Unit Estimated teaching periods: Th Pr
10 2
18
Lungs
Life Processes
Objectives
After completing the study of this unit, students will be able to :
• introduce respiration and explain various breathing organs of organisms, viz.
skin, gills, trachea, spiracles, lungs and stomata.
• explain breathing in plants and animals.
• introduce digestive system in human body and explain it in brief.
• introduce excretion and explain the excretion process in plants and animals in
brief.
Course of Study
• Respiration – Introduction
• Respiration in animals and plants
• Digestive system in human beings
• Process of digestion
• Excretion in plants and animals
• Excretion in human body
Points to be Focused / Questions to be Discussed
• What are life processes?
• What is breathing?
• What is respiration?
• What are the different organs for breathing in plants and animals?
• What is digestive system?
• What is excretion?
BIOLOGY Oasis School Science and Environment - 7 193
18.1 Introduction
Plants and animals perform various activities like breathing, digestion, respiration,
excretion, transport, etc. These activities are called life processes. Living organisms
cannot survive in absence of life processes.
18.2 Respiration
Life is a result of various metabolic activities that take place in a living body
without interruption. Living organisms need energy to perform various physical
and metabolic activities. We eat food to obtain energy. After digestion, the food is
absorbed by our body. Thus absorbed food is oxidized in mitochondria of the cells
and energy is released. This process is called respiration. In this process, water and
carbon dioxide are produced as by-products. Respiration occurs in each and every
living cell. Oxygen is essential for respiration. Living organisms obtain oxygen
through breathing. Respiration is the process of releasing energy by breaking down
food in the presence of oxygen.
Process of Respiration
Respiration occurs in two stages, viz. external respiration and internal respiration.
External respiration
External respiration involves
inhaling of air rich in oxygen
and exhaling of air rich in Nasal cavity Pharynx
carbon dioxide. Energy is not Mouth cavity Larynx
produced in this process. It is Trachea
also called breathing.
Internal Respiration Bronchus
Internal respiration involves Bronchiole Heart
the oxidation of food Right lung Left lung
(glucose) to release energy. Diaphragm
In this process, water and
carbon dioxide are formed
as by–products. Various Figure 18.1: Human respiratory system
enzymes help in this process.
Glucose + Oxygen Enzymes Energy + Water + Carbon dioxide
C6H12O6 + 6 O2 Enzymes Energy + 6 H2O + 6 CO2
Internal respiration takes place in mitochondria of a cell. So, this process is also called cellular
respiration. The energy released is stored in the form of ATP (Adenosine Triphosphate)
molecules. Thus released energy is utilized to operate various life activities.
oxidize /ˈɒksɪdaɪz/ - to combine with oxygen
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Various types of organs are used for breathing in different types of animals. These
structures and organs form respiratory system.
Differences between External Respiration and Internal Respiration
External Respiration Internal Respiration
1. It involves inhaling of oxygen 1. It involves oxidation of food into
and exhaling of carbon dioxide. energy, water and carbon dioxide.
2. It takes place outside the cell. 2. It takes place inside the cell.
3. No energy is released in this 3. Energy is released in this process.
process.
18.3 Exchange of Gases in Simple Organisms
In unicellular organisms like amoeba, O2 inside CO2 outside
paramecium, euglena, etc. and multicellular
organisms like hydra, tapeworm, liver fluke, Figure 18.2: Breathing in Amoeba
sponge, etc. exchange of gases takes place
through the general body surface by diffusion.
This process is called breathing. They do not
have special organs for breathing. Oxygen is
diffused in and carbon dioxide is diffused out
through the body surface.
18.4 Breathing in Insects
Insects like grasshopper, cockroach, mosquito,
butterfly, etc. breathe through a system of air
tubes or tracheae. The tracheae receive air
through paired spiracles present along both
sides of the insect’s body. Tracheae are further
divided into finer tubes called tracheoles which
form a network of tubes throughout the body.
Oxygen enters the body through spiracles and
reaches the cells through a system of tubes by
diffusion. After respiration, carbon dioxide gas
Spiracle
also comes out through the same route. In this Figure 18.3: Breathing in grasshopper
way, exchange of gases takes place in insects.
diffuse /dɪˈfjuːz/ - to mix slowly a substance 195
BIOLOGY Oasis School Science and Environment - 7
18.5 Breathing in Fishes
Fishes and some other aquatic animals like aquatic
insects and molluscs breathe through gills. Gills are
made up of filaments which are richly supplied with
blood capillaries. The dissolved oxygen in water
diffuses into blood through the gills. After respiration,
carbon dioxide leaves these capillaries and enters the Gills
water. These gills are not suitable for breathing in air.
Figure 18.4: Breathing organ in fish
Tadpoles of frogs also breathe through gills.
18.6 Breathing in Frogs
In frogs breathing takes place CO2 outside
through lungs and skin. The skin
of a frog is richly supplied with
blood capillaries. When a frog is O2 inside
submerged in water or when its skin
is moist, exchange of gases takes
place through the skin. This process
is called cutaneous respiration. Some Figure 18.5: Breathing in earthworm and frog
invertebrates like leech, earthworm,
etc. also breathe through gills.
Frog breathes through lungs while on land or floating on water surface or when it
needs more oxygen after jumping. This process is called pulmonary respiration.
18.7 Breathing in Reptiles, Birds and Mammals
In reptiles, birds and mammals, exchange of gases takes place with the help of lungs.
In human beings, well developed respiratory
system is present. This system includes nose,
nasal cavity, pharynx, wind pipe, lungs,
bronchus, bronchioles, alveoli, diaphragm, etc.
In our body, air enters the body through
nose. From the nose, air reaches alveoli after
passing through nasal cavity, pharynx, wind
pipe, bronchus and bronchioles. Alveoli are
microscopic air sacs present in the lungs.
The walls of alveoli are richly supplied with
blood capillaries. Oxygen diffuses from the Figure 18.6: Respiratory system of a mammal
thin walls of capillaries into the blood and
combines with red blood cells. At the same time, carbon dioxide diffuses from the
blood into alveoli and is exhaled through the nose. The upward and downward
movement of diaphragm regulates breathing in human beings.
pulmonary /ˈpʌlmənəri/ - connected with the lungs
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Activity 1
Objective: To make a model of respiratory system of human beings
Materials required: A bell jar, Y-shaped glass tube, two balloons, rubber cork,
thread, rubber sheet, etc.
Procedure
• Take a Y-shaped glass tube and fix two small
balloons to the two arms of the tube as shown in
the figure.
• Fit the free end of the glass tube in the mouth of
the bell jar with the help of a rubber cork.
• Take a thin rubber sheet and tie it around the
open rim of the bell jar tightly.
• Pull the rubber sheet down and release
alternately. What will you observe?
Observation
When you pull down the rubber sheet, air rushes Fig. 18.7
inside the balloons and they fill up with air. When
you release the rubber sheet, air rushes out and the
balloons get deflated.
Compare each part of the given diagram to the real respiratory system and
complete the given table.
Parts of model Parts of respiratory system
1. Balloons inside the bell jar 1. .................................
2. ................................. 2. .................................
3. ................................. 3. .................................
4. ................................. 4. .................................
5. ................................. 5. .................................
18.8 Respiration in Plants Guard cells
Just like animals, plants also respire day
and night in order to get energy. All the
parts of plants like root, stem, leaves, buds,
fruits and germinating seeds respire very
Stomata
actively. Stomata open Stomata closed
Figure 18.8: Opening and closing of stomata
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In plants, exchange of gases takes place through stomata present on the upper and
lower surface of leaves, lenticels of stem and general surface of the roots. During
the day time, carbon dioxide is used and oxygen is given out in photosynthesis. A
part of oxygen, given out during photosynthesis, is utilized in respiration and the
rest is given out through stomata. During night, photosynthesis does not occur,
plants take oxygen from atmosphere and give out carbon dioxide.
Experiment 1
Objective: To prove that carbon dioxide is exhaled during breathing
Materials required: Flat bottomed flask, black paper, thistle funnel, stopcock,
rubber cork, delivery tube, test tube, germinating gram seeds, water, lime water,
Petri dish, etc.
Procedure
• Take a flat bottomed flask and keep some germinating gram seeds into it.
• Cover the flask with a black paper.
• Plug the flask with a rubber cork and fix thistle funnel with stopcock and a
delivery tube into it as shown in the diagram.
Stopcock Delivery tube
Rubber cork
Flat-bottomed flask Black Lime
paper water
Germinating seeds
Figure 18.9
• Keep the free end of the delivery tube Water
inside a test tube containing water.
• Place the apparatus in a darkroom for a Delivery tube
few hours (3-4 hours).
• Remove the test tube containing water Water Lime water
and replace it with another test tube Figure 18.10 turns milky
having lime water.
• Open the stopcock and fill the flask with
water so that the air contained in the flask
moves through delivery tube into the test
tube containing lime water.
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Observation
When air moves through the delivery tube, the lime water turns milky. It is because
carbon dioxide is produced when germinating seeds breathe inside the flask. This
gas reacts with lime water present in the test tube and forms calcium carbonate.
Calcium carbonate is insoluble in water. So the lime water inside the test tube
appears milky.
Conclusion
This experiment proves that carbon dioxide is exhaled during the breathing.
Activity 2
• Take some lime water in a test tube.
• Blow through a straw into the lime water and repeat it for several times.
• What happens to the lime water?
• What do you observe?
• Discuss in your class and write the conclusion of this activity.
18.9 Human Digestive System
Food is necessary to obtain energy to do work and for the growth of a body. The
process by which living beings obtain and use food is called nutrition. The process
of nutrition in human beings involves five different steps. They are: ingestion,
digestion, absorption, assimilation and egestion.
• Ingestion : The process of taking in food is called ingestion.
• Digestion : Digestion is the process in which the complex food taken in is
changed into simple and absorbable form by the action of various enzymes.
