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THE WISDOM ACADEMY FOR CIVIL SERVICES

“YOUR SUCCESS,YOUR WAY,TO BUILD A NATION”

THE WISDOM ACADEMY FOR UPSC

6th NCERT SCIENCE NOTES & SOLVED

QUESTIONS

ALL OTHER SCIENCE NCERT (std VI-XII) NOTES AND THEIR SOLVED QUESTION COMPILATIONS ALSO AVALIBALE

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INDEX PHYSICS ............................................................................................................................................................................. 4

1. MOTION AND MEASUREMENT OF DISTANCES ................................................................................................................. 4

2. LIGHT, SHADOWS AND REFLECTIONS ................................................................................................................................ 7

3. ELECTRICITY AND CIRCUITS ............................................................................................................................................. 12

4. FUN WITH MAGNETS ....................................................................................................................................................... 16

CHEMISTRY .................................................................................................................................................................... 19

1. FIBRE TO FABRIC .............................................................................................................................................................. 19

2. SORTING MATERIALS INTO GROUPS ............................................................................................................................... 21

3. SEPARATION OF SUBSTANCES ......................................................................................................................................... 24

4. CHANGES AROUND US .................................................................................................................................................... 27

BIOLOGY .......................................................................................................................................................................... 30

1. FOOD: WHERE DOES IT COME FROM? ............................................................................................................................ 30

2. COMPONENTS OF FOOD ................................................................................................................................................. 32

3. GETTING TO KNOW PLANTS ............................................................................................................................................ 37

4. BODY MOVEMENTS ......................................................................................................................................................... 39

5. THE LIVING ORGANISMS AND THEIR SURROUNDINGS ................................................................................................... 42

6. WATER ............................................................................................................................................................................. 47

7. AIR AROUND US ............................................................................................................................................................... 51

8. GARBAGE IN, GARBAGE OUT ........................................................................................................................................... 54

DIRECTOR’S MESSAGE Dear students, NCERT forms an important base for preparation of civil services. Aspirants need to understand these books which are basic in nature. Student should be thorough with this books conceptually and well versed with the facts. There are number of subject like HISTORY, GEOGRAPHY, and POLITY….

whose NCERT needs to be covered. Timely revision and re-reading becomes a challenging task for aspirant. Wisdom academy has come up with a

solution by proving aspirant for comprehensive GIST with solved questions below the chapter. The purpose of providing these short summary notes is to travel with the aspirant in achieving their dream in competitive exam.

ALL THE BEST!!!!

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PHYSICS

1. MOTION AND MEASUREMENT OF DISTANCES Transportation and Distances

Evolution of Transport

Before the invention of the wheel, the only means of transportation was walking. For transporting goods, people used

animals like donkeys, horses, mules, elephants, oxen, sled dogs, and even bison. Boats were also used as a means of

transportation on water. The earliest boats were simple logs of wood with a hollow cavity.

The oldest wheel was discovered in Mesopotamia, and is believed to be over 5,500 years old. Fixed wheels for carts

were invented around 3500 BC, according to some historians. After the invention of the wheel, man started using

animals to pull vehicles that moved on wheels, and thus, bullock carts and chariots came into existence. Till the 19th

century, most forms of transport used only animals

The bicycle was invented in the late 18th century bicycles. The first bicycles did not have brakes, though. It was up to

the rider to the control the speed of the bicycle! Later on, motors were fitted to bicycles, and thus, mopeds came into

existence. Further research and development led to the invention of the motors car.

The steam engine and the rail road were invented in the 19th century. Apart from these, motorised boats and ships

were used as a means of water transport. Roads, rail road and water remained the major means of transport for a very

long time. The Wright brothers invented the airplane and gave the world another means of transport – airways. In his

effort to explore his universe, man even stepped into space and invented the spaceship to travel in space.

There are various means of transport, such as road, rail, water and airways. The mode of transport can be chosen,

usually depending upon the distance to be travelled, but sometimes also upon how fast you want to get to your

destination.

Measuring Length and Distance

Various means of measurement, such as the palms, fingers, arm length and feet, were used to measure length and

distance before standardised systems were introduced. Standards needed to be set to ensure consistency and to

standardise measurements. Several systems were devised, but almost the entire world now follows the metric system.

The base measurement for the pyramids is the cubit, which was formulated by the Egyptians. A cubit was measured on

the arm, from the point where the elbow bends, to the tip of the middle finger. One cubit is equal to 18 inches.

However, the inch was invented by the Romans.

In order to avoid confusion in measurements, the French created in 1970 the metric system, which is a standard for

measurement. A further development to ensure uniformity measurement of lengths and distances, and other

quantities, was a standard of measurement called the International System of Units or SI.

The SI unit of length is the metre, and is denoted by the small letter ‘m’. This is the basic unit of length.

1 metre =100 centimetres

1 centimetre=10 millimetres

10 millimetres=1 centimetre

Large distances are measured in kilometres, and 1 km=1000 m.

The length and type of an object determines the kind of measuring tool one can use.

Motion and Measurement of Distances

A body is said to be at rest if its position does not change with time with respect to an observer (or a reference point).

For example, the chairs of the dining table are at rest with respect to the dining table; the passengers sitting in a

moving bus are said to be at rest with respect to the driver of the same bus, because their positions do not change with

respect to the driver.

Motion:

A body is said to be in motion if its position changes with time with respect to an observer (or a reference point). The

passengers sitting in a moving bus are said to be in motion with respect to an observer standing outside the bus,



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Similarly, the blades of a rotating fan, the hands of a working wall clock, a spinning top and satellites are all in motion

with respect to a fixed axis .

Rest and motion are relative terms. A body may seem to be at rest with respect to one object, but may appear to be in

motion with respect to another object. If you consider a passenger in a moving train, he is at rest with respect to his co-

passengers, but is in motion with respect to an observer standing on the ground.

Types of Motion:

There are different types of motion. They are rectilinear motion, circular motion and periodic motion.

Rectilinear motion is the motion of a body along a straight line. For example, a train moving on a straight track and a

stone falling from a height are in rectilinear motion.

Circular motion is the motion of a body that moves along a circular path. Examples of bodies in circular motion are the

rotating blades of a fan, a child sitting on a merry-go-round, and the tips of the hands of a clock.

Periodic motion is the motion that repeats itself at regular intervals of time. Every object executing uniform circular

motion can be said to be executing periodic motion. The motion of the pendulum in a pendulum clock, the motion of a

swinging cradle and the motion of the needle in a sewing machine are some examples of periodic motion.

Sometimes an object can display combinations of different types of motion. For example, a moving car which moves

straight on the road displays rectilinear motion but at the same time the wheels of the car which are moving in circles

display circular motion. So the wheels of a moving car execute both rectilinear and circular motions. In a sewing

machine, the tip of the needle is in rectilinear motion as well as in periodic motion.

SOLVED QUESTIONS

Q1. Name few means of transport available in ancient times before the invention of wheel.

Ans 1. Boats and domestic animals.

Q2. Which invention made a great change in modes of transport

Ans2. invention of the wheel.

Q3. Name some commonly used units of measurements in ancient times.

Ans. the length of a foot, the width of a finger, and the distance of a step, a handspan and a cubit.

Q4. In taking measurement of a length using a scale, what precautions should we take?

Ans. we need to take care of the following:

Place the scale in contact with the object along its length as shown in Fig.10.7. NCERT

In some scales, the ends may be broken. You may not be able to see the zero mark clearly (Fig.10.8 (a)].

In such cases, you should avoid taking measurements from the zero mark of the scale. You can use any other full mark

of the scale, say, 1.0 cm . Then you must subtract the reading of this mark from the reading at the other end.

Correct position of the eye is also important for taking measurement. Your eye must be exactly in front of the point

where the measurement is to be taken.

Q5. How do you decide whether an object is in motion or at rest?

Ans. If a body changes its position with respect to its surroundings, it is said to be in motion, and if it does not change its

position with respect to its surroundings, it is at rest.

Q6. How can we decide that how fast or slow a motion is.

Ans. Motion is a change in the position of an object with time.

The change in this position can be determined through distance measurements. This allows us to know how fast or slow a

motion is.

The movement of a snail on the ground, ----SLOW An aeroplane flying high up in the air - Fast

Q7. Name the S.I. unit of length.



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Ans. Metre is the unit of length in SI unit.

Q8. The ball is rolling on the ground – Name the type of motion exhibited by it.

Ans. the ball undergoes a rectilinear motion as well as rotational motion.

Q9. What do you mean by measurement?

Ans. measurement means the comparison of an unknown quantity with a known quantity.

Q10. In how many parts do we express the result of a measurement ?

Ans. The result of a measurement is expressed in two parts.

One part is a number. The other part is the unit of the measurement. For example, if in Activity 1, the length of the room is

found to be 12cm. 12 is the number and cm is the unit selected for the measurement.

Q11. When is the motion of a body said to be rectilinear ,circular, periodic ?

Ans. When objects move along a straight line,the type of motion they possess is rectilinear motion.

When the distance of the object from the centre remains the same, the type of motion It possesses is circular motion.

When an object or a part of it repeats its motion after a fixed interval of time, the type of motion It possesses is periodic

motion.



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2. LIGHT, SHADOWS AND REFLECTIONS Types of Media

Luminous objects

Objects that emit light on their own are called luminous objects. The light emitted by luminous objects enables us to

see things around us. Examples of luminous objects are a tubelight, the sun, a lit candle, glowing bulb, a bonfire and a

lit torch.

Non-luminous objects

Objects that do not emit light on their own are called nonnon –luminous objects. The light emitted by luminous objects

falls on non-luminous objects, and then bounces back to our eye, which enables us to see non-luminous objects.

Examples of non-luminous objects are the moon, a book, a pen, a wooden box, a cupboard and a chair.

Opaque objects

Objects through which we cannot see are called opaque objects. A medium that does not allow light to pass through it

is called an opaque medium. Examples of opaque medium are a pencil box, a wooden screen, a book, a towel, a

ceramic plate and chart paper.

Transparent objects

If we are able to see anything clearly through an object, then such an object is said to be a transparent object. A

medium that allows all the light incident on it to pass through it is called a transparent medium. Examples of

transparent objects are plain glass, a reading glass, a plastic scale, windowpanes, a soap bubble and pure water.

Translucent media

Objects that allow only a part of the light incident on them to pass through it are called translucent media. Examples of

translucent media are a shower stall, smoked glass, sun glasses and butter paper.

Light travels in a straight line, and its rays represent the path of light

Shadows and Pin Hole Camera

Shadow

An opaque object blocking the path of light is called a shadow. A shadow is a dark region, and is formed only when a

light source, an opaque object and a screen are present. For example, during a lunar eclipse, we see a part of the

earth’s shadow on the surface of the moon. This happens when the earth, the sun and the moon are in a straight line,

with the earth between the sun and the moon. Here, the sun acts as the light source, the earth as the opaque object,

and the moon as the screen. Opaque objects form shadows because light is not able to bend around them.

Shadows are seen more clearly on light screens. Whatever the colour of the object, its shadow is always black because

it is not illuminated by light. The length and shape of a shadow depends on the object by which it is formed. In the

olden days, shadows caused by objects placed in the sun were used to measure time. Such a device is called a sun dial.

The Jantar Mantar in Jaipur consists of a sundial or Samrat Yantra, which can be used to tell the time, as its shadow

moves visibly at one millimetre per second, or roughly six centimetres every minute.

