HPE-book-5-for-press

Dicotyledonous plants

The seeds which contain two cotyledons are called dicotyledonous seeds.
Plants that produce dicotyledons seeds are called dicotyledonous plants.
Gram, mustard, bean, pea, etc are some examples of them.

Gram Bean Mustard Pea

Dicotyledonous plants have tap root system. They have broad leaves with
reticulate venation. Floral parts of flower are in multiples of four or five.

Mustard plant Gram plant Rose plant Sunflower plant

Activity 6

• Collect some leaves of rice, maize, apple, mango, onion, mustard,
spinach, whatever are possible and observe the shape and venation
in those leaves. Identify and separate the monocotyledon plant and
dicotyledon plant.

• Collect some seeds of maize, rice, wheat, pea, grams, mango, apple
or any seasonal grains, observe the cotyledons present in those seeds.
Identify and separate dicotyledon seeds and monocotyledon seeds.

Science, Health and Physical Education Book - 5 47

Points to Remember

1. A plant body consists of two systems; the root system and the shoot
system.

2. Roots are present inside the soil and they are of two types; tap root
and fibrous root.

3. Roots perform many functions like absorption of water and minerals
from the soil, conduction of water and minerals from the soil,
conduction of water and minerals upwards, fixation of plants to the
soil and in some cases storage of foods.

4. Water and minerals are conducted upwards in roots and stems
through xylem.

5. The shoot of the plant lies above the soil and bears stem, leaves,
flowers and fruits.

6. Plants lose excess amount of water in the form of water vapour
through the stomata of their leaves. This is called transpiration.

7. At the time of reproduction, most of the plants bear flowers. A flower
has four floral parts- sepal, petal, stamen and pistil.

8. The outermost whorl of a flower is called calyx. It protects a flower in
the bud stage.

9. The second whorl of a flower next to the calyx is called corolla. It
helps in pollination.

10. Androecium forms the third inner whorl of a flower. It consists of a
number of male reproductive organs called stamens.

11. Gynoecium forms the fourth innermost whorl of a flower. It represents
the female reproductive part i.e. pistil.

12. A flower is called complete flower when it contains calyx, corolla,
androecium and gynoecium.

13. The plants having only one cotyledon in its seed are called
monocotyledonous plants.

14. The plants having two cotyledons in seeds are called dicotyledonous
plants.

48 Science, Health and Physical Education Book - 5

Exercise

1. Choose the best answer from the given alternation.

a. What type of root does grass have?

i. tap roots ii. fibrous roots

iii. secondary roots iv. tertiary roots

b. Xylems are responsible for ___________.

i. transpiration ii. conduction

iii. photosynthesis iv. respiration

c. Which of the following is not necessary for the process of
photosynthesis?

i. sunlight ii. chlorophyll iii. water iv. oxygen

d. To test for starch, we use ____________.

i. iodine solution ii. alcohol solution

iii. iodine water solution iv. alcohol-water solution.

e. The process by which excess amount of water is removed as water
vapour into the atmosphere is ____________.

i. conduction ii. transpiration

iii. evaporation iv. reproduction

f. Which of the plant has fibrous roots?

i. garlic ii. jack fruit c. banyan d. peepal

2. Fill in the blanks with appropriate words.

a. Plants are fixed to the soil with the help of ___________.

b. Roots absorb ___________ and ___________ from the soil.

c. ________ increase the surface area of roots for water absorption from
the soil.

d. ___________ present in roots and stems conduct water and minerals
upwards in the plant body.

e. Soft and green stem is called ___________.

f. The green colour of leaves is due to the presence of a pigment called
____________.

g. The process by which green plants prepare their food is called ____.

Science, Health and Physical Education Book - 5 49

h. Plants give out __________ in the process of photosynthesis.
i. Minute pores present on the surface of a leaf are called ___________.

j. ___________ part of a flower is green in colour.
k. Unisexual flower has either ___________ or ___________.
l. Monocots have ___________ venation.
m. The plant with dicot leaves have ____________ root system.

3. Write 'T' for true and 'F' for false statements.

a. Roots are green in colour.
b. Grasses have tap roots.

c. Woody stems are green in colour.
d. Nodes and internodes are found on stems.
e. Lamina is the flat and wide portion of a leaf.
f. All parts of a flower develop into a fruit.
g. Petals are beautiful coloured in a flower.

h. Androecium is not found in complete flower.
i. The transfer of pollen grains from anther to stigma is known as

pollination.
j. Seeds are present outside the fruits.

4. Match the following:

Corolla outermost whorl of a flower

Seed female reproductive part of a flower

Calyx male reproductive part of a flower

Androecium mature ovule

Fruits mature ovary

Gynoecium colourful part of a flower

5. Define the following process in plants.

a. photosynthesis b. transpiration c. pollination d. fertilization

6. Answer the following questions:

a. What are the functions of roots?
b. How can you differentiate between the tap roots and fibrous roots?

Give two examples of each.
c. Name two important functions of the leaves.

50 Science, Health and Physical Education Book - 5

d. How do plants purify air?
e. Name the gases that are involved in photosynthesis.
f. Mention the function of

i. stomata ii. sepals iii. stamens iv. lamina
g. How are seeds useful to plants?
h. Which whorl of the flower attracts insect and why?
7. Differentiate between
a. Sepals and petals
b. Pollination and fertilization
c. Self pollination and cross pollination
d. Monocotyledonous and dicotyledonous plants
8. Give an experiment each to show that
a. Roots absorb water and mineral salts from the soil.
b. Sunlight is essential for photosynthesis.
c. Oxygen is given out during the process of photosynthesis.
9. Draw the labelled diagram of the following.
a. Tap root and fibrous root
b. Structure of a flower
c. A leaf

Activity

1. Divide the students of your class into six teams. Write team A, Team B, team C, team D,
team E and team F on 6"×3" cards. Now, place cards at their respective positions i.e.
team A's card on team A's table, team B's card on team B's table and so on.

2. Make another six cards. Write ROOT on one card, STEM on the second, LEAF on the
third and FLOWER, FRUIT, SEED likewise on the other three cards.

3. Appoint one student as a time keeper.
4. Request your teacher to be the judge.
5. Ask the team leaders to pick up their cards. Give them five minutes to discuss about

their topic.
6. Now ask them to speak on each topic continuously without any break for one minute.
7. Your teacher will give points on the basis of the information given out by the teams.
8. Display the list of the students of the winning team on the bulletin board of your class.

Science, Health and Physical Education Book - 5 51

Subject Link

Create a name chain with names of fruits and vegetables. Make this list 20 words long.
Eg. Mango Orange .......................................................................

Fun 7 Across
Time
1. Pigment required for
1 making food by green
plants.
2
6 2. Small opening on the
surface of leaves.
3
3. Male reproduction part of
4 the plant.
5
4. It carries water from roots
to the other parts of the
plant.

5. Food storing the part of the
potato

Down

1. Gas required by plants to
manufacture food.

6. Female reproductive part
of the flower.

7. The process of making food
by green leaves.

Project work

• Collect five common flowers from your locality. Do all these flowers look alike?

Study parts of each flower and note the differences among them.

• Collect the leaves of various plants found in your locality. Press and paste them

in your scrapbook.

• Make a list of various roots, stems and leaves that we eat. Also draw their

diagram.

52 Science, Health and Physical Education Book - 5

5Lesson Life Processes

Specific After the completion of the lesson, students will be able to:
Objectives • explain different life process in living organisms.

• show difference between autotrophic and heterotrophic organisms.

• explain relationship between plants and animals for food.

• identify inter-relationship between living organisms and the
environment.

Mind Opener

• Explain in five sentences that living things do for their survival.

• Match the following human systems with their respective organs.

Circulatory system lungs

Excretory system stomach

Respiratory system kidney

Digestive system heart

• Match the following human systems with their respective
function.

Circulatory system exchange of O2 and CO2
Digestive system removal of waste materials

Respiratory system digestion of food

Excretory system Circulation of blood

Science, Health and Physical Education Book - 5 53

Introduction

Living organisms perform various important activities that are necessary for
them to be alive. The basic activities which are performed by living organisms
for their survival are called life process. Some of the common life process in
the living things are nutrition, respiration, internal transportation, excretion,
growth, reproduction, etc.

