Modern Concept Science and Technology 4

Unit 12 EARTH

3. Atmosphere

The mixture of di erent gases, which is
present around the earth’s surface, is called
the atmosphere. The atmosphere is com-
posed of di erent gases like nitrogen, Exosphere (10,000 km)

oxygen, carbondioxide, argon, neon, water
vapor. The atmosphere extends up to 720
km from the earth’s surface. But about 99
Thermosphere (720 km)

percent of air is found upto 30 km from the
earth’s surface. The atmosphere near the
earth’s surface is thick, but as we go up to a
higher altitude, the thickness of the air Mesosphere (80 km)

becomes less. On the basis of change in Stratosphere (50 km)
the temperature, there are di erent layers
in the atmosphere. They are the tropo-
sphere, stratosphere, mesosphere, ther- Troposphere (20 km)

mosphere and exosphere. Troposphere is
the rst layer of the atmosphere. It is
present just above the earth’s surface.
Maximum amount of air is present in the

troposphere. All living beings need air to
breathe. The atmosphere provides air
(oxygen) to all organisms for breathing.
Oxygen burns nutrients and releases
Fig. 12.5 Earth and its atmospheric layers

energy in the body of living organism. All living organisms are found within a few
kilometers of the troposphere because the layer of air above the troposphere is very
thin, and no organisms get air for breathing. The atmosphere also blocks the harmful
rays coming from the sun. It also maintains constant temperature on the earth’s surface.

Rapid fire revision

* The earth is a single planet where living beings are present.
* The earth takes 365 days and 6 hours to complete one revolution around the sun.
* The earth also rotates on its own axis. It completes its one rotation in 24 hours.
* The earth is composed of land, water and air.
* The water portion of the earth’s surface is called the hydrosphere.
* Water bodies like springs, streams, rivers, ponds, lakes, seas, oceans constitute

hydrosphere.
* The solid portion of the earth’s surface made up of rocks and soil is called the litho-

sphere.
* Lithosphere is made up of mountains, hills, deserts, plains, islands, peninsulas,

plateaus.

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EARTH Unit 12

* The mixture of di erent gases which is present around the earth’s surface is called
the atmosphere.

* Atmosphere is composed of di erent gases like nitrogen, oxygen, carbon dioxide,
argon, neon, water vapor.

Three steps exercise

Step: 1

1. Tick (√) the correct statement and cross (x) the false one.
a) The diameter of the earth is more at the equator and less at the poles. ( )
b) The earth is a blue planet. ( )
c) Oxygen is an important gas for breathing. ( )
d) The lithosphere of the earth is smooth and at. ( )
e) Continents are large masses of the lithosphere. ( )

2. Fill in the blanks with appropriate words.
a) The polar diameter of the earth is……..
b) ……… are the large masses of water.
c) The……… blocks the ultraviolet rays of the sun.
d) The lithosphere occupies………parts of the earth’s surface.
e) The mixture of di erent gases is called………

3. Match the following: o 12,714 km
a) Shape of the earth o Water of the earth
b) Equatorial diameter o Mixture of gases
c) Polar diameter o 12,756 km
d) Hydrosphere o Oval like an orange
e) Lithosphere o Hills, mountain, valley, etc.
f ) Atmosphere

4. Select the best answer from the given alternatives.

a) Which gas is used for breathing?

i. Nitrogen ii. Carbon dioxide

iii. Oxygen iv. Argon

b) The lithosphere is made up of

i. Rocks and soil ii. Water

iii. Air iv. Animals

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Unit 12 EARTH

c) ................ are large masses of land.

i. Continents ii. Plateaus

iii. Islands iv. Valleys

d) .................... protects living beings from ultraviolet rays of the sun.

i. Hydrosphere ii. Atmosphere

iii. Lithosphere iv. Biosphere

e) The earth takes……. for a complete rotation around its axis.

i. 365 days ii. 24 days

iii. 30 days iv. 1 day

Step: 2

5. Di erentiate between:
a) Ocean and continent
b) Atmosphere and hydrosphere
c) Lithosphere and atmosphere

6. Give reasons.
a) Why do mountaineers carry oxygen cylinders?
b) Why is the earth called a living planet?
c) Why is the atmosphere called a protective layer?

7. Find out the odd ones.
a) Hydrosphere, sphere, lithosphere and atmosphere
b) Lakes, rivers, tap, seas
c) Buildings, mountains, hills, island
d) Nitrogen, oxygen, carbon dioxide and dust particles

8. Identify and categorize into hydrosphere and lithosphere.

a) b) c)

d) e) f)

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EARTH Unit 12

9. Identify the given gure and label its parts, a, b, c, d, and e.

e
d
c
b
a

Step: 3

10. Answer the following questions.
a) Write down any three features of the earth.
b) What makes the earth a living planet?
c) Name three major spheres of the earth.
d) What is hydrosphere? Which components are included in it?
e) De ne lithosphere. Name any three components which make up the litho-

sphere.
f ) State the meaning of atmosphere. Write down the major gases present in it.
g) Name the layers of the atmosphere.
h) Write one importance each of the lithosphere, hydrosphere and atmosphere.
i) What are oceans and continents?

11. Draw the gure of the earth showing the equator and poles.

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13Unit SOLAR SYSTEM
Scientific terms and terminologies of the unit

1. Solar system : The family of the sun, including the eight planets and their
satellites, asteroids, comets, etc., is called the solar system.

2. Planets : Those non-luminous heavenly bodies which revolve around the
sun in their own elliptical orbit are called planets.

3. Stars : Those luminous heavenly bodies which produce their own heat
and light are called stars.

4. Satellites : The smaller heavenly bodies which revolve around the planets
in their elliptical orbit are called satellites.

5. Natural satellites : Natural satellites are the natural heavenly bodies which revolve
around the planets in their own orbit.

6. Artificial satellites : Man-made satellites which revolve around the planets are called
artificial satellites.

7. Sidereal month : The moon completes one revolution around the earth in 27 days,
7 hours and 43 minutes. This period of the moon is called a
sidereal month.

8. Lunar month : The same phase of the moon recurs after 29 days, 12 hours and
44 minutes. This period is called a lunar month or synodic month.

9. Comets : The comma shaped heavenly bodies of ice, dust and gases which
revolve around the sun in an elliptical orbit are called comets.

Introduction

There are many heavenly bodies in the
universe. Among them, some are stars,
some are planets, some are satellites and
some are comets. The bright shining heav-
enly bodies which are seen in the clear night
sky are called stars. Stars produce their own
heat and light. They are very far from the
earth. So, they twinkle with little light.

Fig. 13.1 Stars

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SOLAR SYSTEM Unit 13

The sun is a medium sized star. It looks bigger and brighter because it is near to the
earth. It provides heat and light to the earth. The word solar system is derived from the
sun. Thus, the family of the sun including eight planets, their satellites, asteroids,
comets, etc., is called solar system. The gravitational force of attraction of the sun
holds all the heavenly bodies in the solar system. All heavenly bodies revolve around
the sun in their own orbit.

Sun

Venus

Mercury Mars

Earth Uranus Neptune

Jupiter Saturn

The Planets Fig. 13.2 Solar system

Those non-luminous heavenly bodies which revolve around the sun in their own ellip-
tical orbit are called planets. Planets get heat and light from the sun. They re ect the
light of the sun and look brighter. There are eight planets in the solar system. They are
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Among them life
exists on the earth only.

Mercury

Mercury is a terrestrial (rocky) planet. It is the
nearest planet to the sun. It is the second
hottest planet after Venus. It does not have
its moon.

Fig. 13.3 Mercury

Venus

Fig. 13.4 Venus Venus is a terrestrial (rocky) planet. It is the
second nearest planet to the sun. It does not
have its moon. It is the hottest planet. After
the moon, it is the brightest heavenly body
in the sky and can be seen before sunrise
and after sunset.

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Unit 13 SOLAR SYSTEM

Earth Fig. 13.5 Earth

The earth is a terrestrial (rocky) planet. It is
the third nearest planet to the sun. It has
one moon. Life exists on earth because it
has a suitable environment for living
beings.

Mars

Fig. 13.6 Mars Mars is a terrestrial (rocky) planet. It is the
fourth nearest planet to the sun. It looks
red in color due to the presence of iron
oxide on its surface. It has two moons. It is
the most investigated planet by scientists
due to its similarity to the earth.

Jupiter

Jupiter is a jovian (gaseous) planet. It is the
fth nearest planet to the sun. It is also the

largest planet in the solar system. It has 67
moons.

Saturn Fig. 13.8 Jupiter

Fig. 13.9 Saturn Saturn is a jovian (gaseous) planet. It is
mainly composed of hydrogen. It is the
Uranus sixth nearest planet to the sun. It is a planet
with beautiful rings of gases, dust and
Uranus is a jovian (gaseous) planet. It is rocks. Saturn has 62 moons.
the seventh nearest planet to the sun.
Uranus also has rings outside its body Fig. 13.10 Uranus
but they are not very clear as those of
Saturn. It has 27 moons.