Pinhole Camera

The image formed by a pinhole camera is inverted and smaller in size when compared to the original object. These

cameras work on the principle that light travels in a straight line. Pinhole cameras are cheap and simple to make. An

eclipse can be viewed using a pinhole camera.

Making a Pinhole Camera

Take two rectangular boxes that fit into one another without leaving any gap.

Cut open one side of each box.



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Make a small hole in the larger box at the centre of the closed end opposite the side that has been cut open.

Cut a square of side five centimetres in the smaller box in the closed end opposite the side that has been cut open.

Cover this square with tracing paper.

Finally, slide the smaller box into the larger box, ensuring that the pinhole and the tracing paper are in line with one

another, but at the opposite ends.

Slide the smaller box to adjust the focus so that you can capture the image of any object you want.

This is the basic structure of the pinhole camera. However, the developed form of a pinhole camera uses photosensitive

film instead of translucent paper to capture images. The film can be developed later to obtain photo prints. Nowadays,

of course, we use digital cameras that store images in a computer chip. However, the basic principle of capturing the

image remains the same.

Mirrors and Reflection

Image

The likeness of an object carried and formed by light in a mirror is called an image. For example, your image is a

reflection of your face in the mirror. An image can be seen in the mirror because the light reflected from an object falls

on the mirror and it is reflected. So, light incident on any smooth shiny surface like a mirror bounces back into the same

medium. This bouncing of light by any smooth surface is called reflection of light.

Mirrors change the direction of light incident on them. The image in a plane mirror is the same size and colour as that

of the object. Moreover, the distance between the image and the mirror, is the same as the distance between the

mirror and the object.

Shadow

When an opaque object blocks the path of light, a shadow is formed. A shadow is a black dark outline. Its length

changes with a change in the position of the source of light. Shadows can be seen only on a surface or a screen.

Two-Way Mirror

A glass that acts as a mirror on one side and plain glass on the other is called a two-way mirror. A two-way mirror is

used when you want to observe people without letting them know that they are being watched, for example, by police

or in psychological institutions.

Pinhole Camera

Images formed by a pinhole camera are entirely different from the images that are formed by a mirror. The image

formed by a pinhole camera is inverted and smaller in size when compared to the object. The image is also not clear.

Moreover, the distance between the object and the pinhole is not the same as the distance between the pinhole and

the image.

A periscope is an instrument used for observing objects from a hidden position. This instrument is mostly used in

submarines, and works on the concept of reflection in plane mirrors. Using mirrors, it enables people in a submarine to

view objects on the surface of the water.

SOLVED QUESTIONS

Ql. Does the flame of a gas stove emit light?

Yes.

Q2. What is rectilinear propagation of light?

Light travels in a straight line.

Q3. Write the names of 4 different sources of light?

Bulb, sun, stars, firefly



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Q4. Give one example of living thing which emits light?

Jugnu {firefly)

Q5. Sometimes you are able to see sun or moon behind the clouds .What can you say about the ability of such clouds to

transmit light?

Yes, clouds transmit light.

Q6. Image formed in a pinhole camera is inverted .Why?

It is inverted because of the rectilinear propagation of light.

Q7. Can you suggest the shape of the shadows?

It is usually similar to the object.

Q8. Does the length of shadow change from season to season?

Yes if observed at same time .

Q9. What is shadow?

A dark patch formed behind an opaque object when it is placed in the path of light.

Qll. What do you mean by reflection of light?

Coming back of light ray incident on a surface is called reflection.

Ql2. What is the principle of working f a pin hole camera?

A pinhole camera is based on rectilinear propagation of light?

Ql3. Can light pass through opaque objects?

No

Ql4. What is an artificial source of light?

Man made sources of light. For example: electric bulb, candle etc.

Ql5. Classify the following into transparent, translucent, and opaque objects.

{Glass, air, oil paper, rubber sheet)

Transparent: air, glass Translucent: oil paper Opaque: rubber sheet

Ql6. Name two artificial sources of light?

Electric bulb, candle

Ql7. Name one transparent and one opaque body?

Transparent: air Opaque: stone

Ql8. Define reflection of light?

The process of returning {Or bouncing back) the light to the same medium after Striking a surface is called reflection of light.

Q19. What is a reflector?

A surface which reflects the light is called reflector.

Q20. Give one example of most commonly used reflector?

Looking glass or plane mirror

Q21. Does the reflection of light from the surface similar to the bouncing back of a rubber ball after it strikes from a ball?

Explain.

Yes, because of reflection, light falling on a surface bounces back to the same medium.



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Q22. Give the properties of the image formed by the pane mirror?

l. The image formed by plane mirror is erect and virtual.

1. Size of the image formed by plane mirror is equal to the size of the object.

2. The distance of the image behind the plane mirror is equal to the distance of the object from the mirror.

Q23. Define luminous objects?

The objects which emit light are called luminous objects.

Q24. What is light?

Light is a form of energy which produces the sensation of sight.

Q25. What are non luminous objects?

Objects which do not emit their own light.

Q26. Why do objects in a room become visible even if sunlight does not enter it?

The objects in a room become visible, even if the sunlight does not enter the room because the air around the objects allows the

scattered light to pass through it and we can see the objects.

Q27. How can you convert a transparent glass sheet into a translucent glass sheet?

By covering one side with butter paper.

Q28. Does the colour of the shadow depend upon the colour of the object?

No, it is always dark.

Q29. In a completely dark room, if you hold up a mirror in front of you, will you see a reflection of yourself in the mirror?

No, because there is no source of light .We can see our image only when light is reflected from the mirror.

Q30. Give few examples of opaque, translucent and transparent objects?

Opaque: a piece of rock, a sheet of aluminium, a mirror, a wooden board, a wall a sheet, a sheet of cardboard, a CD

Translucent: a sheet of polythene , smoke, fog, a sheet of carbon, a sheet of cellophane.

Transparent: air, water, a sheet of plane glass QlS. What do you understand by lateral inversion?

The right side of the object appears to be the left side of its image and vice-versa This is called lateral inversion.

Q31. Give one example to show that light travels in a straight line?

When sunlight falls on a solid object like a building or a stone, a shadow is formed behind the solid object {opaque object) .This

shows that light travels in a straight line.

Q32. Distinguish between transparent, translucent and opaque materials?

Transparent materials: which allow light to pass through them and through which we can see clearly are known as transparent

materials.

Translucent materials: substances through which light can pass partially and through which we can't see clearly are called

translucent materials.

Opaque materials: substances which don't allow light to pass through them at all are called opaque materials.

Q33. Can the opaque object cast shadow?

In the presence of light, opaque objects act as obstacles to propagate {travel) light

and form a shadow behind them

Q34. How are shadows formed?

Light coming from the source of light falling on the objects gets obstructed by the objects and does not go ahead. So, a shadow

is formed.



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Q35. How can we protect our eyes while glaring at a strong source of light?

By placing our hand in front of our eyes, light coming from the source does not fall on our eyes directly. {Since we know light

travels in a straight line.)

Q36. What happens when light falls on an object?

l. It is almost completely transmitted through the object.

a) Only one part of it may be transmitted and the rest is absorbed or spread out.

b) It may not be allowed to pass through at all.

Q37. Consider a wooden stick about half a meter long. Fix one end of it in open ground where there are no trees and buildings

near it. Look its shadow in the morning and mark its points of shadow. Note the direction of sun with respect to stick. Where

is shadow of the object formed?

The shadow of the object is formed in the direction opposite to the side of the source light i.e. it is formed opposite to the

direction of the sun. This activity also shows that shadow moves according to the movement of the sources of light and the

length of the shadow changes with time and the shadow of an object is formed in the direction opposite to that of the source of

light.



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3. ELECTRICITY AND CIRCUITS Electricity And Circuits

An electric cell provides electricity to various devices that are not directly fed by the supply of electricity.

Electric Cell

An electric cell consists of two terminals. One is a positive terminal and the other one is a negative terminal. A

chemical that helps produce electricity to connected devices.

Bulb

A bulb consists two terminals.

A filament is a spirally wound wire inside the bulb supported by two thick wires at its ends. An electrical cell is

connected to the terminals of a bulb so that electricity from the cell can pass through the bulb. This electricity makes

the filament in the bulb glow and emit light.

Electrical circuit:

Electricity needs a path to pass from the positive terminal to the negative terminal of an electric cell. A connection that

provides a path outside an electric cell, for the electricity to pass from the positive terminal to the negative terminal of

the cell, is called an electrical circuit.

For example, a bulb glows only when the positive terminal and the negative terminal of an electric cell are connected to

the two terminals of the bulb.

If the wires from the bulb are connected to the same terminal (either positive or negative), then the bulb doesn't glow.

Sometimes, the bulb may not glow even though the connections are properly made.

This is because the flow of electricity is incomplete as the filament in the bulb is broken. A broken filament bulb is said

to be fused.

Switches:

A device that is used to stop the flow of electricity by breaking the circuit is called a switch. Switches have wide range of

applications. Some common types are:

Toggle switches, which are used in our houses.

Pushbutton switches, which are used in the starter of a water pump.

Joystick switches, which are used in the remote control unit of a toy car

Electric Conductors and Insulators:

All materials do not allow electricity to pass through them. Materials that allow electricity to pass through them are

called conductors. Conductors conduct electric current. Since metals are good conductors of electricity, electric wires

are made of metals. These electric wires act as conducting materials. So they are used to make electrical circuits. Some

common conductors that conduct electric current are copper, silver, gold and aluminium. Copper is the most popular

material used for wires. Sometimes we receive electric shocks because our bodies are also good conductors of

electricity.

Materials that do not allow electricity to pass through them are called insulators. Insulators oppose electric current and

so they are used as protection from the dangerous effects of electricity. Some common insulators are glass, air, plastic,

cotton, thermocol, wood and rubber.

Water is a good conductor of electricity, but in its purest form, called distilled water, it acts as an insulator. Distilled

water is, therefore, used in batteries as an insulator.

We use various electrical appliances every day. Without the help of insulators, the use of electrical appliances is

impossible. The parts of the electric appliances that we touch are covered with insulating material. For example, plugs

and switches are covered with an insulating material such as plastic, and the wire attached to the plug is a metal wire,

which is a conductor. So conductors and insulators work hand in hand.



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SOLVED QUESTIONS

Q1 List some uses of electricity?

Ans1 We use electricity for many purposes to make our tasks easier. Electricity makes it possible to light our homes, roads,

Offices, markets and factories. Electricity is used to run various appliances like television, refrigerator, computers etc.We use

electricity to operate pumps that lift water from ground level to roof top tank.

Q2 List the components of an electric circuits?

Ans2 The various components of an electric circuit are bulb, cell, battery, switch and wires.

Q3 What are the uses of an electric cell?

Ans3 Electric cell provides electricity to the bulb of a torch. Electric cell are also used in alarm clocks, wristwatches, transistor

radios, cameras and many other devices.

Q4 What does an electric cell look like?

Ans4 An electric cell has a metal cap on one side and a metal disc on other side.

Q5 How many terminals are there in an electric cell?

Ans5 All electric cells have two terminals; positive and negative. The metal cap is the positive terminal of the cell. The metal disc

is the negative terminal.

Q6 How does an electric cell produces electricity?

Ans6 An electric cell produces electricity from the chemicals stored inside it. When the chemicals in the electric cell are used up,

the electric cell stops producing electricity. The electric cell then has to be replaced with a new one.