Nutrition

All the living organism need food for their survival. Living things get energy
from the food they eat and perform various activities. The process of obtaining
various nutrients and water through different modes to get energy is known
as nutrition. Food provides nutrients for the growth and development of
organisms. Various nutrients help them to keep their body functioning well.
Depending upon the mode of nutrition, it is of two types. They are described
below.

a. Autotrophic nutrition

Green plants can prepare their own food from water, minerals, carbon dioxide
and sunlight. The mode of nutrition in which living organisms can prepare
their food by themselves, utilizing water, carbon dioxide and sunlight is called
autotrophic mode of nutrition. This process is known as photosynthesis and
plants are called autotrophs.

Carbon dioxide + Water Sunlight Glucose + Oxygen
Chlorophyll (food)

b. Heterotrophic nutrition

Animals and non-green plants cannot prepare the food on their own. Hence,
they obtain their food from plants and other animals. The mode of nutrition
in which living organisms cannot prepare their own food and hence depend
on other animals and plants for their survival is called heterotrophic mode of
nutrition and the organisms are called heterotrophs. Mushroom, yeast, mucor,
human, cow, elephant, rat, etc are some examples of heterotrophs. They
depend upon other for their food.

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Mushroom Dog Elephant Lion

Depending upon feeding habits, organisms are grouped as herbivores,
carnivores, omnivores, saprophytes and parasites.

Animals which depend on plants and plant products for food are called
herbivores. Some examples of herbivores are goat, rabbit, deer, cow, sheep,
zebra, etc.

Animals which depend upon the flesh of other animals for food are called
carnivores. Some examples of carnivores are lion, tiger, leopard, vulture,
snake, python, etc.

Animals that feed upon both plants and flesh of animals are called omnivores.
Some examples of omnivores are crow, pig, bear, cockroach, human beings,
etc.

Saprophytes are the non-green plants that feed on dead and decaying matter
for their survival. Examples of saprophytes are mushroom, mucor, yeast,
fungi, etc.

Mushroom Yeast Mucor Mould

Some minute living organisms live on the larger living organisms and suck
their blood for their survival. These smaller living organisms are called
parasites and larger organisms are called hosts. Examples of parasites are
liverfluke, mosquito, tapeworm, roundworm, etc.

Science, Health and Physical Education Book - 5 55

Mosquito Tapeworm Liverfluke Leech

Respiration

All the living organisms need oxygen to survive. Respiration is the basic feature
of all living things. Plants and animals get energy from the food through
respiration. The process of breaking down of food materials by oxygen with
the release of energy is called respiration.

Glucose + Oxygen → Carbondioxide + Water + Energy

Animals and plants respire throughout the day and night to get energy. They
take oxygen from the surrounding atmosphere. When oxygen reaches to the
cell, it oxidizes food materials which are stored in the cell. During this process,
energy is released in the body that helps to survive. Carbondioxide gas and
water are also produced as by products, which are released from the body as
waste products.

Simply, respiration is the process of taking oxygen inside our body and releasing
carbondioxide from our body to the surrounding. The process of taking in
oxygen is called inhalation and the process of releasing carbondioxide is called
exhalation. In various animals, respiration is done by several types of organs
like lungs, gills, trachea, skin etc whereas it is done by tiny opening structures
in the leaves known as stomata in plants.

Lungs Gills Stomata

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During respiration, plants release carbondioxide as a byproduct. The released
carbondioxide is used again by the plants during photosynthesis and
release oxygen. This process helps to maintain the balance of oxygen and
carbondioxide in the nature.

Internal transport

All the living things need food, air and water Internal transport in plant
for their survival. These materials should be
transported to cells of the different parts of
the body. The process of transporting different
materials from one part of the body to another
is called transport system. This process occurs
inside the body of living organisms which is
called internal transportation.

Plants have vascular tissues, called xylem and phloem for the purpose of
transportation of various substances within the body. Generally, xylem
transports water and minerals from roots to leaves for photosynthesis and

phloem transports prepared food from leaves to various parts
of the plants.

In higher animals, circulatory system transports food, oxygen
and other necessary materials to all parts of the body. Waste
substances are also carried by blood to respective excretory
organs. In unicellular microscopic organisms, cytoplasm or protoplasm
helps in internal transport.

Excretion

The process of removal of waste materials from the body of living things is
called excretion. Plants and animals excrete to get rid of waste products which
are supposed to be harmful for their bodies. Lungs, skin and kidneys are the
major organs of excretion in developed animals. Kidneys help in the filtration
of blood and unnecessary wastes present in the body. They excrete urea, uric
acid and excessive amount of water through urethra in the form of urine.
Similarly, the solid waste i.e. faeces are removed through anus. In the same
way, they excrete carbondioxide through the nose.

Science, Health and Physical Education Book - 5 57

In plants, there are no special organs for the process of excrection. However,
the excess amount of water vapour, carbondioxide and oxygen are removed
through the stomata. Other substances like resins, gums, latex, etc are also
excreted through the barks and leaves of the plants. These substances are
useful for human beings.

Reproduction

The process of producing of young ones by living organisms of their own kind
is known as reproduction. Reproduction is necessary to increase their number
and continue their generation. Different organisms reproduce in various ways.
Some animals give direct birth to young ones and some animals lay eggs. Cow,
donkey, dog, man, etc give birth to young ones directly whereas hen, duck,
crocodile, snake, etc lay eggs.

Lower animals reproduce by different methods. Hydra reproduces by budding
and regeneration. Amoeba and paramecium reproduce by fission.

The process of reproduction in case of plants is different. Some plants reproduce
sexually whereas others reproduce asexually. Sexual reproduction takes
place by the fusion of male and female gametes. The lower plants reproduce
asexually. Fern reproduces by spores. Spirogyra reproduces by fragmentation.
Some plants reproduce by root, stem and leaf. This type of reproduction is
called vegetative propagation.

Roots of some plants like sweet potato develop into new plants from the
small buds present at the swollen portion of the root. Similarly, leaves of some
plants like bryophyllum have buds along the edge. New tiny plants like rose
develop from stem cuttings. These cuttings have one or more buds on them.
When grounded into the soil, they develop into new plants after some days.
Sugarcane and hibiscus develop from the stem cuttings. The potato is an
underground stem. It has 'eyes' which give rise to new plants.

Interrelationship between plants and animals

Plants and animals are interrelated to each other. They depend on each other
for their survival. Animals depend on green plants directly or indirectly for
their food. Similarly, carnivores feed on herbivores. It shows that carnivores
depend on green plants indirectly. In the same way, when animals die, their
bodies are decayed by the fungi and bacteria into simpler substances. These
substances are mixed into soil and act as fertilizer. Green plants absorb those

58 Science, Health and Physical Education Book - 5

materials from soil and use them to prepare food. Hence, plants and animals
have deep interrelationship for their growth and survival.

When herbivores feed on the green parts of the plants, food and energy is
transferred from plants to herbivores and when carnivores feed on herbivoroes,
energy is transferred from herbivoroes to carnivoreus. This continuous process
of eating and being eaten forms a chain called food chain. When these living
organisms die, they are decomposed by the decomposers and nutrients in
them get mixed with soil. These processes make balance in the environment.

Similarly, plants and animals take oxygen inside and throw carbondioxide
outside during respiration. Plants take carbondioxide and release oxygen
during photosynthesis. These two process help to maintain the balance of
oxygen and carbondioxide in the environment.

being being
eaten by eaten by

Interrelationship between living things and environment

All living things depend upon environment. Environment is the surrounding
in which an organism lives. All living things obtain food, water, air, shelter
from the environment to live, grow and respire from air. Similarly, plants
need carbondioxide for photosynthesis. Water is also necessary for different
purposes for plants and animals. Similarly, plants and animals also release
other waste materials in the environment. Microbes break down these waste
materials, dead and decaying organisms and convert them into useful minerals.
Plants use minerals for their growth and animals feed on plants for survival.
Hence, all living things are directly or indirectly dependent on environment
for their survival. Living things play an important role in maintaining balance
in nature.

Activity 1

• Observe a house lizard. Find out what it eats and how it catches its
food. Also find out where it goes during winter.

• Visit a pond or a lake and observe the water animals and how they
come up to breathe. Be careful.