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SOLAR SYSTEM Unit 13

Neptune

Neptune is also a jovian (gaseous)
planet. It is the eighth nearest planet to
the sun. It is the farthest planet in the
solar system. It is also the coldest planet.
It has 13 moons.

Stars Fig. 13.11 Neptune

Those luminous heavenly bodies which produce
their own heat and light are called stars. Stars are
massive bodies of hot gases. They are mainly com-
posed of hydrogen and helium. All stars are not
visible to the human eye. The stars which we see in
the clear night sky are group of stars called Milky
Way galaxy. There are many such galaxies in the
universe. The solar system also lies in the Milky
Way galaxy. The sun is amedium sized star. It is the
Fig. 13.12 Stars

nearest star from the earth. Stars also have life. The brighter stars are young stars and
the dimmer stars are old stars. A star dies when all the gases of the star are nished.

Satellites

Satellites are the smaller heavenly bodies in
space that revolve around the planets in their
own orbit. Satellites are of two types. They
are natural satellites and arti cial satellites.
Natural satellite (moon)

Artificial satellite

Natural satellites are the heavenly bodies Fig. 13.13 Satellites
which revolve round the planets in their own
orbit. Titans, Europa are examples of natural satellites of Jupiter. Di erent planets have
di erent numbers of natural satellites. Mercury and Venus have no natural satellites.
Man-made satellites which revolve around the planets are called arti cial satellites.
Arti cial satellites are widely used for communication. These satellites are also used to
provide information about the planets and weather.

Moon Fig. 13.14 Moon

The moon is a natural satellite of the earth. The earth has only
one moon. After the sun, the moon is the second brightest
body in the sky. The moon does not produce its own light. It
re ects sunlight and looks brighter. The completes one revolu-
tion around the earth in 27 days, 7 hours and 43 minutes. This
period of the moon is called a sidereal month. The same phase

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Unit 13 SOLAR SYSTEM

of the moon recurs after 29 days, 12 hours and 44 minutes. This period is called a lunar
month. The moon does not have its atmosphere and water.

Comet

The comma shaped heavenly bodies of ice, rock, dust and gases which revolve around
the sun in an elliptical orbit are called comets. Comets revolve around the sun in their
highly elliptical orbit. While revolving, when the comets approach the sun, they get
heated. Due to the solar heat, the ice of the comet coverts into gas. The mixture of
gases and dust particles glows, forming a tail. So, we see a bright tail in a comet.
Comet is a Greek word. It means “long-haired star”. Halley’s Comet, Hale-bopp Comet,
Benet, Enke, Holmes are some examples of comets.

Fig. 13.15 Comet

Rapid fire revision

* The family of the sun including eight planets, their satellites, asteroids, comets, etc.,
is called the solar system.

* The gravitational force of attraction of the sun holds all the heavenly bodies in the
solar system.

* The sun is a medium-sized star. It looks bigger and brighter because it is near to the
earth.

* Those non-luminous heavenly bodies which revolve around the sun in their own
elliptical orbit are called planets.

* There are eight planets in the solar system. They are Mercury, Venus, Earth, Mars,
Jupiter, Saturn, Uranus and Neptune.

* Mercury is a terrestrial planet. It is the nearest planet to the sun.
* Venus is a terrestrial planet. It is the second nearest planet to the sun. It is the hottest

planet.
* The earth is a terrestrial planet. It is the third nearest planet to the sun.
* Life exists on earth because it has a suitable environment for living beings.
* Mars is a terrestrial planet. It is the fourth nearest planet to the sun. It looks red in

color due to the presence of iron oxide on its surface.
* Jupiter is the fth nearest planet to the sun. It is also the largest planet in the solar

system.
* Saturn is a jovian planet. It is a planet with beautiful rings of gases, dust and rocks.
* Uranus is a jovian planet.

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SOLAR SYSTEM Unit 13

* Neptune is also a jovian planet. It is the farthest planet in the solar system. It is also
the coldest planet.

* Those luminous heavenly bodies which produce their own heat and light are called
stars. They are mainly composed of hydrogen and helium.

* Satellites are the smaller heavenly bodies in space that revolve around the larger
bodies in their own orbit.

* Natural satellites are the heavenly bodies which revolve round the planets in their
own orbit. For example, Titans, Europa.

* Man-made satellites which revolve around the planets are called arti cial satellites.
* They are sent for research, weather forecast, etc.
* Moon is a natural satellite of the earth.
* The moon completes one revolution around the earth in 27 days, 7 hours and 43

minutes. This period of the moon is called a sidereal month.
* The same phase of the moon recurs after 29 days, 12 hours and 44 minutes. This

period is called a lunar month.
* The comma shaped heavenly bodies of ice, dust and gases which revolve around

the sun in elliptical orbit are called comets.
* Examples of comets are Halley’s, Hale-bopp, Benet, Enke, Holmes.

Three steps exercise

Step: 1

1. Tick (√) the correct statement and cross (x) the false one.
a) The family of the sun is called the solar system. ( )
b) The sun is the farthest star from the earth. ( )
c) A group of planets is called a galaxy. ( )
d) Venus is the hottest planet. ( )
e) Titan is a natural satellite. ( )
f ) Oxygen and nitrogen are the major gases found in stars. ( )

2. Fill in the blanks with appropriate words.
a) The family of the sun is called……….
b) ………is the largest planet of the solar system.
c) ………is the hottest planet of the solar system.
d) The moon is a natural satellite of the……..
e) ………looks red colored due to the presence of ……….
f ) ………. have a glowing tail.
g) The moon takes ………. to complete one rotation of the earth.

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Unit 13 SOLAR SYSTEM

3. Match the following: o Hot ball of gases
a) Planets o Revolve round the planets
b) Stars o Nearest star to the sun
c) Comets o Natural satellite of the earth
d) Satellites o Comma shaped heavenly body
e) Moon o Revolve round the sun
f ) Sun

4. Select the correct alternatives.

a) The sun is a…...

i. Planet ii. Star

iii. Satellite iv. Comet

b) ……….. have their own heat and light.

i. Stars ii. Satellites

iii. Planets iv. Comet

c) Which is the hottest planet?

i. Mercury ii. Venus

iii. Jupiter iv. Neptune

d) Which is the largest planet?

i. Mercury ii. Venus

iii. Jupiter iv. Neptune

e) Which heavenly body revolves around the planets?

i. Comets ii. Satellites

iii. Stars iv. Asteroids

f ) Which heavenly body is made up of ice and dust?

i. Comets ii. Satellites

iii. Stars iv. Asteroids

Step: 2

5. Di erentiate between:
a) Stars and planets
b) Arti cial and natural satellites
c) Mercury and Neptune
d) Comets and satellites
6. Give reasons:
a) Why do the moon and planets look brighter though they do not have their

own light?
b) Why do stars look small from the earth?
c) Comets show a long tail. Why?

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SOLAR SYSTEM Unit 13

d) The moon is called as a natural satellite. Why?
e) Why is Mars called a red planet?
7. Name the planets in the given gure.

8. Name the following:
a) The nearest star from the earth
b) A planet with rings
c) Nearest planet from the sun
d) Farthest planet from the sun
e) The red planet
f ) The hottest planet
g) The coldest Planet
h) Natural satellite of the earth
i) The largest planet
j) The smallest planet

Step: 3

9. Answer the following questions.
a) De ne solar system.
b) What are planets?
c) Name eight planets according to the distance from the sun.
d) What are stars? What is a star made up of?
e) What are satellites? De ne natural and arti cial satellites.
f ) What do you mean by a comet? What is a comet made up of?
g) De ne sidereal month and write down its time period.
h) De ne lunar month and write down its time period.

10. Draw a labeled diagram of the solar system.

104 Modern Concept Science, Health & Physical Education - 4

14Unit MEANS OF INFORMATION
COMMUNICATION AND
THEIR IMPORTANCE

Scientific terms and terminologies of the unit

1. Information : Information is the collection of facts, knowledge and data
about a particular thing.

2. Sources of information : Things and places from where we can get facts and
knowledge are called sources of information.

3. Communication : The process of transferring information from one place
to another or one person to another by using various means

is called communication.

4. Means of cummunication : The resources through which information is transferred
from one place to another are called means of
communication.

5. One-way communication : The mode of communication in which the information
flows only from one side is called one-way communication.

6. Mass communication : The sources through which large numbers of people get
information at a time are called mass communication.

7. Personal communication : The sources through which one or a few people get
information at a time are called personal communication.

8. Two-way communication : The mode of communication in which information
transfers both ways is called two-way communication.