Q7 What is filament of the bulb?

Ans7 A thin wire that gives off light is called the filament of the bulb. The filament is fixed to two thicker wires, which also

provide support to it.

Q8 How are terminals formed in an electric bulb?

Ans8 One of the thick wires which is supporting filament is connected to the metal case at the base of the bulb. The other thick

wire is connected to the metal tip at the centre of the base. The base of the bulb and the metal tip of the base are the two

terminals of the bulb. These two terminals are fixed in such a way that they do not touch each other.

Q9 Why does an electric cell and an electric bulb has two terminals each?

Ans9 An electric cell and an electric bulb have two terminals to form an electric circuit.

Q10 What is an electric circuit?

Ans10 An electric circuit is an arrangement which provides a complete path for electricity or current to pass between the two

terminals of electric cell.

Q11 What is current?

Ans11 Flow of charges from an electric cell constitutes current.

Q12 What is the direction of electric current?

Ans12 The direction of current is taken to be from the positive to negative of the electric cell.

Q13 When does a bulb glow?



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Ans13 When the terminals of the bulb are connected with that of the electric cell by wires, the current passes through the

filament of the bulb. This makes the bulb glow.

Q14 What is an electric switch?

Ans14 A switch is a simple device that either breaks the circuit or completes it.

Q15 What are electric conductors?

Ans15 Electric conductors are materials which allow electricity to pass through them. Example of conductors are metals like

aluminum and copper, human body etc.

Q16 What are electric insulators?

Ans16 Electric insulators are materials which do not allow electricity to pass through them. Examples of insulators are paper,

rubber, glass, wood etc.

Q17 What are the uses of conductors and insulators?

Ans17 Conductors and insulators are equally important to us. Switches electrical plugs and sockets are made of conductors. On

other, rubber and plastics are used for covering electrical wires, plug tops, switches and other parts of electrical appliances,

which people might touch.

Q18 Under what conditions does an electric bulb glow?

Ans18 Conditions necessary for bulb to glow are:

1. The switch should be closed.

2. There should not be any break in path of current.

3. The terminal connections should be proper.

4. The wire used to make electric circuit should be a conductor.

Q19 What precautions should be taken to make an electric circuit?

Ans19 Following precautions should be taken:

a) The connections between the terminals of components of a circuit should be tight.

b) The bulb should not be fused.

c) The chemicals in an electric cell should not have been used up.

d). There should not be any insulator in path of current.

Q20 Why does a bulb not glow when it is fused?

Ans20 An electric bulb may fuse due to many reasons. One reason for bulb to fuse is a break in its filament. A break in filament

of an electric bulb means a break in the path of the current between the terminals of the electric cell. Therefore, a fused bulb

does not light up as no current passes through its filament.

Q21 What happens when two or more bulbs are connected

f) in series

g) in Parallel.



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Ans21 When bulbs are connected in series the glow of bulbs decreases .

When bulbs are connected in parallel the glow of bulb remains the same.

Q22 Draw the diagram of a torch and label its components.

Ans22 Torch has a reflector, plastic casing, slide switch, bulb and electric cells.

Q24 Why do covering of switches, appliances, plugs socket is made of insulator?

Ans24 They are covered with insulators because insulators don’t allow current to pass through them so we don’t get shock if we

touch them.

Q25 Write (C) in front of conductors and(I) in front of insulators

a) Plastic scale - I

b) Match stick - I

c) Iron nail - C

d) Mica - I

e) Human body - C

f) Eraser - I

g) Thread - I

Q24 What happens when wire used to make circuit is replaced by cotton thread?

Ans24 Thread does not allow current to pass through it.

Therefore, no current reaches the filament of bulb. So the bulb does not glow.

Q25 What happens when we place eraser in path of cell and bulb?

Ans25 Since eraser is insulator it causes a break in path of

current so the bulb does not glow.

Q26 Draw and see in which case does the bulb glows

When the positive of bulb is connected with positive of the cell and negative of bulb is connected with negative of cell.

Ans1 The bulb will glow.

When the positive of bulb is connected with negative cell and negative of bulb is connected with positive of cell.

Ans2 The bulb will glow.

When the positive of bulb is connected with positive of the cell and negative of bulb is connected with negative of cell

but switch is open.

Ans3 The bulb wont glow.



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4. FUN WITH MAGNETS Magnetic and Non-magnetic Materials

A Greek shepherd named Magnes discovered magnets 4,000 years ago in Magnesia, Greece. The name magnetite has been

derived from Magnesia or Magnes. Magnets are named after Magnetite.

Magnets attract magnetic materials. Natural rocks that have the property of attracting iron are called naturals magnets.

Magnes discovered a natural magnetic rock, called the lodestone. In the form of a bar, it was used to find directions on the

earth, and so the name, ‘lodestone,’ which means the stone that leads. Lodestone has a compound of iron called magnetite.

These natural magnets have the magnetic property of attracting materials like iron.

"Archimedes", the ancient Greek scientist, is believed to have used lodestone to pull nails from enemy ships. Taking the nails

out made the ships sink.

Magnetic Materials

Materials that are attracted by a magnet are called magnetic materials. Objects made of materials such as iron, cobalt and nickel

are magnetic objects. Examples of magnetic materials include iron nail, key, metal spade, needle and metal door handle.

Non-Magnetic Materials

Materials that are not attracted by magnets are called non-magnetic materials. Modern coins are made of uniform mixtures of

different metals so they become non- magnetic. Examples of non-magnetic materials include rubber, coins, feather and leather.

Properties of a Magnet

Substances that possess the property of attracting iron are called magnets. The two ends of a magnet are called its poles. All

magnets have two poles, and they are called dipoles. A magnet with a single pole doesn't exist. Since poles have high magnetic

power, they attract objects easily. The poles of a magnet are named as the north pole and the south pole. In order to identify

the poles, the north pole is usually painted in red colour. The other end of the magnet will, therefore, be the south pole. In

laboratories, magnets are painted completely red in colour with a white dot to indicate the north pole. The other end will,

therefore, be the south pole. A magnet can be cut into two pieces. Each piece will behave like an independent magnet, with a

north pole and a south pole.

Types of magnets

Bar magnets

In these magnets, the poles are located at the ends of the bar.

Cylindrical magnets

In these magnets, the poles are located at the two circular ends of the cylinder.

Dumb-bell shaped magnets

In such magnets, the poles are located at the two dumb-bell shaped ends.

Horseshoe magnets

In these magnets, the poles are located at the two free ends of the 'U' shape.

Compass

A compass is an instrument that is used to find the directions. It has a thin magnetic needle supported from a pivot so

that it can rotate freely. The needle is placed over a dial with the directions marked. The entire assembly is placed

inside an airtight box.



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The north pole of the magnetic needle is painted red. The magnetic needle in the compass points in the north-south

direction. By aligning the dial properly, the directions can be found. In the ancient days, an old pointing device, called

the south pointing fish, was used to know the directions. The head of the fish pointed towards the south.

Alignment of a compass

Take a compass and make sure that the magnetic needle comes to rest. Rotate the box so that the red tip of the

magnetic needle coincides with the north mark of the dial. The compass is now aligned. Next, select any object around

you. Then, with the help of the compass, identify the direction in which the object lies relative to you.

Law of magnets

Unlike poles attract each other and like poles repel each other.

Artificial magnets

Magnets can be made artificially, too. A rectangular iron bar, an iron needle, a blade or an iron nail can be turned into a

magnet by rubbing a bar magnet over it.

Precautions to protect magnets from losing their magnetic properties

Never drop magnets from heights.

Never heat a magnet.

Do not hammer a magnet.

Certain items such as CD's, DVD's, debit cards, credit cards or ATM cards, audio and video cassettes, and mobile phones

contain magnetic material. Keep them away from magnets to prevent damage.

SOLVED QUESTIONS

Q1 How were magnets discovered?

A1 There was a Shepard named Magnes who lived in ancient Greece .He used to take his herd of sheep and goats to the

mountains for grazing He would take a stick with him to control his herd the stick had iron attached at one end. One day he was

surprised to find that he had to pull hard to free his stick from a rock on the mountains. It seemed if the stick was being

attracted by the rock. The rock was a natural magnet.

Q2 What is magnetite?

A2 Magnetite is a natural magnet It contains iron.

.Q3 What are magnets?

A3 Magnets are substances having property of attracting iron or iron like materials.

Q4 Name some different shapes of magnets.

1. Bar magnet

2. horse shoe magnet

3. cylindrical magnet

4. ball ended magnet

5. needle magnet

Q5 What are magnetic and non magnetic materials?



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A5 The materials which get attracted to magnets are known as magnetic materials example: iron nickel cobalt. The materials

which do not get attracted to magnets are known as non magnetic materials example plastic rubber wood.

Q6 Demonstrate what happens when we move a bar magnet through iron filings (draw the diagram also)

A6 When we move bar magnet through iron filings they get attracted to magnet. Minimum iron filings get attached to the centre

region and maximum iron filings get attached to the end regions of bar magnet which is known as the poles showing the

attraction is maximum at the poles.

Q7 How many poles exist in a magnet?

A7 Every magnet has two poles north pole and a south pole. North Pole is denoted by N and South Pole is denoted by S

Q8 What is the property of magnet which is used by travelers to find directions?

A8 When we freely suspend a magnet it always points in N-S direction This property is used by travelers to find directions

Q9 What is a magnetic compass?

A9 A device which was developed based on the property of magnets of finding directions is known as magnetic compass.

A compass is usually a small box with glass cover on it A magnetized needle is pivoted inside the box which can rotate freely The

compass also has a dial with directions marked on it Its needle indicates north south directions when it comes to rest.

Q10 How can you prepare your own magnet?

A10 We can prepare magnet by the following processes

a) By rubbing one pole without lifting 20-30 times on an iron nail or iron strip.

b) By passing current through an iron nail or iron strip we obtain a magnet and this magnet is known as electromagnet.

Q11 what happens when we bring like poles of a magnets close to one another?

A11 Like poles repel.

Q12 what happens when we bring unlike poles of a magnets close to one another?

A12 Unlike poles attract.

Q13 How do magnets lose their properties?

A13 Magnets loose their property if they are heated, hammered or dropped from some height.

Q14 How can we keep our magnets safe?

A14 To keep magnets safe Bar magnets should be kept in pairs with unlike poles on same side They must be separated by a

piece of wood while two pieces of soft iron should be placed across their ends For horse shoe magnet one should keep a piece

of iron across the poles.

Q15 what precautions should be taken in handling magnets?

A15 We should keep magnets away from cassettes, mobiles, TV music systems compact disks and computers.



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CHEMISTRY

1. FIBRE TO FABRIC Fibre to Fabric

Fabrics are made up of strands called yarns, which are made from even thinner strands,called fibres.

Cotton, silk, wool and jute are called natural fibres as they are obtained from natural sources. We get cotton and jute

from plants. We get silk from the cocoons of silk worms.

Synthetic fibres like nylon, polyester and acrylic were invented about a hundred years ago. These are man-made and

are not obtained from any plant or animal sources.

Cotton fibre is obtained from cotton plants that grow in black soil in a warm climate. In India, cotton is grown in

Gujarat, Maharashtra, Andhra Pradesh, Punjab, Haryana, Karnataka, Tamil Nadu, Rajasthan, Orissa and Madhya

Pradesh.

The cotton plant bears fruits about the size of a lemon, called cotton bolls. The bolls are full of seeds and cotton fibre.