Science, Health and Physical Education Book - 5 59

Points to Remember

1. Those process which are performed by living things to survive are
called life process.

2. The process by which plants and animals obtain food and utilize
nutrients present in food is called nutrition.

3. Green plants can prepare their own food. They are called autotrophs
and the mode of nutrition of autotrophs is called autotrophic nutrition.

4. All non-green plants and animals which cannot prepare food materials
themselves are known as heterotrops and the mode of nutrition is
called heterotrophic nutrition.

5. The process in which the digested food combines with oxygen to
release energy is called respiration.

6. Living organisms carry various substances from one part of the body
to another to survive. This process is called internal transport.

7. The removal of waste materials from the body of the living things is
called excretion.

8. Living things reproduce their own kinds to continue the existence of
their species on the earth.

9. The process by which living organisms produce their own kinds is
called reproduction.

10. Plants and animals depend on each other for their survival.

11. Plants and animals play a great role to maintain ecological balance.

Exercise

1. Choose the best answer from the given alternatives.

a. Which of the following is heterotrophic?

i. grass ii. apple tree iii. mushroom iv. tomato plants

b. Fungi are examples of _________.

i. autotrophs ii. parasites iii. saprophytes iv. green plant

c. _________ is the process in which digested food combines with
oxygen to release energy.

i. digestion ii. circulation iii. excretion iv. respiration

60 Science, Health and Physical Education Book - 5

d. Fish breathe through _________ .

i. lungs ii. scales iii. skins iv. gills

e. Generally, plants reproduce by means of _________.

i. Seeds ii. fruits iii. eggs iv. stomata

f. The process of throwing excess amount of water by plants is called
________.

i. transportation ii. digestion iii. reproduction iv. transpiration

g. _________ is one of the excretory organs of human.

i. kidney ii. veins iii. heart iv. stomata

2. Fill in the blanks with appropriate words.

a. The plants that can prepare their own food are called _________ .

b. Organisms which consume food from dead and decayed matters of
other living things are _________ .

c. During respiration, plants release _________ gas.

d. Plants respire through the tiny holes in their leaves called the ______.

e. The process of throwing waste products by living things is called
_________.

f. Carnivorous animals feed on _________.

g. The vascular tissues of plants are _________ and _________.

h. Balance of oxygen and carbondioxide gas in the environment is done
by _________ and _________.

3. Write 'T' for true and 'F' for false statements.

a. Life processes are not important for living things.

b. Food is essential to perform various activities.

c. Green plants are called autotrophs.

d. Deers and rabbits are called heterotrophs.

e. Elephant and giraffe are called carnivores.

f. Chlorophyll of the leaves trap light at night.

g. Mosquito and leech are examples of parasites.

h. In higher animals, circulation of blood is carried out by the circulatory
system.

i. Plants remove water from roots.

j. Xylem transports water and minerals.

k. Animals depend on plants for their food and shelter.

Science, Health and Physical Education Book - 5 61

4. Match the following.

Yeast Autotrophs

Mosquito Herbivore

Green plants Saprophytes

Rabbit Parasite

Tiger Omnivores

Crow Carnivores

5. Answer the following questions.

a. What are life process? Give any three examples.

b. What is meant by autotrophs? Write its two examples.
c. What is heterotophic nutrition? Write its two examples.
d. Define carnivoroes and omnivoroes with two examples of each.
e. Why respiration is necessary for living things?
f. List the various respiratory organs of different animals.
g. What is meant by internal transport? How it is occured in plants?
h. What is excretion? Why do animals excrete?
i. Name any two waste materials produced by plants.
j. What is reproduction? Why do living things reproduce?
k. What kinds of reproduction does it take place in following:

bryophylum, rose, hydra, spyrogyra.
l. "Reproduction helps to continue the race of life from generation to

generation". Explain with reference to reproduction as an important
part of life process.

m. Draw a simple food chain and write few sentences about it.
n. How are plants and animals interrelated? Describe in brief.
o. Describe the interrelationship between living things and environment.
6. Differentiate between

a. Autotrophs and Heterotrophs
b. Xylem and phloem
c. Saprophytes and parasites
d. Respiration and excretion

Project work

Cut a branch or stem of a rose plant and plant it in soil. Water it regularly. What
do you observe? Write a report on it.

62 Science, Health and Physical Education Book - 5

6Lesson Effects of Human Activities
on Environment

Specific After the completion of the lesson, students will be able to :
Objectives • describe various activities of human beings that affect the

environment.

• explain the causes and effects of environmental pollution.

• describe about natural disasters like flood, landslide and soil
erosion.

Mind Opener

• Categorize the following waste materials and put them in respective
bins.

Bio-degradable waste bin • Pieces of glasses and Non-bio-degradable waste bin
metals

• Food wastage, vegetable
wastage

• Packet of milk, oil and
food

• Additives boxes of cups
and plates, old toothpaste,
brush

• Have you ever seen or heard about different types of natural disasters
happening around you? If yes, mention their names.

• Why these events happen? Can't we control them?

Science, Health and Physical Education Book - 5 63

Introduction

Everything that surrounds us including air, water, animals, plants is called
environment. Environment consists of both biotic and abiotic components.
Life on earth is a complex interdependence of both biotic and abiotic factors.
The biotic components include all living things like plants, animals and human
beings. The abiotic components include all non-living things like air, water,
soil, land, light. Clean air, clean water and food are the basic needs of all living
organisms.

Our forefathers were conscious of their environment and they never did
anything that could cause harm to it. So they lived in a clean and green
environment and led a healthy life. But in today's world, people are clearing
forests to make shelters. More and more cars are running on the roads.
Industries and factories are increasing day by day. All these things are polluting
air, water and soil.

Pollution

Pollution can be defined as the presence of harmful substances in air, water
or land. The harmful substances which pollute air, water and land are called
pollutants. As these harmful substances, gases, chemicals and garbage are
added to the environment, they affect the quality of life of all living things.
Pollution is very dangerous for our health and environment. It can cause
sickness and even death of living things.

Human activities and increase in population destroy the natural ecosystem.
An ecosystem is a natural unit consisting of all plants, animals and micro-
organisms functioning together with all the non-living components. Example,
pond ecosystem, forest ecosystem, etc.

Human activities such as cutting and clearing of forests, release of harmful
substances into the air and water, mining, construction of highways, buildings,
etc have led to destruction of ecosystem and environmental pollution.

In this lesson, we are going to study about the adverse effects of human
activities on air, water, soil and forest.

64 Science, Health and Physical Education Book - 5

Air

The earth is surrounded by a layer of air. This layer of air is called the
atmosphere. It is a renewable natural resource which consists of many gases
such as nitrogen, oxygen, carbondioxide and so on. It is found in unlimited
amount and it will never be used up. Above the atmosphere is space. There is
no air in space.

Every living thing needs air to breathe. The oxygen gas present in the air helps

to burn food in the body to provide energy which helps to perform work.

Thus, oxygen is known as a life supporting gas. We cannot see air but can feel

its presence.

The contamination of air with harmful Explore
and unwanted substances is called air
pollution. So, air pollution is the addition Find out the main pollutants
that cause air pollution.

of substances to the atmosphere that can

cause adverse effects to human health and to other living things that breathe

the polluted air. Various human activities are responsible for air pollution. The

burning of fossil fuels (coal and oil) to generate heat and power for human

consumption is the main source of air pollution. Transportation, burning of

industrial wastes and other solid wastes also cause air pollution.

Causes of air pollution

Some of the causes of air pollution are as follows:

1. Factories and vehicles burn coal, petrol and diesel, which produce smoke.
Some toxic gases like carbondioxide, sulphur dioxide and methane come
out of them and pollute the air.

2. Cutting down of trees on a large scale i.e. deforestation also causes air
pollution.

3. Smoke produced due to forest fire, burning of tyres, plastics, etc.
4. Bad odour released by dumping of waste materials, garbage, dead bodies

of animals, open sewage, etc.
5. Dust particles released during construction of buildings, road, etc.

Science, Health and Physical Education Book - 5 65

Smoke from factories Smoke from vehicle Deforestation Bad odour of waste

Effects of air pollution

Various effects caused due to air pollution are as follows:

1. Polluted air causes respiratory diseases like asthma, bronchitis, lungs
cancer, etc.

2. Polluted air results the acid rain which destroys the cultural heritages like
temples, idols, etc.

3. Polluted air causes global warming that increases the temperature of earth's
surface which leads to climate change.

4. Polluted air can also cause allergy and skin diseases.
Preventive measures to control air pollution
1. Use of solar energy, hydroelectricity should be increased.
2. Factories must be situated far away from residential areas.
3. Waste products should be disposed properly.
4. Plantation should be done in bare areas.
5. Awareness about air pollution should be increased.