• Absorption : The process of taking in digested food by the body is called
absorption.
• Assimilation : The absorbed food material is utilized by the body to release
energy. This process is called assimilation.
• Egestion : The process by which undigested and insoluble food material is
eliminated from the body is called egestion.
Cells cannot absorb food in the form eaten by an organism. So the complex food
is broken into a simple absorbable form. This process is called digestion. The
system formed by alimentary canal and digestive glands is called digestive
system. This system is responsible for ingestion, digestion, absorption and
egestion of food.
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Alimentary Canal and Digestive Glands
The human alimentary canal is a muscular
tube which starts from the mouth and
terminates at the anus. This canal includes
mouth, buccal cavity, pharynx, food pipe
(oesophagus), stomach, small intestine, large
intestine and anus.
The alimentary canal is associated with some
glands called digestive glands. They are:
salivary glands, gastric glands, liver, pancreas
and intestinal glands.
The mouth forms the entry of alimentary canal.
It is guarded by two lips with the help of which
mouth is opened and closed. The mouth contains
three pairs of salivary glands. One parotid gland
is present beneath each ear. Similarly, one pair of
salivary gland lies below the tongue and another
Figure 18.11: Digestive system
pair is found in the inner side of the lower jaw.
Salivary glands secrete saliva which contains an enzyme called ptyalin.
Tongue is a soft muscular structure present in the mouth. It helps in chewing
food. Mouth opens behind into a muscular tube called oesophagus or food pipe. It
connects pharynx to the stomach.
Stomach is a large muscular bag-like structure. The part of stomach which is
connected to the oesophagus is called cardiac part and the part which is connected
to the duodenum is called pyloric part. The inner wall of the stomach contains
gastric glands which secrete enzymes and hydrochloric acid.
Stomach is connected to a highly coiled narrow tube like structure called small
intestine. It can be divided into three regions, viz. duodenum, jejunum and ileum.
Duodenum is a C - shaped part which is connected to the stomach. Jejunum is
the middle part whereas ileum is the posterior part of small intestine which is
connected to the large intestine. The wall of the small intestine contains numerous
finger-like projections called villi which help to absorb the digested food. The inner
wall of small intestine secretes intestinal juice which contains various enzymes.
Posteriorly, small intestine is connected with large intestine. The large intestine can
be divided into five major parts. They are: caecum, ascending colon, transverse
colon, descending colon and rectum. A small blind
projection called vermiform appendix is present at the
junction of small intestine and large intestine. It is a
vestigial part and has no role in digestion. The large
intestine is shorter than the small intestine; however, its
diameter is more than that of the small intestine. Large
Figure 18.12: Large intestine intestine does not produce any enzyme and no absorption
of food takes place here. But water is absorbed by the
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large intestine from the undigested food. Rectum is the hind part of large intestine
which is connected to the anus.
Process of Digestion of Food
Food is chewed in the mouth with the help of teeth and mixed with saliva. The
saliva softens the food in mouth. The saliva contains an enzyme called ptyalin or
salivary amylase which acts on starch and converts it into maltose. After chewing,
the food is swallowed into the pharynx. Then the food moves to the stomach
through oesophagus.
The muscles of stomach wall contract rhythmically, crushing and mixing the food
with gastric juice. This juice contains two enzymes – pepsin and renin. It also
contains hydrochloric acid which kills microbes present in the food. Pepsin acts
upon proteins and converts them into smaller protein molecules called peptones.
Similarly, renin changes milk protein (caesin) into insoluble curd.
After two to four hours of meal, the food moves into the duodenum in the form of a
thick paste (i.e. chyme) where bile juice from the liver mixes with the food. Bile juice
does not contain any enzyme. However, it helps to digest fat. It also provides an
alkaline medium in the duodenum for the action of enzymes of the pancreatic juice.
Pancreatic juice contains three enzymes – trypsin, amylase and lipase. Trypsin acts
on proteins and converts them into peptones. Similarly, amylase converts starch
into maltose and lipase acts on fats and changes them into fatty acid and glycerol.
From the duodenum, the food moves to ileum where food is acted upon by erepsin,
maltase, sucrase and lactase. Erepsin acts upon
peptones and peptides to convert them into
amino acids (simple proteins). Maltase acts upon
maltose and converts it into glucose. Sucrase acts
upon sucrose and converts it into glucose and
fructose. Similarly, lactase acts upon lactose and
converts it into glucose and galactose. In this way,
digestion of proteins, fats and carbohydrates
completes in small intestine.
The inner surface of small intestine contains
finger-like projections called villi (singular Figure 18.13: Structure of Villus
- villus). They increase the surface area for
absorption of digested food. The digested food passes through the thin walls of
blood vessels and enters the blood stream. This process is called absorption.
All food cannot be digested and the undigested food passes into the large intestine
where absorption of water takes place. The undigested food forms faeces which
move to the rectum and is passed out of the body through the anus. This process is
called egestion.
alkaline /ˈælkəlaɪn/ - having the nature of an alkali or a base 201
BIOLOGY Oasis School Science and Environment - 7
Digestion Chart
Parts of Digestive Secretion Enzyme Food acted Food converted into
alimentary glands upon
canal
Mouth Salivary Saliva Ptyalin Starch Maltose
glands
Gastric juice Pepsin Protein Peptones
Stomach Renin Milk Insoluble curd
protein (Paracaesin)
Gastric (Caesin)
glands
Hydrochloric No enzyme Provides acid environment to pepsin
acid and kills bacteria
Liver Bile juice No enzyme Divides fat globules into tiny
droplets to be acted upon by lipase
Pancreas Pancreatic Trypsin Proteins Peptides
juice and
Amylase peptones Maltose
Small intestine Lipase Starch Fatty acid and glycerol
Fats
Intestinal Intestinal juice Erepsin Peptides Amino acids
glands Maltase Maltose Glucose
Lactose Glucose and galactose
Lactase
Sucrase Sucrose Glucose and fructose
18.10 Excretion
Various metabolic activities take place in all living organisms. Those activities are
chemical reactions. Various products are formed due to these reactions. Some of
these products may be poisonous or toxic to the organisms if allowed to accumulate
inside the body. All organisms contain special organs to remove waste materials.
The process of removing waste materials, formed as a result of chemical reactions
in the body, is called excretion. The system which is responsible for excretion is
called excretory system. This system consists of a set of excretory organs. The main
excretory organs are kidneys and lungs.
Animal cells produce various types of waste materials like carbon dioxide, salts,
ammonia, urea and uric acid. Different organisms have different organs to remove
their waste materials.
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18.11 Excretion in Primitive Animals
Unicellular animals like amoeba, paramecium, euglena, etc. remove waste materials
through the general body surface. Similarly, sponges, coelenterates, etc. remove
their waste materials from their body surface. They do not have special organs to
remove their wastes.
Flatworms like liver fluke, tapeworm, etc. contain special organs called flame cells
for excretion. Similarly, earthworms have nephridia and insects like cockroach
have malphighian tubules for excretion.
Vertebrates contain well developed excretory organs. They include kidneys, lungs,
skin, liver, intestine, etc.
18.12 Excretion in Human Beings
Human beings have well developed urinary system which is responsible for
eliminating urea. This system is made up of a pair of kidneys, ureter, urinary
bladder and urethra. Kidneys are bean-shaped organs present on either side of the
backbone. They convert urea into urine. Ureter leads out from each kidney which
carries urine from kidneys to a pouch-like urinary bladder. It has a tubular structure
called urethra through which urine is eliminated from the body.
Kidneys Cortex Renal artery
Medulla Renal vein
Ureter
Ureter
Urinary bladder
Urethra
Figure 18.14: (a) Urinary system (b) Detailed structure of kidney
Besides urinary system there are various organs that help in excretion of various
waste materials. These organs are lungs, liver, large intestine and skin.
Lungs
During cellular respiration, carbon dioxide and water are formed as by–products,
carbon dioxide and excess water are eliminated in the air exhaled by the lungs
through nose.
Liver
Liver produces bile pigments from the haemoglobin of
broken RBCs. It also converts toxic ammonia produced
by the body cells into urea. Urea is then carried to the
kidneys through blood circulation, from where it is
eliminated.
Figure 18.15: Human liver
toxic /ˈtɒksɪk/ - containing poison
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Large Intestine
Our body cannot digest all food particles eaten by us. The undigested food particles
are eliminated out by large intestine through the rectum and anus.
Skin
Skin excretes urea, salts, excess of water and other waste materials in the form of
sweat. These waste materials are carried away by blood from various body parts to
sweat glands in the skin.
Figure 18.16: Structure of human skin
Activity 3
• Blow on a looking glass. What do you observe on its surface?
• Small droplets of water are formed on the glass. Where did the droplets
come from?
• Write down the conclusion on the basis of this activity.
18.13 Excretion in Plants
Plants do not have any special organs for eliminating waste materials. Plants
produce carbon dioxide as a waste material during respiration and oxygen as a
waste material during photosynthesis. They give out carbon dioxide and oxygen
through stomata.
Plants combine other waste materials with inorganic salt and form harmless
insoluble crystals. These crystals are deposited in the bark, dead wood, old leaves,
etc. Tannins, resins, gums, latex, oils, etc. are excretory products from the plants
which are useful for human beings.
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Summary
• Respiration is the process of releasing energy by breaking down food in the
presence of oxygen.
• Breathing is the process in which oxygen is taken in and carbon dioxide is given
out.
• Unicellular organisms and simple multicellular animals breathe through the
body surface by diffusion.
• Fishes and some aquatic animals and tadpoles breathe through gills.
• Human beings have well developed respiratory system which includes
nose, pharynx, larynx and lungs.
• Human digestive system includes alimentary canal and digestive glands.
• The process of removing waste materials like urea, uric acid, carbon dioxide,
etc. from our body is called excretion.
• Unicellular animals and some simple multicellular animals excrete through
general body surface.