They burst open when they are ripe.

The cotton fibres are collected by hand from the ripe cotton bolls. This process is called picking.

Next, the cotton fibres are separated from the seeds by combing them. This is known as ginning.

Earlier, ginning was done by hand, but nowadays, a machine is used.

6.Jute fibre comes from jute plants, which are mainly grown in places that have high temperatures and plenty of

rainfall. Jute is cultivated during the rainy season. In India, jute is cultivated in West Bengal, Bihar, Andhra Pradesh,

Uttar Pradesh, Assam, Chhattisgarh and Tripura.

The jute plant is generally harvested when it is in the flowering stage.

The stems of jute plants are soaked in water for a few days until they start rotting.

Then the fibres are separated by hand from the rotting stems.

Once the fibres have been obtained, they are made into yarn by twisting the strands together. This process of making

yarn from fibre is called spinning.

7.Not just jute, even cotton, silk and other fibres are spun to convert them into yarn.

8.Machines are used for spinning yarn on a large scale. Fabrics like khadi are made by spinning yarn on hand-operated

devices like charkhas and taklis. The process of arranging two sets of yarns to produce a fabric is called weaving.

Evencoconut fibre can be woven into a fabric called coir. Coir is too rough to be made into garments. It is mostly used

to make doormats, carpets and other flooring material.

9.In ancient Egypt, flax and cotton plants were cultivated near the River Nile and were used for making fabric. At the

beginning of civilisation, people used bark, leaves and animal fur to cover themselves. As people settled down and

started farming, they learned to weave vines and animal fleece to make fabrics.

In the next stage of civilisation, flax and cotton were woven into garments. In those times, people just draped the fabric

to cover themselves. It was only after the invention of the sewing needle that people started stitching their garments.

Even today, in older cultures like India, you see people wearing unstitched garments like turbans, saris and dhotis.

SOLVED QUESTIONS

Q1. Define a fibre.

Ans. A very thin, thread like strand from which cloth is made is called a fibre.

Q2. What are natural and synthetic fibres? Give examples.

Ans: Natural fibres: Fibres that are obtained from plants or animals are called natural fibres. For example: cotton, jute, wool and

silk.

Synthetic fibres: the fibres which are prepared from chemical substances in industry are called synthetic fibres. Example: Nylon,

polyester, rayon etc.



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Q3. Describe briefly the two processes of making fabric from fibre.

Ans. The fabrics are made from fibres in the following two steps:

2. Fibres are first converted to yarn by the process of spinning.

3. Fabric is made from yarn by the process of weaving or knitting.

Q4. What is a yarn?

Ans. Yarn is a spun thread which is used for weaving fabrics.

Q5. Name three devices which are used for making yarn from fibre.

Ans. Yarn can be made by using:

1. Hand spindle or takli

2. Spinning wheel or charkha

3. Spinning machines

Q6. Name two processes by which fabric can be made from yarn.

Ans. Fabric can be made from yarn by weaving and knitting.

Weaving: it is the process of making fabric by arranging two sets of yarn at right angles to each other.

Knitting: it is the process of making fabric by forming a series of connected loops of yarn by using knitting needles.

Q7. For what purpose is a loom used?

Ans. The weaving of yarn to make fabric is done byusing a loom.

Q8. Explain how, jute fibre is obtained from jute plants.

Ans. Jute fibre is obtained from the stem of jute plant. The stems of harvested jute plant are immersed in water for a few days.

During this time, the stems rot and fibres are left behind. The jute fibre is then separated from water by hand.

Q9. What type of soil and climate are good for growing cotton?

Ans. Cotton cloth is grown in black soil and warm climate.

Q10. What is ginning? How is it done?

Ans. The process of separating cotton fibre from the seeds is called ginning. Ginning can be done either by hand or by using

machines.

Q11. Name two things that are made from coconut fibre.

Ans. Coconut fibre is used for making ropes and mats.

Q12. Name two products obtained by weaving twigs and grass.

Ans. Mats and baskets.



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2. SORTING MATERIALS INTO GROUPS Sorting Materials into groups

Properties of Materials

Objects are categorised on the basis of their shapes, the materials they are made up of, and the properties of these

materials.

All objects around you have definite shapes. For example, eggs are oval and ice-cream cones are conical in shape.

Objects can be classified on the basis of their shapes.

Objects can be made from many different kinds of material, such as plastic, wood, glass, metal, cotton, paper, leather,

wool, rubber, and even soil. Therefore, all objects can be grouped on the basis of the material that they are made from.

Sometimes, the same object can be made from different materials.

For instance, a pen could be made from metal or plastic, your shoes could be made from leather or cloth, and even the

tumbler that we drink from could be made from plastic, glass or metal. Bottles could be made from plastic or glass, and

chairs could either be wooden, metallic or plastic.

Property - Lustre:

Materials can be grouped as lustrous and non-lustrous on the basis of lustre/shine possessed by them.

Lustrous materials are those that have a shine on them. E.g. gold, silver and most metals are lustrous in nature.

Non-lustrous materials are dull in appearance. E.g. wood, plastics.

Property - Hard/Softness:

Materials that can be compressed or scratched easily are called soft materials. E.g. Cotton, Sponge.

Some materials that are difficult to compress are called hard. E.g. iron and most of the other metals.

Property - Soluble or Insoluble:

A substance (solid or a liquid) is said to be soluble in water if a single layer is observed. E.g. Lemon juice, vinegar, sugar,

salt are completely soluble in water and form a single layer with water. Materials (solids or liquids) that form distinct

layers with water are said to be insoluble in water.

Property - Float or Sink:

Materials that are insoluble in water either float on the surface or sink in water. Light materials float in water. E.g.

paper, Plastic boll etc.

Heavy materials sink in water. E.g. metals, stones etc.

Property - Transparency:

Materials can be classified as transparent, opaque and translucent on the basis of transmittance of light by them.

Transparent Materials:

Transparent materials allow light to pass through them completely. One can see through such materials

E.g. Glass,Wwater, Air and Some plastics

Opaque Materials:

Opaque materials do not allow light to pass through them. You cannot see through them. E.g. Wood, Cardboard and

Metals.

Translucent Materials:

Translucent materials allow light to pass through them only partially. They are partially transparent and partially

opaque. E.g. Butter paper, Frosted glass.



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SOLVED QUESTIONS

1. What do you mean by sorting of materials?

Ans. Classification of materials into various groups on the basis of similarities and dissimilarities in properties is known as sorting

of materials.

2. What is the need to classify materials?

Ans. Classification of materials is done to make the study of objects easier. Also, classification makes it easier to locate objects.

3. How are hard materials different from soft materials? Give two examples of each.

Ans. Hard materials: Those materials which cannot be easily scratched or compressed are called hard materials. Example: Wood,

stone, glass etc.

Soft materials: Those materials which can be easily scratched or compressed are called soft materials. Example: wool, foam,

butter etc.

4. Classify the following materials on the basis of their solubility in water:

Material Solubility in water

Milk Soluble

Alcohol Soluble

Sand Insoluble

Copper sulphate Soluble

Wax Insoluble

Chalk powder Insoluble

5. What is the importance of oxygen dissolved in water?

Ans. Oxygen gas dissolved in water is used by the aquatic plants and animals for respiration.

6. Why does water play an important role in the functioning of our body?

Ans. Water plays an important role in the functioning of our body as it can dissolve a large number of substances in it.

7. Name any two liquids which are miscible with water and two which are insoluble in water.

Ans.

Liquids miscible with water: Vinegar, lemon juice

Liquids immiscible with water: petrol, groundnut oil

8. Give one word for the following:

a) Shine observed on the surface of metal.

b) Substances through which light cannot pass.

c) Substances which do not dissolve in other substance.

9. Name two materials which float on water and two which sink in water.

Ans.

Materials which float on water: Dry leaves, oil

Materials which sink in water: stone, chalk

10. How are transparent objects different from translucent objects?

Ans. Transparent materials: The materials through which we can see clearly are known as transparent materials. Example: glass,

air etc.

Translucent materials: The materials through which we cannot see clearly are known as translucent materials. Example: butter

paper, ground glass, frosted glass etc.

11. Name two gases which dissolve in water to some extent.

Ans. Oxygen, carbon dioxide



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12.Fill in the blanks:

1. a) A feather on the surface of water.

2. b) _ cannot be compressed easily.

3. c) Coconut oil on the surface of water.

4. d) Common salt is in water.

5. e) Materials usually lose and appear dull if kept exposed to air and moisture for a long time.

6. f) Water contains _ oxygen that supports life under water.

13. State one property of metals which is used for making jewellery.

Ans. Lusture

14. State true or false:

a) Bark of tree is rough.

Ans. True

b) Wood is a transparent material.

Ans. False

c) Carbon dioxide is insoluble in water.

Ans. False

d) Coconut oil is immiscible in water. Ans. True

15. Find the odd one out from the following :

Aluminium, iron, copper, silver, sand

Ans. Sand as it is not lusturous.



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3. SEPARATION OF SUBSTANCES Separation of Substances

Methods of Separation

Separation of substances can be carried out under two conditions

Dry conditions

Wet conditions

Separation of substances under dry conditions:

There are various methods for separating substances, such as handpicking, threshing, winnowing and sieving.

Handpicking:

It involves simply picking out substances by hand and separating them from others. The substances being separated

may be impurities that have to be thrown away. Or it may be that both the substances being separated are useful –

such as if you separate green grapes from black ones from a mixture of the two.

Threshing:

This is done after harvesting of crops. Once wheat is harvested, the stalks are dried. Then, each grain of wheat is

separated from the stalks to which it is attached, so that it can be ground into flour. This method of separating grains

from stalks is called threshing.

Winnowing:

Winnowing follows threshing and is used to separate heavier and lighter components of a mixture by wind or by

blowing air. The husk is separated from the grains by winnowing.

Sieving:

The method used to separate the wheat bran from the flour is called sieving. Sieving is a method of separating

substances that are of different sizes.Separation of wheat bran from flour is performed by sieving.

Grains can be separated from dirt by sedimentation and decantation. When water is added to the grains, the dust and

dirt dissolve in the water, making it muddy. Thus, the dirt and grains are separated.

Methods of separation of substances under wet conditions:

Sedimentation

The grains settle at the bottom because they are heavier. This process of the settling of the heavier substance is called

sedimentation.

Decantation:

Now, the grains can be separated by simply pouring out the water. This process is called decantation.

Oil and water can also be separated by decantation and sedimentation. Water is heavier than oil, so it settles at the

bottom if left alone for some time. The oil can then simply be poured out.

The water left behind can be further cleaned using a filter paper. While water passes through the fine pores of the

filter, dirt will sift out, leaving the water clean.This process of using a filter to separate substances is called filtration.

Salt and water from salty water can be separated by evaporation. We need to boil this water so that its temperature

rises and it converts into steam. This process is called evaporation.

The steam turns back into water when it comes in contact with a cold metal lid. This process is called condensation.

A mixture of sand and salt can be separated by combination of methods.

The first method is sedimentation and decantation. This mixture is put in water and left for the sand to settle for some

time. Then, we will decant the salty water, which will separate the sand from the mixture.

Now the salt can be separated from the water by evaporation. The water will boil away, leaving the salt behind.



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So, the mixture of the sand, salt and water has been separated successfully using a combination of sedimentation,

decantation, evaporation and condensation.