Water

Water is one of the most essential substances for the existence of life. Plants
and animals cannot survive without water. Thus, there would be no living
things on earth in the absence of water. Water is the most abundant substance
available on the surface of the earth. About three - fourth (3/4th) of the earth's
surface is covered with water. In nature, it is found in all the three states; solid,
liquid and gas.

Except drinking, we use water for bathing, washing, transportation, irrigation,
energy production and recreation. It is used in many industries and in the
construction of roads, buildings, etc.

66 Science, Health and Physical Education Book - 5

We get water from various sources like river, lake, pond, stream, well, etc. We
all need clean and pure water to drink and use. But the sources of water are
being polluted day by day due to human activities.

Water gets contaminated when wastes from industries and farms, sewage
from homes and hospitals are thrown into rivers, lakes, streams, etc. The
contamination of water due to the mixing of harmful and unwanted substances
is called water pollution. The physical and chemical properties of the water are
changed when water get polluted.

Causes of water pollution

Some of the causes of water pollution are as follows:

1. Mixing of sewage and dirty water from house in the sources of water cause
water pollution.

2. Mixing of industrial waste materials into water resources cause water
pollution.

3. Defecating and urinating in the sources of water or near the sources of
water cause water pollution.

4. Mixing of factories toxic chemicals directly into the water sources makes
water dirty.

5. Excessive use of fertilizers and pesticides in the agricultural field also cause
water pollution.

Washing Sewage water Toxic element Throwing
clothes in river into river into the river garbage in river

Effects of water pollution

The harmful effects of polluted water are as follows:

1. Water pollution causes growth of such micro-organisms which cause
water-borne diseases such as cholera, typhoid, jaundice and dysentery, etc.

2. It reduces oxygen availability in water for the aquatic life.

Science, Health and Physical Education Book - 5 67

3. Harmful substances like lead and mercury enter into the human body
through the food chain.

4. It leads to abnormal growth of unnecessary plants if polluted water is used
for irrigation.

Preventive measures to control water pollution

The following preventive measures can be taken to control water pollution.

1. Do not throw wastes directly into the water sources.
2. Stop people and animals, urinating and defecating near the water sources.
3. Industrial effluents should be treated before their discharge into water.
4. We must use optimum amounts of pesticides and fertilisers.
5. We must not wash clothes, utensils or bath animals in water sources.
6. We should clean rivers and lakes from time to time.
7. Awareness should be increased about water pollution.

Activity

Prepare a list of sources of air and water pollution in your village/city/
town in the format given below. Write their names in the space provided.

Type of pollution

1. Air pollution,

• inside houses i. ____________

• on the roads ii. ____________

• near industrial areas iii. ____________

2. Water pollution, in

• ponds i. ____________

• rivers ii. ____________

• wells iii. ____________

Soil

Soil is the soft substance that forms the surface of the land. It is a precious
natural resource which is made of fine sand particles, clay, humus, etc. Soil
stores minerals and nutrients for the growth of plants. All living things make
their habitat basically in the soil. There are many living organisms present in

68 Science, Health and Physical Education Book - 5

the soil. Most plants grow in soil. We cultivate crops in the soil. The quality
of the soil should be good for the growth of the crops. All animals depend
directly or indirectly on plants for their food. Thus, soil is important for the
continuity of the life. But soil is being polluted day by day due to human
activities. The mixing of harmful and unwanted substances in the soil is
called soil pollution.

Causes of soil pollution

Some of the causes of soil pollution are mentioned below:

1. Dumping of non-biodegradable garbage like plastics, metals.
2. Using excessive pesticides, fertilizers and insecticides by the farmers.
3. Passing of poisonous waste from the hospital, laboratories, industries and

factories into the soil.
4. Flowing wastage from the drains in the fallon land.
5. Construction activities also cause soil pollution.
Effects of soil pollution

The harmful effects of soil pollution are

1. Non-biodegradable wastes like polythene and pieces of metals, glasses do
not allow the soil to have air.

2. The chemical waste from factories when thrown into the soil, makes it
toxic.

3. Soil becomes less fertile, so, plants cannot grow well on polluted soil.
4. Bad smell from the polluted soil affects the environment.
Preventive measures to control soil pollution
The following preventive measures can be taken to control soil pollution.
1. We must throw garbage in separate garbage bins, wet garbage in one bin

and dry garbage in another bin.
2. Bio-degradable wastes must dump into decomposing pits to convert them

into manures.
3. Non-biodegradable wastes garbage must be recycled to make usable

things.
4. We must dispose polythene bags and plastics properly. Polythene bags and

plastic choke drains. As a result, they pollute the air by giving out foul
smell.
5. We must say 'No' to polybags.
6. Use pesticides and chemical fertilizers in wise manners.

7. Awareness should be increased about soil pollution.

Science, Health and Physical Education Book - 5 69

Forest

Forests are the area that cover the land with diverse plant, vegetation
supporting varied faunal species. Forests provide food and shelter for animals
and plants. We get firewood, timber, fruits, fodder, medicinal herbs, etc from
forest. Forests enhance the natural beauty and promote tourism industries.
Forests also prevent soil erosion. Forests help to reduce the amount of carbon
dioxide and balance the amount of oxygen in the atmosphere. The trees and
other plants in forests help to keep the environment clean. They also provide
other essential materials like rubber, paper, timber, medicines, etc.

The importance of forests are mentioned below:

1. They protect water resources and soil.

2. Forests provide habitat to a large number of plants, animals, birds and
insects.

3. Trees release oxygen which is needed for survival.

4. They provide us useful products such as timbers, paper, medicines, gum,
etc.

5. Dead plants and trees decompose to form humus, which helps in
maintaining soil fertility.

6. They increase natural beauty and prevent pollution.

Though, human beings have such benefits from forests, they have not taken
good care of forests. Forests are being destroyed to fulfill the increasing
demands of land for cultivation and urbanization. Hence, tremendous impacts
in the environment have been created due to deforestation. Deforestation
refers to the continuous destruction of forests due to natural or human related
activities. The following figures show the major causes of deforestation.

Requirement of Conversion Overgrazing of
wood of forests to cattles
agricultural land

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Effects of deforestation

The following are the effects of deforestation.

1. It destroys the natural habitat of wild animals and plants.
2. It decreases water resources.
3. It causes flood and landslides.
4. It causes scarcity of firewood and medicinal plants.
5. It also promotes global warming. (increase in global temperature)
Conservation of forests

Here are some practices that could help in conserving the forests.

1. Trees should be planted on a large Info bits
scale on the available land (barren
lands). Afforestation : Planting of saplings
in large scale.
2. More forest reserves and botanical Reforestation: Afforestation on
gardens should be established. deforested land.

3. Overgrazing of cattle in the forest

should be avoided.

4. Measures should be taken to prevent and control forest fires.

5. People should be made aware regarding the value of afforestation and
reforestation.

6. Since paper is obtained from wood pulp, recycling of paper will also help

to conserve trees to some extent.

Natural Disasters

The nature nurtures all creatures by providing shelter, food, air, water, etc.
It keeps all creatures alive. Sometimes this friendly relationship turns into
devastation. There are events that take away life and property of humans.
They are called calamities. If these calamities or disasters are caused by nature
or natural force, we call them natural calamities or natural disasters. Thus,
naturally occurring events that cause a lot of harms or damage are called
natural disasters. Here, we are going to discuss some of the natural disasters.

Science, Health and Physical Education Book - 5 71

Flood, landslide and soil erosion

The overflow of water from the river channel is Flood
called a flood. During the rainy season, the level of
water in river starts rising. This results in river water
flooding into villages and cities. Floods are caused by
abnormally high rainfall, rapid melting of glaciers,
dam failures, land slides, etc.

Flood affects thousands of people in Terai every year Landslide
and cause damage of life and property on a large scale.
Besides, the crops are swept away and the cultivable
land changes into unsuitable for cultivation. The flood
deposites sand and stones carried by it over the land.
Flood can also cause shortage of food and drinking
water. Diarrhoea, cholera, typhoid, etc may spread in
communities due to it.

