New Creative Science and Environment Book 7

Write the characters of rocks in the following chart:

Igneous rock Sedimentary rock Metamorphic rock

Some important rocks found in Nepal

Conglomerate: It is a sedimentary rock. It is formed by aggregation of
pebbles, gravels and sand. It is one of the common types of rock that are found in
Nepal. It is found in and around river and their basins.

Sandstone: It is a sedimentary rock that is formed by the cementation of
sand particles. It is found in rivers and at their banks. It is used as aggregate in
various construction works especially road paving and flooring. Red sandstone
is used for decorative purposes.

Silica: It is generally obtained as silica sand from the weathering of silicate
rocks. It is formed from silicon and oxygen. It is also one of the important
constituents in cement and glass manufacturing. It is one of the important
constituent in most of the silicate rocks. Karra Khola (Makwanpur) has a deposit
of high quality silica sand. It is suitable for glass industry.

Limestone: Limestone is also a sedimentary rock. It is formed from high
percentage of calcium carbonate. It is one of the widely extracted mineral rocks
in Nepal. It is the major constituents for the manufacturing of cement. Some of
the main limestone deposits are Sindhali and Galtar (Udaypur), Bhainse, Okhare
and Nibuwatar (Makwanpur), Jogimara and Beldada (Dhadhing), Chovar,
Bhattedanda (Lalitpur), Balthali and Nandu (Kavre), Kakaru Khola (Sindhuli),
Nigale (Dhankuta), Chaukune and Lakharpata (Surkhet), and Gandari (Dang).

Marble: Marble is a metamorphic rock. It is formed by the metamorphosis
of limestone. This rock is widely used for making decorative items and flooring
houses, temples, monasteries etc. Pink, gray and white coloured marble deposit
is located in Godavari, (Lalitpur district). Other deposits of marble are Anekot
(Kavre) and Chhatre Deurali (Dhadhing).

Slate: Slate is also a metamorphic rock. It is also formed by metamorphosis
of mudstone or shale. Slate is the common roofing and pavement material. Boards
made of slate are also used in schools for writing purpose. They are extensively

Struc tru e of the Earth 197

mined from different parts of Tanahun, Nuwakot, Sindhupalchok, Dhadhing,
Baglung, Parbat, Jajarkot, Accham, Doti, Dadeldhura, Baitadi, Bajhang, Bajura
and many other districts.

1. Pearl is not a mineral. Why?
Ü Pearl is not a mineral because it is produced by a living being known as the

oyster.
2. Igneous ricks donot have fossils? Why?
Ü Igneous rocks do not have fossils because they are made from the hot molten

magma.
3. Plutonic rocks have big crystails in them. Why?
Ü Plutonic rocks have big crystals in them because they are formed by the

slow cooling of magma inside the earth crust.

F Rocks are the mixture of different types of minerals.
F Rocks are of three types i) Igneous rock ii) Sedimentary rock

iii) Metamorphic rock
F Igneous rocks are formed by the cooling of hot magma.
F Sedimentary rocks contain fossils but igneous and metamorphic rocks do

not contain fossil.
F Metamorphic rocks are formed from other rocks.

1. Fill in the blanks.
a) Rocks are of different kinds. They are igneous rocks, __________ and
___________.
b) Molten hot rocks are called _____________.
c) Different substances settle in layers and form ___________.
d) The ____________ of organisms are also fixed in rocks.
e) Because of extreme heat inside the earth, ____ melts and forms magma.

198 New Creative Science and Environment; Book 7

2. Distinguish between:

a) Igneous rock and sedimentary rock

b) Sedimentary rock and metamorphic rock

c) Rock and mineral

3. Name the type of the following rocks:

a) Granite b) Pumice c) Slate d) Obsidian

e) Basalt f) Marble g) Shale h) Limestone

4. Answer the following questions.

a) What is a rocks? Write their types.

b) Describe how metamorphic rocks are formed?

c) What are igneous rocks?

d) Define sedimentary rocks.

e) Write two examples each of igneous, sedimentary and metamorphic
rocks?

f) Write any four uses of rocks.

g) Name any two rocks and heir deposits in Nepal.

h) Write one use each of the following rocks.

i) Slate

ii) Silica

iii) Marble

iv) Limestone

Interior - internal part
Exterior - outer part
Eruption - coming out of

Struc tru e of the Earth 199

19 Weather and Climate

After the completion of this unit, students will be able to:

Æ explain weather and climate.
Æ describe the elements that determine weather and climate.
Æ explain water cycle.
Æ describe the layers of atmosphere.
Æ describe the instruments that are used to measure the

elements of weather.

Weather and climate

When we talk about weather, we refer to what is happening now or what
may happen in a next few days. Then what is climate? Our grandparents used to
say that winters of Kathmandu valley in the past were very cold or temperature
of Kathmandu in summer was low in comparison to that of the present days.

Climate describes the weather conditions occurring over a long period of
time in a given place.

For the climatic study, we need to have the data of rainfall, temperature,
humidity, pressure, sunshine, cloud and wind of about 30 years.

The climate of the earth depends on the distance from the sun, tilt of its
rotational axis, the size of the planet, the composition and denseness of its
atmosphere and human factors. On the basis of the with mentioned factors, the

climate of the earth is broadly divided into:

§ tropical climate § subtropical climate
§ temperate climate § alpine climate

The study of weather and climate in the present days has become a new
discipline of science. The branch of science that deals with the weather system
is called meteorology and the branch of science that deals with the climate is
known as climatology.

The applications of these subjects can be seen in different parts of our society.
Climatology is used in the agricultural society and is termed as agro climatology.

200 New Creative Science and Environment; Book 7

Elements that determine weather and climate

There are various factors that affect the weather of a certain place, which are
as listed below:

a) Temperature b) Rainfall c) Pressure

d) Humidity e) Wind f) Cloud

Cloud

Water on the earth’s surface evaporates due to intense heating by solar
energy. The evaporated water vapour rises and combines with each other to
form tiny water droplets expanding its volume. The huge mass of tiny water
droplets in the sky is known as clouds. They study of different types of clouds
helps meteorologists to predict the weather of a day.

Water cycle

Water from the seas,

oceans, river, ponds as well

as vegetations of the land

evaporates due to the heat of

the sun. This heated water is cloud
lighter and so rises in the sky in

the form of water vapour. This rain
water vapour on cooling on the vapour
atmosphere is condensed into

water droplets. Water droplets

cling together to form clouds. Watercycle
These clouds flow toward the

direction of the wind. When these clouds collide with each other or become

heavier, the water droplets fall on the earth’s surface in the form of rain. The rain

water finds its way back to their sources. In this way, water cycle continues in the

nature. Therefore, the circulation of water from earth’s surface to the atmosphere

and back from atmosphere to the earth’s surface is known as water cycle.

Atmosphere

The thick layer of the air which surrounds the earth is called the atmosphere.
Air is the mixture of different gases. Living beings can survive on the earth because
the earth consists of suitable air in its atmosphere. As the height increases from
the surface of the earth, the air becomes thinner and thinner. The atmosphere
is divided into five layers according to the heights from the earth’s surface and
change in temperature. The layers of atmosphere are

Weathe r and Climate 201

(i) Troposphere (ii) Stratosphere
(iii) Mesosphere (iv) Thermosphere
(v) Exosphere

(1) Troposphere

It is the lowermost and thinnest
layer of the atmosphere. It extends
upto 16km from our earth’s surface.
The main constituents of this layer are
N2, O2, CO2, water vapour, dust, etc.
All the changes in weather take place
in this layer because this layer consists
of clouds. This layer is greatly affected
by human activities. As the height
increases, the temperature decreases
in this layer.

(2) Stratosphere

It is the second layer of the
atmosphere. It extends from 16-50 km
upwards. The main constituents of this
layer are ozone and oxygen. So, this
layer is also known as ozonosphere.
The ozone layer protects us from the harmful effects of sun light coming from the
sun. As the altitude increases, the temperature increases in this layer.

Memory Tip

Jet planes fly in stratosphere.

(3) Mesosphere

It is the third layer of the atmosphere. It extends between 50-80 km above
the earth. In this layer, strong winds blow eastward in winter and westward in
summer. In this layer, the temperature decreases as the height increases.