Introduction

We often read newspapers and maga- Watching television
zines, listen to the radio and FM and watch
television. Why do we do this? We read Reading book
newspapers, listen to the radio and watch Listening radio Fig. 14.1
television to get di erent information.
After reading a newspaper, listening to the
radio and watching television, we know
what is happening in our country and in
other countries. Not only these, we also
learn about songs, cinemas, vehicles,
clothes through advertisements.

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MEANS OF INFORMATION COMMUNICATION AND THEIR IMPORTANCE Unit 14

Similarly, we get information about health, environment, arts, science and technol-
ogy through di erent programs. Have you ever heard or watched a children’s
program on radio or television?

Sources of information
Newspapers, radio, television are sources of information.
Books and magazines also provide di erent information to
us. They also provide us subjective information. Magazines
provide information about current a airs of di erent sectors.
Newspapers provide us information covering most of the
important events required for a common man. Do you read
newspapers daily? Thus, the things and places from where Television

we can get facts and knowledge are called sources of infor-
mation. For example, radio, television, library, teachers, news-
papers, posters, hoarding boards etc. are sources of informa-
tion.

Newspaper

Library Teacher teaching

Fig. 14.2 Sources of information

Information

A fact or knowledge about a thing or place is obtained through a means of commu-
nication like radio, television, newspaper, books, magazinesis called information.
Thus, information is the collection of facts, knowledge and data about a particular
thing. All facts cannot be information to all types of people. “The earth is round like
an orange”, this statement could be information for children who do not know about
it. But it may not be information for a scientist.

Activity 1

What are your favorite sources of information? List any ve sources of information.
Also, draw their pictures or paste these pictures on your project work book.

Communication

The process of transferring information from one place to another place by using
various means is called communication. Communication is an important and basic
activity to get information. There are various methods of communication.

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Unit 14 MEANS OF INFORMATION COMMUNICATION AND THEIR IMPORTANCE

For example, talking, discussing, reading, lecture, presentation. We communicate
with our family members and friends by talking. We communicate with animals by
touching, showing signs of love and caressing them. We communicate with our
friends and relatives in far away places by writing letters or by calling on the
telephone.

Caressing a dog

Talking with family

Talking through mobile phone Fig. 14.3 Writing letter

Means of communication
The resources through which the informa-
tion is transferred from one place to another
are called means of communication. News-
paper, radio, telephone, television, letters,
email, faxe are the means of communica-
Mobile Internet

tion. Di erent means of communication are
required to transfer information. Some
means of communication transfer informa-
tion faster and some slower. For example,
email, fax, telephone, mobile phone, chat,
Letter

video call, video conference are faster Television
means of communication. Similarly, letters,
magazines, newspaper are slower means of
communication. Assume that a house is on
re. It needs a re brigade as soon as possi-
ble to put out the re. Newspaper Fig. 14.4 Telephone

So, the re brigade must be informed immediately. What happens if the information
about the re is not sent quickly? The re will destroy the house. It will also kill
people and domestic animals. Therefore, information needs to be sent in time.

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MEANS OF INFORMATION COMMUNICATION AND THEIR IMPORTANCE Unit 14

Mode of communication

We can read a newspaper, listen to the radio and watch television to get information.
But after getting information, it is not possible to reply through a newspaper, radio or
television. But on a telephone or mobile, we can talk both ways. So, on the basis of
the way of communication, there are two di erent modes of communication. They
are one-way communication and two-way communication.

i. One-way communication Watching television

Do you watch news on television? We can watch
and listen to the events being shown on televi-
sion. But does the speaker on television listen to
us? Can we share our queries wuth the speaker?
We cannot. The mode of communication in
which the information ows only from one side
is called one-way communication. Communica-
tion from television, radio, newspaper, books is
an example of one-way communication.

Radio, television and newspaper can communi-
cate with a large number of people at one time.
Such types of communication are called mass Reading newspaper Listening radio
communication. Thus, the sources through
Fig. 14.5 One-way communication

which large numbers of people get information at a time are called mass communi-
cation. Similarly, letters, emails, chats provide information for one or a few people.
Such means of communication are called personal communication. Thus, the
sources through which one or a few people get information at a time are called
personal communication.

Radio Television
Fig. 14.6 Sources of one-way communication
Newspaper

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Unit 14 MEANS OF INFORMATION COMMUNICATION AND THEIR IMPORTANCE

ii. Two-way communication

We use a telephone, mobile to call our friends and relatives. We can ask our friends
about our homework, class routine, holidays by telephone or mobile phone. Simi-
larly, people use e-mail, internet, chat to talk both ways. Nowadays, di erent kinds of
programs like Viber, Skype, imo, messenger are used to talk online. We can also give
interviews to international o ces through video conferencing. We can discuss with
our friends and teachers about any matter. Through these sources, there is transfer of
information to each other. Such types of sources are called two-way communication.
Thus, the mode of communication in which information transfers to both sides is
called two-way communication. In two-way communication, both sides get informa-
tion and react instantly.

Press conference

Talking

Mobile conversation Table talk
Fig. 14.7 Two-way communication

Activity 2

Listen to the radio or watch television and list any ve advertisements and ve
national news. Note them down on the following table.

Advertisements National news
1. 1.
2. 2.
3. 3.
4. 4.
5. 5.

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MEANS OF INFORMATION COMMUNICATION AND THEIR IMPORTANCE Unit 14

Importance of communication

Communication of the right information at the right time is very important. We
cannot live in a society without communicating with our friends and families. Sources
of mass communication like the radio, television, newspaper make us aware about
national and international events. Books, magazines and programs on television,
radio provide valuable information related to health, education, invention, safety
measures, science and technology. The means of communication also have an impor-
tant role in every aspect of our life. We can grab opportunities in business, education,
sports, music, arts through the means of communication. It helps us to update our
existing knowledge and prepares us to compete in our life. It also helps us to move
forward according to the times and situation. Sometimes, there is an outbreak of
highly communicable diseases. The information about such diseases helps us to
adopt preventive measures . Therefore, information about various events and their
communication is important in our daily life.

Activity 3

List the sources of information you have used. Also, write down the advantages that
you have taken from these means of communication.

Rapid fire revision

* Information is the collection of facts, knowledge and data about a particular thing.
* The things and places from where we can get facts and knowledge are called

sources of information. For example, radio, television, library, teachers, newspa-
pers, posters, hoarding boards.
* The fact or knowledge about a thing or place which is obtained through means of
communication like radio, television, newspaper, books, magazines, is called
information.
* The process of transferring information from one place to another by using various
means is called communication.
* There are various methods of communication. For example, talking, discussing,
reading, lecture, presentation.
* The resources through which the information is transferred from one place to
another are called means of communication.
* Newspaper, radio, telephone, television, letters, email, fax are the means of
communication.
* The mode of communication in which the information ows only from one side is
called one-way communication.
* Communication through television, radio, newspaper, books is one-way commu-
nication.

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Unit 14 MEANS OF INFORMATION COMMUNICATION AND THEIR IMPORTANCE

* The sources through which large numbers of people get information at a time are
called mass communication.

* Radio, television and newspaper can communicate within a large number of
people at one time. Such types of communication are called mass communication.

* The sources through which one or a few people get information at a time are
called personal communication. For example, letters, email, chat.

* The mode of communication in which information transfers both sides is called
two-way communication. For example, telephone, mobile, Viber, Skype, imo,
messenger.

* Communication of the right information at the right time is very important.
* Sources of mass communication like radio, television, newspaper make us

aware about national and international events.

Three steps exercise

Step: 1

1. Tick (√) the correct statement and cross (x) the false one.
a) Information means collection of facts and data. ( )
b) Talking is an example of two-way communication. ( )
c) Radio, television and newspapers are means of two-way communication. ( )
d) Telephone, mobile, Viber, Skype, imo, messenger are modern means of

two-way communication. ( )
e) A letter is the fastest means of communication. ( )
f ) Information should be communicated as fast as possible. ( )
g) Communication makes people aware of negative impacts. ( )

2. Fill in the blanks with appropriate words.
a) ............................ means transferring information from one pace to another.
b) The telephone is an example of ............................communication.
c) A letter is an example of ............................communication.
d) ............................ is an example of mass communication.
e) ............................ is an example of personal communication.

3. Match the following with suitable pairs. o Television
a) Facts and data o Letter
b) Transfer of information o Telephone
c) Mass communication o Information
d) One-way communication o Communication
e) Two-way communication

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MEANS OF INFORMATION COMMUNICATION AND THEIR IMPORTANCE Unit 14

4. Select the correct answer from the given alternatives.

a) Which is a means of mass communication?

i. Letter ii. Mobile

iii. Phone iv. Radio

b) Which is a means of personal communication?

i. Newspaper ii. Letter

iii. Radio iv. Television

c) ………. is a means of two way communication.

i. Newspaper ii. Library

iii. Chat iv. Letters

d) ……….means of transferring information from one place to another.

i. Transportation ii. Communication

iii. Information iv. Library

e) Which is one-way means of communication?

i. Chatting ii. Letter

iii. Telephone iv. Talking

f ) Which is two-way means of communication?

i. Television ii. Mobile phone

iii. Radio iv. Newspaper

Step: 2

5. Di erentiate between:
a) Information and communication
b) Email and letter
c) Mass communication and personal communication
d) One-way communication and two-way communication

6. Give reasons:
a) Why do we need information?
b) Telephone conversation is a two-way communication. Why?
c) Radio is a means of one-way communication. Why?
d) Newspapers are means of mass communication. Why?