Sliding down of land mass from a sloping surface is called a landslide. Regular

rainfall for a long time is the main cause of landslides. It is common in hilly or

mountainous region in rainy season. It destroys houses, roads, bridges, water

supply, electric supply and communication networks.

It kills people, wildlife and destroys the vegetation.

It disturbs natural environment. It also causes water

pollution. The topmost layer of the soil contains most

of the nutrients. It is a fertile layer which is essential for

growth of plants. Blowing off or washing of the fertile

top soil from higher land levels to lower levels because

of heavy rains and strong winds is called soil erosion. Soil erosion

The main causes of soil erosion are deforestation,

cultivation in slope land, construction of buildings, roads and dams in the

steep land. Soil erosion damages soil and reduces the fertility of soil. In our

country, every year a large amount of fertile soil is carried away by floods.

Causes of flood, landslide and soil erosion
Some of the causes of flood, landslide and soil erosion are mentioned below:
1. Increase rate of deforestation.
2. Overgrazing of livestock in grass land.
3. Agriculture in the slope land without making terrace.

72 Science, Health and Physical Education Book - 5

4. Heavy and continuous rainfall and wind.
5. Unscientific construction of roads, buildings, dams, etc.
Effect of flood, soil erosion and landslide
1. Landslide and flood damage human settlement, roads, houses, bridges,

temple, etc.
2. Landslide block the rivers and sudden release of blocked water may cause

flood.
3. Landslide damage agricultural field by depositing rocks and sediments.
4. Soil erosion removes the fertile soil and reduces the crop productions.
Measures of controlling flood, landslide and soil erosion
Flood, landslide and soil erosion can be controlled by the following ways:
1. By planting trees on barren and slope land on large scale.
2. By managing terrace farming on slope lands.
3. By making dams and embankment on the bank of river or rivulets.
4. Launching rotational grazing programme.
5. By managing scientific construction of roads, buildings, bridges, etc.

Activity

Take two wooden boxes. Fill both
of them with equal amount of soil.
In one box, fix some plants like
grass. Tilt both the boxes and pour
equal amount of water in both the
boxes. Note what happens. You
will see only water flows out from
the box in which plants are fixed
while from the other box water
along with soil is drained out. This shows that plants help prevent the soil
from flowing out.

Science, Health and Physical Education Book - 5 73

Points to Remember

1. Environment includes air, land, water, plants, animals human beings
and their property.

2. Population growth and development of cities have created
environmental pollution.

3. Addition of unwanted substances in the environment is known as
environmental pollution.

4. The substances that pollute air, water and soil are called pollutants.
5. When any harmful substances is added to air, it is called air pollution.
6. Polluted air is harmful and injurious to human health.
7. The presence of harmful substances in the water of rivers, lakes,

ponds, oceans is known as water pollution.
8. Polluted water can cause several diseases like cholera, diarrhoea,

dysentery, typhoid, etc.
9. The presence of harmful substances in the soil is called soil pollution.
10. Conservation of forests can be done by planting more trees.
11. Flood, landslide and soil erosion are interrelated natural disasters

which cause heavy loss in lives and properties.
12. The overflow of water from the river channel is called a flood. The

sliding down of land mass from a sloping surface is called a landslide.
13. The loss of top layer of soil due to flood, landslide, rainfall or wind is

called soil erosion.
14. Soil erosion damages soil and reduces the fertility of soil.

Exercise

1. Choose the best answer from the given alternatives.
a. Harmful substances that pollute the environment are called ______ .
i. elements ii. pollutants iii. factories iv. industries
b. Which is the most abundant constituent of air?
i. nitrogen ii. oxygen iii. carbondioxide iv. hydrogen

74 Science, Health and Physical Education Book - 5

c. Sources of air pollution are ________ .

i. forests ii. vehicles iii. diseases iv. forest

d. Process of destroying forest is called ________ .

i. afforestation ii. reforestation iii. deforestation iv. sapling

e. Which one is not the cause of pollution?

i. urbanization ii. industrilization

iii. deforestation iv. afforestation

f. Sliding of land mass in the hilly region is called __________ .

i. deforestation ii. flood iii. land slide iv. soil erosion

g. Which method is used to control soil erosion in Nepal?

i. terrace farming ii. overgrazing

iii. crop rotation iv. deforestation.

2. Fill in the blanks with appropriate words.

a. The environment comprises of the _______ and ______ components.

b. Human beings belong to _________ component of the environment.

c. The harmful substances that make air, water and soil dirty are called
__________ .

d. Burning leaves or trash contributes to _________ pollution.

e. _________ pollution causes asthma and lungs problems.

f. Disposal of untreated sewage in water causes __________ .

g. The mixing of harmful substances in soil is called _________ .

h. Flood and landslide occur due to__________

3. Write 'T' for true statement and 'F' for false statement.

a. Our surrounding with living and non living things is our
environment.

b. Green plants help in keeping the environment clean.

c. Since plastic is freely available, it is wise to use and throw plastic
bags very frequently.

d. Smoke and dust from vehicles do not pollute air.

e. Soil pollution causes asthma and bronchitis.

f. Soil pollution increases the fertility of soil thereby producing more
food.

Science, Health and Physical Education Book - 5 75

g. Garbage should not be thrown in river.
h. Landslide and soil erosion are very common in hilly region.
i. Excessive use of pesticides and fertilizers is responsible for flood.

4. Match the following

Biotic components smoke, industrial gases

Abiotic components plastics
Air pollution air, water, soil
Water pollution overuse of fertilizers
Soil pollution human beings, plants

5. Define the following.

a. Air pollution b. Soil pollution

c. Land pollution d. Natural disaster

e. Landslide f. Eco-system

6. Answer the following questions:

a. What things make up your environment?

b. Briefly explain some of the human activities that have led to the
reduction in the quality of the environment.

c. What is pollution? Write the name of any three types of pollution.

d. Name two gases that pollute air.

e. Write any three ways to prevent air from being polluted.

f. Name any two diseases that are caused by drinking polluted water.

g. Why should farmers use insecticides and pesticides wisely?

h. Write any two steps to prevent water pollution.

i. Name any four soil pollutants.

j. Write short note on the impact of pollution on human health.

k. Write any two causes of deforestation and also mention its effects.
l. What natural disasters are caused by heavy rain?

m. What are the differences between the flood and soil erosion?

n. Write down the causes of flood, landslide and soil erosion.

o. How does afforestation help to control floods and landslides?

76 Science, Health and Physical Education Book - 5

7. Observe the given pictures and answer the following questions.
a. What is the picture about?
b. What are the reasons behind it?
c. What measures can be taken to control it?
d. Write any two effects of it.

8. Sketch the diagram to demonstrate air pollution.

Think and discuss

1. It is said that planting trees will reduce air pollution. How?
2. If you throw away an empty mineral water bottle it will pollute the land. If you burn it,

it will cause air pollution. Can you think of a way of avoiding both?

In your leisure

Find the name of six biotic components of the environment in the given grid. The words
may read forward, backward and across.

E L E P H AN TWO T U
DR T I Y B LKOTU S
GAVACKHZ LOVO
I Y B AC T E R I AA I
K F T N AMC L E P O L
H S GDOG I WA E T R
A I RE TCAB X S AR

Project work

• Make a list of things you can do to protect the environment. Compare your list

with your classmates lists and make a consolidated lists.

• Prepare charts and posters on the topic 'Save our Environment'

Science, Health and Physical Education Book - 5 77

Be Sensitive !

Most of you have heard the terms green house gases and global warming many times. But do
you know what green house gases are? What is global warming? Is it good for our earth or
not? Let's learn more about them.

What are green house gases and what is green house effect ?

A green house is a small house used to grow plants, especially in cold countries in winter. The
glass panels of the green house trap heat from the sun and prevent it from escaping, hence
keeping the plants warm enough to survive in winter.

Our earth is also like the green house. The atmosphere which is made up of gases acts like
the glass panels of the green house and traps some of the heat of the sun. In this way, the
temperature of the earth remains constant and it does not become too hot or too cold, hence
supporting life. Gases like carbon dioxide, methane, water vapour, nitrous oxide and ozone
possess the property of trapping energy from the sun. These gases are therefore known as
green house gases. The natural process of maintaining the earth's temperature and keeping it
warm is known as the green house effect.