(4) Thermosphere

It expends from 80-720 km above the earth’s surface. Its main components
are helium, nitrogen and oxygen. The particles in this layer are electrically
charged. Radio waves travel in this layer. The temperature increases as the height
increases in this layer.

(5) Exosphere

It is the outermost layer of the atmosphere which extends beyond 720 km
away from the earth’s surface. There is very less gravity and the presence of air
is also negligible.

Air and Wind

Air is a mixture of different gases. The
molecules of gases remain far from each other.
It causes the air to spread widely. When the sun
light strikes on the surface, the air near to the
surface gets heated. The heat causes the gaseous
molecules to expand. The expanded hot air rises
in the sky. The space created by the rising of air
is occupied by cold air from the surrounding
area. This process of movement of air is called convection. This is a main cause of
the blowing of air. Blowing air is called the wind. The wind helps to dry clothes,
seeds and frost. When air blows at a high speed, it is called a storm. Storms can
sweep crops, uproot communication tower, break the branches of trees, and
sweep the roofs of houses and carries dust and dirt with it. It also can cause
electrical hazards. Therefore, we should not go outside during storms.

Movement of air

We know that the sun provides heat energy for the movement of the air.
During the day, the land is heated quickly than the water of seas and oceans. Due
to this, the air near to the surface of land is hot while the air above the surface
of the ocean is comparatively cold. The hot air then rises in the sky. The cold air
moves from the ocean to the land to occupy the space formed by the rising of hot
air. This movement of cold air from the ocean to the land during the day is called
a sea breeze.

Weateh r and Climate 203

During the night, land cools faster than the water of the ocean. The air above
the land surface becomes cold while the air above the ocean surface remains
warmer. Due to this, the warm air from the ocean rises in the sky and cold air
from the land blows to occupy that space over the ocean. The movement of cold
air from the land to the ocean during the night is called a land breeze.

Question

# How do a sea breeze and a land breeze occur?
# Islands have a cool and calm weather throughout the year. Why?
Weather

Weather is a state of the air at a particular time and in a particular place. The
elements of weather include temperature, humidity, cloudiness, precipitation,
wind, and pressure. The branch of science that studies about weather is called
Meteorology.

The radio and television provide us the information about the condition of
sunshine, cloudiness, humidity, temperature and rainfall. These are the elements
that affect the weather of a given place. The weather elements are measured from
different stations and the result is provided to the general public from the news.
It makes us ware of the weather events occurring in our region.

Some instruments for measuring elements of weather

Different types of instruments are needed to measure different elements of
weather. Here, we will discuss some of the instruments for measuring weather
elements.

Barometer

The force exerted by atmosphere on per
unit area of the earth surface due to its weight is
called atmospheric pressure. A barometer is the
instrument that measures the atmospheric pressure
of a given place. Traditional barometers are made
using mercury as barometric fluid. Now digital and
aneroid barometers are widely used to measure the
atmospheric pressure. As the height from the earth
surface increases, the value of atmospheric pressure
decreases. Storms generally occur in low-pressure
areas. Rapidly falling pressure usually leads to a storm whereas rapidly rising
pressure generally leads to a clear atmosphere.

204 New Creative Science and Environment; Book 7

Maximum and minimum thermometer

Atmospheric temperature is
measured by using a thermometer.
The maximum and minimum
temperature of the atmosphere
within a period of 24 hours is
measured by using a special
thermometer called maximum-
minimum thermometer. Mercury or alcohol is used as a thermometric liquid
in this thermometer. This thermometer allows mercury to expand upward
but it avoids the back flow of mercury. Therefore, maximum and minimum
temperature is recorded. After the measurement, mercury is forced to back by
shaking vigorously and set for measurement for another day.

Hygrometer

Humidity is the amount of water vapour
content in air. Relative humidity is the ratio of water
vapour present in a given volume of air at a given
temperature. It shows the maximum water vapour
that the air can hold. A hygrometer is an instrument
that measures the relative humidity of air in a given
place. It contains moisture absorbing fibre. This
fibre is connected with a dial. The dial shows the
percentage amount of moisture content in air. If the
temperature of air rises and the amount of water vapour in air decreases then
the relative humidity also decreases and vice versa. The chance of a rainfall or
snowfall is high when the relative humidity is high.

Anemometer

An anemometer is an instrument
that measures the speed and direction of
the wind. It consists of three or four cups
attached to the short rods that are connected
at right angles to a vertical shaft. As the
wind blows, it pushes the cups. The cups
then turn the shaft. The number of turns per
minute is translated into wind. The speed
of wind differs in different times of the day.

Weathe r and Climate 205

The speed of wind depends upon the pressure belt of the region. Most of the
winds occur in low pressure regions. Winds in the evening is common at high
altitudes of Nepal.

Rain gauge

A rain gauge is an instrument that
measures the rainfall of a given region. It is a
calibrated cylinder with a funnel on the top. The
amount of water falling as the rain enters the
cylinder through the funnel. The total rainfall in
the cylinder is observed and its reading is noted.
Usually the rainfall is measured in millimeter.
Monsoon is the major season for rainfall in
Nepal. Most of the rainfalls in Nepal occur from
June to September.

Weather forecasting

The prediction of weather events that could occur in the given time and
region is called weather forecasting. Weather forecasting is important for flights
of air crafts, agriculture, water navigation and saving people and properties
from storms, tsunamis and tornadoes which case catastrophes. The forecasting of
weather is done on the basis of the measurement of weather elements like the state
of clouds, pressure distribution, temperature distribution, etc. The department of
Hydrology and Meteorology under the Ministry of Science, Teachnology and
Environment, measures weather elements and predicts the weather of Nepal.

Many artificial satellites are launched by developed countries and research
agencies. Some of these satellites are only dedicated to weather and climate
systems. These satellites take photographs of clouds, land surfaces and ocean
surfaces. These photographs are then interpreted to forecast weather. Based on
the forecasting, people will prepare themselves to face the weather events. The
weather forecasted by using these techniques is far more scientific and accurate
than on the basis of a daily measurement.

Record the minimum and maximum temperature, rainfall and humidity
of your region for 10 days from the radio or television news. Then find the
average temperature, average rainfall and average humidity of that region and
show your findings to your teacher.

206 New Creative Science and Environment; Book 7

1. Ozonosphere protects us. How?
Ü Ozonosphere consists of ozone layer which blocks the harmful ultraviolet

rays coming from the sun. Hence, it protects us from the harmful effects of
ultraviolet radiations.

2. It is very dangerous to keep fire at night in an unventilated room. Why?
Ü When fire is kept in an unventilated room, then it uses the oxygen of the

room to burn fire. It forms carbon monoxide. This carbon monoxide is very
toxic and the people sleeping in the room may die. So, it is very dangerous
to keep fire at night in an unventilated room.

F The layer of the air which surrounds the earth is called atmosphere.
F Our atmosphere has five layers.

(a) Troposphere (b) Stratosphere (c) Mesosphere

(d) Thermosphere (e) Exosphere
F Air is a mixture of different gases.
F Blowing air is called a wind.

F The movement of cold air from the ocean to the land during the day is

called a sea breeze.

F The movement of cold air from the land to the ocean during the night is

called a land breeze.

F Weather is a state of air at a particular time and place.
F The elements of weather are temperature, humidity, cloudiness,

precipitation, wind and pressure.
F A barometer is an instrument that measures the atmospheric pressure of

a given place.
F The maximum and minimum temperature of air within a period of 24

hours is measured by using a special thermometer called maximum-

minimum thermometer.
F A hygrometer is an instrument that measures the humidity of air in a

given place.
F An anemometer is an instrument that measures the speed and direction of

the wind.
F A rain gauge is an instrument that measures the rainfall of a given region.

F Prediction of weather events that could occur in the given time and region

is called weather forecasting.

Weathe r and Climate 207

1. Fill in the blanks.

(a) The atmosphere consists of different gases, water vapour and ________.

(b) Rain, cloud, snow and lightening take place in _____________.

(c) Jet planes fly in ___________.

(d) ______ gas is produced when petrol, diesel are not completely burnt.

2. Write short notes on:

(a) Stratosphere (b) Mesosphere (c) Exosphere

(d) Troposphere (e) Thermosphere

3. Define.

(a) atmosphere (b) land breeze (c) wind (d) sea breeze

4. Answer the following questions.

(a) A sea breeze occurs during the day and land breeze occurs at night.
Why?