SOLVED QUESTIONS

Ql. Why do we need to separate the components of a mixture?

Ans. Components of a mixture need to be separated in order to:

1. remove undesirable waste

2. remove harmful components from a mixture

3. obtain useful components

4. obtain the pure sample of a substance.

Q2. Name the different methods of separation of substances.

Ans. Different methods of separation of substances are:

1. handpicking

2. threshing

3. winnowing

4. sieving

5. magnetic separation

6. sedimentation & decantation

7. filtration

Q3. Define the terms:

a) Threshing

Threshing is the process in which stalks are beaten to separate grains from the stalks.

b) Winnowing

Winnowing is the method of separating husk from grains with the help of wind.

Q4. What type of mixtures can be separated by hand-picking?

Ans. Hand-picking is usually used to separate those mixtures where one of the components is in small quantity and can be easily

picked up by hand. Example: stones from rice and pulses.

Q5. What is the principle behind sieving?

Ans. Sieving is used to separate those solid mixtures which have components of different sizes. Larger particles are retained on

the sieve and the smaller particles pass through the pores of the sieve.

Example: a mixture of sand and stone can be separated by using a sieve.

Q6. What do you mean by the terms sedimentation and decantation?

Ans. Sedimentation: it is the process of setting down the insoluble component of a mixture on leaving undisturbed for

sometime.



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Decantation: The process of pouring of a liquid from a vessel without disturbing the sediment is called decantation.

Q7. What is filtration?

Ans. The process of removing insoluble solids from a liquid by using a filter paper is known as filtration.

Q8. Discuss evaporation and condensation as methods of separation.

Ans. Evaporation is a method of obtaining soluble solids from their solutions by heating. In this process the liquid changes into

its vapours by heating the solution and the soluble solid is left behind.

On the other hand, condensation is the process of changing back of the hot vapours into the liquid state by cooling.

Q9. What is a saturated solution?

Ans. A solution in which no more of solute can be dissolved in the solvent at a given temperature is known as a saturated

solution.

Ql0. What happens if the saturated solution of a substance in water is:

a) heated? b) cooled?

Ans. a) If the saturated solution of a substance in water is heated then the undissolved solute will dissolve.

a) ) If the saturated solution of a substance in water is cooled then some of the dissolved substance will reappear in the form

of solid crystals.

Ql1. How is cream obtained from milk?

Ans. When milk is churned or rotated at a high speed, cream gets separated from milk.

Ql2. You are given a mixture of salt & sand, how would you separate them?

Ans. For separating the given mixture of salt & sand following steps are carried out:

• add water to the given mixture and allow it to stand undisturbed

• sand particles settle down at the bottom of the container & salt gets dissolved

• sand can be separated by filtration leaving behind salt solution

• salt can be obtained from the solution by evaporation.

Ql3. How would you separate a mixture of sand & iron fillings?

Ans. The mixture can be separated by the method of magnetic separation .



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4. CHANGES AROUND US Every day, we see different types of changes around us, like day turning into night, the season changing from winter to

summer, melting of ice to water, cooking of food, and so on.

Changes take place around us all the time. However, all changes are the same. We get back the original substance in

some, and can’t get them back in others.

A reversible change is a change that can be undone or reversed.

Melting is an example of a reversible change.

Boiling, evaporation and condensation are all examples of reversible changes.

For example, if you could capture all the steam that is made when a kettle boils, you could turn it back into water by

cooling it.

Some other examples of reversible changes are the melting of ice, folding a paper and blowing a balloon.

A blacksmith changes a piece of iron into different tools. For that, a piece of iron is heated to red hot. This also softens

it. It is then beaten into the desired shape. It is a reversible change.

An irreversible change is a permanent change that cannot be undone. In an irreversible change, new substances are

formed.

Cake batter is made from eggs, flour, sugar and butter. Once the cake has been baked, you cannot get the ingredients

back.

Heating a substance can cause an irreversible change.

Cooking is another example. We cannot get back the substances that we originally started with

Mixing substances can also cause an irreversible change.

For example, when vinegar is mixed with bicarbonate of soda, you can observe the release of

carbon dioxide gas in the form of bubbles. Again, here, we cannot get back the original substances.

Some other examples of irreversible changes are the digestion of food and heating of lime stone.

The burning of wood is also an irreversible change. Once wood is burned, it changes to

ash, and we cannot get back the wood again.

Finally, our growth itself, as you can see, is an irreversible change.

SOLVED QUESTIONS

Q1. Give any five examples of changes taking place in your daily life.

Ans. The examples of various changes are:

1. Germination of seeds

2. Growing of height

3. Inflating a balloon

4. Melting of ice

5. Burning of candle

Q2.What are the various types of changes?

Ans.

a) Slow & fast change

b) Reversible & irreversible change

c) Desirable & undesirable change

d) Physical & chemical change

Q3. Diiferentiate between reversible & irreversible change. Also give examples.



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Ans. Reversible change: Those changes which can be reversed to the original form by removing the cause of change are called

reversible changes.

Example: melting of ice, stretching of rubber band, folding of paper etc.

Irreversible change: Those changes which cannot be reversed to the original form are called irreversible changes.

Example: burning of candle, formation of flower to bud, bursting a balloon etc.

Q4. What are desirable & undesirable changes?

Ans. Desirable changes: Those changes which are desired to occur that is we want them to take place are known as desirable

changes.

Example: ripening of fruits, germination of seeds etc.

Undesirable change: Those changes which we do not want to take place are called undesirable changes.

Example: rusting of iron, souring of milk, rottening of fruits etc.

Q6. How do following changes differ from each other:

1. Burning of wax

2. Melting of wax

Ans. Burning of wax is an irreversible change whereas melting of wax is an example of a reversible change.

When we light a candle, then the wax present burns to produce various new substances like carbon dioxide, water vapour,

smoke etc. which cannot be combined together to give back wax.

Also, solid wax on heating melts to form liquid wax which can be solidified again by cooling it.

Q7.What are slow & fast changes? Give example.

Ans. Slow change: Those changes which take place in a long period of time are called slow changes.

Example: rusting of iron, germination of seeds etc.

Fast change: Those changes which take place in a short time are called fast changes. Example: burning of paper, bursting a

balloon.

Q8. How is inflating a balloon different from bursting an inflated balloon?

Ans. Inflating a balloon is an example of a reversible change whereas bursting a balloon is irreversible change.

When we blow air into a balloon, its shape & size changes. But it regains its original form when the air is allowed to escape. On

the other hand a bursted balloon cannot be changed back to the original form.

Q9. Differentiate between physical & chemical change. Give 2 examples of each.

Ans.

Physical Change

a) Those changes in which no new substance is formed are called physical changes.

b) Physical changes are usually reversible.

c) Example: melting of wax, tearing of paper etc.

Chemical Change



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d) Those changes in which a new substance with new chemical properties is formed are known as chemical changes.

e) Chemical changes are irreversible.

f) Example: burning of paper, baking a chapatti etc.

Q10. Explain how, a metal wheel is fixed around the wooden wheel of a cart.

Ans. The iron rim is fixed around the wooden wheel of a cart by the process of expansion on heating. The rim is made slightly

smaller than the wooden wheel. On heating; the rim expands & fits onto the wheel.

After that cold water is poured over the rim, as a result, it contracts & fits tightly onto the wheel.

Q11.Explain how, the iron blade of the digging objects like spade is fixed to a wooden handle.

Ans. The iron is fixed by the process of expansion on heating.

The iron blade of tools has a ring in which the wooden handle is to be fixed. The ring is slightly smaller than the handle. To fix the

handle, the ring is heated & it expands. Now, the handle easily fits on the ring. When the ring cools down then it contracts & fits

tightly on the handle.

Q12.When water is mixed with Plaster of Paris & allowed to dry, it sets into a hard mass. State whether the change is

reversible or irreversible. Justify your answer.

Ans. The above change is an example of an irreversible change. This is because when water is added to Plaster of Paris then it

sets as a hard mass & cannot be converted back into the original form.

Q13. A bag of cement lying in the open gets wet due to rain. Can the change which takes place in cement on getting wet be

reversed by drying?

Ans. No, this change cannot be reversed on drying as some changes occur in cement on getting wet due to which it gradually

sets as a hard mass. Even if it is kept in bright sunshine, then also the change cannot be reversed.

Q14. Milk can be changed into curd but curd cannot be changed back into milk. What is the general name of such changes?

Ans. Such changes are known as irreversible changes.

Q15.How does a blacksmith change a piece of iron into different tools?

Ans. A blacksmith first heats a piece of iron till it becomes red hot. It then becomes soft

& can be beaten into desired shape.

Q16. You must have seen that construction workers heat a black material called coal tar for repairing a road. State whether

the change which has occurred in coal tar on being heated is reversible or irreversible.

Ans. When coal tar is heated, it melts to form a thick dark liquid. The melting of coal tar is a reversible change as it solidifies

again on cooling.

Q17. Why is shaping of wet clay into clay pot a reversible change whereas baking a clay pot an irreversible change?

Ans. The shaping of wet clay into a clay pot, a reversible change as wet clay can be converted back into the original clay.

Whereas a baked clay pot cannot be changed back into the original form, therefore it is an irreversible change



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BIOLOGY

1. FOOD: WHERE DOES IT COME FROM? Sources of Food

All ingredients is a component of a mixture.

Certain food items are made with few ingredients, but some are made with many ingredients.

Some ingredients are common for several food items.

Vegetables, cereals, pulses, fruits and spices come from plant sources.

Mean, poultry, fish and milk products come from animal sources.

Animals are categorized based on their eating habits into herbivores, carnivores and omnivores.

Herbivores are animals that eat only plants and plant products.

Carnivores are animals that eat meat.

Omnivores eat both plants and animals.

SOLVED QUESTIONS

Q1) Why does an organism need food?

Ans1-1.To get energy.

2. For growth , repair and maintenance of the body.

3. To fight diseases.

Q2)Why is glucose given to sportspersons?

Ans2-glucose is a type of carbohydrate, which can be quick source of energy.

Q3)Why do we cook food?

Ans3-1.to make food digestible and to improve its taste.

2. cooking also kills the germs that are sometimes present in food.

Q4)Why is it necessary to drink about 1.5 litres of water everyday?

Ans4-Excretion ,sweating and breathing makes us lose about 2-3 litres of water everyday. About 1.5 litres is made up for by

drinking water and other liquids.

Q5)Why water is needed for our body?

1. Water helps to carry digested food around the body.

2. Water help to carries wastes out of the body

3. It helps to regulate the body temperature.

Q5) List the various edible parts of the plants, mention some examples also.

Ans5-ROOT-carrot, raddish, beetroot, turnip, sweet potato STEM-sugar cane, ginger, onion, potato, colocasia (arbi) LEAF-

spinach, cabbage, lettuce, methi

FLOWER-cauliflower, broccoli, banana, pumpkin, clove, saffron FRUIT-banana, mango, brinjal, tomato, cucumber

SEED- pulses, peanuts, coconut, methi seeds, almonds



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Q6) Classify the following as herbivore, carnivore or omnivore.

Ans6-Herbivore-cows, goats, horses, elephants, giraffes, parrot, squirrel

Carnivore-crocodile, shark, tigers, lions, snake

Omnivore-bears, crow, humanbeing, cockroach

Q7)Where does honey come from?

Ans7-Bees collect NECTAR(sweet juices) from flower, convert it into honey and store it in their hive.