• Humans have well developed excretory system which includes kidneys,
lungs, liver, nose, skin and large intestine.
• Kidneys excrete urine; lungs excrete carbon dioxide; skin excretes urea, salt
and water; and liver excretes bile pigments.
• Plants excrete carbon dioxide and oxygen as waste materials through
stomata. Other waste products like tannins, resins, gums, latex, oil, etc. are
stored in leaves, bark, dead wood, etc.
Exercise
1 Choose the best answer from the given alternatives:
a. Earthworms breathe through ________.
(i) moist skin (ii) gills
(iii) lungs (iv) trachea
b. Exhaled air contains more ________.
(i) oxygen (ii) carbon dioxide
(iii) water (iv) all of the above
c. The products of cellular respiration are ________.
(i) water and oxygen (ii) water and carbon dioxide
(iii) nitrogen and oxygen (iv) carbon dioxide and energy
BIOLOGY Oasis School Science and Environment - 7 205
d. The enzyme found in saliva is ________.
(i) renin (ii) pepsin
(iii) ptyalin (iv) lipase
e. The process of removing waste materials from the body is________.
(i) respiration (ii) digestion
(iii) excretion (iv) expiration
f. Frogs breathe through________.
(i) lungs (ii) skin
(iii) buccal cavity (iv) all of the above
2 Tick (√) the correct statement and cross (×) the incorrect one.
a. The exchange of gases through skin is called cutaneous respiration.
b. Breathing is a chemical process.
c. Amoeba breathes through trachea.
d. Saliva contains an enzyme called pepsin.
e. Uric acid and urea are harmful for human body.
f. Intestinal juice contains four types of enzymes.
g. Excretory organs of liver fluke are flame cells.
3 Fill in the blanks with appropriate words.
a. In insects, atmospheric air enters through................
b. In human beings, exchange of gases takes place through.................
c. Amylase acts on ..................... and converts it into .....................
d. Gastric juice contains two enzymes. ..................... and .....................
e. The main function of kidney is ..................... of urine.
f. .....................carries urine from kidneys to urinary bladder.
g. ...............are excretory organs of earthworm.
4 Answer the following questions.
a. What is respiration ? Write its two types.
b. What is breathing ? How does it take place in unicellular organisms ?
c. What is cellular respiration ? Write with its chemical equation.
d. How do fishes and frogs breathe ?
e. Name various organs involved in the human respiratory system.
f. How do plants breathe ? Describe.
g. What is digestive system? What is meant by digestion?
h. Name the enzymes found in saliva, gastric juice and intestinal juice. Also,
write the major function of each.
i. What is excretion ? How do primitive animals excrete ?
j. How do human beings excrete ? Describe in brief.
k. What are kidneys ? Where are they located ?
l. What are other organs of excretion besides kidneys in human beings ?
206 Oasis School Science and Environment - 7 BIOLOGY
m. What happens to lime water when exhaled air is passed through it ?
n. How does excretion take place in plants ?
5 Differentiate between:
a. External respiration and Internal respiration
b. Excretion in plants and Excretion in animals
c. Kidneys and Lungs
6 Match the following living creatures with their organs for breathing.
A B
Amoeba Skin
Earthworm Gills
Fish Trachea
Frog Lungs
Cockroach Body surface
Bird Stomata
Rose
7 Draw a neat and labelled figure showing the respiratory system in human beings.
8 Arrange the following organs in the correct order to show the path of air:
lungs, bronchus, alveoli, nose, trachea, pharynx, bronchioles, larynx
9 Draw a neat and labelled figure showing the digestive system of human beings.
10 Describe in brief the process of digestion in human body.
11 Draw a neat and labelled figure showing the urinary system in human beings.
12 Write down the role of given organs/body parts in human body.
(a) (b) (c)
13 Pick the odd one out. Give reason for your answer.
(a) urethra, kidney, lung, ureter, urinary bladder
(b) heart, skin, kidney, liver, lung
BIOLOGY Oasis School Science and Environment - 7 207
Unit Estimated teaching periods: Th Pr
5 1
19
Earth
Structure of the Earth
Objectives
After completing the study of this unit, students will be able to :
• define rocks and explain their structures and physical properties.
• introduce different types of rocks and explain their importance and uses.
• identify some important rocks found in Nepal.
Course of Study
• Introduction to rocks
• Structure of rocks
• Physical properties of rocks
• Types of rocks (igneous rock, sedimentary rock and metamorphic rock)
• Uses of rocks
• Some important rocks of Nepal
Points to be Focused / Questions to be Discussed
• What are rocks?
• What are the physical properties of rocks?
• What are different types of rocks?
• What are the uses of rocks?
• What types of rocks are found in Nepal?
208 Oasis School Science and Environment - 7 GEOLOGY AND ASTRONOMY
19.1 Introduction
The earth is the place where we live in. We construct buildings, houses, roads, etc.
on the surface of the earth. We make agricultural fields, canals, drainage, channel,
etc. on the surface of the earth. The surface of the earth consists of soil, water, rocks,
etc. The hard and solid parts on the surface of the earth are called rocks. The surface
of the earth is mostly covered by soil. If we dig the layer of soil to a certain depth,
the layers of rocks can be seen. Rocks have been used by human beings throughout
history. From stone age, rocks have been used for making tools and getting metals
and minerals.
19.2 Rocks
The hard solid materials that
form the part of the surface of
the earth are called rocks. Most
part of the earth’s crust is made
of rocks. Hills and mountains are
made of rocks. Rocks are found
at the bottom of the sea. Rocks
are found on the bank of rivers,
streams, etc. Soil is formed by the
weathering of rocks. Therefore,
soil also contains pebbles, sand Figure 19.1: Rocks
and particles of rocks. In geological point of view, rocks are naturally occurring
hard and solid substances having one or more minerals. The earth’s outer solid
layer, i.e. lithosphere is made of rocks. Over the course of time, rocks can transform
from one type into another.
19.3 Physical Properties of Rocks
(i) Structure
Rocks are made of grains of minerals. The size of the grains may be small or
big. Rocks contain different types of minerals. The minerals forming a rock
are held together by chemical bonds. Some rocks contain various layers. The
rocks that are formed by big grains are rough and the rocks made of small
grains are smooth.
(ii) Hardness
Generally, rocks are hard substances but soft rocks are also found in different
parts of the earth. Soft rocks are not suitable for construction purpose.
(iii) Colour
Rocks have different colours such as white, black, green, red, yellow, gray,
etc. Different types of rocks have different colours. The minerals present in a
rock determine the colour of the rock.
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 209
19.4 Types of Rocks
On the basis of origin and the method of formation, rocks have been classified into
following three types.
(i) Igneous rocks
(ii) Sedimentary rocks
(iii) Metamorphic rocks
(i) Igneous rocks
The rocks which are formed by cooling down of hot molten magma are called
igneous rocks. During the process of cooling, magma may come out on the earth’s
surface or may solidify in the crust in colder region. For example, granite, pumice,
basalt, gabbro, etc. The magma also tries to come out on the earth’s crust due to the
high pressure and temperature. Sometimes, it erupts in the form of volcano and the
lava cools down to form rocks. Similarly, magma cannot bring volcanic eruption
and cools down inside the earth’s surface to form rocks. On the basis of above fact,
igneous rocks may be plutonic or volcanic.
(a) Plutonic rocks
The magma tries to come out of the earth’s surface bringing volcanic eruption.
Sometimes the magma solidifies or gets cooled inside the earth’s surface and forms
rocks. Such rocks are called plutonic rocks. Plutonic rocks are those igneous rocks
which are formed by cooling down of magma inside the earth’s surface. It takes a
long period of time to form such types of rocks. These are the hardest rocks with
big crystals. They are also called intrusive rocks. For example, gabbro, granite,
peridiotite, dunite, etc.
Gabbro Granite Peridiotite Dunite
Fig. 19.1: Plutonic rocks
(b) Volcanic rocks
As the magma gets weak spot or cracks on the surface of the earth, it comes out
in the form of volcanic erruption. The magma is then called lava and the lava
slowly and gradually cools down to form rocks. These rocks are called volcanic
rocks. Volcanic rocks are formed after the eruption of volcano. Volcanic rocks are
those rocks which are formed by cooling down of magma or lava on the earth’s
surface after volcanic erruption. These rocks have small crystals. They may be porous
magma /ˈmæɡmə/ - very hot liquid rock found below the earth’s surface
extrusive /ɪkˈstruːsɪv/ - that has been pushed out of the earth by a volcano
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and glassy too. These are also called extrusive rocks. For example, basalt, pumice,
obsidian, etc.
Basalt Pumice Obsidian
Fig. 19.3: Volcanic rocks
Some Important Igneous Rocks
(a) Granite
Granite is a coarse-grained plutonic igneous rock. It is black or
gray in colour. It mainly contains quartz and feldspar minerals.
Granite is hard and strong. So it is used in contruction of houses,
pavements, roads, etc. Fig. 19.4: Granite rock
(b) Pumice
Pumice is a light porous igneous rock formed by cooling of
the lava having gas. It may or may not contain crystals. It is
generally pale in colour ranging from white, cream, blue-grey
to green-brown or black. Pumice is used to make light-weight
concrete. It is also used in polishes, pencil erasers and cosmetic Fig. 19.5: Pumice rock
items, toothpastes, etc.
(c) Obsidian rock
Obsidian rock is a dark coloured volcanic igneous rock. It is
formed from the very rapid cooling of molten rock material.
It does not contain crystals. Obsidian is a weak rock and
appears like glass. So, it is also called volcanic glass.