(b) Explain the water cycle in short.
(c) Name different layers of atmosphere.
(d) Describe the structure of a barometer, rain gauze, hygrometer,

anemometer, and maximum and minimum thermometer.
(e) Name the instruments that are used for measuring:

(i) atmospheric pressure
(ii) amount of rainfall
(iii) temperature
(iv) speed and direction of the wind
(v) relative humidify

(f) What do you mean by weather forecasting? Why it is necessary?

5. Give reasons.

(a) Air blows from colder to hotter places.

(b) Stratosphere is also called ozonosphere.

(c) Troposphere is affected most by human activities.

Breeze – a soft blowing wind

Pollution – contamination of air, water or soil

Ultraviolet rays – the rays having short wave length (10–10m)

208 New Creative Science and Environment; Book 7

20 Earth and Space

After the completing this unit, students will be able to:
Æ define the solar system.
Æ explain the characteristics of planets.
Æ describe stars galaxies and constellations.

The Solar system

The group of the sun, planets, satellites, asteroids, comets, meteoroids and
other heavenly bodies is called the solar system. There are eight planets in the
solar system. They revolve round the sun in their fixed elliptically orbits.

The sun Corona

The sun is a medium sized star, which Chromo
is the nearest star from our earth. Its colour is sphere
yellow. It is about 15 × 108 km away from the
earth. Some facts about the sun are given below: Photo sphere
Earthand Sapc e 209
Diameter = 13.92 × 108 km

Temperature of its surface = 5000°C

Temperature of the centre = 1.5 × 107°C

Main constituent gases = Hydrogen and Helium
Layers of the sun = Photosphere, chromospheres and corona

Memory note

Proxima Centauri is the second nearest star from our earth which is about
4.2 light year away from it.

Planets

Planets are the heavenly bodies which revolve round the sun in their fixed
orbits. They cannot emit their own light. There are 8 planets. They are:

1. Mercury 2. Venus

3. Earth 4. Mars

5. Jupiter 6. Saturn

7. Uranus 8. Neptune

Among these 8 planets mercury, venus and earth are called inner or
terrestrial planets and rest are called outer planets or Jovian planets.

The description about the individual planet is given below.

1. Mercury

Mercury is the smallest planet in the solar system. It
is nearest to the sun. It takes 88 days to revolve around the
sun, but each day on the mercury is nearly equal to two
months on the earth. This is because it rotates very slowly
on its axis. The temperature on the mercury reaches about
400°C during day and –180°C at night. It doesn’t have any
satellite.

2. Venus

Venus is the hottest and brightest planet in the solar
system. Its size is nearly equal to the size of the earth. It
reflects a lot of sunlight and appears shiny during mornings
and evenings. That is why it is called the mornings or
evenings star. It takes 224 days to revolve around the sun.
Its surface temperature is about 400°C. It has atmosphere,
mostly consisting carbon dioxide. But traces of nitrogen and
water vapour are present on this planet. Like mercury, it
does not have any satellite.

210 New Creative Science and Environment; Book 7

3. Earth
Earth is the only living planet in the solar system.

About 70% of the earth’s surface is covered by water. It
takes 365 days to revolve around the sun. It has atmosphere
consisting of 78% nitrogen, 21% oxygen and rest 1% carbon
dioxide, methane and other inert gases. Moon is the earth’s
only natural satellite.

4. Mars

Mars is about half the size of the earth. It looks red,
due to the presence of an enormous amount of rusted iron
dust on it. So, it is also called a red planet. It takes 687 days
to revolve around the sun. Its atmosphere has a lot of carbon
dioxide and a small amount of oxygen and water vapour. It
has two natural satellites.

5. Jupiter
Jupiter is the largest planet. It takes about 12 years

to revolve around the sun. It has atmosphere mainly of
hydrogen gas. The number of natural satellites of the Jupiter
is 63.

6. Saturn

Saturn is the second largest planet in the solar system.
It can be easily identified because of the rings around it.
These rings are made up of water, ice and rocky particles
with ice coatings. It takes 29.5 years to revolve around the
sun. It has atmosphere of helium, methane and ammonia.
Saturn has 60 natural satellites.

7. Uranus

Uranus is the third largest planet. All the planets of
the solar system revolve in the anticlockwise but the uranus
revolves around the sun in the clockwise. The methane gas
in its atmosphere gives it a blue green colour. It takes 84
years to revolve around the sun. It has 27 natural satellites.

Earthand Spac e 211

8. Neptune

Neptune is the farthest planet of the solar system. It is
the coolest planet. It takes 164 years to complete a revolution.
Its surface temperature is about –220°C. It has 13 natural
satellites.

Some of the interesting facts of planets are given below in the table.

Name of Average Diameter Revolution Rotation Number

the planet distance from (km) period period of moon

the sun (km) (satellites)

1. Mercury 5.6 × 108 5000 88 days 59 days 0

2. Venus 1.08 × 108 12100 224 days 243 days 0

3. Earth 1.5 × 108 12700 1 year 24 hours 1

4. Mars 2.26 × 108 6750 687 days 24 hrs 2
37 min

5. Jupiter 7.68 × 108 1139040 12 years 10 hr 63

6. Saturn 1.5 × 109 120000 29.5 years 10 hr 60
39 min

7. Uranus 2.87 × 109 51000 84 years 17 hr 27
14 min

8. Neptune 4.48 × 109 49000 164 years 16 hr 13

Memory note

Æ Mercury is the smallest and nearest planet to the sun.
Æ Venus is the brightest and hottest planet.
Æ Earth is the only planet where living things exist.
Æ Jupiter is the largest planet.
Æ Saturn is a beautiful planet surrounded by a ring of gases.
Æ Neptune is the farthest and coldest planet.
Æ Pluto has been removed from the planet list.

Question

Why can we see venus in the morning in the eastern sky before
the sun rises but not during the day time?

212 New Creative Science and Environment; Book 7

Stars

The heavenly bodies which have their own heat and light and revolve
around the galactic centre of their galaxy are called stars.

You must have seen stars twinkling in the sky in a clear night. Stars are
made up of hot glowing gases.

Our sun seems to be so big but it is only a medium-sized star. There are
many stars bigger than the sun but they appear smaller because they are far away
from us.

Age of stars and their colour

The colour of a star is determined by its age and temperature. The hottest
and the youngest stars having their temperature about 25000°C appear bluish
white.

The medium-aged stars having temperature of about 6000°C appear
yellow. Our sun is a medium aged star. Orange stars have the temperature of
about 4000°C and the red stars are the coldest and the oldest stars. They have the
temperature of about 3000°C.

Thus, stars also born, grow, become old and die.

Brilliance of stars

The brightness or the brilliance of the stars depends upon their age,
temperature and the distance from the earth.

Young stars having high temperature are seen bright whereas the older
stars are not bright. The stars nearer to the earth are seen to be bright than those
farther from it. Thus, our sun though not a giant star, appears as the brightest star
in the sky because it is nearer to our earth’s surface.

Galaxy

The group of billions of stars, dust and gases which revolve around the
galactic centre is called galaxy. The stars in the galaxy are continuously changing
their position. So, the shape of galaxies are also changing. Our Milky Way galaxy
is a spiral shaped galaxy whereas circular and spherical galaxies are also there.
The nearest galaxy to our Milky Way galaxy is the Andromeda galaxy. It is said
that there are 1012 galaxies in our universe.

Earthand Spac e 213

Constellations

Have you ever observed the sky
in clear nights and observed the stars?
Have you noticed that some groups of
stars never change their shape though
they may change their position?

The group of few stars which
may change their position in the sky
but never change their shape are
called constellations. There are 88
constellations in the space. The twelve
of these are used as the signs of zodiac
(rashis). They are given names of the
ancient heroes, animals, gods, etc.
Examples,

Orion, Ursa-major, Cassiopeia, Scorpio, etc.

Identification of constellation

To identify the constellations,
we need two things (i) a star map
(ii) you should be able to identify
one or two constellations. To
identify constellations, Ursa Major
should be identified at first. It is
the most recognizable constellation
as it is a big ‘question mark’ in the
northern sky. It also looks like a
‘dipper’ in which the four stars
form the bowl and three form its
handle. This constellation is also
known as Saptarishi.