7. Write down two examples of each:
a) Means of two-way communication
b) Means of one-way communication
c) Means of personal communication
d) Means of mass communication

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Unit 14 MEANS OF INFORMATION COMMUNICATION AND THEIR IMPORTANCE

8. Identify the given pictures and separate them into one-way and two-way
mean of communication.

a) b) c)

d) e) f)

9. Identify the given pictures and separate them into one-way and two-way
activities of communication.

a) b) c)

Step: 3

9. Answer the following questions.

a) What do you mean by information?

b) What are the sources of information? Name any four.

c) De ne communication?

d) Name any four means of communication.

e) De ne one-way means of communication with any two examples.

f ) What is two-way means of communication? Give two examples.

g) What is personal communication? Give two examples.

h) What do you mean by mass communication? Give two examples.

i) Write down the importance of information and communication.

10. Draw pictures of any two means of mass communication.

Modern Concept Science, Health & Physical Education - 4 113

15Unit LOCAL
TECHNOLOGIES

Scientific terms and terminologies of the unit

1. Local technologies : Those technologies which are invented and used by local people
to make their work easier and faster are called local
technologies.

2. Water mill : A water mill is an example of local technology, which is used
for grinding grains.

3. Madani : A madani is a fan which is made of wood or metal.
4. Janto : A janto is a set of two circular stony discs used for grinding

grains.

5. Turbine : The improved, modified and complex form of Paani Ghatta
is called turbine.

6. Pump sets : A pump set is a device made using local technology to lift
underground water.

Introduction

People use di erent kinds of tools and techniques to make their work easier and
faster. In ancient times, people invented technologies to perform their work. These
technologies used simple tools to do di erent works. These technologies are called
local technologies. Thus, those technologies which are invented and used by local
people to make their work easier and faster are called local technologies. Local tech-
nologies are cheap and simple to use. Most of these technologies are displaced by
modern tools, and some are modi ed into di erent forms. Some of the tools and
techniques are still in practice. Local technologies are used for various purposes. We
have our local technologies for tilling the land, harvesting crops, processing oil,
grinding our, making curd, etc.

In this unit, we will discuss about some important local technologies like the water
mill, turbine, pump set.

Water mill (Paani Ghatta)

Rural and remote areas of Nepal do not have grinding machines and electric mills for
grinding grains. In these areas, people grind cereals like wheat, maize, millet, barley,
rice by using the janto, water mill, etc. The local name of the water mill is ‘Paani Ghatta’.

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LOCAL TECHNOLOGIES Unit 15

A water mill uses the energy of owing water to grind cereals. It is an example of
local technology. It is made by local people. Thus, a water mill is an example of local
technology which is used for grinding grains. It is based on the theory that water in
motion generates motion in a still object.

Structure of a water mill

A water mill has a very simple construction. It is also easy to operate. It is made up of
two di erent units called the madani and janto. The madani is a fan which is made of
wood or metal. The fan is kept at the level of the owing water. The janto contains
two circular discs. These discs are placed one over the other. The upper disc moves
over the lower disc. It has a hole in its middle to put grains. The madani and the
upper disc of the janto are joined by a wooden axle.

Grains

Janto

Madani

Working of a water mill Fig. 15.1 Water mill

In a water mill, water from a higher level falls on the madani (fan). The high speed
water rotates the madani (fan). The madani rotates the axle, and the axle rotates the
upper disc of the janto. When grains are kept in the hole of the Janto, the upper disc
moving over the lower disc grinds the grains and converts them into our. After
grinding the grains, the our comes out from the sides of the disc.

Activity 1

If possible, visit a nearby water mill and observe its structure and working. Prepare a
short report on it. Discuss your observation in class. Ask your subject teacher if you
have questions.

Turbine

The improved, modi ed and complex form of
the Paani Ghatta is calleed a turbine. The
turbine is the most important component in a
hydropower station. It is used to produce
hydroelectricity. Have you ever seen a turbine?

Fig. 15.2 115
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Unit 15 LOCAL TECHNOLOGIES

Structure of a turbine

In structure, the turbine is similar to the madani of a watermill. A hydropower turbine
is larger and has many blades on it. In a water mill, the wooden axle from the madani
is connected to the janto (grinder). But in a hydropower station, the metallic axle
from the turbine is connected to the generator.

Working of a turbine

In a turbine, water falls at high speed through a pipe. The high speed water causes
the fan to rotate. It can even rotate more than hundred times in a minute. When the
turbine rotates, it also rotates the axle of the generator. The generator then produces
electricity. The electricity generated in the power house is supplied to our homes
through an electric wire.
Nowadays, a turbine can be rotated by a high speed wind and water vapor, too. All
electric power stations use a turbine to produce electricity.

Activity 2

Visit a hydropower station near your school or house. Observe the structure and
working of a turbine. Also ask the responsible persons about its other structures
which are required to produce electricity. Note how many times the turbine rotates in
a minute.

Pump set

A hand pump is another common name for a pump set.
Pump set is a device which is made using local technology
for lifting underground water. It is another example of local
technology. It is a simple and easy technique of lifting shal-
low groundwater. It is widely used in the plain areas of our
country, i.e, in the Terai region.

Structure of a pump set

In a pump set, a long metallic pipe is dipped into the Fig. 15.3 Pump set
ground. The pipe must reach below the water level. A pump
set with a handle and a mouth is attached to the pipe. A
rubber valve is t onto the long metallic rod that moves up
and down as long as the handle is moved up and down.

Working of a pump set
Do you know how the pump set works? When we press the handle down, the valve
creates a vacuum in the pipe and water travels upward. The valve allows water to lift
up but does not allow water to ow back. After continuously pressing and releasing
the handle, water comes out from the mouth of the pump set. In this way, ground
water is drawn out by using a pump set.

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LOCAL TECHNOLOGIES Unit 15

Activity 3

Make a list of the di erent devices which are made by using local technology. Draw
their diagrams in your project work book. Also, describe their structure and working
mechanism.

Rapid fire revision

* People always use di erent kinds of tools and techniques to make their work
easier and faster.

* Those technologies which are invented and used by local people to make their
work easier and faster are called local technologies.

* Local technologies are cheap and simple to use.
* A water mill is an example of local technology, which is used for grinding grains.
* A water mill is based on the theory that water in motion generates motion in a

still object.
* A water mill is made up of two di erent units called the madani and a janto.
* The improved, modi ed and complex form of the Paani Ghatta is called turbine.
* The turbine is the most important component in a hydropower station. It is used

to produce hydroelectricity.
* Pump sets are devices which are made by using local technology and used for

lifting underground water.

Three steps exercise

Step: 1

1. Tick (√) the correct statement and cross (x) the false one.
a) Local technologies are invented by local people. ( )
b) A water mill is an example of local technology. ( )
c) A water mill consists of a janto and madani. ( )
d) A turbine is a modi ed form of the madani. ( )
e) A turbine is used to grind grains. ( )
f ) Turbines are used to generate electricity. ( )

2. Fill in the blanks with appropriate words.
a) …………technologies are simpler and easier to use.
b) A madani rotates with the help of running …………
c) …………is a modi ed form of the madani.
d) We can lift …………water by using a hand pump.
e) …………of pump set prevents back ow of water.

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Unit 15 LOCAL TECHNOLOGIES

3. Match the following with best pair.

a) Janto o Prevents back ow of water

b) Madani o Hydropower station

c) Turbine o Draw underground water

d) Pump set o Wooden fan

e) Valve o Stones

4. Select the best answer from the given alternatives.

a) …………technologies are simple and easy to use.

i. Modern ii. Local

iii. Eastern iv. Western

b) ………… is made of wood.

i. Madani ii. Janto

iii. Pump set iv. Turbine

c) High speed running water falls on…………

i. Madani ii. Janto

iii. Axle iv. Grinder

d) Turbine is an improved form of ………..

i. Madani ii. Janto

iii. Pump set iv. Grinder

e) ……………is used to pump underground water.

i. Madani ii. Janto

iii. Pump set iv. Turbine

Step: 2

5. Di erentiate between:
a) Turbine and water mill
b) Pump set and turbine
6. Give reasons.
a) Why do people use the Paani Ghatta?
b) Why is a turbine called a modi ed form of the madani?