(ii) Sedimentary rock Fig. 19. 6: Obsidian rock
The weathered substances are taken away during erosion
which is subsequently followed by deposition. Similarly, different kinds of organic
and inorganic substances are also taken away by the agents like air, water, glaciers,
etc. and are deposited at some place. Under the high pressure and temperature, the
deposited materials change into rocks after a very long period of time. These rocks
are called sedimentary rocks. Those rocks which are formed from the deposited and
sedimented substances under high pressure and temperature after a long period of
time are called sedimentary rocks. These rocks are comparatively soft in nature and
also help in the study of living things and their evolution as they contain fossils. For
example, sandstone, shale, limestone, coal, conglomerate, evaporates, dolostone, etc.
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 211
Sandstone Shale Limestone Coal
Conglomerate Evaporates Dolostone
Figure: 19.7: Some sedimentary rocks
Some Important Sedimentary Rocks
(a) Conglomerate
Conglomerate is the sedimentary rock having rounded
granules. It consists of small rock particles, granules
and sand connected together with quartz or silica. The
conglomerate having silica is very strong. Figure: 19.8: Conglomerate
(b) Sandstone
Sandstone is a classic sedimentary rock having sand–sized
grains of mineral, rock and organic material. Most sandstone
is composed of quartz or felspar or both. Like sand, sandstone
may be of any colour such as gray, brown, yellow, red, white,
pink, black, etc. Sandstone may be soft or hard. It has been
used for domestic construction. Figure: 19.9: Sandstone
(c) Shale Shale is the sedimentary rock having silt and clay. The
granule which is smaller than sand is called silt and the
collection of granules that are smaller than silt is called clay.
Shale is gray to black in colour.
Figure: 19.10: Shale
granule /ˈɡrænjuːl/ - small grain-like structure
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(d) Limestone
Limestone is a sedimentary rock made of calcium carbonate.
It is made of skeletal fragments of marine organisms. This
rock contains fine granules. Limestone may be red, gray,
white, black, green, etc. It is an important building material.
It is very common in architecture.
Figure: 19.11: Limestone
(iii) Metamorphic rock
Due to the high pressure and temperature inside the surface of the earth, different
types of igneous rocks and sedimentary rocks undergo metamorphosis. Those
rocks that change their properties resulting in the formation of other types of rocks
are called metamorphic rocks. These rocks are formed by the physical and chemical
change of igneous or sedimentary rocks. Metamorphic rocks are those which are
formed from other types of rocks under the action of high temperature and pressure
over a long period of time. Some examples of metamorphic rocks and their original
rocks are listed below:
S. No. Metamorphic rocks Formed from
Limestone or dolestone
1. Marble Shale
Sandstone
2. Slate Granite or diorite
Shale or slate
3. Quartzite Shale or slate
4. Gneiss
5. Schist
6. Phyllite
Marble Slate Quartzite
Gneiss Schist Phyllite
Fig. 19.12: Some metamorphic rocks
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 213
Activity 1
• Collect various types of rocks from your surroundings and write down
their characteristics.
• Classify them in terms of igneous rock, sedimentary rock and metamorphic rock.
19.5 Uses of Rocks
Rocks play a major role in the life of human beings. Rocks are used for different
purposes. Some of the uses of rocks are described below:
(i) Construction purposes
Different types of houses, buildings, monuments, bridges, roads, palaces, temples,
etc. are made and constructed by using rocks.
(ii) Decorative purposes
Rocks like marble, slate, limestone, etc. are used in decoration of tables, houses,
walls and so on. For example, marbles are paved in toilets, house floors, etc.
Similarly, limestone is used in colouring old and traditional houses.
(iii) Mineral extraction
Rocks contain different types of minerals such as iron, copper, cobalt, nickel, gold,
diamond, graphite, etc. Such minerals are extracted from the rocks and are used for
various purposes.
(iv) Economic advantages
The minerals extracted from mines are bought and sold. Similarly, rocks play an
important role in tourism industry as the tourists from different areas visit the
country for rocks. It also strengthens the national economy.
(v) Study
Some of the rocks, especially sedimentary rocks play an important role in the
study of evolution of living beings. They provide different evidences related to the
evolution and development of living beings on the earth.
19.6 Some Important Rocks Found in Nepal
Different types of rocks are found in Nepal. Some important rocks that are found in
Nepal are given below:
(i) Conglomerate: It is a sedimentary rock having rock particles, granules and silica
connected together with quartz or silica. It is found on the banks of rivers and
streams of Nepal.
monument /ˈmɒnjʊmənt/ - a building, column, statue, etc.
evolution /ˌiːvəˈluːʃn/ - the development of a complex organism from a primitive one over
a long period of time
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(ii) Sandstone: It is a sedimentary rock having sand-sized granules. It is also found on
the banks of rivers and streams of Nepal.
(iii) Silica: It is the sand formed by weathering of rocks. It is formed by combination of
silicon and oxygen. Silica is found on the banks of rivers and streams.
(iv) Limestone: It is an important rock for construction works. It is made of calcium
carbonate. It may be of different colours like red, brown, black, white, etc. It is used
for making lime and cement. In Nepal, it is found in Godawari, Bhaise, Chobhar,
Udaypur, Jogimara and some other parts of the country.
(v) Marble: It is a modified form of limestone. It consists of different layers. It is widely
used for construction and decorative purpose in houses, temples, pavements, etc.
A large mine of marble is located in Godawari, Lalitpur.
(vi) Slate: It is a metamorphic rock formed by modification of schist. It consists of fine
granules and different layers. It is used for roofing of houses and making writing
boards. A large mine of slate is located in Bandipur, Tanahun district of Nepal.
Summary
• The hard and solid parts on the surface of the earth are called rocks.
• From stone age, rocks have been used for making tools and getting metals and
minerals.
• In geology, rocks are naturally occurring hard and solid substances having
one or more minerals.
• The rocks that are formed by big grains are rough and the rocks made of small
grains are smooth.
• The rocks which are formed by cooling down of hot molten magma are called
igneous rocks.
• Plutonic rocks are those igneous rocks which are formed by cooling down of
magma inside the earth’s surface.
• Volcanic rocks are those rocks which are formed by cooling down of magma
or lava on the earth’s surface after volcanic erruption.
• Those rocks which are formed from the deposited and sedimented substances
under high pressure and temperature after a long period of time are called
sedimentary rocks.
• Metamorphic rocks are those which are formed from other types of rocks
under the action of high temperature and pressure after a long period of time.
• Different types of houses, buildings, monuments, bridges, roads, palaces,
temples, etc. are made and constructed by using rocks.
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 215
Exercise
1 Choose the best answer from the given alternatives.
a. Which of the following is an igneous rock?
(i) shale (ii) granite
(iii) marble (iv) sandstone
b. Which of the following rock contains fossils?
(i) gabbro (ii) conglomerate
(iii) pumice (iv) basalt
c. Which of the following is a sedimentary rock?
(i) shale (ii) obsidian
(iii) marble (iv) dunite
d. Which of the following is a metamorphic rock?
(i) conglomerate (ii) gneiss
(iii) periodiolite (iv) dolostone
e. Which of the following rocks is used for making cement?
(i) pumice (ii) limestone
(iii) granite (iv) marble
2 Fill in the blanks using appropriate words.
a. The hard solid materials that form the earth’s crust are called ..................
b. There are .................. types of rocks. They are: igneous rock, .................. and
..................
c. Fossils are found in .................. rocks.
d. .................. rock is formed by modification of igneous rock and sedimentary
rock.
e. Shale is made of silt and ..................
3 Answer the following questions.
a. What are rocks?
b. How many types of rocks are there? Name them.
c. What is igneous rock? How is it formed? Describe in brief.
d. What is sedimentary rock? Give any three examples.
e. How are sedimentary rocks formed? Describe in brief.
f. What are metamorphic rocks? Give any two examples.
g. Why are fossils not found in igneous rocks?
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4 Differentiate between:
a. Igneous rock and Sedimentary rock
b. Plutonic rock and Volcanic rock
c. Sedimentary rock and Metamorphic rock
d. Igneous rock and Metamorphic rock
5 Classify the given rocks in terms of igneous, metamorphic and sedimentary
rocks.
pumice, obsidian, marble, granite, limestone, gneiss, basalt, shale, sandstone,
dunite, gabbro
6 Write any four uses of rocks.
7 Name any five types of rocks found in Nepal.
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 217
Unit Estimated teaching periods: Th Pr
5 1
20
Cloud
Weather and Climate
Objectives
After completing the study of this unit, students will be able to :
• introduce cloud, rain, snow and dew drops.
• introduce atmosphere and describe the various layers of atmosphere.
• explain the causes and effects of movement of air.
• describe the methods of weather forecasting and forecast local weather.
• introduce the equipment for measuring the factors of weather.
Course of Study
• Introduction to weather and climate
• Cloud, rain, snow, dew drops
• Atmosphere and its layers
• Wind and movement of air
• Weather forecasting and equipment for measuring factors affecting
weather
Points to be Focused / Questions to be Discussed
• What is meant by weather and climate?
• What are cloud, rain, snow and dew?
• What is atmosphere? What are different layers of atmosphere?
• What is the cause of movement of air?
• What is weather forecasting?
• What are different equipment for measuring factors affecting weather?
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20.1 Introduction
Most days are sunny, some are cloudy and others are rainy. Some days are hot and
some days are cold. It may be sunny in the morning but the day may suddenly
become dark and rainy. It is due to the change in weather. The condition of the
atmosphere at a particular place and time is called weather. At any given place,
weather does not remain constant. The weather changes from hour to hour, day
to day and so on. The weather differs from place to place also. Climate is the
average atmospheric condition over a long period of time ranging from months
to thousands of years. Climate is the totality of existing temperature, atmospheric
pressure, humidity, rainfall, etc.
20.2 Cloud
The water in the ocean, river, lake, pond, etc. gets
evaporated due to heat of the sun and the vapour
rises up in the atmosphere. It mixes with dust
particles and undergoes condensation. As a result,
cloud is formed. A grey or white mass made of very
small drops of water that floats in the sky is called
cloud. When water vapours turn back into water
droplets in the sky, clouds are formed. Clouds have
various shape, size, colour and appearance. Cirrus, Figure 20.1: Cloud
cumulus, stratus and nimbus are the main types of
clouds.