Ursa Major helps to identify
Polaris (pole stars). The line
connecting the first two stars of the
bowl shows the star which is at the
tail of Ursa Minor.

214 New Creative Science and Environment; Book 7

The line through the last star of the handle of dipper shows Cassiopeia
which is a ‘w’ shaped constellation. In the same way, we can identify other
constellations with the help of a star map.

Some major constellations

1. Great Bear/Ursa Major/Big dipper
It is the most recognizable constellation in the sky. It consists of seven bright

stars and called saptarishi. The names of saptarishi given to the stars are Dubhe,
Merak, Phecda, Megrez, Alioth, Mizar and Alkaid.
2. Cassiopeia

It is a ‘w’ shaped constellation made
up of five bright stars. Cassiopeia and
Ursa Major are at about the same distance
from the Polaris.
3. Orion

It is also one of the distinct and
interesting constellations in the sky. It
looks like a hunter. It consists of three
bright stars forming the belt of the
hunter. There are two brightest stars of
this constellation. They are Betelgeuse
and Regel.

1. On which factors do the brilliance of stars depend?
Ü Brilliance of stars depends upon their age, surface temperature and the

distance from the earth.
2. Why can’t we see venus during the day time?
Ü Venus is the brightest planet. It does not have its own light but reflects the

light of the sun. In the day time, the light reflected by venus is negligible in
comparison to the light produced by the sun. So we can’t see venus in the
day time.

Earthand Sapc e 215

3. What are satellites? What is the satellite of the earth?
Ü Satellites are small heavenly bodies that revolve round their planets. The

natural satellite of the earth is the moon.

F The vast space which consists of all heavenly bodies is called the universe.
F The solar system is the group of the sun, planets, their satellites, asteroid,

meterors and comets, that are attracted by the sun and they revolve
round it in their own orbit.
F The sun is a medium sized star which is the nearest star from the earth.
F Those heavenly bodies that revolve around the sun in their own orbits
are known as planets.
F Mercury is the nearest and smallest planet.
F Venus is the brightest and the hottest planet.
F Jupiter is the largest planet.
F Days and nights are caused due to the rotation of the earth.
F Seasonal change and change in days and nights are due to the revolution
of the earth in its orbit.
F Always only one side of the moon is seen.
F Moon is the natural satellite of the earth.
F Earth is the only planet where living beings exist.

A. Fill in the blanks:
1. __________ is the centre of solar system.
2. ___________ has ring of gases on it.
3. The moon takes ___________ days to revolve around the earth.
4. The time taken by the earth for a complete revolution is _______ days.
5. The coldest planet in the solar system is ____________.

B. Correct the following incorrect statements and rewrite them:
1. Earth is the only planet where non-living things exist.
2. Seasonal changes occur due to the rotation of the earth in its axis.
3. The moon takes 29.5 days for its one revolution of the earth.

216 New Creative Science and Environment; Book 7

4. Saturn is the largest planet in the solar system.
5. The surface temperature of the sun is 1000°C.
6. Mercury has 21 satellites.
7. There is atmosphere in the moon.

C. Match the following: Column B
satellite
Column A blue planet
1. Nearest planet largest planet
2. Venus mercury
3. Earth brightest planet
4. Earth’s diameter 12800 km
5. Jupiter
6. Moon

D. Define the following terms: 2. Planets
1. Solar system 4. Galaxy
3. Stars
5. Constellation

E. Differentiate between: 2. Earth and moon
1. Earth and sun 4. Galaxy and constellation
3. Planets and satellites
5. Blue star and red star

F. Answer the following questions:

1. What are planets? Name the planets of the solar system.

2. Planets shine though they do not have their own light. Why?

3. Why do living beings exist on the earth but not in the moon?

4. What makes the moon remove round the earth?

5. What is the solar system?

7. Write down about the age of the star, their colour and surface temperature.

8. Name any two galaxies.

9. Give the names of any six constellations.

Arranged - planned or organised in advance
Creatures - small living beings
Enormous - vast, large
Swirling - moving around quickly

‰‰

Earthand Sapc e 217

21 Environment and Its Balance

After completing this unit, the students will be able to:
Æ describe the meaning and types of natural resources.
Æ name the protected areas of Nepal and their importance.
Æ explain water resources and their importance.
Æ name the elements of the environment.

1. Natural Resources

Natural resources are materials and components that can be found within
the environment. Natural resources are naturally available useful materials. These
resources are formed in the nature. Air, water, minerals, soil, forest, wildlife are
some examples of natural resources. These resources are necessary to fulfill the
needs of human beings. People cannot survive without the resources like air,
water minerals, soil, etc.

2. Kinds of Natural Resources

There are different kinds of natural resources. Some natural resources
remain forever even after their continuous use and some are limited in amount.
We can have sunlight for millions of years. Its amount does not decrease even if
we consume it. But on the basis of their renewability and characteristics, natural
resources can be classified into three groups. They are renewable, non-renewable
and perpetual resources.

Natural Resources

Renewable Non-renewable Perpetual
eg. Fresh air eg. Minerals eg. Solar energy
Fresh water Fossil fuel Flowing water wind

a. Renewable Natural Resources

Renewable natural resources are the natural resources that get renewed
through natural processes after their utilization. These resources are the ones that

218 New Creative Science and Environment; Book 7

can be renewed naturally. For example, fresh air is a renewable natural resource.
It is renewed naturally. During respiration CO2 is exhaled and oxygen (O2) is
inhaled. Carbon-dioxide is utilized by green plants during photosynthessis and
oxygen is released into the atmosphere. Hence, fresh air is a renewable natural
resource.

b. Non-renewable natural resources

Non-renewable natural resources are the natural resources that do not
get renewed after their use. These resources form very slowly and do not form
naturally. Minerals are non-renewable resources. They are limited in amounts.
We cannot use them again. Hence, such resources should be utilized in minimum
amounts as far as possible.

c. Perpetual natural resources

Perpetual natural

resources are the natural

resources that persist forever

even after their continuous use.

These resources do not finish.

Their amount remains constant.

Flowing water is a perpetual spring sun

natural resource. There is continuous flow of water in a river or stream. We can

have an unlimited amount of energy from flowing water.

List out the natural resources found in your locality and classify them as

Renewable Non-renewable Perpetual

Environment and Its Balance 219

3. Importance of Natural Resources

Natural resources are very important for us. We cannot survive without
natural resources. We cannot fulfill our needs in the absence of natural resources.
Whatever we eat or whatever we have, they all are from naturally available
resources. The importance of natural resources can be discussed under the
following topics.

a. Sources of food
Living beings get their food from natural resources. Plants need water, air,

etc. to prepare food. Herbivores feed on plants. Human beings get their food
from plants and animals.

b. Habitat/shelter
A habitat means the place where a living being resides. Land provides a

habitat for terrestrial plants and animals whereas water provides a habitat for
aquatic plants and animals.

c. Fresh air and water
Fresh air and fresh water are natural resources. Fresh air is necessary to

breathe and fresh water is necessary to drink,.

d. Natural beauty
Nature is beautiful. Plants and animals add beauty to nature. Natural

resources create beauty of nature. Mountains, rivers, springs, etc. make nature
attractive.

e. Economic development
Natural resources provide raw materials for industries. We know that

industries are the backbone for the economic development of a nation.

f. Tourism development
Natural resources attract people. People visit the places where they can find

plants, animals, beautiful geographic structure, etc.

4. Protected Areas in Nepal

Nepal is rich in biodversity.
Different kinds of valuable plants and
animals are found in different parts
of Nepal. Protected areas contribute
to conserve, promote and manage
environmental resources such as plants,
animals including the landscape. About
23.23% of total land of Nepal is declared

220 New Creative Science and Environment; Book 7

as protected areas in Nepal. There are 10 National parks, 3 wildlife reserves, 6
conservation areas and one hunting reserve in Nepal .

National parks

A national park is a park which is used for the conservation purpose.
National parks are established to conserve, promote and manage different kinds
of plants, wildlife, landscapes, etc.