Causes of the greenhouse effect

The green house gases are naturally present in the atmosphere. But some human activities also
produce these gases. Activities like burning of fossil fuels, cutting down and burning of trees
etc generate a lot of carbon dioxide. Due to this, the natural balance of the green house gases
in the atmosphere gets disturbed. Use of aerosols, hairspray cans, refrigerators, plastics etc,
release another groups of highly dangerous green house gases called chlorofluorocarbons
or CFCs. These are so harmful that even small amounts can trap large quantities of heat,
making the earth extremely hot. This phenomenon is known as global warming and has a highly
dangerous effect on the earth.

Consequences of the green house effect

Since the climatic conditions on the earth are perfect for our survival, any high increase in the
temperature can cause drastic changes which can be dangerous or life threatening for all living
organisms.

The earth is becoming extremely warm as more heat is getting trapped in it. Some of the effects
of global warming are as follows:

• Change in weather • Melting of glaciers
• Increase in the sea level • Flooding of places near the sea

Our efforts to reduce the green house effect

Since human activities have disturbed the balance of the green house gases in the atmosphere,
only we have to take some steps to reduce global warming. Each of us can do our bit in the
following manner.

• Do not waste electricity. Use it wisely.
• Use fossil fuels judiciously.
• Use recycled products.
• Grow more and more trees
• Make a minimum use of things which release CFC in the atmosphere.

78 Science, Health and Physical Education Book - 5

7Lesson Environment Conservation

Specific After the completion of the lesson, students will be able to:
Objectives • introduce importance of environment and its components.
• explain various methods of conservation of environment.
• apply the methods of environment conservation in practice.

Mind Opener

• Mention your daily activities that pollute the environment.
• List out the way for the conservation of environment.
• Mention the things that can be recycled and reused.
• Which of the following represent environmental degradation?

Science, Health and Physical Education Book - 5 79

Introduction

The surrounding where we live is called environment. It constitutes the
physical world made up of air, soil, water, etc and biological world made
up of plants and animals. Human beings are the only organisms who can
modify the natural environment to fulfill their needs to get food, clothing,
housing, transport, etc. Human beings are cutting down the trees, causing
pollution, killing wild animals, etc for the purpose of fulfilling their needs.
This environmental imbalanced created by various human activities has given
rise to a number of problems in the environment. Therefore, conservation of
environment is an issue of vital importance.

Human beings should be aware about Info bits

the use of environmental resources Natural resources: Valuable
by adopting environment friendly things that are provided by

activities like planting trees, reuse and nature to our uses.

recycle of resources and waste materials.

Conservation of environment is the act of saving natural resources for future

use. Wise use of natural resources is called conservation of environment. It is

the major issue of global concern. We have to take various steps to make the

environment good and healthy and to maintain balance of nature. The various

ways of maintaining a healthy and balanced environment are given below.

Reduction of air pollution

The smoke produced by burning of fuels in vehicles, automobiles, burning of
plastics, firewood, kerosene, etc is a major cause of air pollution. Therefore old
automobiles should be renewed and maintained properly so that they do not
produce more smokes and cause air pollution.

Air pollution can also be reduced by the use of alternative sources of energy
like solar energy, wind energy, hydro-electricity etc. We can develop electric
vehicles and solar vehicles. We can also use biogas, solar cooker and electricity
for the purpose of cooking food. Besides, the plantation of green trees around
houses and along the road sides can also be done for controlling air pollution.

The industries and factories should be established far away from the residential
area. Such industries and factories should be advised to use tall chimneys for

80 Science, Health and Physical Education Book - 5

the escape of smoke and hot air from the nearby ground. Besides, pollution
free source should be used instead of petroleum products. The dead bodies of
animals should be burried and the waste materials should be dumped properly
to reduce air pollution. If we adopt such practices on time, air pollution is
greatly reduced.

Causes of air pollution

Protection of wild animals

The animals living in the forest and different types of environment are called
wildlife. They add beauty to the environment. They contribute for the balance
of nature in various ways. The process of eating and being eaten keeps balance
in the environment. Human beings have damaged settlement of wildlife.
Human beings are destroying the
habitat of wild animals for their
benefit. Similarly, people hunt
animals for their meat, bones, musk,
ivory, horn, skin, fur or simply for
fun. Such activities distract wildlife
as well as healthy balance of the
environment. The natural habitat
of wildlife is also destroyed due to
human activities like construction of
roads, establishment of industries,
settlement areas, etc. Due to destruction of habitat, the number of wild animals
have been lost forever and some are endangered.
Conservation and protection of wildlife (animals and birds) should be done.
Natural habitat of wild animals can be conserved by the establishment of
National park, Conservation areas and Wild life reserves. Similarly, government

Science, Health and Physical Education Book - 5 81

should focus on formulation and implementation of strict rules and regulations
to control illegal hunting, poaching and prohibit the use of goods made of
wild animal, fur, skin and bone. Animal rights must be promoted in practice
to protect wildlife.

Protection and conservation of forest

Forest is a large area of land covered with
trees and thickly growing bushes. It is
the natural habitat of wild animals, birds,
insects, etc. Human beings obtain fruits,
fodder, timber, wood, raw materials for
industries, medicinal plants, etc from
forest. Forest resources also help in
maintaining environmental balance. It
maintains the balance of oxygen and
carbondioxide in the atmosphere. Every
year, large area of forests are being destroyed by the forest fire. The forest fire
causes the death of many animals, birds, and plants. Similarly, it leads to the
destruction of habitat, which in turn, causes the disappearance rare plants and
animals. Besides, forest are being cleared extensively. Because of this, world
is facing climate change and various natural disasters. Therefore, special
efforts should be made for the conservation of forests. The illegal cutting of
trees for timber trade should be stopped. Overgrazing in the forests should
be controlled. In case of legal cutting of trees, saplings should be planted to
cover up the loss. Similarly, we should encourage everyone for afforestation
and wise utilization of forest products.

Afforestation

The process of plantation of trees in
uncultivated land for the growth of forest
is called afforestation. A lot of barren land
and uncultivated land is found in our
surroundings. In such land, we can plant the
small trees or saplings. Gradually, the plants
grow and develop into forest. Forest makes
the air pure and fresh. It also conserves water
resources. Besides, it helps to improve the

82 Science, Health and Physical Education Book - 5

humidity in dry area where atmosphere is extremely dry. Afforestation also
provides habitat and food for wild animals, birds and insects and helps to
preserve the rare plant species. Trees also prevent various natural calamities
like flood, landslides and soil erosion by retaining particles with their
roots. Similarly, afforestation around the residential areas creates a healthy
environment. So, awareness should be made about the importance of forest
for environmental conservation.

Protection and conservation of water sources

Water is the most important thing for every living organism for their survival.
Though, water is a renewable resources, a small amount of fresh water is
available for use. We use water resources for various purposes like drinking,
cleaning, cooking, washing, agricultural irrigation, etc. Though our country is
rich in water resources, in some parts of our country, people face water crisis
in dry seasons. Hence, we should conserve water resources like wells, taps,
streams, river, ponds, etc. Water also plays a vital role in the conservation and
balance of the environment. Therefore, conservation of water source is a must.

Water gets polluted due to the mixing of unwanted harmful chemicals from
industries, factories which may contain germs. Drinking of such water can
cause diseases such as dysentery, jaundice, typhoid, cholera, etc. Such water
can also affect the aquatic plants and animals. Hence, garbage, industrial
waste and sewage should be rectified and used for making fertilizers, instead
of throwing them directly in water resources. To conserve water resources, we
should not defecate and urinate near water resources. Drainage, sewage and
garbages should not be added into water resources. Excessive use of fertilizers
and pesticides should also be avoided. Also water resources should be cleaned
from time to time. In the same way, we should reduce the wastage of water
and recycle water for different purposes such as cleaning, manufacturing, etc.
Harvesting of rain water can be done. It provides water for domestic use and
irrigation.

Use of scientific agricultural techniques

In Nepal, traditional agricultural techniques have been practiced. These
practices help in soil erosion and reduction of fertility of soil. Instead of
traditional methods of agriculture, we should follow modern scientific
techniques to prevent soil erosion and retain the fertility of the soil.