20.3 Rain
In Nepal, heavy rainfall occurs in the months of Asar
and Shrawan. Have you seen the rainfall? What is the
cause of the rainfall? Do you know? The cloud moves
from one place to another in the sky due to wind.
When the cloud reaches near high hills and forests, it
gets cooled. After cooling, the cloud changes into rain
and falls down to the earth. In this way, rainfall occurs
on the earth.
Figure 20.2: Rainfall
Activity 1
• Take a kettle and boil some water in it. When the water boils, it changes
into vapour. Observe the vapour carefully. Now, put some cold water in a
plate and drive the vapour from the kettle to the cold surface of the plate.
What happens? Does the vapour change into water droplets? What can
you conclude from this activity?
condensation /kɒndenˈseɪʃn/ - the process of gas changing into a liquid
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 219
20.4 Snow
Snow is precipitation in the form of flakes of crystalline water ice that falls from
clouds. Snow is a granular material made of small ice particles. It is a soft, white
and fluffy form of frozen water. In Nepal, snowfall occurs in winter season. The
northern peaks of our country, i.e. the Himalayas remain covered with snow
throughout the year.
Figure: 20.3: (a) Snow fall (b) Himalaya
20.5 Dew
Dew is the water in the form of droplets that appears
on leaves or other objects in the morning or at night
due to condensation. The water vapour present in the
atmosphere cools down mainly in winter and changes
into water droplets. So, dew drops can be seen in the
morning during winter season since winter nights are
very cold.
Figure 20.4: Dew drops
When the temperature of the atmosphere is very low,
dew cools further and takes the form of ice which is commonly known as frost.
20.6 Air
Air is the mixture of various gases. It consists of nitrogen, oxygen, carbon dioxide,
inert gases, water vapour, etc. The atmosphere contains about 78% of nitrogen, 21%
of oxygen and 0.03% of carbon dioxide by volume. The earth’s crust is surrounded
by a thick layer of air called atmosphere.
20.7 Atmosphere
The thick layer of air that surrounds the earth’s crust is called atmosphere. It consists
of different gases like nitrogen, oxygen, carbon dioxide, etc., water vapour and dust
particles. The amount of gases in the atmosphere decreases with an increase in
the height from the surface of the earth. The atmosphere has been divided into
following five layers.
220 Oasis School Science and Environment - 7 GEOLOGY AND ASTRONOMY
(i) Troposphere
It is the lowermost layer of the atmosphere. TEhexromspohsperhee (raeb (o8v0e-7 72200 k kmm) )
It is extended upto 16 km vertically upward Mesosphere (50-80 km)
from the earth’s surface. Troposphere consists Strraoptoosspphheerree ((01-61-65 k0m k)m)
of various heavy gases like nitrogen, oxygen, T
carbon dioxide, etc. Various activities related
to weather like cloud formation, lightning,
rainfall, snowfall, dew formation, hailstones,
etc. occur in this layer. The temperature of
this layer decreases as the height increases.
(ii) Stratosphere
The layer of atmosphere located above the
troposphere and below the mesosphere is
called stratosphere. It is extended from 16 km Figure 20.5: Various layers of atmosphere
to 50 km vertically upward from the earth’s
Figure 20.5: Layers of atmosphere
surface. The temperature of this layer increases when the height increases. The
upper layer of stratosphere contains ozone layer. This layer is called a protective
layer for living beings as it absorbs the harmful radiations from the sun and protects
living beings on the earth.
(iii) Mesosphere
It is the middle layer of the atmosphere. It is located just above the stratosphere
and below the thermosphere. This layer extends from 50 km to 80 km vertically
upward from the earth’s surface. Strong wind blows in this layer. In mesosphere,
the temperature decreases as the height increases.
(iv) Thermosphere
The layer of atmosphere located between exosphere and mesosphere is called
thermosphere. It extends from 80 km to 720 km vertically upward from the earth’s
surface. It is a very hot layer of atmosphere. It has a very thin layer of air. In
thermosphere, the temperature increases as the height increases.
(v) Exosphere
It is the uppermost layer of the atmosphere. It is located above 720 km vertically
upward from the earth’s surface. It has very less amount of air.
20.8 Wind
Wind is the fast blowing air. In Nepal, wind generally
blows in the months of Falgun and Chaitra. It carries
away dust particles, pieces of paper, plastics, leaves
and other light objects.
We know that air is the mixture of various gases. The
molecules in the gas are loosely held together. Air Figure 20.6: Strongly blowing wind
lightning /ˈlaɪtnɪŋ/ - a flash or several flashes, very bright light in the sky caused by electricity
hailstone /ˈheɪlstəʊn/ - a small ball of ice that falls like rain
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 221
becomes light due to heat of the sun and rises up. Now, cold air comes and occupies
the space of the hot air. This movement of air is called convection. Wind blows due
to the convection of hot and cold masses of air. Strong wind may blow roofs of
houses, crops, dust particles, plastics, papers, sand and dry soil. It may break trees
and their branches.
20.9 Movement of Air
Cold air is heavier than light air. Air
becomes light due to the heat of the
sun during the day and it becomes
heavy at night after cooling. During
day time, the air above the ground
gets heated faster than the air above
the sea. So, the air above the land
becomes lighter and moves upwards.
The space of hot air is taken by cold Figure 20.7: Sea breeze
air from above the sea. The cold air blows towards the land from the sea during
the day time. This movement of air is called sea breeze. Therefore, sea breeze is the
blowing of cold air from sea to the land during the day time.
During the night, the land cools down faster than the water of the sea. So the air
above the land cools down and becomes heavier but the air above the sea remains
hot and rises upward. So cold air blows towards the sea from the land at night.
This movement of air is called land breeze. Therefore, the movement of cold air
towards the sea from the land at night is called land breeze. Please note that the
temperature near the sea remains constant throughout the year due to land breeze
and sea breeze.
20.10 Information Regarding the Weather
Nowadays, we get information regarding the weather from television, the radio,
smart phone, newspapers, etc. These means of communication disseminate
information regarding rainfall, wind, cloud, humidity, snowfall, etc. Meteorologists
study the various factors of weather such as direction of air, humidity, amount of
rain, temperature, movement of clouds, types of clouds, etc. and after the study
of those factors they forecast weather of a particular place at a particular time.
Meteorologists use various equipment to measure the factors that affect weather.
20.11 Equipment for Measuring the Factors Affecting Weather
Meteorologists use following equipment for measuring the factors affecting weather.
(i) Barometer (ii) Maximum-minimum thermometer
(iii) Hygrometer (iv) Anemometer (v) Rain gauze
(i) Barometer
breeze /briːz/ - a light wind
the water vapour present in air
humidity /hjʊˈmɪdɪti/ -
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Barometer is a device used for measuring atmospheric Vacuum
pressure. The weather of a particular place depends Glass tube
on the atmospheric pressure of that place. Generally, Mercury column
weather remains clear when the atmospheric pressure Air
increases. Similarly, days become windy and cloudy Height
(76 cm (29.92 in.)
Air
when atmospheric pressure decreases. pressure pressure
Mercury in dish
(ii) Maximum-minimum Fig. 20.8 Barometer
thermometer
This device is used for measuring the maximum and
minimum temperature of a day in a particular place. It
measures the degree of hotness and coldness of a day.
Fig. 20.9 Maximum-minimum
thermometer
(iii) Hygrometer
It is a device used for measuring the humidity in air.
The amount of water vapour present in atmosphere is
called humidity. Generally, humidity increases when the
temperature of air decreases and amount of water vapour
in air increases. Similarly, humidity decreases when the
temperature of air increases and the amount of water
vapour in air decreases. The relative amount of vapour in Fig. 20.10 Hydgrometer
air is called relative humidity. The possibility of rainfall
increases when the relative humidity increases and vice-versa.
(iv) Anemometer
Anemometer is used for measuring the velocity and
direction of air. The direction and velocity of air changes
from time to time. The speed of air is less in the morning
and the speed increases from the noon. Strong wind
blows in the evening in mountainous regions of Nepal.
(v) Rain gauze Fig. 20.11 Anemometer
Rain gauze is the device used for measuring
Funnel
the amount of rainfall in a particular place. The
amount of rainfall is measured in millimeter. measuring
For example, the amount of rainfall in device
Kathmandu valley is 20 mm means that if all
rain remains in the same place where it falls, Overflow
it would be 20 mm high from the ground. In cylinder
Nepal, heavy rainfall occurs in the months of
Asar and Shrawan. Fig. 20.12 Rain guaze
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 223
Activity 2
• Observe the condition of weather in the morning, afternoon and evening
for seven days.
• Observe the condition of the sun, air, wind, cloud, rainfall and humidity.
• Prepare a short report and submit to your science teacher.
20.12 Weather Forecasting
Weather forecasting is the process of predicting the forthcoming weather of a
particular region. The scientist who helps in forecasting the weather with its study
is called a meteorologist. Weather forecasting is done with the application of
science and technology. Meteorologists try to give complete and accurate picture
of weather conditions beforehand. It helps people to be aware of the forthcoming
weather and take necessary precautions.
Weather forecasts are made by collecting quantitative data about the current
atmospheric state. In this process, scientific understanding of atmospheric process
is used. This understanding helps to forecast how the atmosphere will change in
the near future.
Some Simple Ways of Weather Forecasting
(i) In the rainy season, it might rain in the afternoon if the day begins with very
hot shiny morning.
(ii) The possibility of rain increases with the sudden hot sunshine.
(iii) It may not rain throughout the day if the day is partially cloudy from the morning.
(iv) There is a possibility of rain if the sky is suddenly covered with dark clouds.
(v) In context of our country, if the cloud moves towards the east from the west
at the end of the rainy season, rainfall stops after a few days.