National parks in Nepal

S.N. National Parks Declared Year Area(Km)
1. Chitwan NP 1973 932
2. Langtang NP 1976 1710
3. Sagarmatha NP 1976 1148
4. Rara NP 1976 106
5. Shey Phokshundo NP 1984 3555
6. Khaptad NP 1984 225
7. Bardiya NP (1976) 1988 968
8. Makalu Barun NP 1991 1500
9. Shivapuri NP 2002 144
10. Banke NP 2010 550

Chitwan National Park

Chitwan national
park is the first national
park in Nepal. It was
established in 1973 and
granted the status of
the world heritage site
in 1984. It covers an
area of 932 km2 . It is
located in the sub-topical
inner Terai lowland of
southern central Nepal in
the chitwan district . This
park covers 70% sal forest only. Bengal tigers, one horned rhinocerous, asiatic
elephants, bears, leopards, gharials, crocodiles, asiatic rock pythans are found in
this park.

Environment and Its Balance 221

Langtang National Park

Langtang national park was
established in 1976 to conserve the
unique flora and fauna of the region.
It has an area of 1710 km2 and extends
over parts of Nuwakot, Rasuwa and
sindhupalchok districts. Sal, Chirpine,
rhododendron, alder, oak are some
of the plants found in this park. This
park is well known for its populations
of red pandas, himalayan black bears,
snow leopards, wild dogs, ghorals,
himalayan thars, etc.

Sagarmatha National Park

Sagarmatha National Park was
established in 1976. It covers an area of
1148 km2. The park includes the upper
catchment area of the Dudhkoshi and
Bhotekoshi rivers. This park includes
different peaks like Sagarmatha,
Lhotse, Cho oyu, Thamserku Neptse,
Amadablam and Pumari. Pine,
hemlock forest, fir, juniper, birch,
rhododendron are common plant
communities found in the park. The park is home to the red panda, snow leopard,
musk deer, himalayan thar, himalayan mouse, hare, etc.

Rara National Park

It is located in the north-western
high mountains of Nepal. It was
established in 1976 to conserve the
unique beauty of Lake Rara and to
protect the representative flora and
fauna of the Humla Jumla region.
Rara Lake is home to the snow trout
the only fish recorded in the lake.
Rhododendron, fir, oak, and birch

222 New Creative Science and Environment; Book 7

species are found in the sub alpine region. Musk deer, himalayan black bear,
leopard, jackal, red panda are animals found in this region.

Shey Phoksundo National Parks

It is situated in the Trans-
Himalayan region of northwest Nepal.
It is Nepal’s largest national park.
It covers an area of 3,555 km2. It was
established in 1984. This park provides
an important habitat for endangered
species including snow leopards, grey
wolves, musk deer and blue sheep.
Similarly, bluepine, spruce, hemlock,
cedar, silverfir, rhododendron are some of the plants found in the park.

Khaptad National Park

It is located in the mid-mountain
region of far western Nepal. It was
gazatted in 1984. It covers an area of
225 km2. The flora of the park are sal,
pine, alder, spruce, fir, hemlock, oak,
etc. The park provides a habitat for
some 20 different species of animals.
Common animals include barking
deer, wild boars, ghoral, himalayan
black bears, leopards and musk deer.

Bardiya National Park

It is the largest park in the lowland
Terai. It covers an area of 968 km2. It
was gazatted as the Royal Karnali,
wildlife reserve in 1976. The reserve
was given the status of a national
park in 1988. This park is home to
endangered animals such as bengal
tigers, wild elephants, one horned
rhinoceroses, swamp deer and black
buck. Major vegetation and forest type
are wooded grassland and riverine forest.

Environment and Its Balance 223

Makalu-Barun National Park

It was established in 1992. It
covers an area of 1500 km2. Snow
leopards, red pandas, musk deer, wild
boars, wild yaks, himalayan thars,
leopards, etc. are found here. The area
contains 25 species of rhododendrons,
47 species of orchids and 56 species of
rare or endangered plants.

Shivapuri National Park

It is situated on the northern fringe of the Kathmandu valley and lies about
12 km away from the capital city . The area was gazatted as the country’s ninth
national park in 2002. It includes pine, oak, rhododendron as plant communities.
Recorded wildlife in the park includes himalayan black bears, leopards, jungle
cats and rhesus monkeys.

Banke National Park

It is the 10th national park of
Nepal. It was established in 2010. It
covers an area of 550 km2. Sal, Sisau,
khayar are some of the trees found in
this park. Similarly, tigers, gharials,
elephants leopards, wild boars, etc. are
the animals found in this region.

224 New Creative Science and Environment; Book 7

Wildlife Reserve

S.N. Wildlife Reserve Area (km2) Established

1. Shukla phante WR 305 1976

2. Koshitappu WR 175 1976

3. Parsa WR 499 1984

Shuklaphanta Wildlife Reserve

It is located in far western terai. In 1976, it was gazetted as shuklaphanta
wildlife reserve. Its area is 305 km2. Wild elephants, bengal tigers, blue bulls,
barking deer, etc. are found in this reserve.

Koshi Tappu Wildlife Reserve

The reserve was gazetted in 1976 to preserve the habitat for the only
remaining population of wild buffaloes. Its area is 175 km2. It was declared as
ramsar site in 1987. Wild boars, blue bulls, rock pythons and a large number of
birds are found in this reserve.

Parsa Wildlife Reserve

It is located in the central development region. It is extended up to eastern
part of Chitwan national park. Its area is 499 km2. Wild elephants, bengal tigers,
leopards, wildboars, etc. are found in this reserve.

Conservation area

A conservation area is a tract of land. It has been given a status in order to
ensure that natural features, cultural heritages or biota are safe guarded. There
are altogether six conservation areas in Nepal .

Conservation areas in Nepal

S.N. Conservation area Area (km2) Established

1. Annapurna CA 7629 1985

2. Api Nampa CA 1903 2010

3. Gaurishankar CA 2179 2010

4. Kanchenjunga CA 2,035 1997

5. Manasalu CA 1,663 1998

6. Black buck CA 19.95 2009

Environment and Its Balance 225

Annapurna Conservation Area

It is Nepal’s largest protected area covering 7,629 km2. It spreads in the
Annapurna range of the Himalayas across the Manang, Mustang, Kaski, Myagdi
and Lamjung districts. It was established in 1985. It is managed by National Trust
for Nature conservation.

Api Nampu Conservation Area

It is a protected area in the far western development region. It was
established in 2010. It covers an area of 1903 km2. It is named after the two peaks.
Api and Nampa. It was established to conserve the unique biodiversity and
cultural heritage of the area. Snow leopards, himalayan black bears, red pandas,
himalayan thar, himalayan musk deer, ghoral, etc. are found in this region.

Gaurishankar Conservation Area

It is a protected area in the himalayas of Nepal. It was established is 2010. It
covers an area of 2179 km2. It spreads in Ramechhap, Dolakha, Sindhupalchowk
districts. It is rich in species diversity. Pinus, Alnus, quercus, rhododendron
forest are found in this region. Red panda is one of the most rare animals found
in this area.

Kanchenjunga Conservation Area

It is a protected area in the Himalayas of eastern Nepal. It was established
in 1997. It covers an area of 2,035 km2 in the Taplejung district and comprises two
peaks of Kanchenjunga. Snow leopards, red pandas, snow cocks, etc. are found
in this region.

Manasalu Conservation Area

It is a protected area in Nepal. It was established in 1998. It covers an area of
1663 km2. Snow leopards, musk deer, himalayan thars, etc. are found in this area.
There are over 110 species of birds.

Black buck Conservation Area

It is located in the far western development region. It was established in
2005. It was established to conserve endangered black buck. It covers 15.95 km2
in the Bardiya district.

Hunting Reserve

Dhorpatan Hunting Reserve
It is the only hunting reserve in Nepal. It covers an area of 1325 km2. It

spreads in Rukum, Myagdi and Baglung districts. Snow leopards, musk deer,

226 New Creative Science and Environment; Book 7

blue sheep, cheer pheasants are found in this reserve.

Ramsar sites

Ramsar sites in Nepal

S.N. Ramsar sites Established date Area (ha)

1. Beeshazai Tal 2003 3200

2. Ghodoghodi Tal 2003 2563

3. Jagdispur Reservoil 2003 225

Beeshazar Tal

It is a ramsar site in Central Nepal. It was established in 2003. It covers an
area of 3200 ha. It is situated between Muhabharat mountain range and the north
siwalik range. Bengal tigers, one horned rhinocerouses, gharials, etc. are found
in the site.