7. Where do we use these parts?
a) Madani
b) Janto
c) Turbine
d) Valve

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LOCAL TECHNOLOGIES Unit 15

8. Identify and name the following gures.

a) b)

c) d)

Step: 3

9. Answer the following questions.
a) What are local technologies? Name any three.
b) What is a water mill? How does it work?
c) What is a turbine? Where is it used?
d) Explain the working process of turbine.
e) How can you say a turbine and madani are similar?
f ) What is a pump set? Explain its structure.
g) How does a pump set work? Explain.
10. Draw a well-labeled diagram of:
a) Water mill
b) Pump set

Modern Concept Science, Health & Physical Education - 4 119

16Unit OUR BODY AND
PERSONAL HYGIENE

Scientific terms and terminologies of the unit

1. Cells : The body of a living organism is made up of very small and tiny
structures called cells.

2. Tissue : A group of cells which have the same structure and perform a
particular function are called tissue.

3. Organ : A group of tissues form an organ.
4. Body : A group of organs form a complete body.

5. Head : The uppermost, sensitive and controlling part of the body is called
the head.

6. Neck : The neck is the part of the body that joins the head with the trunk.

7. Trunk : The big part of the body below the neck to the anus is called the trunk.
8. Hands : The upper limbs of our body are called hands.

9. Legs : The lower limbs of our body are called legs.

10. Hygiene : The science of cleanliness of the body is called hygiene.

11. Personal hygiene : Personal hygiene means keeping our external and internal organs
clean and healthy.

Introduction Eyebrow Forehead Head
Eye Ear Neck
The body of a living organism is made up Teeth Trunk
of very small and tiny structures called Nose Chin
cells. A group of many cells which have the Mouth
same structure and perform a particular Chest Stomach
function are called tissue. A group of Arm
tissues form an organ and a group of Knee
organs form a complete body. In the Hand Foot
human body, there are many organs.
These organs are broadly divided into Leg
three groups. They are the head, trunk and
limbs.

Toe

Fig. 16.1 Human body

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OUR BODY AND PERSONAL HYGIENE Unit 16

Head

The head is the uppermost part of our body. A group of skull bones provide the frame-
work of the head. The head consists of important sense organs of the body. They are
the eyes, ears, tongue and nose. The brain is the most important part of the body. It is
protected by the skull. The uppermost part of the head is covered with hair. It is neces-
sary to clean the sense organs and hair regularly.

Neck

The neck is the part of the body that joins the head with the trunk. Neck contains a
food pipe and air pipe. Air and food pass to their respective organs through the neck.
The neck also has a vocal cord. We produce sound from the vocal cord. It is necessary
to clean the neck. We should keep the neck neither too cold nor too hot.

Trunk

The part of the body below the neck to the anus is called the trunk. It is the biggest
part of the body. The trunk includes the chest, abdomen, reproductive organs, back-
bone, anus, etc. The bones in the trunk protect the heart, lungs, liver, etc. All the organs
for digestion, respiration, reproduction, circulation are found in the trunk. We should
clean the anus and reproductive organs regularly.

Limbs

The hands and legs of our body are called limbs. The upper limbs are called the hands
and the lower limbs the legs. Limbs develop from the trunk. They have ngers in them.
They have strong bones and muscles to perform di erent activities. We use our limbs
for doing physical activities like pulling, pushing, lifting, playing, running, standing,
writing, washing. Can you imagine a body without limbs?

All the body parts are equally important to us. They are responsible for keeping us alive
and active. Therefore, we should keep both external and internal organs healthy and
active. We need to eat a balanced diet. We should do regular exercise. We should keep
our body clean by bathing or washing regularly. We need to take care of our body
parts.

Personal hygiene

The science of health is called hygiene. Personal hygiene means maintaining our exter-
nal and internal organs clean and healthy. Good health makes us happy and cheerful.
Most of the communicable diseases occur due to lack of cleanliness. Generally, di er-
ent kinds of microbes enter our body through nine openings of the body. They are two
openings of the nose, mouth, anus, genital opening, eyes and ears. We need to carry
out some basic sanitation activities to keep our body clean and healthy. Timely

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Unit 16 OUR BODY AND PERSONAL HYGIENE

bathing, wearing dry and clean clothes, brushing the teeth, washing the sense
organs with clean water, washing our hands and legs regularly are some basic ways
of maintaining personal hygiene.

Some personal hygiene activities

1. We should take bath regularly

We should take a bath regularly. Bathing removes dirt and
germs from our skin. A clean body without germs and dirt
makes us healthy and smart. We should take a bath every-
day if possible. We need to bathe at least twice a week. We
should clean all our body parts while bathing. While bath-
ing, we should give especial care to our eyes, nose, ears,
head, skin, underarms, genital pores, anus. After bathing,
we should wipe our body with a soft, clean and dry towel.

2. We should wear clean clothes Fig. 16.2 Bathing

Wearing dirty clothes make us dirty. It also brings poor feeling. Dirt and germs from
dirty clothes can cause di erent diseases to us. So, we should always wear clean and
comfortable clothes. Clean clothes make us feel happy and cheerful. So, we should
change our clothes regularly. Clothes like socks and underwear should be changed
every day. We should wash our clothes as frequently as we can. Ironing kills the
germs in the clothes. So, we need to iron our clothes regularly. We should use clean
water, soap and detergent powder to clean our clothes.

Washing clothes Clean and dry cloth Wearing clean clothes
Fig. 16.3

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OUR BODY AND PERSONAL HYGIENE Unit 16

3. We should keep our hair clean

Hair in the body grows regularly. Long and dirty hair is home to
dirt and lice. Long hair is also di cult to wash and clean. We
should wash our hair regularly with shampoo or soap and clean
water. Washing removes dirt and lice. Therefore, we should wash
and comb our hair regularly.

4. We should trim nails regularly Fig. 16.4 Combing hair

Nails in the ngers grow regularly. The gap
between the nails and the muscle at the tip of our

ngers is home for many germs. Dirt and germs get
into the long nails. These germs and dirt may enter
our body along with the food. So, we should trim
our nails regularly. Trimming nails is a measure of
personal hygiene. We should never bite our nails.

5. We should clean our teeth regularly Fig. 16.5 Cutting nails

The teeth help to break and chew the food. While chewing, some pieces of food get
struck in the teeth. These food particles decay the teeth and gums. The decayed food
causes diseases and foul smell in the mouth. So, we need to brush our teeth regularly.
People are advised to brush their teeth twice a day. It should be done after lunch and
dinner. We should use a soft brush and paste to brush our teeth.

Fig. 16.6 Brushing teeth
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Unit 16 OUR BODY AND PERSONAL HYGIENE

6. We should wash our body parts regularly

We perform di erent kinds of activities in
our daily life. While carrying out these
activities, our hands, legs, face become
dirty. So, we should wash these body parts
regularly. We should wash our face at least
twice a day. We should always wash our Washing hands
Washing leg

hands, legs and face after playing. Fig. 16.7

We should also wash our hands with soap and clean water after going to the toilet
and before eating food.

7. We should take proper care of sense organs

It is necessary to wash our sense organs regularly. We should splash our eyes with
clean water at least twice a day. We should use a handkerchief to clean our nose. Soft
ear buds should be used to clean our ears. We should gargle our mouth with clean
water. Gargling cleans our teeth and tongue.

Splashing eyes with water Cleaning nose with handkerchief Cleaning ear with earbud
Fig. 16.8

Rapid fire revision

* The human body is made up the head, neck, trunk and limbs.
* The head is the uppermost part of the body. The skull bones provide the frame-

work of the head.
* The neck is present in between the head and trunk. It contains the food and air pipe.
* The part of the body below the neck to the anus is called the trunk.
* The hands and legs of our body are called limbs.
* Personal hygiene means keeping our external and internal organs clean and

healthy.
* We should take proper care of our eyes, nose, ears, head, skin, underarms, genital

parts, anus, etc.
* Ironing clothes kills germs in them. So, we need to iron clothes regularly.
* The gap between the nails and the muscle at the tip of our ngers is home for

many germs. So, we should trim our nails regularly.

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OUR BODY AND PERSONAL HYGIENE Unit 16

* Long and dirty hair is home to dirt and lice. So, we should wash and comb our hair
regularly.

* The food that is stuck in the teeth decays and causes disease and foul smell. So, we
need to brush our teeth twice a day.

* We should wash our hands with soap and water aftergoing to the toilet and
before eating food.