In Nepal, there are meteorological laboratories in different parts of the country for
the study of the weather and the factors responsible for weather change. With the
help of this study, meteorologists know how the weather is going to change. Now-
a-days, weather forecasting is done by observing the situation and the speed of
the cloud in the sky. Similarly, weather forecasting can be done on the basis of the
balloon and weather charts. Meteorologists study the pictures received from the
artificial satellites that revolve around the earth. Such forecasting is reliable to a
large extent.
Importance of Weather Forecasting
(i) Weather warnings are important forecasts because they are used to protect
lives and property.
(ii) Forecasting of temperature and rainfall are used in agricultural sector.
224 Oasis School Science and Environment - 7 GEOLOGY AND ASTRONOMY
(iii) People use weather forecasting to determine what to wear on a particular day.
(iv) Weather forecasting helps to plan and perform outdoor activities.
Activity 3
• Listen to the radio or watch television at 7 o’clock every morning for one
week to know about the weather.
• Observe the weather carefully on a particular day and keep its record.
• Evaluate yourself if the weather forecasting is reliable or not.
Summary
• The condition of the atmosphere at a particular place and time is called weather.
• Climate is the average atmospheric condition over a long period of time ranging
from months to thousands of years.
• A grey or white mass made of very small drops of water that floats in the sky is
called cloud.
• Snow is precipitation in the form of flakes of crystalline water ice that falls from
clouds.
• Dew is the water in the form of droplets that appears on leaves or other objects
in the morning or evening due to condensation.
• The thick layer of air that surrounds the earth’s crust is called atmosphere.
• Ozone layer is a protective layer for living beings as it absorbs the harmful
radiations from the sun and protects living beings on the earth.
• Strong wind may blow roofs of houses, crops, dust particles, plastics, papers,
sand and dry soil. It may break trees and their branches.
• Sea breeze is the blowing of cold air from the sea to the land during day time.
• The movement of cold air towards the sea from the land at night is called land
breeze.
• Barometer is a device used for measuring atmospheric pressure.
• Maximum-minimum thermometer is used for measuring the maximum and
minimum temperature of a day in a particular place.
• Anemometer is used for measuring the velocity and direction of air.
• Rain gauze is the device used for measuring the amount of rainfall in a particular place.
• Weather forecasting is the process of predicting the forthcoming weather of a
particular region.
• Weather forecasts are made by collecting quantitative data about the current
atmospheric state.
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 225
Exercise
1 Choose the best answer from the given alternatives.
a. The condition of the atmosphere at a particular place and time is called ______.
(i) climate (ii) cloud
(iii) weather (iv) wind
b. A grey or white mass made of very small drops of water is called ______.
(i) cloud (ii) dew
(iii) frost (iv) rain
c. The percentage of nitrogen in the atmosphere is ______.
(i) 78 (ii) 87
(iii) 21 (iv) 0.03
d. The lowermost layer of the atmosphere is ______.
(i) stratosphere (ii) troposphere
(iii) thermosphere (iv) exosphere
e. The device for measuring the humidity is called ______.
(i) barometer (ii) anemometer
(iii) thermometer (iv) hygrometer
2 Fill in the blanks using appropriate words.
a. At any given place, the weather does not remain .........................
b. In Nepal, snow fall mainly occurs in ......................... season.
c. Ozone layer is found in .........................
d. ......................... is used for measuring the velocity and ......................... of air.
e. The amount of rainfall is measured in .........................
3 Answer the following questions.
a. What is meant by weather and climate?
b. What is cloud? How are clouds formed?
c. What is rain? How does it occur?
d. What are snow and dew drops?
e. What is atmosphere? Name the various layers of atmosphere.
f. What is troposphere? Write any three features of this layer.
g. What is mesosphere? Why is stratosphere important for living beings?
h. What is thermosphere? Write any two features of exposphere.
i. What is convection? Define land breeze and sea breeze.
j. What is weather forecasting? How is weather forecasting done?.
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4 Name any four devices that are used for measuring the factors affecting weather.
5 Draw neat and labelled figure of the given devices with the major use of each:
a. Barometer
b. Hygrometer
c. Maximum-minimum thermometer
d. Anemometer
e. Rain gauze
6 Differentiate between:
(a) Cloud and Snow
(b) Troposphere and Exosphere
(c) Troposphere and Thermosphere
(d) Land breeze and Sea breeze
(e) Anemometer and Barometer
7 Describe an activity to demonstrate that water vapour changes into water on
cooling.
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 227
Unit Estimated teaching periods: Th Pr
6 2
21
Solar System
The Earth and Space
Objectives
After completing the study of this unit, students will be able to :
• introduce solar system and its members (size, distance, days and year).
• introduce planets and stars and differentiate between them on the basis of
surface, colour, temperature and size.
• introduce some major constellations.
Course of Study
• Solar system
• Sun and planets
• Star and its features
• Distance, brilliance and colour of stars
• Structure and motion of stars
• Differences between stars and planets
• Constellations–introduction and description of some famous constellations
• Identification of constellations
Points to be Focused / Questions to be Discussed
• What is solar system?
• What are the features of the sun?
• What are planets? Name the planets of the solar family.
• What are stars? What are their features?
• What are differences between stars and planets?
• What are constellations?
• How are constellations identified?
228 Oasis School Science and Environment - 7 GEOLOGY AND ASTRONOMY
21.1 Solar System
The family of the sun that includes the sun, eight
planets, satellites, asteroids, comets, etc. is called
solar system. All the planets of the solar system
revolve around the sun in elliptical orbits due to
the gravitational force. Solar system is existing in
the universe due to the influence of gravitational
force among the members of the solar system. The
heavenly bodies that revolve around the sun are Figure 21.1: Solar system
called planets, e.g. Earth, Mars, Jupiter, etc. The
heavenly bodies that revolve around the planets are called satellites, e.g. Moon,
Titan, etc. Solar system also includes asteroids, comets, meteors and meteorites.
21.2 Sun
The sun is the central component of the solar system. It is a large ball of fire. It is a
medium sized star. Heavenly bodies like planets, asteroids, satellites, comets, etc.
revolve around the sun in elliptical orbits. The sun appears big as it lies near the
earth as compared to other stars. It has its own source of heat and light. The sun is
about 15 crore kilometres far from the earth. It has been estimated that the surface
temperature of the sun is about 5400°C and the temperature of its core is about
1,50,00,000°C. The diameter of the sun is about 13,92,400 km. The sun is the nearest
star to the earth.
21.3 Planets
Planets are the heavenly bodies that revolve around the sun in elliptical orbits.
There are eight planets in the solar system. These are: (i) Mercury (ii) Venus (iii)
Earth (iv) Mars (v) Jupiter (vi) Saturn (vii) Uranus and (viii) Neptune. The Mercury
is the nearest planet to the sun whereas Neptune is the farthest. Jupiter is the largest
planet and Mercury is the smallest planet of the solar system. Venus is the hottest
planet whereas Neptune is the coldest planet. Similarly, Mercury, Venus, Earth and
Mars are called inner planets whereas Jupiter, Saturn, Uranus and Neptune are
called outer planets. A brief description of the eight planets of the solar system is
given below:
1. Mercury
Mercury is the nearest planet to the sun. It is the smallest planet
of the solar system. It is very hot during the day time since it
is closest to the sun. Life does not exist in Mercury as it has
no water and atmosphere. There is no water on the Mercury.
It revolves around the sun in 59 days. Due to its closeness to
the sun, it revolves faster than the other planets. It has similar
surface with that of the moon due to the formation of craters.
Fig. 21.2: Mercury
crater /ˈkreɪtə/ - a large hole on the top of sth
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 229
2. Venus
Venus is the second nearest planet from the sun and closest
planet from the earth. It is the brightest object in the night sky
(except moon). It is visible in the eastern sky in the early morning
and in the western sky in the evening. So, Venus is also called
morning star and evening star. Due to its nearness to the sun, it
is too hot to support life and has no water.
Fig. 21.3: Venus
3. Earth
Earth is the third nearest planet from the sun and the fifth
biggest planet in the solar system. This planet appears blue
when viewed from the outer space. It is due to the reflection
of light from the water body on the earth. The earth is the only
planet which supports the existence of life. The existence of
living organisms is due to the following reasons:
Fig. 21.4: Earth
(i) The earth has suitable temperature for the survival of life.
(ii) It has sufficient amount of water.
(iii) It has oxygen and carbon dioxide in the atmosphere.
(iv) It has protective layer of ozone gas (i.e. ozone layer) which protects living
organisms from the ultra-violet radiation coming from the sun.
4. Mars
Mars is the fourth planet of the solar system. It has the atmosphere
containing traces of carbon dioxide, hydrogen, oxygen, nitrogen,
etc. The oxygen in Mars is too little for the survival of life. This
planet appears red due to the presence of limonite rock on it. So,
it is also called the red planet. Mars does not have water on its
surface so it cannot support life on it.
Fig. 20.5: Mars
5. Jupiter
Jupiter is the fifth planet from the sun and the largest planet of
the solar system. It is made up of hydrogen and helium gas. It is
seen as a colourful object when viewed through a telescope.
Jupiter has thin rings around it. It is believed that cloud is formed
due to the freezing of methane and carbon dioxide. Jupiter has a
giant red spot in its atmosphere due to atmospheric hurricane. It Fig. 20.6: Jupiter
is not visible due to the dense cloud on its surface.
6. Saturn
Saturn is the sixth planet from the sun and the second biggest
planet of the solar system. As Jupiter, Saturn also has hydrogen
and helium. It is surrounded by narrow rings. This is the unique
feature of this planet. This planet has the minimum density
among all planets. Titan is the largest satellite of this planet.
Fig. 20.7: Saturn
230 Oasis School Science and Environment - 7 GEOLOGY AND ASTRONOMY
7. Uranus
It is the seventh planet from the sun and the third largest planet
of the solar system. It is the first planet which was discovered by
using telescope. It is also made up of hydrogen and helium gas.