Ghodaghodi Tal

It is a ramsar site in western Nepal. It was established in 2003. It covers an
area of 2563 Ha. Swamp deer, turtles, crocodiles, many species of fishes and birds
are found in this site.

Jagdishpur Reservoir.

It is a ramsar site in southern Nepal. It was established in 2003. It covers an
area of 225 ha. The reservior was constructed in the early 1970s for irrigation.

Visit a nearby protected area. Prepare a report on the area stating the
background, climate features, flora and fauna of the area. You can also mention
suggestions on how to improve the existing situation of the reserve.

4. Water Resources

Rivers, streams, ponds, lakes, ocean, well, springs, etc. are some sources
of water. One third of the earth is covered by water and the remaining part is
covered by land. Water resources can be mainly classified into two groups. They
are surface water and underground water.
Surface water

The water which is present on the surface of the earth is called surface water.
Rivers, lakes, ocean, etc. are the resources of surface water.

Environment and Its Balance 227

Sub-surface/Ground/Underground water
The water which is present below the earth surface is called under ground

water. Well, springs, aquifers, etc. are ground water resources.

Importance of water resource
• Water is necessary for drinking
• It is used to carry out daily activities such as washing, cleaning,
bathing, etc.
• It is used for irrigation
• It is used to generate electricity
• It is used as a medium to transport goods.
• It is used for recreational activities like swimming, rafting, fishing, etc.
• It is used to cool machines.
• It is used as a solvent.
• Our body contains about 70% water.

228 New Creative Science and Environment; Book 7

Conservation of water resource

There is a limited amount of
fresh water on the Earth. Only about
2% water is fit for drinking. Because
of human activities, the amount of
drinkable water is also decreasing.
People need to conserve water
resources. We can adopt following
conservation measures to maintain
quality of fresh water:

• Use water in a required amount.
• Do not pollute water resources.
• Do not throw wastes near the water resources.
• Do not mix sewage into water bodies.
• Increase plantation
• Stop uncontrolled deforestation.

List out the water resources in your locality and mention the causes of
water pollution.

5. Watershed

A watershed is the land area that
delivers water, sediment and dissolved
substances through small streams to a
major stream. A watershed is the total land
area from where water is accumulated to
a particular point. When a rainfall occurs,
water flows towards lowland. Water
flows through small channels. Small channels meet together and starts to flow
in the form of rivers. Shivapuri and Nagarkot are the main watersheds for the
Kathmandu valley.

Conservation of watershed

Conservation of watersheds is necessary. Plantation is necessary to conserve
watersheds. It is better to control settlements in watershed regions. Unscientific

Environment and Its Balance 229

cultivation, excessive use of chemicals should be controlled. Local people should
be made aware about the importance of watersheds. Controlling measures for
soil erosion should be applied.

6. Wetland

Wetland is the land that is covered
partialy or completely with salt water or
fresh water. Rivers, lakes, streams, pond,
paddy field, etc. are some examples of
wetland. Wetland is a source of drinking
water. Such land is rich in biodiversity.
Different kinds of plants and animals are
found in such a place. It should be noted
that depth of water bodies should be less
than 6 m to be a wetland.

Importance of Wetlands

A wetland is a land area that is saturated with water, either permanently
or seasonally. A wetland is very important. It plays a number of roles in the
environment. It contributes in water purification, flood control, etc. It provides
a habitat for different plants and animals. It prevents flooding by holding water
like a sponge. When water levels are low, wetland slowly releases water. So,
wetland is a source of water.

Conservation of wetland

Wetland is very important. It is associated with our life. So, it needs to
be conserved. Human activities should be decreased in a wetland. Plantation
also contributes to protect wetland. The vegetation serves to slow the velocity
of overland flow. In wetland areas, grazing should be protected. Throwing
solid wastes, drying water and setteling of colonies, etc. should be avoided.
The excessive use of chemical fertilizers also pollute the wetland. So, alternative
measures should be used to maintain quality of wetland areas.

Visit a wetland area. Identify the human activities that cause adverse
effects on that wetland. Identify the measures through which the wetland can
be improved.

230 New Creative Science and Environment; Book 7

Elements of environment

The totality of matter including living and non-living things is called
environment. Environment comprises the basic elements like water, air, soil,
land, plants and animals. Quality of elements of environment determines health
status of people.

Air

Air is a mixture of different gases. It has about 78% nitrogen and about 21%
oxygen. Living beings cannot survive without air. Green plants need CO2 to
prepare their food. The air surrounding the earth maintains its temperature. So,
the earth is suitable for living beings. Ozone layer protects us from the harmful
rays coming from the sun. Human beings are responsible for air pollution.
The burning of petroleum products releases harmfull gases such as carbon
dioxide, sulphur dioxide, oxides of nitrogen into the atmosphere. Deforestation,
mismanagement of solid waste and drainage system, excessive use of chemicals
on agricultural land, etc. are responsible for degrading quality of air. Plantation,
management of solid waste and drainage system should be done to control air
pollution. Alternative sources of energy should be utilized rather than petroleum
products .

Water

About 71% of the earth’s surface is covered with water. It is found in solid,
liquid and gaseous forms. About 2% water is fresh that is fit for drinking. Saline
water is found in oceans. The molecular structure of water contains two part of
hydrogen and one part of oxygen. Pure water has a neutral pH. Liquid water is a
universal solvent. Solar energy heats water present on the earth. Water evaporates
and the vapour rises up. When it reaches the upper part, it cools and falls down
as a rainfall. It is called the water cycle.

The mixing of saline water into fresh water, oil spillage, soil erosion,
deforestation, mixing municipal waste into water bodies and the disposal of waste
into water resources pollute water. Water should be used in required amount.
Preventive measures should be applied to control water pollution. Plantation
should be done to protect water resources.

Land

Land is the part of the earth. The surface layer of land is called soil. Land is
important for cultivation. Minerals are found on land. Without land, we would
not be able to construct infrastructures, plant trees, food crops, etc. Land provides

Environment and Its Balance 231

habitat for terrestrial plants and animals. Soil contains mainly 3 parts. Organic
matter includes the upper part of soil. Inorganic matter includes soil particles
and void includes the space between the soil particles.

Human activities pollute land. Improper disposal of solid wastes, discharge
of waste water on land and unscientific use of chemicals in agricultural land
play, important role to pollute land. So, such activities should be controlled to
conserve soil.

Plants

Plants include all producers. Grasses, weeds, trees, etc. are plants. Plants
can produce their food themselves. So, they are called producers. Plants take CO2
from atmosphere and water and minerals from soil to prepare their food. This
process of making food is called photosynthesis. Animals get their food from
plants. They use plants and plants products as their food. Plants are sources of
food, medicine and habitats for animals.

Plants maintain a balance in the environment. They take CO2 from the
atmosphere and released O2 into the atmosphere. They control soil erosion as
well as landslides. Plants add beauty to the nature.

Animals

Animals are important parts of the environment. They depend on plants
for their food. Herbivores feed on plants. Carnivores depend on herbivores for
their food. When animals die, their bodies decay and mix into soil. Plants utilize
decayed organic parts as minerals. Domestic animals are used for domestic
purposes. Wild animals such as tigers, elephants, etc. attract tourists. It contributes
in the economic development of a nation.

Visit a forest land near you. Name plants and animals found in the forest.

8. Living Community

A living community includes all the living beings. Simply, a living
community includes plants and animals. Living beings depend on each other
for their food . Plants can prepare their own food. Animals depend on plants for
their food. On the basis of food, living communities can be classified as:

(a) Producers
(b) Consumers
(c) Decomposers

232 New Creative Science and Environment; Book 7

(a) Producers

All green plants are producers. They
produce their food themselves. So, they
are also called autotrophs. Plants prepare
their food through photosynthesis. Plants
take CO2 from the atmosphere, H2O from
soil to make their food. Plants prepare
their food in the presence of sunlight.
Plant leaves have stomata on their
dorsal side. CO2 is absorbed through the
stomata. It should be noted that all plants
are not producers.

(b) Consumers

Consumers are the living beings
which depend on other beings for
their food. They cannot prepare their
food themselves. Consumers feed on green plants and animals for their food.
Consumers can be classified as :

(i) Primary consumers (ii) Secondary consumers

(iii) Tertiary consumers

Primary Consumer

Primary consumers are herbivores.
They eat plants for their growth and energy.
They get their food from green plants. Cows,
buffaloes, goats, deer, etc. are some examples
of primary consumers.