Science, Health and Physical Education Book - 5 83

Soil can be conserved by planting trees in barren
lands. It prevents soil erosion and landslide. In
hilly regions of Nepal, the scientific techniques
of farming should be practiced such as terrace
farming, rotation of crops, etc. Terrace farming
reduces the speed of flow of water in the hilly
regions. It helps to reduce soil erosion.

Planned Urbanization Terrace Farming

Urbanization is the process of turning the cultivable or barren lands into the

cities with the proper managements of facilities. In our country, towns and cities

are not properly managed. In our cities, a lot of houses are built with narrow

roads, lack of space between

houses, lack of green area, lack of

water supply and drainage. Such

types of urbanization is called

unplanned urbanization. A well

managed city should have proper

management of roads, electricity, Planned Urbanization Unplanned urbanization
drinking water, sewage disposal,

latrines, supermarkets, park, hospitals, schools and colleges. Unplanned

urbanization has a very little scope of healthy environment. Hence, there

should be planned urbanization to maintain a healthy environment.

Embankment on the river banks

During monsoon, many rivers overflow and take the shape of flood in the terai
region of Nepal. Similarly, after a heavy rainfall, a large amount of extra water
flows on both sides of river. Such flooded water cause a lot of soil erosion.
Retaining walls or gabbion wall are build along the banks of river to prevent
the cutting of lands and overflow of rivers. Similarly, dams can also be built to
control the flow of water and soil erosion.

Proper disposal of waste materials

Proper disposal of waste materials plays important role for the conservation
of environment. The waste materials from houses, industries, laboratories and
hospitals should be disposed properly according to their nature. Importance
should be given in recycle and reuse of materials as far as possible. Disposal of

84 Science, Health and Physical Education Book - 5

sewage directly into the water sources should be prohibited. The use of plastics
and plastic products should be banned. The harmful chemicals from vehicles,
industries, hospitals, etc should be treated and changed into harmless forms
before mixing into the soil, water and air. Generally, waste materials can be
categorized into two types.

a. Bio-degradable wastes

The solid wastes that get decay easily are called bio-degradable wastes. Peels of
vegetables and fruits, used flowers, animal excreta, leaves, dead bodies, pieces
of paper, etc are the examples of biodegradable wastes. All materials derived
from living organisms are biodegradable wastes as these get mixed with soil.

b. Non-biodegradable wastes

Those solid wastes that do not decay easily are called non-biodegradable
wastes. Plastics, glasses, old bottles, metal cans, cold drink bottles, light bulb,
etc. are the examples of non-biodegradable wastes. These wastes remain in its
form in the soil for a very long time and can cause environmental pollution.
Domestic animals fall sick and may even cause death on eating such things.
Similarly, these wastes become a breeding place for flies and other microbes
which spread diseases.

We should develop the habit of "Reduce, Reuse and Recycle" for the proper
management of waste materials. Some of the safe methods of waste disposal
are given below:

a. Sanitary landfill

In this method, a landfill site is constructed away from residential areas and
solid wastes are buried. When the landfill is full, it is covered with soil to
prevent foul smell and breading of microbes and insects.

b. Recycling

The solid wastes like polythene bags, glass bottles, etc can be treated again.
This process is called recycling.

c. Incineration

This method is applicable to burn household wastes, chemical wastes from
industries. Incineration is carried out in incinerators (furnaces). This method
does not allow germs to grow, but causes air pollution. That's why, it should
be done away from the residential areas.

Science, Health and Physical Education Book - 5 85

Preparation of compost and biogas

Compost is the organic manure produced by decaying biodegradables
wastes. The cooking gas which is produced by decaying cattle dung and
other biodegradable wastes is called biogas. The compost can be prepared at
our homes by using biodegrable wastes. This method also helps to keep the
environment clean.

Conservation of coal and petroleum

Coal is formed from vegetation matter buried under earth in the distant
past. It is believed that about 300 million years ago, there were dense forests,
marshlands and rivers. The forests destroyed, decayed and were submerged
in the water and got covered with sand and clay. Due to huge pressure and
high temperature, those matters got converted into coal. Coal is thus known
as a fossil fuel. ("Fossil" refers to any remains or impression of living beings of
past geological ages that have been preserved in the earth's crust).

Coal deposits are limited and once finished, will never be produced again.
Thus, coal is a non renewable source of energy.

Petroleum is found beneath the earth's surface. It is formed from the bacterial
decomposition of the remains of animals and plants which got buried under
the sea, million of years ago. Over that long period, due to high temperature,
pressure and catalytic action, these remains got converted into petroleum. In
its natural form, petroleum looks like a thick black liquid and it is called crude
oil. The crude petroleum is pumped out by driling a hole in the earth. During
this process, natural gas also comes out.

Different products are obtained from the distillation of crude petroleum and
their uses are as follows:

a. Petroleum gas: It is mainly used as a fuel as such or in the form of liquified
petroleum gas (LPG).

b. Petrol: It is mainly used as a fuel in motor vehicles.
c. Kerosene: It is used as a household fuel.
d. Diesel: It is used as a fuel in heavy vehicles like buses and trucks, etc.
e. Lubricating oil: It is used as a lubricant.
f. Paraffin wax: It is used for making vaseline, ointments, candles, etc.

The name natural gas has become quite familiar. Nowadays, Compressed
Natural Gas (CNG) is being used as an alternate automobile fuel in many parts
of the world. Nepal too is fast adopting it as an almost pollution free fuel.

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Coal and petroleum are exhaustible non-renewable resources. Coal and
petroleum if once finished, would take million of years to be produced
again. The fast increasing human population, the multiplying industries, the
expanding transport system are fast consuming these energy resources. It is
estimated that at the current rate of consumption, the petroleum resources
may last a couple of centuries and the coal deposits only a few more centuries.
It is therefore, urgently needed that their uses are minimised and whenever
possible replaced by alternate sources of energy such as the wind, solar, tidal,
geothermal energy. Biogas generated by microbial action on human, animal
and agricultural wastes will greatly help in prolonging the availability of coal
and petroleum.

Activity 2

Read the newspaper/magazines daily and spot any news related to
pollution or conservation efforts made by some agency. Cut such news and
paste them in your scrap book. Discuss these news with your classmates
and if possible, with your teacher also.

Points to Remember

1. The surrounding in which living things live and survive is known as
environment.

2. The process of wise use of natural resources is called conservation of
resources.

3. The growth of population and pollution have created disturbances in
our natural environment.

4. The emission of smoke and dust containing harmful gases must be
reduced.

5. We should protect forest and stop hunting wildlife.
6. We should not set fire in the forest and we should conserve the forest.
7. Afforestation should be done on unused land before they get polluted.
9. Urbanization should be managed properly to maintain a healthy

environment.
10. Embankment should be built properly on the banks of river, streams,

etc.
11. Conservation of petroleum and coal can be done by using solar energy,

hydroelectricity, bio-gas, etc.

Science, Health and Physical Education Book - 5 87

Exercise

1. Choose the best answer from the given alternatives.

a. Environment consists of ________ .

i. Plants only ii. animal only

iii. plants and animal iv. living and non-living things

b. Environment friendly activities can be performed by __________ .

i. afforestation ii. deforestation ii. urbanization iv. pollution

c. _________ helps to reduce soil erosion.

i. urbanization ii. deforestation

iii. afforestation iv. fertilizers

d. ________ is the best way to manage non-biodegiadable wastes.

i. reuse ii. recycle iii. compost manure iv. bio gas

e. ________ is the process of making towns and cities.

i. conservation ii. pollution iii. afforestation iv. urbanization

f. _________ is an example of fossil fuel.

i. forest ii. biogas iii. electricity iv. coal

2. Fill in the blanks with appropriate words.

a. _____ are the only responsible factor for the environment pollution.

b. The act of wise use of natural resources is called _________ .

c. Air pollution can be reduced by using _________ sources of energy.

d. Deforestation may hamper the habit of __________ .

e. Afforestation programme should be done on _______ and _______
land.

f. Fertilizers and _________ should not be used excessively.

g. ________ on the either side of rivers controls the flood and soil
erosion.

h. Coal and petrol are the _________ sources of energy.

3. Write 'T' for true statement and 'F' for false statements.

a. Smoke released from industries and vehicles causes soil pollution.

b. Hunting should be banned for conservation of wild life.