Uranus rotates from the east to the west.
Fig. 20.8: Uranus
8. Neptune
Neptune is the eighth planet from the sun and the farthest planet
of the solar system. It has a ring-like structure around it. It is
an extremely cold planet. Its surface contains hydrogen, helium,
neon, silica and water. It has a great dark spot having a size as
big as the earth. The biggest satellite of this planet is Triton.
Fig. 20.9: Neptune
The comparative study of various planets of the solar system is tabulated below:
S. Name of Average Average Period of Period of Number of
rotation revolution satellites
No. the planet distance diameter (hour,
(days/
from the (in km) days) years)
sun (in km)
1. Mercury 5.76 × 107 4851.2 58.85 days 87.97 days 0
2. Venus 10.7 × 107 12035.2 2 4 3 . 0 2 224.7 days 0
days
3. Earth 14.88 ×107 12672 23 hrs. 56 3 6 5 . 2 5 1
min. days
4. Mars 22.56 × 107 6742.4 24 hrs. 37 2 8 6 . 9 8 2
min. 22 sec. days
5. Jupiter 76.8 × 107 1139040 9 hrs. 55 12 years 63
min. 30 sec
6. Saturn 144 × 107 115811.2 10 hrs. 30 29.5 years 60
min.
7. Neptune 288 × 107 50441.6 17 hrs. 14 84 years 27
min. 24 sec.
8. Uranus 448 × 107 48972.8 16 hrs. 6min 164 years 13
36 sec.
Source: World Almanac – 2007 AD
21.4 Stars
When we see in the clear sky at night, we see numerous twinkling objects. These
twinkling objects are called stars. So, stars are the bright twinkling objects having
twinkle /ˈtwɪŋkl/ - to shine with light that keeps changing from bright to faint to bright again
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 231
their own sources of light. Stars are hot and bright Fig. 21.10: Stars and moon
luminous objects. The sun is also a kind of medium–
sized star. Stars differ from planets in many ways.
Stars are the masses of hot gases. Some stars are very
large and others are very small. The stars that are
comparatively nearer to the earth appear large and the
stars that are far away from the earth appear small.
The sun appears large as it is the nearest star to the
earth. We get heat and light from the sun. Other stars
are located far away from the earth, so we do not
receive heat and light from the distant stars.
Distance of Stars
Stars are located millions of kilometers away from the earth. So, it is impossible
to measure the distance between the stars and earth in metres and kilometres.
Therefore, the distance between stars and the earth is measured in light year. Light
year is the total distance covered by light in one year. Light travels 3 lakh kilometres
in one second and it covers 9.5 ×1012 kilometres in one year.
One light year = Speed of light × One year
= 300000 km/s × 365 days
= 300000 km/s × 365 × 24 hours
= 300000 km/s × 365 × 24 × 60 minutes
= 300000 km/s × 365 × 24 × 60 × 60 seconds
= 9.5 × 1012 km
\ One light year = 9.5 × 1012km
Brilliance of Stars
Different types of stars have different level of brilliance. The brilliance of a star
depends on its size, surface temperature and distance from the earth. The distant
large stars may appear faint and the nearby small stars may appear bright.
Colour of Stars
Stars have different colours. They may be red, orange, yellow, white and blue in
colour. The temperature of a star determines its colour. Generally, the stars having
comparatively less temperature are red and the stars having comparatively more
temperature are blue. The stars having different colour with different temperature
are given below:
Colour of star Red Orange Yellow White Blue
4000°C 6000°C 11000°C 25000°C
Temperature 3000°C
232 Oasis School Science and Environment - 7 GEOLOGY AND ASTRONOMY
Structure of Stars
Stars are large heavenly bodies made of gases. They are made of hydrogen and
helium gases. In stars, nuclear fusion reaction takes place continuously which
produces heat and light energy.
Motion of Stars
Stars are not stationary heavenly bodies. One star is in a state of motion with respect
to another. Stars change their relative position in the space.
21.5 Differences between Planets and Stars
Planets do not have their own source of light for shining but stars. Similarly, planets
revolve around the sun in elliptical orbits but stars don’t. Planets and stars differ
from each other on the basis of structure, size, colour, temperature, etc. The major
differences between planets and stars are as follows:
Planets Stars
1. Planets do not have their own 1. Stars have their own source of light.
source of light.
2. Planets revolve around the sun. 2. Stars do not revolve around the
sun.
3. Planets are made of rocks, dust 3. Stars are made of hydrogen and
particles and water vapour. helium gases.
4. The temperature of planets is quite 4. The temperature of stars is very
low. It ranges from – 330°C to high. It ranges from 3000°C to
865°C. 25000°C.
5. Their diameter ranges from 4851 5. Most of the stars are very big but
km to 1139040 km. some are smaller than the earth.
21.6 Constellations
When we see the sky at clear moonless night, we see thousands of stars of different
size. Some of the stars are large and others are small. Similarly, some of them are
seen bright and others are seen dim. When we arrange some of the bright stars, we
find a recognizable shape such as animal or shape of some objects, etc.
A small group of stars, which seems to form the pattern or shape of some objects, is
called constellation. For example, Ursa major, Big dipper, Orion, Virgo, Sagittarius,
etc. Astrologists have named 88 constellations so far. Out of these, 12 constellations
are called zodiac.
Formerly, astrologists after observing the northern sky, arranged the stars into
different groups and gave the names of animals, zodias, heroes, virgo, etc.
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 233
Some Famous Constellations Fig 21.11 Ursa major
Fig 21.12 Ursa Minor
1. Ursa Major
Ursa major is the common and easily recognizable or
detectable constellation. It has seven big stars appearing
like the shape of a question mark. This group of stars
is called big dipper or great bear. In Hindu mythology,
big dipper is called ‘saptarishi’. The saptarishi includes
Dubhe, Merak, Phecda, Megrez, Alioth, Mizar and Alkaid.
It appears in the summer season in the northern sky.
2. Ursa Minor
This constellation is also known as little bear. It is a group
of seven stars that seem to form the shape of a dipper or
ladle. Out of the seven stars, four stars form the ‘bowl’ of
the little dipper and three stars form the handle of the ladle.
This constellation can be seen in the northern hemisphere.
The stars of this constellation are less bright and nearer
than that in the big dipper.
3. Orion
Orion consists of a large number of stars arranged in the shape of a
hunter. It is named after the name of a hunter in Greek mythology.
The stars present in it are Betelgeuse, Rigel, Saif, Mintaka, Alnilam,
etc. It appears in the winter season in the northern hemisphere.
4. Cassiopeia Fig 21.13 Orion
Cassiopeia consists of five stars in the shape of an English
alphabet ‘W’. It is named after a mythological Ethiopian queen
Cassiopeia, the mother of Andromeda. It appears in the northern
sky in no moon night.
Fig : 21.14 Cassiopeia
Identification of Constellations
The sky above the earth has been divided into northern and southern hemispheres.
Nepal lies in the northern hemisphere. So, we can see only the constellations of the
northern hemisphere. Since the earth revolves round the sun, the constellations
seen in a particular season are not visible in another season. In order to identify
constellations, first of all we should observe the position of two famous constellations
of the north pole, viz. Ursa major and Ursa minor. Ursa major can be recognized
easily. It has seven bright stars arranged in the shape of ladle or dipper. Similarly,
we can identify other constellations by using sky map or chart of constellations.
234 Oasis School Science and Environment - 7 GEOLOGY AND ASTRONOMY
Activity 1
• Prepare a model of solar system and submit it to your science teacher.
Activity 2
• Observe the sky at clear night and identify some of the famous constellations.
Draw their figures and submit them to your science teacher.
Summary
• The family of the sun that includes the sun, eight planets, satellites, asteroids,
comets, etc. is called solar system.
• Heavenly bodies like planets, asteroids, satellites, comets, etc. revolve around
the sun in elliptical orbits.
• Planets are the heavenly bodies that revolve around the sun in elliptical orbits.
• Mercury, Venus, Earth and Mars are called inner planets whereas Jupiter,
Saturn, Uranus and Neptune are called outer planets.
• Stars are the bright twinkling objects having their own source of light.
• The stars that are comparatively closer to the earth appear large and the stars
that are far away from the earth appear small.
• Light year is the total distance covered by light in one year. Light travels 3 lakh
kilometres in one second and it covers 9.5 ×1012 kilometres in one year.
• The brilliance of a star depends on its size, surface temperature and distance
from the earth.
• Generally, the stars having comparatively less temperature are red and the
stars having comparatively more temperature are blue.
• A small group of stars which seems to form the pattern or shape of some objects
is called constellation.
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 235
Exercise
1 Choose the best answer from the given alternatives.
a. How many planets are there in the solar system?
(i) 9 (ii) 8
(iii) 7 (iv) 10
b. The smallest planet of the solar system is
(i) Earth (ii) Jupiter
(iii) Mars (iv) Mercury
c. The largest planet of the solar system is ______.
(i) Jupiter (ii) Uranus
(iii) Saturn (iv) Venus
d. The heavenly bodies that revolve around the planet are called
(i) satellites (ii) constellations
(iii) stars (iv) sun
e. Which of the following is a constellation?
(i) Ursa major (ii) Uranus
(iii) sun (iv) moon
f. The colour of the hottest star is ______.
(i) red (ii) yellow
(iii) blue (iv) orange
2 Fill in the blanks using appropriate words.
a. The solar system includes the sun, ........................., satellites, .........................
b. Planets do not have their own source of .........................
c. The group of stars having a certain recognizable shape is called .........................
d. The distance travelled by light in one year is called .........................
e. The twinkling bright objects in the sky are called .........................
3 Answer the following questions.
a. What is solar system?
b. How many planets are there in the solar system? Name them.
c. What are planets? Why do planets revolve around the sun?
d. What is the average distance between the earth and the sun?
e. What are stars? Give one example.
f. What is one light year? Convert one light year into kilometres.
g. What are stars made of? What is meant by the brilliance of a star?