Secondary Consumers

Secondary consumers depend on
primary consumers for their food. They are
called carnivores. Some consumers may eat
plants as well as primary consumers. Such
consumers are called omnivores.

Environment and Its Balance 233

Tertiary Consumer

Tertiary consumers depend
on secondary consumers. Tigers,
lions, snakes, are some examples of
tertiary consumers.

Decomposers

Decomposers are those miro-
organisms and fungi which decompose
the dead bodies of animals and plants.
They break down complex organic
molecules into simple elements. Such
simple inorganic materials are used
by green plants. Some decomposers
are saprophytes. They feed on dead
bodies of plants and animals. Mucor,
mushroom, yeast, bacteria, etc. are
some decomposers.

Producers, consumers, and decomposer are interrelated with each other.
Consumers get their food from producers. Decomposer get their food from
decayed parts of producers and consumers. So, producers, consumers and
decomposers are interrelated to each other.

Visit a nearby grassland or pond. Observe producers, consumers and
decomposers of the place.

Role of Human in Environmental Balance

Human beings and the environment are interrelated to each other. Human
beings depend on natural resources for their survival. People fulfill each and
every need from the environment. People need air to breath, water to drink,
land to cultivate crops, food to eat, clothes to wear, minerals to make different
equipment and so on. Life is not possible without natural resources. People fulfill
their needs from natural resources.

We need the environment. So it is our duty to conserve the elements of the
environment. Plantation should be done in open and bare lands. Deforestation

234 New Creative Science and Environment; Book 7

must be controlled. Hunting and poaching of wild animals should be stopped. Air
pollution, water pollution and land pollution must be controlled. Slopes should
be covered with plants. Watersheds should be conserved and development
activities should be done reducing environmental damage. Resources must be
used wisely. Humans are the superior organisms. So it is our duty to conserve
environment wisely without disturbing the environmental balance.

The use of natural resources without disturbing an environmental balance
is called environmental conservation. It helps to sustain life easily for us and for
our generations. It makes the environment clean and fresh for the healthy living
of humans and other living beings. Therefore, activities that cause a disturbance
in the environmental balance should be reduced as far as possible.

1. Define natural resources with examples.
Ü Materials that are gifted from nature and can be used for human welfare

and development are called natural resources. Air, water, forest, wildlife,
rocks, minerals, etc. are some examples of natural resources.

2. What type of natural resource is air? Why?
Ü Air is a perpetual natural resource because it does not get exhausted even

after continuous use.

3. What is a watershed? Why should we conserve it?
Ü The part of land that delivers water, sediment, dissolved substances from

highland stream channels to low land major streams is called a watershed.
We should conserve watersheds because it is the main source of water that
is necessary for our day to day life.

4. Write two differences between producers and consumers with examples.
Ü Two differences between producers and consumers are:

S.N Producers S.N. Consumers

1. They can prepare their own 1. They depend upon other for
food. their food.

2. All green plants are produces. 2. All animals are consumers.

Their examples are algae, Their examples are deer,
fern, grass, etc. leopards, snakes, etc.

Environment and Its Balance 235

F Natural resources are materials and components that can be found
within the environment.

F On the basis of renewability, natural resources can be classified into
three groups.

F Natural resources are the gift of the nature.
F Nepal is rich in biodiversity
F Protected areas contribute to conserve, promote and manage

environmental resources
F A watershed is the land area that delivers water, sediment and dissolved

substances through small streams to a major stream.
F Wetland is the source of fresh water.
F Air is the mixture of different gases.
F The surface layer of earth is called soil.
F Plants include all producers.
F Animals depend on plants for their food.
F Producers, consumers and decomposers are interrelated to each other.
F People get each and every need from the environment.

1. Fill in the blanks
a. Natural resources are formed in the ______________
b. Renewable natural resources get renewed through ______________
process.
c. Perpetual natural resources ______________ forever.
d. A habitat means the place where a living being ______________
e. There are 10 ______________
f. Sagarmatha national park was established in ______________
g. ______________ the nearest national park from Kathmandu.
h. ______________ Nepal’s largest protected area
i. Water is necessary for ______________
j. Green plants need O2 to ______________
k. Secondary consumers depend on ______________

236 New Creative Science and Environment; Book 7

2. Choose the correct answer

a. Which type of resource is fresh air?

i. Renewable ii. Non-renewable iii. Perpetual iv. None

b. When was Chitwan national park established?

i. 1983 ii. 1983 iii. 1993 iv. 2010

c. How many wildlife reserves are there in Nepal?

i. 2 ii. 3 iii. 4 iv. 5

d. What is the percentage of O2 in air?

i. 11% ii. 21% iii. 31% iv. 78%

e. Among the following which one is the producer?

i. Tiger ii. Cow iii. Fungus iv. Algae

f. In which protected area of Nepal are wild buffaloes found

i. Koshitappu WR ii. Chitwan NP

iii. Sagarmatha NP iv. Dhorpatan hunting reserve.

3. Short answer questions
a. What do you mean by the environment?
b. Define renewable natural resources.
c. Define a national park.
d. How many conservation areas are there in Nepal?
e. What is the importance of a watershed?
f. How are consumers and producers related?

4. Long answer questions

a. Discuss the importance of natural resources.

b. List out conservation areas of Nepal with their areas.

c. How can water resources be conserved?

d. Why are watersheds important?

e. Write short note on

a. Air b. Plants

f. Show the interrelationship of producers, consumers and decomposers.

g. How are humans and the environment interrelated?

Afforestation : plantation
Perpetual : lasting forever
Ramsar : Named after the convention of wetland in Iranian city Ramsar
Stabilized : To make stable
Watershed : Portion of land that drains in main channel; basin

Environment and Its Balance 237

22 Environmental Degradation and
Its Conservation

After the completing this unit, students will be able to:
Æ explain the environmental degradation.
Æ describe the causes of environmental degradation.
Æ explain the impact of environmental degradation.
Æ name the organizations and agencies involved in environmental

conversation.

Environment means the surrounding that includes physical, biological
and socio-cultural aspects. Physical aspect includes non-living beings. All living
beings are biological aspects whereas our social and cultural activities come under
socio-cultural aspect. These three aspects maintain status of environment. When
the aspects are disturbed, environmental quality also decreases. Environmental
degradation means decrease in quality of environmental resources. Environment
is degraded by human activities as well as the natural plenomenon.

Human induced causes for environmental degradation and their effects are
described here.

a. Deforestation

Deforestation means cutting down
trees in a large number. It decreases forest
land. People cut down trees to fulfill
their needs. We need more agricultural
land and residential areas along with the
population growth.

Human induced causes

• To establish industries

• To expand agricultural land

• To get fire wood

• To exploit minerals

238 New Creative Science and Environment; Book 7

• To be safe from wild animals
• To make roads and canals
• Grazing domestic animals in forest.
• Natural causes.
• Landslide
• Flood
• Forest fire
• Acid rain
• Extreme snowfalls, hailstorms, etc.

Effects: Deforestation causes soil erosion.
• It causes landslides.
• It decreases the productivity of land.
• It enhances floods.
• It causes loss of plants and animals.
• It increases the amount of carbon dioxide in the atmosphere.
• It affects climate.
• There is loss of the habitat of wild animals.
•

b. Urbanization

Urbanization is the process of creating towns
in the country. It decreases open space and increases
the number of buildings. It is mainly classified into
two groups. They are namely planned and unplanned
urbanization. Nowadays, urbanization is taking place in
an unmanaged way.

Causes: Rapid population growth
High migration rate in urban areas.
• Lack of services and facilities in rural areas
• Lack of security in remote parts of a country
•
• Lack of facilities
Effects Lack of a healthy environment
Improper distribution of population
• Conflict among community members
• Environmental pollution
• Increase in social crimes
•
•
•

Environmental Derg adation and Its Conservation 239

c. Industrialization

Industrialization means

establishment of industries.

Industries are the backbone for

economic development of a nation.

When industries are established

many people get jobs. People have

their own income resources. They

become independent. They can easily

fulfill their needs.