88 Science, Health and Physical Education Book - 5

c. Natural habitat should be conserved by establishing national parks,
wildlife reserve and conservation area.

d. We should throw wastes in the sources of water.

e. Afforestation causes irregular rainfall.
f. Excessive use of pesticide and fertilizers is responsible for flood.
g. Plastics, glass and metal pieces are non-biodegradable.
h. Coal and petroleum are exhaustible non-renewable resources.

4. Match the following:

Conservation cutting of forest trees

Afforestation causes air pollution

Deforestation control flood and soil erosion

Smoke wise use of natural resources

Embankment bio-degradable and non-biodegradable

Wastes to plant trees

5. Answer the following questions.

a. Define environment and its components.
b. What is meant by environment conservation?
c. Establish the relationship between biotic and abiotic aspects of the

environment.

d. Mention the methods of reducing air pollution.
e. What measures should be taken to protect wildlife?
f. How conservation of water resources is important for the conservation

of environment.
g. What is afforestation? Why should we conserve forests?

h. How does the modern scientific techniques help to prevent soil
erosion?

i. What is urbanization? How is it differ from unplanned urbanization?
j. Why planned urbanization is necessary for the conservation of

environment?
k. What is meant by terrace farming? Why is it done?
l. How do you manage the wastes of your house?

m. Why is coal called a fossil fuel?

Science, Health and Physical Education Book - 5 89

6. Differentiate between
a. Deforestation and afforestation
b. Biodegradable wastes and non-biodegradable wastes
c. Sanitary landfill and incineration.

7. Give reasons.
a. We should conserve the natural environment.
b. Air pollution can be reduced.
c. Afforestation around the residential areas creates a healthy
environment.
d. The scientific methods must be applied to agriculture.
e. Coal is considered as a non-renewable source of energy.

Project work
• Find out more on global warming and discuss in class.
• Design and make a poster on conservation of air on water.

90 Science, Health and Physical Education Book - 5

8Lesson States of Matter

Specific After the completion of the lesson, students will be able to:
Objectives • define matter and change in state of matter.

• describe how the particles are arranged in solids, liquids and gases.

• explain various process of changing matters from one form to
another them.

• explain melting, freezing, sublimation, evaporation and condensation.

Mind Opener

• Do you observe different By cooling Solid On heaStionlgidification
substances around you? Sublimation
Condensation
• Do these substances have Vaporization
the same state?
Gas Liquid
• How do they differ from
each other?

• What is the main things

that differ an object into
solid, liquid and gas?

• Have you ever seen ice

and water vapour? What
forms of water are they?

• Complete the following chain.

Science, Health and Physical Education Book - 5 91

Introduction

We have learnt in previous classes that anything which has mass and occupies
space is called matter. All objects are made of matter. Matter consists of tiny
particles known as molecules. These molecules are so small that they cannot
be seen with naked eyes. These molecules are further composed of very small
particles called atoms. Atoms are the smallest unit of matter and therefore also
known as the 'building blocks of matter.'

In class four, we have already
learnt that matter has three
physical states; solid, liquid
and gas. Also in the lesson of
energy of class four, we have
studied that the heat applied
to the matters can change its
states. A solid can be changed
into liquid and liquid into gas.
Similarly, gas can be changed
back to liquid and liquid into
solid. This can be done only
when sufficient amount of
heat is supplied or taken out
from the matters at certain
temperature i.e. these three form of water are interchangeable on heating
or cooling. But the temperature at which they change their state is different
for different substances. This type of change of physical state of matter into
another physical state is called change of state of matter.

When matter is heated or cooled, the space between the molecules change.
The molecules either move closer or move away from each other. This results
in a change of state.

When a substance is heated, its molecules move away from each other. So
when a solid is heated, it changes into liquid, and when the liquid is heated
further, it changes into gas. The process by which a solid changes into a liquid
is called melting or fusion. When you take out an ice cube from the freezer and
leave it in normal room temperature you will see that ice starts to melt into
water. Similarly, the process by which a liquid changes into vapour on heating

92 Science, Health and Physical Education Book - 5

is called evaporation. When you heat liquid, you see vapour forming on theMelting
surface of the liquid.
SolidificationIn the same way, when gas is cooled, its molecules come close to each other Evaporation
and it changes to liquid. When cooled further, the liquid changes to solid. The
process by which gas changes into a liquid on cooling is called condensation.
When you hold a cold steel plate over a pot of boiling water, you will see tiny
drops of water condensing on the tray.
The process by which liquid changes into a solid on cooling is called
solidification or freezing. Freezing of water into ice is a form of solidification.
If you fill water in an ice tray and keep it in the freezer, you will see that after
some time the water turns into ice.

Solid

Liquid

Gas

Science, Health and Physical Education Book - 5 93

Sublimation

We have learnt that, when solid is heated it melts. But certain solids can change

directly into vapour on heating. When solid camphor is heated, it directly

changes into vapour, without being liquid. It means camphor sublimates on

heating. The process by which a solid changes directly into vapour without

changing into liquid is known as sublimation.

solid heating vapour (gas)
cooling

The substance such as iodine, camphor, ammonium chloride and naphthalene
are some sublimates as they get changed directly into the gaseous state on
heating.

Activity

To demonstrate sublimation process.

Take a porcelain basin, a glass funnel,

tripod stand, wet cottons or papers,

bunsen burner and camphor. Take some

pieces of camphor into a porcelain basin

and cover it with an inverted funnel.

Block the steam of the funnel with moist

cotton or paper. Keep the basin on a Fig. Sublimation process
tripod stand as shown in the figure. Heat

the basin gently with the burner. What do you observe after some time?

When solid camphor is heated, it directly changes into gaseous state or
vapour. While the vapour of camphor comes in contact of moist cotton or
paper, it changes back into solid camphor. The solid camphor can be seen
on the inner surface of the funnel. This process is called sublimation.

Points to Remember

1. Anything that occupies space and has weight is called a matter.
2. All substances are made of minute particles called molecules.
3. A molecule is the smallest particle of a substance that has all the

properties of the substance.

94 Science, Health and Physical Education Book - 5

4. A substance can exist either as solid, liquid or gas.

5. The changing of a substance from one physical state to another state
by heating or cooling is called change of state.

6. The process by which a solid changes into a liquid state on heating is
called melting or fusion.

7. The process by which a gas changes into a liquid on cooling is called
condensation.

8. The process by which a liquid changes into its solid state on cooling is
called freezing or solidification.

9. The process of conversion of a solid directly into its gaseous state by
heating is called sublimation.

Exercise

1. Choose the best answer from the given alternatives.

a. Anything which has mass and occupies space is called _________ .

i. solid ii. molecule iii. atom iv. matter

b. Matter exists in _________ states.

i. one ii. two iii. three iv. four

c. The process of conversion of water into water vapour is called
_________ .

i. condensation ii. evaporation

iii. sublimation iv. melting

d. What is the term used to explain the change when a liquid becomes
a solid?

i. evaporation ii. condensation

iii. sublimation iv. freezing

e. When camphor is heated, it changes into its _________ state.

i. solid ii. liquid iii. gases iv. fluid

f. Molecules of gas come closer when it is _________ .

i. heated ii. cooled

iii. evaporated iv. sublimated

Science, Health and Physical Education Book - 5 95

2. Fill in the blanks with appropriate words.

a. Matter consists of tiny particles known as _________ .
b. Molecules are composed of very small particles called _________.
c. Liquid wax on cooling changes into _________.
d. The change of gas into liquid is known as _________.
e. Water on heating changes into _________.

f. The conversion of a solid directly into ___________ is called
sublimation.

3. Write 'T' for true and 'F' for false statement.

a. Anything that has weight and occupies space is called matter.

b. The states of matter are interchangeable.
c. Cloud is formed because of condensation.
d. The space between molecules is least in gas.
e. Vapour can be converted into water on heating.

f. On heating, camphor is changed into liquid state.

4. Match the following

Condensation conversion of solid into gas

Evaporation conversion of solid into liquid

Fusion conversion of gas into liquid

Solidification conversion of liquid into solid

Sublimation conversion of liquid into gas

5. Answer the following questions.

a. What is matter? Name three states of matter.
b. What is meant by change in the state of a matter?
c. How can you convert

i. Water into vapour ii. Solid into vapour
iii. Vapour into water iv. Vapour into solid
d. What is melting? Give one example.
e. Describe the activity to show the process of melting of ice with a
diagram.

f. What is solidification? Give one example.

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