236 Oasis School Science and Environment - 7 GEOLOGY AND ASTRONOMY
h. What are constellations? Give any four examples.
4 Differentiate between:
a. Planets and Satellites
b. Planets and Stars
c. Solar system and Constellation
5 Write any three features each of the given heavenly bodies.
(a) Jupiter (b) Earth
(c) Sun (d) Star
(e) Ursa major (f) Orion
6 Draw neat and labelled figure showing:
(a) Solar system
(b) Ursa minor constellation
(c) Ursa major constellation
7 How are constellations identified? Explain in brief.
8 The colour of a star indicates its temperature. Justify this statement.
GEOLOGY AND ASTRONOMY Oasis School Science and Environment - 7 237
Unit Estimated teaching periods: Th Pr
12 4
22
Environment
Environment and Its Balance
Objectives
After completing the study of this unit, students will be able to :
·• classify natural resources (perpetual, renewable and non-renewable) and explain them.
·• explain the need and importance of natural resources.
·• introduce protected areas of Nepal (National Park, Wildlife Reserve and ConservationArea).
·• introduce water resources, watersheds and wetlands and describe the methods of
conservation of these resources.
·• identify the factors of environmental balance and explain their importance.
·• introduce producers, consumers and decomposers and explain their relationship
and importance.
Course of Study
·• Natural resources and their types
·• Importance of natural resources
·• Natural resource conservation
·• Protected areas of Nepal
·• Water resource, their importance and conservation
·• Watersheds and wetlands
·• Elements of environment
·• Role of humans in environmental balance
Points to be Focused / Questions to be Discussed
• What are natural resources?
• What are the types of natural resources?
•· Why should we conserve natural resources?
•· What are protected areas of Nepal?
• What are water resources, watersheds and wetlands? Why are they important?
• What are the elements of environment?
• What is the role of humans in environmental balance?
238 Oasis School Science and Environment - 7 ENVIRONMENT SCIENCE
22.1 Introduction
Various resources like air, water, soil, forest, minerals, vegetation, wildlife, etc.
occur in nature. The resources such as water, minerals, forests, fertile land, sunlight,
wind, etc. that occur in nature are called natural resources. These resources are
used by human beings for economic gain.
Natural resources may include living as well as non-living things. Wildlife, animals,
vegetation, petroleum, etc. include living natural resources whereas air, water, soil,
minerals, sunlight, etc. include non-living natural resources. Natural resources are
derived from the environment. Some of them are essential for our survival while
most of them are used for satisfying our needs/wants. Natural resources are the
materials and components that can be found in the environment. Every man-made
product is composed of natural resources.
22.2 Types of Natural Resources
On the basis of renewability and utility, natural resources are classified into
following three types.
(i) Perpetual resources (ii) Renewable resources (iii) Non-renewable resources
(i) Perpetual resources
Some natural resources like sunlight, wind, tides, etc. are not affected by human
use. These resources are called perpetual resources. The resources having never
ending supply and do not get depleted after use are called perpetual resources.
For example, solar energy, wind energy, tidal energy, etc. Perpetual resources are
important and inexhaustible resources on human time scale.
(ii) Renewable resources
Some natural resources like forests, vegetation, wildlife, air, water, soil, etc. never
deplete while using and they can be produced repeatedly in a short period of time.
These resources are called renewable resources. The natural resources that never
deplete while being used and can be produced again and again are called renewable
resources. For example, air, water, land, forest, wood, wildlife, etc. Renewable
resources grow again and come back again after we use them.
(iii) Non-renewable resources
Some natural resources like petrol, diesel, coal, minerals, natural gas, etc. get
depleted after use and cannot be obtained again and again. These resources are
called non-renewable resources. The resources that get depleted after their use
and cannot be obtained again and again are called non-renewable resources. For
example, minerals, petrol, kerosene, diesel, coal, natural gas, etc. Non-renewable
resources form extremely slowly and cannot be obtained within a short period of
time. These resources take a very long time to come back to nature.
ENVIRONMENT SCIENCE Oasis School Science and Environment - 7 239
Activity 1
• Identify the natural resources in your locality. Make a list of those resources
and classify them as follows:
Perpetual sources Renewable sources Non-renewable
sources
1. 1.
2. 2. 1.
2.
3. 3. 3.
22.3 Importance of Natural Resources
Natural resources are very important for human beings and other animals. There is
a close relationship between living beings and non-living things of the environment.
There is a great importance of natural resources like air, water, sunlight, vegetation,
wildlife, etc. The importance of natural resources is described as follows:
(i) All living beings get food from natural resources. Green plants use sunlight,
carbon dioxide, water and minerals for making their own food. Animals
depend on plants directly or indirectly for their food. Human beings get food
from plants and animals.
(ii) Natural resources provide habitat to all living beings. Land, water, forests,
etc. are the habitats of living beings. Human beings use various natural
resources to build houses, buildings, etc.
(iii) Fresh air, i.e. oxygen is essential for survival of living beings. Air is obtained
from nature.
(iv) Living beings get water from nature. Water is essential for the survival of
living beings.
(v) Natural resources like forest, wildlife, fountains, lakes, mountains, rivers,
birds, wild animals, etc. add beauty to nature.
(vi) Natural resources attract tourists. So, tourists travel from one place to another.
Natural resources help in economic development of a country.
(vii) Natural resources are used for making various substances like cement,
plastics, metals, etc. Raw materials are obtained from nature to run industries.
So natural resources are essential for economic development of a country.
240 Oasis School Science and Environment - 7 ENVIRONMENT SCIENCE
22.4 Natural Resource Conservation
Human beings use natural resources to meet their needs. The conservation of
natural resources is a fundamental problem in today’s world. Natural resources
are being depleted day by day due to human activities. There should be wise and
economic use and well planned conservation of natural resources. Human beings
solely depend on natural resources for getting food, habitat and other things to
fulfil their needs. Therefore, natural resources should be conserved properly for the
existence of human beings on the earth.
22.5 Protected Areas of Nepal
Nepal has established a network of protected areas of different categories for
conservation of natural resources. Protected areas are the reserved areas like
national parks, wildlife reserves, conservation areas, etc. established for protection
and promotion of wildlife, vegetation and natural environment.
The government of Nepal has established twelve National Parks, one Wildlife
Reserves, one Hunting Reserve and six Conservation Areas.
ConserAvpiatiNoanmArpeaa Rara National Park
Shey-phoksundo National Park
Khaptad National Dhorpatan Annapurna Conservation Area
Park
Manaslu Conservation Area
Shuklaphanta Langtang National Park
National Park Sagarmatha National Park
Makalu Barun National Park
Bardiya National
Park Shivapuri
Banke National Nagarjun
Park National Park
Chitwan National Kanchanjangha
Conservation
Park Parsa National Area
Park
Koshi Tappu Wildlife Reserve
Figure 22.1
A brief description of protected areas of Nepal is given below:
A. National Park
A national park is an area set aside for the conservation and management of
natural environment including wild animals, plants and landscapes together with
their utilization. By taking permission from the concerned authorities, we can visit,
entertain ourselves and conduct scientific research inside the National Parks. Nepal
government has established ten national parks in different parts of the country.
These are:
ENVIRONMENT SCIENCE Oasis School Science and Environment - 7 241
1. Chitwan National Park
2. Langtang National Park
3. Rara National Park
4. Sagarmatha National Park
5. Shey-Phoksundo National Park
6. Khaptad National Park
7. Bardia National Park
8. Makalu-Barun National Park
9. Shivapuri Nagarjun National Park
10. Banke National Park
11. Shukla Phanta National Park
12. Parsa National Park
1. Chitwan National Park
Chitwan National Park is the first national park of Nepal. It was established in 1973
AD and granted the status of a World Heritage Site in 1984 AD. It covers an area of
932 km² and is located in the sub-tropical inner terai of Chitwan, Makawanpur and
Parsa districts.
Chitwan National Park is an excellent habitat for one–horned rhinoceros, gharial
crocodile and tiger. Animals like one-horned rhino, tiger, sloth bear, leopard,
elephant, sambar deer, Rhesus monkey, gaur, wild boar, wild dog, wild cat, long
snouted gharial, marsh mugger crocodile, python, etc. and plants like Sal, Sissoo,
Khair, Simal are found in this National Park.
2. Sagarmatha National Park
Sagarmatha National Park is a protected area in the Himalayas of eastern Nepal. It
was established in 1976 AD. It encompasses an area of 1148 km². In 1979, it became
the country’s first National Park that was inscribed as a Natural World Heritage
Site. It is located in Solukhumbu district. High peaks like Lhotse, Nuptse, Pumori,
Amadablam, Thamserku and Mt. Everest also lie in this National Park. Plants like
Gobre salla, Thingre salla, Bhojpatra, Dhupi, Rhododendron, etc. animals like
Himalayan Tahr, Ghoral, Musk deer, Pika (mouse hare), Jackal, Black bear, Wolf,
Lynx, Snow leopard and birds like Danphe (Impeyan pheasant), Blood pheasant,
Redbilled chough, Snow cock, Snow pigeon, etc. are found in this national park.
3. Langtang National Park
Langtang National Park is the Himalayan national park which covers an area of
1710 km². It was established in 1976 AD. It occupies parts of Rasuwa, Nuwakot and
Sindhupalchowk districts. The famous religious place Gosainkunda is also located
in this national park. Plants like Khote salla, Gobre salla, Khasru, Rhododendron,
Langtang salla, etc.; animals like Wild dog, Red panda, Pika, Muntjac, Musk deer,
Ghoral, Himalayan tahr, Rhesus monkey, Snow leopard and different species of
birds like Impeyan pheasant are found in this national park.
242 Oasis School Science and Environment - 7 ENVIRONMENT SCIENCE
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