Three steps exercise

Step: 1

1. Tick (√) the correct statement and cross (x) the false one.
a) Personal hygiene means to maintain personal cleanliness. ( )
b) Regular brushing makes our teeth weak. ( )
c) We should trim our nails and hairs regularly. ( )
d) Ironing increases the number of germs in our clothes. ( )
e) Hands and legs of our body are called the trunk. ( )

2. Fill in the blanks using the appropriate words.
a) ………… means keeping our external and internal organs clean and

healthy.
b) We should ………… our teeth twice a day.
c) Long hair and nails are home to…………and…………
d) We should wash our hair with soap or shampoo and clean …………
e) Soft earbuds should be used to clean our …………
f ) We should always wash our hands after ……… and before …………

3. Match the following: o Dirt and lice
a) Personal hygiene o The biggest part of the body
b) Limbs o Soft handkerchief
c) Trunk o Brush
d) Hair o Personal cleanliness
e) Teeth o Hands and legs
f ) Nose

4. Select the best answer from the given alternatives.

a) …….. is made up of skull bones.

i. Head ii. Legs

iii. Hands iv. Trunk

b) The trunk of our body contains……….

i. Heart ii. Brain

iii. Hands iv. Legs

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Unit 16 OUR BODY AND PERSONAL HYGIENE

c) Which of the following is a sense organ?

i. Heart ii. Lungs

iii. Skin iv. Kidneys

d) We should trim our ………. regularly.

i. Clothes ii. Teeth

iii. Nails iv. Shoes

e) Lice grow in dirty ……….

i. Nails ii. Hands

iii. Nose iv. Hair

Step: 2

5. Di erentiate between:
a) Trunk and limbs
b) External and internal organs

6. Give reasons.
a) Why should we trim our nails regularly?
b) Why should we iron our clothes?
c) We need to brush our teeth daily. Why?

7. Identify and write down the activities shown in the given gures.

a) b)

c) d)

126 Modern Concept Science, Health & Physical Education - 4

OUR BODY AND PERSONAL HYGIENE Unit 16

e) f)

g) h)

8. Write down the materials required for:
a) Cutting nails
b) Washing hair
c) Brushing teeth
d) Combing hair

Step: 3

9. Answer the following questions.
a) How is the human body divided? Name the three major parts of the body.
b) Write the meaning of personal cleanliness.
c) List six ways of personal cleanliness.
d) How should we take care of our sense organs?
e) When does the mouth produce foul smell?
f ) What happens when we do not wash our hair regularly?
g) When do lice occur in our hair?
h) What are limbs?

10. Draw a picture showing a human body.

Modern Concept Science, Health & Physical Education - 4 127

17Unit HEALTHY
ENVIRONMENT AND
HEALTHY LIFE

Scientific terms and terminologies of the unit

1. Environment : The surrounding natural word around us in which both
living and non-living things are present is called
environment.

2. Pollution : The decrease in the quality of the natural environment
is called environmental pollution.

3. Wastes : The materials which are discarded by the people after
their use are called wastes.

4. Biodegradable waste : The waste that decays easily in nature is called
bio-degradable waste.

5. Organic waste : Biodegradable waste is made up of plants and animals
and their residues. So, they are also known as organic
waste.

6. Compost manure : The manure gotten from decaying biodegradable waste
is called compost manure.

7. Non-biodegradable waste : The waste that does not decay easily in nature is called
non-biodegradable waste.

8. Inorganic waste : The waste which are made up of inorganic materials are
called inorganic wastes.

9. Composting : Composting is the process of making manure from the
decaying organic waste in a pit.

10. Sanitary landfill : Sanitary landfill is a process in which a low-lying area
or unused land is filled with wastein such a way that the

surroundings are kept healthy.

11. Incineration : The process of burning waste materials in a large chamber
at high temperature is called incineration.

12. Incinerator : A chamber which is used for burning waste materials is
called an incinerator.

13. Reuse : Reuse means using the same thing again and again.

14. Recycle : Recycle means using the things in same or different forms
after processing.

15. Reduce : Reduce means decreasing the use of waste producing
goods.

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HEALTHY ENVIRONMENT AND HEALTHY LIFE Unit 17

Introduction

We can see both living and non-living things
around us. The living thing includes animals and
plants. Similarly, the non-living thing includes air,
water, soil, sunlight, etc. Both living and non-living
things make environment. Thus, the surrounding
natural word around us in which both living and
non-living things are present is called environ-
ment. Environment includes animals, plants, air,
Fig. 17.1 A healthy environment

water, soil, rocks, sunlight, etc. All the components of the environment directly or
indirectly a ect the living things. Human beings and other animals obtain food,
water, air, etc. from the environment.

Environmental Pollution
All living organisms require clean and healthy environment to live in. Clean and
healthy environment provides healthy life to the living beings. Human beings play a
signi cant role to conserve or destroy the environment. Nowadays, the di erent
kinds of bad activities of human beings are responsible to degrade the components
of the environment. Thus, the decrease in the quality of the natural environment is
called environmental pollution. Water pollution, air pollution, noise pollution and
land pollution are the major environmental pollutions.

Smoke and dust from the industries and vehicles cause air pollution. Draining dirty
water and throwing waste materials into water bodies cause water pollution.
Unpleasant sound from industries and vehicles cause noise pollution. Chemical ferti-
lizers, insecticides, pesticides, etc. cause land pollution. All these pollutions occur due
to bad human activities. But the pollution is not only a ecting human beings but also
to other living beings.

Air Pollution Water Pollution

Land Pollution Sound Pollution

Fig. 17.2 Different types of pollutions

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Unit 17 HEALTHY ENVIRONMENT AND HEALTHY LIFE

Wastes

The materials which are discarded by the people after their use are called waste. Plas-
tic bottles, plastic bags, papers, leftover foods and vegetable, peels of fruit, metallic
objects, bones, chemicals, animal excreta, dead bodies, pieces of clothes are some
examples of waste. Throwing waste here and there is a major cause of environmental
pollution. Some wastes decay easily in nature and some do not. On this basis, wastes
are of two types. They are:
a. Biodegradable waste
b. Non-biodegradable waste

a. Biodegradable waste

The waste that decays easily in nature is called bio-
degradable waste. Food waste, vegetables, peels of
fruit, paper, leaves and litter, soft wood, straw, pieces
of clothes, animal excreta are examples of biode-
gradable waste. Biodegradable waste is made up of
plants and animals and their residues. So, they are
also known as organic wastes.
Fig. 17.3 Biodegradable wastes

Biodegradable wastes decay in the soil and provides nutrients to the plants. The
manure gotten from by decaying biodegradable waste is called compost manure.

b. Non-biodegradable waste

The waste that does not decay easily in nature is called non-biodegradable wastes.
These wastes remain in the soil for a long time. Some examples of non-biodegradable
wastes are plastic bags, polythene pipes, metal scraps, hard wood, bottles, cans. Basi-
cally non-biodegradable wastes are not made from animals and plants or their parts.
They are mostly made up from inorganic materials except hard wood. So, they are also
called inorganic waste. Inorganic waste is the major type of waste causing pollution in
the environment.

Activity 1

List the biodegradable and non-biodegradable waste that comes from your home.

Waste Management Practices

A variety of waste comes from homes, schools, cattle sheds, agricultural elds, indus-
tries. Among these, some are biodegradable and some are non-biodegradable. These
wastes need di erent methods of disposal. For this, rst of all we need to separate
biodegradable and non-biodegradable wastes in di erent containers. After that we
use some safe disposal methods. These safe methods are described below:

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HEALTHY ENVIRONMENT AND HEALTHY LIFE Unit 17

1. Composting

Organic waste can be managed by composting. It is an
environment-friendly way of managing wastes. Composting
is the process of making manure from organic waste by
allowing it to decay in a pit. Compost manure is the best
fertilizer to use on agricultural land. To get compost manure,
we should dig a pit. We put degradable waste in the pit and
cover it with soil. After a few months, compost manure is
ready for use.

Fig. 17.4 Composting

2. Sanitary land ll

Sanitary land ll is a process in which a low-lying
area or unused land is lled with waste in such a
way that the surroundings are kept healthy. A land-
ll site is always chosen away from residential areas,
water resources and farm land. Both organic and
inorganic wastes can be land lled. In this method,
the waste is dumped all over the land and compressed
using heavy vehicles. Then a layer of soil is used to
cover the waste. This is done to prevent Fig. 17.5 Sanitary landfill

the spread of foul smell and breeding of microbes and insects. Large quantities of
solid waste can be managed by using a sanitary land ll.

3. Incineration Fig. 17.6 Incineration

The process of burning waste materials in a large
chamber at high temperature is called incinera-
tion. This method is used to manage solid waste
which is harmful to human health or cannot be
degraded easily. The plant which is used for burn-
ing is called an incinerator. Wastes from hospitals,
factories, municipalityis fed into an incinerator.
This method does not allow foul smell and
diseases to spread but it causes air pollution.

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Unit 17 HEALTHY ENVIRONMENT AND HEALTHY LIFE

4. Recycling

Di erent kinds of solid waste like plastic bags, bottles, paper, pieces of metals can be
recycled in the factories. Therefore, old and broken plastic buckets, bags, plates,
mugs, jugs should not be disposed o like other solid wastes. They are collected and
sent to the plastic processing factories. In these factories, the plastic materials are
melted and remolded into new materials. Similarly, the metal pieces, glass bottles,
unused books and papers are sent to the concerned factories for recycling.