Q8) Mention the source of food as plant or animal, for the following food items.

a)Chicken-animal b)rice-plant c)onion-plant d)oil-plant and animal e)sugar-plant f)milk-animal

g)egg-animal f)wheat flour-plant.

Q9)What are sprouted seeds?

Ans9-a small white structure grown out of the seeds, which will be future shoot of the plants.



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2. COMPONENTS OF FOOD Test For Starch, Proteins and Fats

Nutrients are nourishing components of food that are required by our body. They release energy and help in body

growth. Nutrients found in our food are carbohydrates, proteins, fats, vitamins, minerals and water. Different types of

food contain two or more nutrients in combination. Carbohydrates are instant source of energy. Fats are high energy

reserves. They are stored for future use. Proteins are the building blocks of our body which mainly help in growth. Two

major forms of carbohydrates are starch and sugar.

The following steps are performed to test the presence of starch in a food item

Take small quantity of the food item to be tested.

Put 2-3 drops of iodine solution on it.

Observe the color of the food item.

Blue-black color indicates the presence of starch in the tested food item.

The following steps are performed to test the presence of protein in a food item

Take a small quantity of the food item to be tested.

Grind/mash/paste/powder the food item.

Put the food item into a test tube.

Add 10 drops of water to the test tube.

Add two drops of copper sulphate solution to the test tube.

Add 10 drops of caustic soda solution and shake the test tube.

Observe the color of the mixture.

Violet colour indicates the presence of proteins in the tested food item.

The following steps are performed to test the presence of fat in a food item

Take a small quantity of the food item to be tested.

Wrap the food item in a small piece of paper.

Crush the food item wrapped in the paper.

Straighten the paper.

Dry the paper by keeping it in sunlight for a while.

Observe the paper.

An oily patch on the paper indicates the presence of fat in the tested food item.

Nutrients and Balanced Diet Summary

All living organisms require food. Food has six types of nutrients - carbohydrates, proteins, fats, vitamins, minerals and

water.

These are essential to perform all daily and metabolic activities.

Carbohydrates are compounds of carbon, hydrogen and oxygen, always in the ratio of 2:1:1.

They are oxidised in the cells to release energy. Carbohydrates include sugars, starch and cellulose.

Carbohydrates are oxidised in the body in the form of sugars. They provide instant energy.

When oxidised in the body, one mole of glucose releases 686 kilocalories of energy.

They are mainly present in rice, potato, banana, etc.

Proteins are composed of carbon, hydrogen, oxygen and nitrogen.

Nitrogen is the most essential element in proteins. Some proteins contain sulphur and phosphorus.

Amino acids are the simple, smaller units of proteins. Proteins provide chemical material for the growth and repair of

the body cells and tissues.

In an emergency, they may also oxidise to release energy. Food rich in proteins includes lean meat, fish, eggs, milk,

cheese, nuts, beans, peas, etc.

Fats are also composed of carbon, hydrogen and oxygen. Fats have very little oxygen content, though..

They produce more energy than carbohydrates do.

Fat below the skin protects the body against rapid loss of heat.



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It serves as a solvent for fat-soluble vitamins.

It is an important form for storage of food.

Common foods rich in fats are butter, cream, vegetable oils, meat, and fish liver oils.

Mineral salts are needed in the diet in small quantities. These are obtained from table salt, green vegetables and fruits.

Some important minerals are:

Calcium, required for:

Strengthening bones and teeth

Blood clotting

Muscle contraction

Rich sources: Milk, meat, eggs, fish, pulses, vegetables, etc.

Phosphorus, required for:

Strengthening bones and teeth

For production of ATP in during cellular respiration

Conduction of nerve impulses

Rich sources: Milk, meat, eggs, fish, pulses, vegetables, etc.

Iron, required for:

Forming haemoglobin

Rich sources: Green leafy vegetables, liver, etc.

Iodine, required for:

Proper working of thyroid

Rich sources: Vegetables, mineral water and iodised salt

Vitamins are chemical substances that help maintain a healthy body.

Vitamins A, D, E, and K are fat soluble and can be stored in the body.

Vitamin B complex and vitamin C are water soluble and cannot be stored for a long period of time.

Vitamin A: Promotes growth, vision.

Present in butter, egg yolk, milk, carrot, etc.

Vitamin D: Helps the body to absorb calcium and phosphorus to form bones and teeth.

Present in fish liver oils, milk, eggs, etc.

Vitamin E: Prevents the oxidation of vitamin A.

Present in meat, milk, whole wheat, etc.

Vitamin K: Helps in clotting of blood during injuries.

Present in cabbage, spinach, leafy vegetables

Vitamin B complex: Needed for a healthy brain, nerves and muscles.

Present in wheat, rice and liver.

Vitamin C: Helps fight diseases like the common cold.

Present in oranges, tomatoes, lemons and guavas.

Water: Helps the body to get rid of toxic wastes through urine and sweat, and to absorb the

nutrients in food.

Deficiency Diseses

Diseases or disorders occur mainly due to the deficiency of one or more nutrients in the diet over a long period of time.

For example, wheat is rich in carbohydrates, but poor in nutrients like proteins and fats.

Too much intake of wheat products results in a deficiency of proteins and fats, which reduces growth. Lack of proteins

also results in stunted growth, skin diseases, swelling of the face and discolouration of the hair, and even causes

diarrhoea. So a balanced diet is required to avoid deficiency diseases.

Diseases caused by deficiency of minerals:

Lack of iron in the diet leads to a deficiency disease called anaemia. The symptoms of anaemia are headache, dark

patches under the eyes, weakness and feeling tried. A balanced diet should, therefore, include iron-rich foods such as

apples, fish and raisins to avoid anaemia.



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Lack of iodine in the diet leads to a deficiency disease called goitre. In adults, goitre results in swollen glands at the

throat. In children, iodine deficiency causes stunted mental and physical development. Iodine deficiency can be avoided

by using iodised salt in the diet.

Lack of calcium in the diet makes the bones weak and brittle, and also causes tooth decay. Milk, eggs and other dairy

products contain calcium and give strength to the bones and teeth.

Diseases caused by deficiency of vitamins:

Lack of vitamin A in diet causes loss of vision. Symptoms include night blindness, i.e. poor vision in dim light. Eating food

rich in vitamin A, such as carrot, mangoes, butter and egg yolk, helps avoid loss of vision.

Lack of vitamin B1 in the diet causes a deficiency disease called beriberi. The symptoms are loss of weight and weak

muscles. Food rich in vitamin B1, such as beans, meat, eggs and corn, helps avoid beriberi.

Lack of vitamin C in the diet causes a deficiency disease called scurvy. The symptoms of scurvy are bleeding gums.

Moreover, wounds take longer to heal. Oranges, tomatoes, lemon, guavas and amla are rich in vitamin C, so eating

these helps avoid scurvy.

Lack of vitamin D in the diet causes a deficiency disease called rickets. The symptoms are soft and bent bones. The diet

should include fish, eggs, milk and butter to avoid rickets. In addition, exposure to sunlight produces vitamin D in the

body.

SOLVED QUESTIONS

Q1)What are nutrients?

Ans1-nutrients are the substances that an organism needs for growth, repair and maintenenance of its body.

Q2) Name the various nutrients needed by human body.

Ans2- carbohydrates, fats, proteins, vitamins, and minerals.

Q3) Apart from these nutrients, what are the other components of food?

Ans3- Roughage and water.

Q4)What are energy giving foods? Give 2 examples.

Ans4-carbohydrates and fats on digestion releases energy. Example-sugarcane, potato, Rice, sweet potato, wheat, maize,

banana, papaya etc.

Q5)Which chemical reagent will we use to test the following food items: bread, pea nuts, soyabean, paneer, banana, boiled

rice, pulse, potato.

1.Bread ,banana, boiled rice ,potato

Contain starch: Iodine solution is need

2.Soyabean, paneer

Are rich in protein:can be tested using caustic soda and copper sulphate.

3.Pea nuts

Rich in fats: only a paper is needed

Q6)What are body building food? Give example.

Ans6-protein are body building food. These are necessary for the growth and repair of body that is why growing children,

pregnant women and people recovering from illness need more protein in their diet.

Q7)Name 2 sources of plant proteins and animal proteins.

Ans7-a) plant protein-beans, pulses, cereals

b) animals protein-meat ,fish, eggs



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Q8)What is the function of fats in our body? Name any three sources of fats?

Ans8-Fats give more energy than carbohydrates, however it is difficult for the body to digest fats and excess of fat get stored in

body. Milk, ghee, butter, cream, meat.

Q9)What are vitamins?

Ans9-vitamins are essential nutrients required in small quantities for normal growth,good vision, healthy teeth, gums, bones,

and overall good health.

Q10)Name 4 important vitamins required for overall good health.

Ans10-vitamin A, vitamin B, vitamin C, vitamin D.

Q11)Mention the source and functions of the following vitamins.

A

Green leafy vegetables ,yellow fruits,fish

Maintains healthy eye sight,skin and proper growth

B

Whole grain cereals pulses,nuts,green vegetables, milk, cheese, fish, eggs

Help in proper functioning of digestive system for good skin, formation of healthy blood and proper growth of body.

C

Amla, citrus fruits, green vegetables

For keeping teeth,gums,and joints healthy.it increases the resistance of body to infection fight diseases.

D

Milk, egg yolk, fish, butter, when skin is exposed to sunlight ,vitamin D is produced.

Essential for normal growth of bones and teeth.

Q12)Why do we need to include minerals in our food?

Ans12-minerals are the nutrients which are required by our body for its proper functioning normal growth and good health.

Q13)Mention the sources and functions of following minerals

Ans13

minerals

sources

functions

iron

Green leafy veegtables ,jaggery, egg yolk, groundnut, cereals

Essential for formation of hemoglobin in R.B.C.

Calcium

Milk, cheese, cereals, meat

Essential for healthy bones and teeth ,clotting of blood

iodine

Iodised salt, seafood, green vegetables.

For proper functioning of thyroid gland.

Q14) Define roughage.

Ans14-The fibrous indigestible material present in our food .

Q15)Why is roughage considered to be an important component of our food?name 3 important sources of roughage.

Ans15-i)roughage adds bulk to the food ,prevents constipation.

ii)it can absorb a great amount of water and helps retain water in our body.



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SOURCES-unpeeled fruits (like apple,pear), porridge(dalia),salads

Q16)What is meant by dehydration? How is it caused?

Ans16-excessive loss of water from the tissues of our body is called dehydration.it occurs when water intake is less than water

loss from the body.

Q17)What is a balanced diet?

Ans17-The diet that contains adequate amount of all the essential nutrients, roughage and water sufficient for The normal

growth and development of the body.

Q18)State two beneficial effects of cooking food.

Ans18-i)cooking improves the taste of food material. ii)cooking makes the food digestible.

iii)cooking kills the harmful micro-organisms.

Q19)Name two cooking practices that lead to the loss of nutrients in food materials.

Ans19- If cooking is done in excess of water and the water is thrown away after cooking, many water soluble vitamins and

minerals are lost.

If cooking is done at high temperature, many proteins and vitamins are destroyed. For example vitamin C.

Q20)What is obesity? What are the causes of obesity?

Ans20-overeating of fat rich food leads to an overweight condition called obesity. Due to lack of physical activity, fats get

accumulated in the body and causes obesity.

Q21)Mention some of the methods for maintaining good health.

