3. What is biodiversity?

4. What are the three classes of biodiversity?

5. How many types of ecosystems are found in Nepal?

6. Give an example of short-lived natural ecosystem.

7. Give an example of man-made ecosystem.

B. Write down short notes on:

i. Genetic diversity ii. Species diversity

C. Answer these questions:

1. What is ecosystem? Explain ecosystem diversity.

2. What is sustainable development? Why is it necessary ?

3. Enlist the principles of sustainable development and explain them.

4. Explain the global efforts for the sustainable development.

3UHSDUH D OHDÁHW WKDW PDNHV SHRSOH DZDUH DERXW WKH SURSHU XVH RI WKH QDWXUDO
resources considering the needs of future generations.

Times' Crucial Science & Environment Book - 8 324

dŝŵĞ͗ ϮŚƌƐ ϭϱŵŝŶƵƚĞƐ 6SHFLÀFDWLRQ *ULG WĂƐƐ ŵĂƌŬƐ͗ ϯϬ

Grade: 8 (Science and Environment)

&Ƶůů ŵĂƌŬƐ͗ ϳϱ

Group EŽ͘ ŽĨ ƋƵĞƐƟŽŶƐ Weightage in % and marks
Areas SA LA
Units SA SA SA LA
;ϯϮй<Ϳ ;ϭϴ͘ϲйhͿ ;ϭϲй Ϳ ;ϯϯ͘ϯй, Ϳ

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A Simple Machine+Pressure+ 52 3 221
tŽƌŬ͕ ŶĞƌŐLJ ĂŶĚ WŽǁĞƌн,ĞĂƚн

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Salt+Some Useful Chemicals

325 C ŝŽůŽŐLJ >ŝǀŝŶŐ dŚŝŶŐƐн Ğůů͕ dŝƐƐƵĞ ĂŶĚ 51 3 1 1 1
Organ+Life Processes

Times' Crucial Science & Environment Book - 8 D Environment 'ĞŽůŽŐLJ Θ Structure of the Earth+Weather and Climate+The Earth and 1 or 2 or 1 1 - 1
Science ƐƚƌŽŶŽŵLJ Space none none

Environment and its Balance+

E ŶǀŝƌŽŶŵĞŶƚ ĞŐƌĂĚĂƟŽŶ ĂŶĚ ŝƚƐ ŽŶƐĞƌǀĂƟŽŶн ŶǀŝƌŽŶŵĞŶƚ 5 2 3 2 2 1

and Sustainable Development

Percentage 32% 18.6% 16% 33.4%
Marks 24 14 12 25

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Times' Crucial Science & Environment Book - 8 Practical

Number of Remarks
item

Group dLJƉĞƐ ŽĨ ŝƚĞŵ Diagram ^ƉŽƫŶŐ ; EĂŵĞͬ ĐƟǀŝƟĞƐ &ŝĞůĚͬ KƌĂůͬ Total
Areas (A) ŚĂƌĂĐƚĞƌŝƐƟĐƐͿ (C) Project sŝǀĂͬ Marks
Žƌ ĨƵŶĐƟŽŶ Žƌ Class
ĐůĂƐƐŝĮĐĂƟŽŶ; Ϳ (D)

dŝŵĞ ;ŵŝŶ͘Ϳ ϭϬ ŵŝŶ ϱ ŵŝŶ ϱ ŵŝŶ ϭϬ ŵŝŶ ϮϬ ŵŝŶ ϱ ŵŝŶ

Units ƌĂǁŝŶŐͬ Labelling
ŽƉLJŝŶŐ

Marks ϱ ϱ ϱ ϱϱ ϱ

Measurement+Force &
DŽƟŽŶн
Simple
WŚLJƐŝĐƐ Machine+Pressure+ Each item

A tŽƌŬ͕ ŶĞƌŐLJ ĂŶĚ hold 5
Power+Heat+ marks
Light+
^ŽƵŶĚнDĂŐŶĞƟƐŵн
Electricity

326 ŚĞŵŝƐƚƌLJ DĂƩĞƌн>ĂŶŐƵĂŐĞ ŽĨ
Chemistry+
^ĞƉĂƌƟŽŶ ŽĨ
B Mixture+Metals and

EŽŶͲŵĞƚĂůƐн ĐŝĚ͕ ĂƐĞ
and Salt+
Some Useful Chemicals

>ŝǀŝŶŐ dŚŝŶŐƐн Ğůů͕ ŝŽůŽŐLJ
C Tissue and

Organ+Life Processes

D Structure of theEnvironment 'ĞŽůŽŐLJ Θ
Earth+Weather andScience ƐƚƌŽŶŽŵLJ
Climate+The Earth and
Space