3-R Principle

This is the latest principle in solid waste management. 3-R refers to reuse, recycle and
reduce. It is an environment-friendly method of solid waste management.

Reuse

Reuse means using the same thing again and again. A bottle of coke can be reused
to store water for drinking. A rice bag can be used to store old stu s. Similarly, old
bags, tin cans, boxes can be used to store di erent kinds of materials. This process
reduces the frequency of buying new things for the same purpose. It also reduces
solid wastes.

Recycle

Recycle means using the things in the same or di erent forms after processing. Scrap
paper can be recycled into paper bags, envelopes. Plastic scraps can be recycled into
plastic items like buckets, jugs, pipes, plastic covers. Metallic items can be recycled
into the same or di erent metallic items. Aluminium scrap is melted to produce
aluminium utensils, foils, goods, etc. We can sell or give recyclable materials to the
scrap collector.

Reduce

Reduce means decreasing the use of waste producing goods. We should not use
things unnecessarily. If you have space in your bag to carry a water bottle, do not buy
a new plastic bag to carry one. If you can repair an old watch, do not buy a new one.
Reducing the use of things ultimately decreases wastes. This process also decreases
environmental pollution.

Activity 2

What type of waste management practices do you follow at your home? Write the
process in detail or show it on a chart.

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HEALTHY ENVIRONMENT AND HEALTHY LIFE Unit 17

Rapid fire revision

* The natural world around us in which both living and non-livingthings are present,
is called the environment.

* The environment includes animals, plants, air, water, soil, rocks, sunlight.
* The decrease in the quality of the natural environment is called environmental

pollution.
* Water pollution, air pollution, noise pollution and land pollution make up

environmental pollution.
* The materials which are discarded by the people after their use are called waste.
* A variety of waste comes from homes, schools, cattle sheds, agricultural elds,

industries.
* Plastic bottles, plastic bags, paper, leftover food and vegetables, fruit peel, metallic

objects, bones, chemicals, animal excreta, dead bodies, pieces of clothes are exam-
ples of wastes.
* Waste that decays easily in nature are called bio-degradable wastes.
* Leftover food, vegetables, peels of fruits, paper, leaves and litters, soft wood, straw,
pieces of clothes, animal excreta are examples of biodegradable waste.
* Biodegradable waste is made up of plants and animals and their residues. So, they
are also known as organic waste.
* The manure gotten from decaying biodegradable waste is called compost
manure.
* The waste that does not decay easily in nature is called non-biodegradable waste.
* Composting is the process of making manure from organic waste by allowing it to
decay in a pit.
* Sanitary land ll is a process in which a low-lying area or unused land is lled with
waste in such a way that the surroundings are kept healthy.
* The process of burning waste materials in a large chamber at high temperature is
called incineration.
* 3-Rs refer to reuse, recycle and reduce. It is an environment-friendly method of
solid waste management.

Three steps exercise

Step: 1

1. Tick (√) the correct statement and cross (x) the false one.
a) Environment includes living and non-living things. ( )
b) Smoke pollutes land and water. ( )
c) Bad activities of human beings are responsible for pollution. ( )
d) Compost manure is made from inorganic wastes. ( )
e) Glass and plastic are examples of degradable waste. ( )

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Unit 17 HEALTHY ENVIRONMENT AND HEALTHY LIFE

f ) Reuse means using the same thing again and again. ( )
g) Sanitary land ll must be constructed near a water body. ( )

2. Fill in the blanks using the appropriate words.
a) The decrease in the quality of the natural environment is called ……….
b) ……….wastes decay easily in nature.
c) Biodegradable wastes are also called ……….
d) We get ……….manure from degradable wastes.
e) Incineration is done in………….
f ) The meaning of 3R is…………
g) Scarp collectors collect …………….. materials.

3. Match the following. o Decrease the matter
a) Environment o Use again and again
b) Inorganic matter o Processing for another
c) Organic matter o The sum of living and non-living things
d) Reduce o Biodegradable
e) Reuse o Non-biodegradable
f ) Recycle

4. Select the best answer from the given alternatives.

a) Whose activities are responsible for environmental pollution?

i. Plants ii. Human beings

iii. Animals iv. Animals and plants

b) What is mainly responsible for air pollution?

i. Solid waste ii. E uent

iii. Smoke iv. Liquid waste

c) Which is a biodegradable waste?

i. Glass ii. Pieces of paper

iii. Rubber iv. Metal pieces

d) Which is a non-degradable waste?

i. Dead body ii. Pieces of paper

iii. Rubber iv. Leaves of plant

e) Burning of solid waste at high temperature is called…..

i. Recycling ii. Land lling

iii. Composting iv. Incineration

f ) Decreasing the amount of things that we use is called….

i. Recycling ii. Reuse

iii. Reduce iv. Regenerate

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HEALTHY ENVIRONMENT AND HEALTHY LIFE Unit 17

Step: 2

5. Write two di erences between:
a) Biodegradable and non-biodegradable wastes
b) Composting and incineration
c) Sanitary land lling and composting
d) Reuse and recycle
6. Give reasons.
a) Plastic is a non-biodegradable waste. Why?
b) Why is leftover food called biodegradable waste?
c) Why should we always follow the 3-R principle?
d) Why is hospital waste incinerated?
7. Identify the types of waste management methods which are given in the

following gures.

a) b) c)

8. Circle the odd one:
a) Vegetable peel, clothes, leaves, rubber b) Plastic, metal, glass, leftover food

Step: 3

9. Answer the following questions.
a) What is an environment?
b) What is pollution?
c) Name any three types of environmental pollution.
d) How does water pollution occur?
e) What is responsible for air pollution?
f ) De ne degradable waste with three examples.
g) What are non-degradable wastes? Give any three examples.
h) List any three methods of waste management.
i) Describe the 3-R principle.
j) What do you mean by incineration?
k) What types of wastes are incinerated?
l) De ne compost manure and composting.
m) What is sanitary land lling?
10. Draw a picture of an incinerator.

Modern Concept Science, Health & Physical Education - 4 135

18Unit OUR FOOD AND
NUTRIENTS

Scientific terms and terminologies of the unit

1. Nutrients : The different kinds of useful substances found in food are called

nutrients.

2. Diet : The varieties of food that we eat every day are called a diet.

3. Balanced diet : The diet that provides all the required nutrients in adequate amount

is called a balanced diet.

4. Carbohydrates : The nutrients in food that provide us energy are called carbohydrates.

5. Proteins : The body building nutrients of food are called proteins.

6. Fats : The nutrients in food that provide energy and keep our body warm

are called fats.

7. Vitamins : The nutrients in food that protect our body from various diseases

and keep us healthy are called vitamins.

8. Minerals : The body building and protective nutrients of food are called

minerals.

9. Water : Water is very essential and tasteless liquid required in our body.

10. Nutritious food : The food that is rich in nutrients is called nutritious food.

11. Junk food : Packaged and preserved food which is ready to eat, is called

readymade food or junk food.

Introduction

All living things need energy to perform their

activities. Energy comes from food. So, food is

an essential and basic thing for all living things. Bread Rice Meat Fish
To perform di erent kinds of activities like read-

ing, writing, jumping, playing, working need

energy. Human beings also need food for their Milk Vegetables
growth and development. Plants and animals Eggs

are the sources of food for human beings. Rice,

pulses, wheat, potato, maize, meat, sh, eggs,

milk, milk products, fruits, vegetables are exam- Cheese Butter Fruits
ples of food.
Fig. 18.1 Some examples of food

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OUR FOOD AND NUTRIENTS Unit 18

Nutrients

The di erent kinds of useful substances found in food are called nutrients. They are
essential to keep our body t and healthy. A single food item does not contain all the
required nutrients. So, we should eat a variety of food as far as possible. Carbohy-
drates, proteins, fats, vitamins, minerals and water are the di erent types of nutrients
which are required by our body. The above nutrients are present in di erent food
items. Thus, the varieties of food that we eat every day are called diet. Similarly, the
diet that provides all the required nutrients in adequate amount is called a balanced
diet.
Memory Plus
Why should we eat a variety of food?

Carbohydrates Rice Wheat
Barley Potato
The nutrients in food that provide us energy are
called carbohydrates. We get carbohydrates from
maize, rice, wheat, barley, millet, potatoes, sweet
potatoes, sugar, sugarcane. People doing physical
work need more carbohydrates in their body. Simi-
larly, the people doing mental work need compara-
tively less carbohydrates.

Memory Plus
Carbohydrates are called energy-giving food.