Ans21-1) always take fresh and clean food. 2.) Avoid food that is too oily or spicy.

3.) Avoid junk food.

4.) Eat lots of fruits and green vegetables. 5.) Drink plenty of water.

6.) Do regular physical exercises.

Q22) Who needs more proteins in his or her diet in relation to body weight: a growing child or grown up man? Why?

Ans22-A growing child needs more proteins than a grown up man because child needs proteins for development bone, muscles

of his body.



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3. GETTING TO KNOW PLANTS Categories of Plants

A herb is a non-woody plant that has green and tender stems with few branches and is usually short.

Herbs have a variety of uses including adding flavor to food, providing medicine for diseases and in some cases even

adding a spiritual touch.

Shrubs are taller than herbs and have stems branching out from the base.

The stems of shrubs are hard not but thick.

A common place where shrubs are grown is known as shrubbery.

A tree is a woody plant that has many branches on a single stem.

Trees benefit us by preventing soil erosion, maintaining the carbon dioxide content in the air and in building huts and

making furniture.

Threes are categorised based on their height, width of their trunk, their overall size, and of course their age.

Creepers are plants with weak stems and hence cannot stand straight. They grow on the ground.

Creepers have a tendency to develop new plants on their own.

A few creepers could cause allergies or skin problems if touched.

Climbers are plants that need support from other structures to grow and spread.

Climbers can either move horizontally or vertically unlike creepers that move only horizontally.

Climbers attracts insects and reptiles because of their brightly coloured flowers and fragrance

Parts of a Plant

The different parts of a plant are the roots, stem, leaves, flowers and fruits.

The roots of a plant are mostly seen underground and look brown in colour.

The tiny thread-like structures over the roots are the root hair. The tip of the root is called the root cap.

Roots are of two types - tap root and fibrous roots.

Some plants have a primary root that grows more or less straight down into the soil, and is tapered towards the end.

This main root is called the tap root.

There are many smaller roots that branch out from the tap root, called lateral roots.

Examples of plants with tap roots are hibiscus, carrot, turnip and sunflower.

Some plants have many lateral roots that start from the base of the stem. These are called fibrous roots.

Examples of plants with fibrous roots are banana, grass and onion.

The roots hold the plant firmly in the soil, thereby serving as an anchor to the plant.

One of the main functions of the roots is to absorb water and nutrients from the soil for the growth of the plant.

Sometimes they also store sugars and carbohydrates.

The stem holds the leaves, flowers and fruits in a plant.

The vascular tissue inside the stem helps to transport water and nutrients from the roots to the leaves, and food from

the leaves to the roots.

Plants release excess water in the form of water vapour through minute openings in the leaves, called the stomata. This

process is known as transpiration.

The different parts of a flower include sepals, petals, stamen and pistil.

The green leaf-like parts surrounding the bud are called the sepals.



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The brightly coloured parts of a flower are called the petals.

The male part of a flower is called the stamen, and the female part is called the pistil.

The male and female parts of a flower are involved in the formation of fruit in a process called fertilisation

Parts of a Flower

The flower is the reproductive part of a plant.

The parts of a flower include sepals, petals, stamen and pistil.

The hard, leaf-like structures around the base of a flower are called its sepals.

They protect the bud before it blooms into a flower. The sepals are collectively called the calyx.

The number of sepals varies from plant to plant.

The brightly coloured portions of a flower that attract insects and birds for pollination are called petals.

Like sepals, the number of petals also varies from plant to plant.

The petals are collectively called the corolla.

In some flowers, the petals and sepals combine to form a round shape, which is called the tepal.

The stamens and the pistil are the reproductive parts of a flower.

The stamen is the male reproductive part of a flower.

The small tube with a little bulge at the end of a stamen is called the filament.

The filament has a yellow sac called the anther.

This yellow sac contains pollen grains, which contain male reproductive cells.

12.Like sepals and petals, every flowering plant differs in the number of stamens, too.

13.The female reproductive part of a flower is the pistil.

It consists of three parts – the stigma, the style and the ovary.

The upper end of the pistil is called the stigma, where pollen grains get deposited and enter the pistil.

The narrow tubular part is called the style, which connects the stigma to the lower part of the pistil.

The lower bulgy part of the pistil is called the ovary. It contains ovules.

14.The ovary can be cut longitudinally or transversely to see the female reproductive cells, ovules, which appear as

bead-like structures.

15.The number and arrangement of ovules differ in different flowering plants.

16.Like the stamens, the number of pistils also varies from flower to flower.



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4. BODY MOVEMENTS Body Movements (Joints, Bones and Skeleton)

Joints and their Types

The point at which two separate bones meet is called a joint.

There are four types of joints in the human body.They are:

1.Ball and socket joint:

One end of a bone is rounded and ball-like, and fits into a cup-like depression of the other bone.

This joint provides movement in any direction.

Shoulder joints and hip joints are examples.

In the shoulder joint, the head of the humerus fits into a socket of the shoulder girdle.

In the hip joint, the large ball-like head of the femur fits into the deep socket of the hip girdle.

2.Hinge joint:

This joint moves like a hinge in one plane only, just like the hinge of a door.

The elbow joint between the humerus and the ulna.

The joints between the bones of the fingers and toes, and less perfectly, the knee joint.

Hinge joints usually give sufficient power, because there is less danger of twisting at the joint.

3.Pivot joint:

One bone rotates over a pivot-like end of the other bone.

The skull rotates on the upper end of the back bone.

4.Fixed Joint:

In this joint, no movement is possible between the two bones.

The sutures between the bones of the cranium are an example.

Bones and Skeleton

The skeleton is a framework of all the bones in the human body.

The skeleton consists of the skull, hand bone, shoulder bone, rib cage, pelvic bone, backbone, leg bone and cartilage.

The skull protects the brain.

The shoulder has the ball and socket joint that helps the arm swing.

The rib cage protects the lungs, heart, stomach, abdomen and liver.

The backbone runs from the top of the skeleton to the bottom of the skeleton. It is connected to all the bones.

The pelvic bone protects the lower abdominal organs such as the urinary bladder, rectum and uterus.

Cartilage is a soft bone tissue that connects joints. It is present in external parts like the ear and nose.

Gait of Animals

Gait of earthworms

1. Earthworms move easily on hard and slippery surfaces. Earthworms have tiny, stiff hair-like projections, called bristles,

under their body. They grab the soil with the help of these bristles. Earthworms first stretch and then contract their

muscles to move. As a result, they cover only a small distance with every move. A slimy substance secreted by the

earthworm helps it to move.

2. Earthworms eat their way through the soil. They throw away undigested food, which improves the quality of the soil.

Gait of snails



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The outer skeleton of the snail, the shell, is made of calcium carbonate. The snail pulls this shell along as it moves. The

snail can even hide its head inside the shell. The strong muscular foot below the shell can protrude.

The under surface of the muscular foot is lubricated with mucus. Waves of muscular contractions along this surface

help a snail move. The mucus also reduces the risk of injury from sharp objects. That is why snails can walk over sharp

objects like blades without getting hurt.

Gait of cockroaches

The cockroach has three pairs of legs that help it to walk, and two pairs of wings that help it to fly. A cockroach moves

its legs with the help of muscles near the limbs. It uses its breast muscles help to move its wings and fly. A cockroach

can walk, fly and even climb. A cockroach can move in different terrains like sand and wired meshes because of the

spines on its legs.

Gait of birds

A bird has a body best suited for flying. Its wings are actually modified forelimbs. Birds can fly easily with the help of

these bony forelimbs. Birds have light and hollow bones. The breast bones hold the muscles of flight that help them to

flutter their wings. The tail controls the direction of flight. Birds have very strong shoulder bones. They don’t have the

urinary bladder, which helps them to fly easily. They can walk and perch on trees with the help of their hind limbs.

Gait of snakes

Snakes move in S-shaped loops and in a zigzag manner. They cannot move in a straight line. They have difficulty in

moving on very smooth surfaces. Snakes have a long back bone and many interconnected muscles that help them to

slither. They have muscles connecting the backbone, ribs and skin. Snakes move in grass, sand and water. Snakes do not

have arms or legs, but even then, they can climb trees.

Gait of fish

Fish have a streamlined body, which helps them move fast in water.

Fish swim with the help of their fins. The tail moves from side to side, and helps the fish swim in the right direction.

Some fish, however, move by bending their bodies from one side to another in quick succession, which produces a

thrust that helps it move forward.

SOLVED QUESTIONS

Q1 Define Joints. Name the various types of movable joints

A joint is a place where two or more bones meet. Various types of movable joints are- 1 ball and socket joint 2.Pivotal joint

3 .Hinge joint

Q2 Bones are hard and cannot be bent? How do we bend our limbs at the elbow and knees?

We can bend our limbs at the elbow and knees because of presence of hinge joint .

Q3 What are fixed joints ? Give its example.

Fixed joints do not allow any movement. eg. bones of our skull.

Q4 What is a ball and socket joint? Give its example.

In this type of joint ball of one bone is fitted in the socket of another bone .eg hip joint

Q5 How are we able to move our head up and down and sideways?

Pivotal joint

Q6 Name the joint that allows movement in one plane only?

Hinge joint

Q7 Define pivotal joint.



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In this joint rounded surface of one bone fits into the ring formed by the other.

Q8 What is the significance of human skeleton? (2 points)

1 It provides support to the body and give specific shape to it

2 It helps to protect delicate organs.

Q9 What is a rib cage?

Chest bone and backbone together form a box called ribcage

Q10What are the important organs protected by ribcage?

Heart and lungs

Q11How many bones are present in our shoulder?

Two

Q12 Differentiate between bone and cartilage?

Bone is hard and inflexible and cartilage is soft and flexible

Q13What is the main function of a muscle and how does it work?

Muscles help in movement by contraction and relaxation. Muscles move bones by contracting

and thus pulling them but they cannot push back. That is why muscles work in pairs .One muscle pulls the bone away from the

joint and another pulls it back.

Q14 Why do we say that earthworm are friends of farmers?

Earthworm decomposes organic waste and makes the soil more airy.

Q15 How does earthworm fix its body parts to the ground?

Bristles help to get a good grip on the surface of the ground.

Q16What area the special features that help a bird to fly?

Birds have following features-

1. Wings to fly.

2. streamlined body which reduces air resistance.

3. hollow bones which make them light in weight

Q17 What are the different body parts used by cockroach for its movements?

It has 3 pair of legs and 2 pairs of wings which helps it to fly and climb.

Q18 What is the significance of streamlined body in fishes?

This reduces water resistance and make it easy for fish to swim.



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5. THE LIVING ORGANISMS AND THEIR SURROUNDINGS Habitat

Livings things exist in most places. Life exists even in open volcanoes. The term habitat refers to the surroundings

where organisms live. Every habitat is home for a certain living creature. Habitat includes both living and non-living

components. Plants and animals have different features that help them to survive in their own habitat. Habitat can be

terrestrial or aquatic.

Terrestrial habitat :

Terrestrial habitat refers to the land where all plants and animals survive. It includes deserts, forests and grasslands, as

well as coastal and mountain regions. For example, camels and cactus plants live in deserts only.

Aquatic habitat

Aquatic habitat refers to the water where plants and animals survive. Aquatic habitat includes rivers, ponds, lakes,

ocean and swamps. For example, fish live in water.