Environment and its
Balance+
Environment
ĞŐƌĂĚĂƟŽŶ ĂŶĚ ŝƚƐ
E ŽŶƐĞƌǀĂƟŽŶн

Environment and
Sustainable
Development

Model Test Paper F.M.: 75
P.M.: 30
(Issued by CDC) Time: 2:15 hrs
Class : 8
Subject: Science and Environment

Candidates are required to give answer in their own words as far as practicable.

Attempt all the questions.
Group : A [Physics]

1. a. What is mass? Write two differences between fundamental and
derived unit. [1K+2U]

E :KDW ZLOO EH ÀQDO YHORFLW\ RI YHKLFOH LI LW VWDUWHG IURP UHVW DQG
accelerates at 5 m/s2 after 5 second? [2HA]

D 'HÀQH [1+1+1=3K]

L 0HFKDQLFDO DGYDQWDJH LL 9HORFLW\ UDWLR LLL (IÀFLHQF\

b. Prove that, liquid pressure (P)=hdg [2]

D 'HÀQH ZRUN DQG SRZHU :ULWH WKH UHODWLRQVKLS EHWZHHQ WKHP
[1K+1K+1U]

b. Write two differences between clinical and simple thermometer. [2U]

4. a. What is refraction of light? Which type of mirror is used as side
mirror in vehicles and why? [1K+0.5K+1K]

b. What is unit of frequency? Write any two differences between echo
and reverberation. [0.5K+2U]

5. a. Draw the diagram to show the arrangement of the molecular magnet
in magnetic substance. [2A]

b. Why do we use dry cell in a torch light? Write any three reasons. [3A]

Group : B [Chemistry]

6. a. Write the molecular formula of common salt. Write the balanced
chemical equation of the following word equation. [1K+2U]

Hydrogen + Oxygen → water [2A]
E 'UDZ WKH HOHFWURQLF FRQÀJXUDWLRQ RI 0DJQHVLXP DWRP

7. a. What is chromatography? Which types of mixtures are separated by
the use of chromatography? [1K+2U]

b. Write any one use of sulphur and copper each. [1+1=2U]

327 Times' Crucial Science & Environment Book - 8

8. a. What effect do acid, base and salt have on different indicators? Show
b. in table. [3A]

9. a. How can you detect hardness of water collected from different
E sources? [2U]
10. a.
Group : C [Biology]
b.
11. a. Draw a well labelled diagram of virus. [3A]

b. :K\ GRHV PRGLÀFDWLRQ RI URRW RFFXU" :ULWH DQ\ WZR FDXVHV RU XVHV [2U]

12. a. Write the relationship between cells, tissuse and organs in human
b. body. [2K]

13. a. Write the name of tissues found in animals. [2K]
b.
What do you mean by vegetative propagation? Write the name of
14. a. two plants which reproduce by this process. [1K+1U]
b.
What is photosynthesis? How can you demonstrate that plants prepare
15. a. their food on their leaves? Write with an experiment. [1K+2HA]
b.
Group : D [Geology and Astronomy]

What is soil erosion? Which region of Nepal receives more rainfall?
Why? [1K+1.5U]

What is meant by phases of moon? Write any three reasons for the
existence of living being on earth. [1K+1.5U]

Group : E [Environment Science]

What can human beings get from nature? Write any three
examples. [3U]

Write the differences between national park and wildlife resrve. [2K]

Write any four causes of water pollution. Give any measure that
mitigates water pollution in your region. [2U+1HA]

What is climate change? Write two effects of climate change. [1+1=2K]

What is biodiversity? Write its types. [1.5+1.5=3K]

What can you do in your residential area for protection of
environment? Write any four points. [2HA]



Times' Crucial Science & Environment Book - 8 328