Causes To provide employment to people.
To produce useful materials.
• To use natural resources.
• To develop human resource.
• To develop economic development of a nation.
•
•

Effects Industrial waste water and solid wastes cause environmental pollution.
• Industries emit harmful gases such as CO2, SO2 into the atmosphere.
• Industrial gases are responsible for the change in temperature.
• Industries over exploit natural resources.
• Industries cause air, water soil and noise pollution.
• Industries increase population pressure.
•

Visit a near by a factory. List out effects of the industry on the environment.

Destruction of Natural Resources and its effects.

Human beings depend on natural resources to fulfill their needs. The
dependency on the resources increases with population growth. Nowadays,
due to population growth, natural resources are over-exploited. It results in
destruction of natural resources.

Vegetation

Vegetation includes herbs, shrubs and trees. Vegetation is a source of food,
medicine, fire wood, fodder, grasses for animals, timber etc. The excessive use of

240 New Creative Science and Environment; Book 7

vegetation results in:
• Decrease in vegetation areas
• Loss of plants.
• Loss of the habitat for wild animals
• Occurrence of natural calamities like soil erosion, landslide,
desertification, flood, etc.
• Imbalance in the natural cycle
• Affects on the water cycle

Animals and birds

Animals and birds are reduced due to human activities. People hunt wild
animals and birds for economic benefit. They illegally kill rare animals as well as
birds. It causes the following effects.

• Loss of animals and birds
• Imbalance in the natural cycle
• Ecosystem is disturbed

Water resource

Water resource is an important part of life. It is needed for drinking. It
provides a habitat for aquatic plants and animals. It is used to perform different
kinds of daily activities such as washing, cleaning, bathing, etc. Water resource
is being destroyed due to the excessive use of water. The effects of the excessive
use of water are:

• Loss of drinking water
• Loss of aquatic plants and animals
• Land subsidence due to over exploitation of ground water
• Social conflicts

Fuel

Petrol, diesel, kerosene, coal, fire wood, sun, etc. are some important
sources of energy. Among them, petroleum products are non-renewable natural
resources. When these products are utilized, their amount decreases. As a result,
it causes :

• Lack of fuel in future
• Deforestation
• Social conflicts
• Increase in price of energy resources
• Difficulty in living

Environmental Derg adation and Its Conservation 241

Air

Air is necessary to breathe. During respiration, O2 is utilized and CO2 is
exhaled. Fresh air is necessary for healthy life. If there is air pollution, it causes:

• Air borne diseases
• Acid rain
• Increase in acidity of soil
• Increase in earth’s temperature.
• Corrosion of historically important monuments, buildings, etc.

Land

Land is the solid surface of the earth. It is home to terrestrial plants and
animals. It is needed for cultivation. If land is degraded, it causes:

• Decrease in productivity of agricultural land
• Death of soil organisms.
• Pollution of ground water.
• Occurrence of soil borne diseases
• Air pollution from landfill sites
• Difficulty in the survival of plants and animals.

Minerals

Minerals are metallic or non-metallic substances found on land. Minerals
are necessary to make different equipment like, utensils, machines, and different
infrastructure of the development. Minerals play an important role in the
economic development of a nation. If minerals are over-exploited, it causes:

• Decrease in the amount of minerals
• Lack of minerals for future generation
• Crisis of goods which are made from minerals.
• Increase in the price of goods

Visit your community. Ask old people about the condition of water
resources 40 years ago. Compare the status of water resources before 40 years
and now.

242 New Creative Science and Environment; Book 7

Earthquake

Shaking of the earth is called an
earthquake. It is the result of a sudden
release of energy in the earth’s crust.
It is measured in Richter scales. An
earthquake a magnitude of 7 and over
causes serious damage. In Nepal, high
magnitude earthquake occurred in 1990
BS and 2045 BS. Where many people
lost their lives and property.

Causes of an earthquake

• A sudden lateral or vertical movement of rocks along a rupture surface
causes an earthquake

• Volcanic eruption

• Nuclear explosion/ Nuclear test

• Collapse of large buildings

Effects of an earthquake
• Shaking of land
• Rupture of ground
• Landslides
• Avalanches
• Fires
• Loss of life
• Injuries to many people
• Floods
• Tsunamis
• Loss of property

Preventive measures
• Be away from earthquake prone areas.
• Construct houses, buildings, canals, dams and other infrastructure
that are earthquake resistant.
• Manage emergency services during an earthquake.
• Be in a safe place during an earthquake.
• Do not hurry during an earthquake.
• Manage open areas in urbanized areas.

Environmental Derg adation and Its Conservation 243

Volcano

A volcano is an opening into
the earth surface, which allows hot
lava and gases to escape from the
earth. Volcanoes generally occur
where tectonic plates are diverging or
converging.

Causes

Volcanic eruptions frequently
occur at the boundaries of the earth’s
tectonic plates. Tectonic plates are a
series of large blocks moving between
each other. The movement of these
plates plays a significant role in the volcanic eruption.

Effects

A volcanic eruption is one of the most destructive natural disasters. It causes
the following effects:

• It destroys crops, habitats and cities

• It produces gases that cause global warming

• It can lead to earthquakes and tsunamis

• SO2 produced during a volcanic eruption spreads to the top of
atmosphere where it reflects the rays of the sun and thus leads to
cooling. This SO2 reacts with other gases and particles in the atmosphere
to form volcanic smog.

• It causes acid rain

• Volcanic as decreases visibility.

• It causes various health problems like runny a nose, score throats, etc.

Preventive measures

• It is impossible to prevent a volcanic eruption. But it is possible to
reduce the damage.

• Developing settlements away from volcanic areas.

• Using siren like instruments to make people aware during a volcano.

• Noticing the change in landforms, activities of sea waves sea levels etc.

244 New Creative Science and Environment; Book 7

Environmental sanitation

Environmental sanitation simply means cleaning the surrounding. It creates
a clean environment where we can have a healthy life and a standard of living.
Environmental sanitation can be done by applying ‘3R’ methods.
Reduce

Resources should be utilized in a required amount only. It decreases the
production of waste. When there is less production of waste, the environment is
clean and healthy. Here, reduction means to decrease the production of waste by
using the resources in a required amount only.
Reuse

Reuse means the use of same materials again and again for the same purpose
or other purposes. Reuse states to use an item again after it has been used. Many
items found around our homes can be used for different purposes. For example,
a soft drink bottle can be used as a water bottle. When resources or items are
reused, there is the preservation of environmental resources and environmental
sanitation as well.
Recycle

Recycle means change or modification of materials into new ones. In
recycling, already used materials are again used as raw materials and new
materials are made. For example, waste paper is recycled into paper bags, waste
plastic is recycled into plastic utensils, etc.

List out the materials which can be reused, reduced and recycled.

Local efforts on Environmental conservation
Environmental conservation means the use of natural resources in a wise and

sensible way. There is a need of participation of local people for environmental
conservation. Until and unless there is involvement of local people, conservation
activities cannot be effectively implemented. Some local efforts on environmental
conservations are given below.
Awareness

Awareness is the effective effort for environmental conservation. When
people are aware about the importance of environmental conservation, they
themselves actively participate in conservation activities

Environmental Degr adation and Its Conservation 245

Plantation
Plantation can be done to conserve the environment. Plantation contributes

to control natural calamities like floods, landslides, soil erosions, etc. It maintains
natural beauty and natural processes. It provides a habitat for wild animals.
Integrate development work with conservation

Development work should be integrated with conservation work.
Development should be conducted in such a way that there are minimum adverse
effect and maximum good effects on the environment and natural resources.
Environmental sanitation

Environment should be maintained neat and clean. Air pollution, water
pollution, land pollution as well as sound pollution should be controlled. Anti-
environmental activities should be prohibited.

Observe in your locality. List the activities which are being conducted by
different groups for environmental sanitation.

Organization and Agencies Involved in Environment Conservation

There are number of government and non government agencies, which are
working for the conservation of environmental resources. Some of them are:
a. Government agencies

The Government of Nepal is playing an important role for the conservation
of the environment. The government has established a separate ministry and a
department for the conservation of environmental resources in Nepal. They are :

• Department of forest
• Department of National Park and Wildlife Conservation
• Ministry of Forest and Soil Conservation
• Ministry of Science, Technology and Environment.

b. Non-governmental agencies
There are a number of non-governmental agencies which are contributing

to environmental conservation activities. Some of them are :

246 New Creative Science and Environment; Book 7