Maize
Fig. 18.2 Some sources of carbohydrates

Proteins Meat Fish Eggs
Chicken
The body building nutrients of food are Cheese Soybeans
called proteins. They make bones and
muscles strong. They also help the body
to grow and to repair the cells. Meat, sh,
chicken, eggs, milk, cheese, kidney beans,
soybean, peanuts, curd are sources of
proteins.

Memory Plus Kidney-beans Milk
Proteins are called body-building food.
Fig. 18.3 Some sources of proteins

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Unit 18 OUR FOOD AND NUTRIENTS

Fats Cheese

The nutrients in food that provide energy Oil Eggs
and keep our body warm are called fats.
Fats provide more energy than carbohy-
drates. We get fats both from animals and
plants. Cheese, oil, ghee, butter, nuts,
eggs, yolk, meat, seeds of soybean, mus-
tard and sun owerare rich in fat.

Butter Ghee

Fig. 18.4 Some sources of fat

Vitamins

The nutrients in food that protect our body Vegetables Fruits
from various diseases and keep us healthy are
called vitamins. Vitamin A, B, C, D, E and K are
di erent types of vitamins. We need vitamins in
little amount. Fruits and vegetables are the
sources of vitamins. Vegetables, fruits, and
pulses, milk are sources of vitamins.

Memory Plus Milk Eggs
Vitamins are called protective food. Fig. 18.5 Some sources of vitamins

Minerals

The body building and protective nutrients in food are called minerals. They are
responsible for various functions like blood formation, blood clotting, making bones
and teeth strong, regulating various chemical processes in the body. Iron, calcium,
sodium, uoride, iodine, zinc, chlorine are some minerals that our body require.
Seafood, sh, salt, fruits and vegetables, goat liver are good sources of minerals.

Sea foods Leafy vegetables Fruits Fish Salt

Fig. 18.6 Some sources of minerals

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OUR FOOD AND NUTRIENTS Unit 18

Water

Water is an essential and tasteless liquid required in our body. It does not provide
nutrients to our body. It regulates the temperature of the body, transports nutrients
and helps in digestion. All living organisms need su cient amounts of water in their
body. We should drink about two to three liters of water every day. It is necessary
that the drinking water is clean and germ-free.

Balanced diet

The food that we eat every day is called a diet. A diet contains a variety of nutrients.
We need all nutrients in right quantities to build a strong and healthy body. Thus, the
diet that provides all the required nutrients in adequate amounts is called a balanced
diet. Our body needs di erent nutrients in di erent amounts. Excess or de ciency of
the nutrients causes di erent kinds of problems in the body. Therefore, the food we
eat should contain carbohydrate, protein, fat, vitamin, minerals and water in the right
amount.

Food groups

The food that is rich in nutrients is called nutritious food. On the basis of the presence
of nutrients, food items have been divided into di erent groups-

Cereal group

Food grains that are rich in carbohydrates are called cereals. Wheat, rice, potato,
millet, maize, barley are some examples of cereals.

Pulse group

Pulses are the seed grains that are rich in proteins. Gram, pea, soybean, kidney bean,
moong, rahar are examples of pulses.

Meat group

Meat means the esh of animals. It is rich in proteins. Animals like sh, chicken, goat,
pig, bu alo are sources of meat protein.

Dairy products

Foods that are derived from milk and milk products are called dairy products. Milk,
cheese, curd, butter, yoghurt are examples of dairy products.
Dairy products are rich in proteins, fats and minerals.

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Unit 18 OUR FOOD AND NUTRIENTS

Vegetables and fruits

Fruits and vegetables are food groups that are rich in vitamins and minerals. Spinach,
garlic, pumpkin, gourd, cucumber, lemon, banana, mango, avocado, kiwi, apple are
examples of fruits and vegetables.

Disadvantages of readymade and junk food

Nowadays we see various food items in the market that are ready to eat. These food
items are are oily and spicy. They have attractive taste and colors. The taste and color
are due to di erent kinds of avors and chemicals. Such foods is called junk food.
Thus, packaged and preserved food, which is ready to eat is called readymade or junk
food. Noodles, biscuits, cookies, chocolates, chowmein, pu , daalmoth, bhujia, cakes,
etc. are some examples of readymade and junk foods. Continuous consumption of
such foods causes di erent kinds of health problems like obesity, decaying of teeth,
weakening of bones, digestive problems. Junk food also retards mental and physical
development of the body. Therefore, we should not eat junk food.

Noodles

Chocolates Bhujia

Biscuits

Fig. 18.7 Junk foods Chowmein

Preserving iodine in iodized salt
Iodine is a mineral. It helps in the develop-
ment of the mind and body of children. So,
we need a certain amount of iodine in our
body. Table salt, or common salt, should
contain iodine. Lack of iodine in the salt can
cause a disease called goitre. Have you ever
seen a man or woman with a goitre on his
or her neck? Goitre Iodized salt
Fig. 18.8

Packaged common salt contains iodine. Iodine evaporates easily if we keep it in an
open container. Iodine evaporates even in sunlight. So, we should not expose salt
tosunlight. We should not cook the salt along with our food. We should make the
habit of using salt only after we nish cooking. We should cover the utensils properly
to prevent iodine from evaporating.

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OUR FOOD AND NUTRIENTS Unit 18

Activity 1

List the names of di erent types of junk food available in the market. Make their
pictures withe appropriate color. Paste these pictures in your project work le.

Activity 2

Make a chart of the di erent food items which are required in our balanced diet. Clas-
sify these food items into di erent food groups.

Activity 3

Make a list of the di erent food items that you ate yesterday. Discuss in the class,
whether it is a balanced diet or not.

Rapid fire revision

* All living things need energy to perform their activities. Energy comes from food.
* The di erent kinds of useful substances found in food are called nutrients. They are
essential to keep our body t and healthy.
* Carbohydrates, proteins, fats, vitamins, minerals and water are the di erent types of
nutrients which are required by our body.
* The varieties of food that we eat every day are called diet.
* The diet that provides all the required nutrients in adequate amount is called a

balanced diet.
* The nutrients in food that provide us energy are called carbohydrates.
* We get carbohydrates from maize, rice, wheat, barley, millet, potatoes, sweet pota-

toes, sugar, sugarcane.
* The body building nutrients of the food are called proteins.
* Meat, sh, chicken, eggs, milk, cheese, kidney beans, soybean, peanuts, curd are the

sources of proteins.
* The nutrients in food that provide energy and keep our body warm are called fats.
* Cheese, oil, ghee, butter, nuts, eggs, yolk, meat, seeds of soybean, mustard and

sun owerare rich in fats.
* The nutrients in food that protect our body from various diseases and kee us healthy
are called vitamins.
Vitamins A, B, C, D, E and K are di erent types of vitamins.
* Vegetables and fruits are sources of vitamins like cereals, pulses, milk, spinach,
* lettuce, carrot, cucumber, lemon, apple, banana, orange.

* The body building and protective nutrients in food are called minerals.
* Sea-food, sh, salt, fruits and vegetables, goat liver are sources of minerals.
* Water is an essential and tasteless liquid required by our body.

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Unit 18 OUR FOOD AND NUTRIENTS

* Food that is rich in nutrients is called nutritious food.
* Food grains that are rich in carbohydrates are called cereals.
* Wheat, rice, potato, millet, maize, barley are examples of cereals.
* Pulses are the seed grains that are rich in proteins.
* Meat means the esh of animals. It is rich in proteins.
* Foods that is derived from milk and milk products is called dairy products.
* Fruits and vegetables are food groups that are rich in vitamins and minerals.
* Packaged and preserved food, which is ready to eat, is called readymade or junk

food.
* Noodles, biscuits, cookies, chocolates, chowmein, pu , daalmoth, bhujia, cakes are

examples of readymade and junk food.
* Iodine is a mineral. It helps in the development of the mind and body of children.

Three steps exercise

Step: 1

1. Tick (√) the correct statement and cross (x) the false one.
a) All living things need food for energy. ( )
b) Carbohydrate is also called body building food. ( )
c) A balanced diet is bad for health. ( )
d) Fat gives us energy and keeps our body warm. ( )
e) We should not cook salt along with food. ( )
f ) Junk food is good for health. ( )

2. Fill in the blanks with appropriate words.
a) ……… gives us energy.
b) The varieties of food that we eat every day is called ……….
c) Carbohydrates are also called………food.
d) Ready to eat and packaged food is also called ………food.
e) Biscuits, noodles, chocolates are examples of ……….
f ) ……….help us to protect from diseases.
g) Cheese, curd, yoghurt are examples of……….products.

3. Match the following. o Energy giving food
a) Iodine o Goitre
b) Proteins o Packaged foods
c) Fats o Dairy product
d) Carbohydrates o Provide energy and warmth
e) Vitamins o Body building foods
f ) Yoghurt o Protective foods
g) Junk foods

142 Modern Concept Science, Health & Physical Education - 4