Adaptation:

Plants and animals develop certain features or certain habits that help them survive in their surroundings, and this is

known as adaption. Different living creatures adapt to their habitats in different ways. For example, fish have gills that

help them to live in water and use the oxygen dissolve in it. Plants that live in water have special tissues that help to

take in dissolved gas from water. For example, the ulva has ribbon-like leaves.

It takes thousands of years for a livings being to adapt to its habitat.

Acclimatisation:

The small adjustments by the body to overcome small changes in the surrounding atmosphere for a short period of

time are called acclimatisation.

The components in a habitat are broadly classified into two types. They are

Biotic components

Abiotic components

Biotic components include all the livings organisms in a habitat.

Abiotic components include all the non-living things in a habitat. These include air, rocks, water, sunlight and heat. All

livings things depend on the abiotic components for all their needs. The abiotic components are very useful for the

survival of the biotic components in a habitat.

For example, sprouting is the first step where a new plant grows from a seed. The sprouting of a seed depends on

abiotic components such as air, water, light and heat.

The population of some species of turtles has declined due to the change in the earth’s temperature. Some popular

theories believe that dinosaurs became extinct because of the changes in the earth’s temperature millions of years ago.

Terrestrial Habitat

Habitat is the place that is natural for the life and growth of an organism.

Now let us discuss how animals and plants adapt themselves for the terrestrial and aquatic habitats.

Terrestrial habitat:

All the deserts, mountains and forests and plain lands has come under terrestrial habitat.

Camels have long legs for adaptation.

Snakes and rats live in burrows and come out only during the night when it is cool.

Xerophytes or desert plants shows some adaptations to sustain in the desert conditions.

In desert plants, the leaves are either absent or reduced to spines as in cacti.



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The leaf-like structure seen in cactus is its stem and it carries photosynthesis.

The roots grow deep into the soil for absorbing water.

The reduced leaf and the thick waxy layer of stem minimise transpiration.

The plants and animals in the mountain habitat show some adaptations.

Most of the trees in cold mountains are cone shaped.

The leaves are also very thin and look like needles

For the sliding of water and snow during rains and snowfall.

Animals in mountain areas have long hair and thick skin to protect them from cold climate. Thick fur all over Bodies of

Yak and Snow Leopard protects them from the cold climate.

The mountain goat, have strong hooves that help them run on the mountain slopes easily

The animals living in the grasslands show some adaptations.

Lions live in forests and prey on other animals, like deer, for food.

The lions brown skin colour blends easily with the colour of dry grass in grasslands and helps in the catching the prey.

They have strong claws to tear and eat their food.

The eyes of the lion in front of its head helps in identifying the prey from long distances.

Deeers have long ears to help them sense the presence of a predator.

Deers have eyes on the side of its head to look in all directions for danger and have long legs to run away from

predator.

Aquatic Habitat

All the fresh water and marine water bodies , has come under terrestrial habitat.

Fish have special features that help them to live in water.

They have streamlined bodies, which reduce friction and allow them to move freely in water.

Sea animals like the octopus and the squid do not have streamlined body as they stay deep inside the ocean on the

ocean bed, but make their body streamlined when they move in the water.

Sea animals, like fish, octopus and squid have gills that help them to absorb the dissolved oxygen from the water they

drink!

Dolphins and whales have blowholes to breathe in air when they swim close to the surface of the water and there by

stay inside the water for a long time without breathing.

In general the aquatic plants have much smaller roots and helps the plant in holding on the surface. Stems are long and

light. Leaves and

Submerged plants such as Ulva has narrow and ribbon-like leaves. These allow the plants to bend themselves in the

direction of the flow of water.In milfoil, leaves are highly dissected, making water to easily flow without Frogs usually

live in ponds and lakes.

A frog can live both in water and on land. Frogs have strong hind legs to hop on land and webbed feet to swim in water.

Frogs also have a membrane called the nictitating membrane on their eyes.

This membrane helps protect their eyes inside water.

Characteristics of Living Things

Human beings, animals and plants - all need food to survive. Trees, creepers, birds, flowers, insects, animals and seeds

are all livings things. Soil, bench, water, air and dry leaves are all non-livings things.

The characteristics of livings things are:

Livings Things Need Food

Livings things need food to survive and grow. Food makes the body grow faster, and gives energy to the body to help it

perform the life activities. For example, plants produce their own food by the process of photosynthesis, and grow.

Animals depend on plants and other food for their survival.

Livings Things Grow

As livings things take food, they get more and more energy and grow faster. All living things grow continuously.



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Livings Things Respire

Respiration :

Respiration is the process of breathing in and out. Living things take oxygen into the body as they breathe in and

release carbon dioxide as they breathe out. The oxygen that enters the body during respiration helps the body to create

energy from the food consumed. Some animals have special organs that help them in the process of respiration.

For example, the gills of fish help them to absorb oxygen dissolved in water. Earthworms breathe through their skin.

Plants have tiny pores on the leaves that help them to breathe.

Plants respire day and night, but breathe out oxygen during the day. Plants release more oxygen while producing their

food than they release during respiration.

Livings Things Repond to Stimuli

Stimulus is a change of some kind in the environment of a living organism. Every living thing responds in some way or

the other to stimuli. The response in plants to stimulus can be observed easily.

For example, a plant called touch-me-not closes its leaves when touched. Also, the Evening Primrose blooms only

during the night, while the flowers of Mentzelia Mollis close after sunset.

Livings Things Excrete

The process of eliminating wastes from the body is called excretion. Livings things need food, but they only absorb

some amount of it for various processes, while the remaining food needs to be eliminated from the body. For example,

plants eliminate harmful waste substances in the form of secretions such as resins and gums, whereas some plants

store the harmful substances without any difficulty.

Livings Things Reproduce

All livings things reproduce. Some animals lay eggs, while others reproduce by giving birth to young ones. Plants

produce seeds that can germinate into a new plant, but there are some, such as potato and rose plants, which

reproduce through other parts.

Livings Things Move

Even though plants are livings things, they cannot move as their roots are fixed in the soil. However, the substances

produced and required for their growth, such as water, minerals and food, move from one part of a plant to another.

Some plants show some restricted movement. Animals have various modes of locomotion.

Livings Things Die

All livings things must die one day or another. Plants and animals die.

All livings things possess these characteristics, whereas non-livings do not have these characteristics.

SOLVED QUESTIONS

Q1. Define habitat, adaptation, xerophytes and hydrophytes. Ans. The definitions are as follows:-

1. Habitat- Habitat is the place where an organism lives.

2. Adaptation- Adaptation refers to the presence of specific features or certain habits which enable a plant or animal to live in

its surroundings.

3. Xerophytes-Plants which live in dry conditions

4. Hydrophytes-Plants which live in water.

Q2. Leaves of pine tree are needle- like. Why?

Ans. Leaves of pine tree are needle like because this helps the rain water and snow to slide off easily.

Q3. Stem in desert plants is coloured with a thick waxy layer. Why?



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Ans. Stem in desert plants is covered with a thin waxy layer so as to reduce the loss of water.

Q4. Classify the following as biotic and abiotic components.

a) Bacteria- Biotic

b) Humidity- Abiotic

c) Light- Abiotic

d) Precipitation- Abiotic

e) Soil- Abiotic

f) Dog- Biotic

g) Polar Bear- Biotic

h) Air- Abiotic

i) Temperature- Abiotic

j) Water- Abiotic

Q5. Why frogs are called amphibians of animal kingdom?

Ans. Frogs are called amphibians of animal kingdom because they live both in water as well as on land.

Q6. Why rats and snakes stay in deep burrows in land?

Ans. Rats and snakes stay in deep burrows in land so as to stay away from heat.

Q7. Mention two ways in which animals cope up with low temperature?

Ans. The two ways in which animals cope up with low temperature are:

Thick skin or fur to protect them from cold.

Yaks have long hair to keep them warm.

Q8. Mention two stimuli that plants respond to. Ans. The two stimuli are:

Stem grows towards light.

Some plants like touch me not close their leaves when we touch it.

Q9. Select the animals which can live in water as well as on land:-

a) Frog- Yes

b) Duck- No

c) Crocodile- No

d) Human fish-

e) Monkey- No

Q10. Why lions have eyes in front of their face?

Ans. Lions have eyes in front of their face because this allows it to have a correct idea about the location of its prey.

Q11.How do desert plants control the loss of water? Give three adaptive features.

Ans. The three adaptive features are:-

Leaves are reduced to spine like structure.

Leaves have a thin waxy coating.

Roots are deep and extensive.

Q12. Write True/ False

a) Animals grow throughout their life.

b) All living beings response to stimuli.

Ans. a) True

b) True

Q13. Differentiate between:-

a) Breathing and Respiration

b) Living and Non- Living things.



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Q14. Define excretion.

Ans. Process of getting rid of the wastes by the living organism is called excretion.

Q15. Give three adaptive features of animals living in water. Ans. The three features are:-

Streamlined body.

Presence of scales.

Gills for respiration.

Q16. Give three adaptive features of hydrophytes.

Ans. The three features are:-

Roots are poorly developed.

Stems are long and hollow.

Leaves are narrow and thin ribbon- like.

Q17. Give four examples of terrestrial habitat.

1. Forests

2. Grasslands

3. Deserts.

4. Mountain regions.

Q18. How do plants respire?

Ans. Plants respire with the help of stomata.They are the tiny pores present on leaf surface.

Q19)Mention some adaptations of animals living in the mountain regions.

Ans-animals in mountain region have thick skin or fur to protect them from cold.

YAKS- have long hair to keep them warm.

SNOW LEOPARD- has thick fur on its body including feet and toes which protect them from cold when it walks on the snow.

MOUNTAIN GOAT- has strong hones for running up the rocky slopes of the mountains.

Q20)How deer is adapted to live in forests and grassland?

Ans-1)Deer has strong teeth for chewing hard plant stems of the forest. 2)it has long ears to hear movements of predators.

3)the eyes on the side of its head allow it to look in all directions for danger.

4)the speed of the deer helps to run away from predators.

Q21)How do dolphins and whales breathe,as they don’t have gills?why they come on surface time to time?

Ans- they breathe in air through nostrils or blowholes that are located on the upper parts of their heads.

They can stay inside the water for a long time without breathing,they come out to the surface from time to time , to breathe in

air.

Q22)What is stimuli and response?give example.

Ans- changes in our surroundings that makes us respond to them , are called stimuli. Reaction in return of stimuli is termed as

response.

Example-wild animals run away when bright light is flashed towards them. Bright light is a stimuli and running of animals is

response.

Q23)Which part of the following organisms do respiration:

1)frog- skin and lung

2)earthworm- moist skin

3)plants- stomata

4)human being-lung

5)fish- gill

6)dolphins-lungs



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6. WATER Water Cycle :

Our Earth is covered by two-thirds of water, but most of the water is not potable and contains salt. Water is used for

various activities such as agriculture, industries, cooking, cleaning utensils, bathing, washing clothes, and, most

importantly, for drinking.

Ponds, wells, streams, lakes and rivers are the different sources of drinking water.They are supplied water by the

oceans and seas.Oceans and seas supply water to other water bodies through the water cycle.

The circulation of water from the oceans and the surface of the earth, to the air as water vapour, and its return to the

ocean as rain, hail or snow, is called the water cycle

Water cycle: Different steps of water cycle are elucidated.

Evaporation

A variety of salts, like sodium chloride, calcium, magnesium and potassium, are present in saline water. The

evaporation of water takes place in the water cycle, leaving the salts behind in the ocean.

The water present on the surface of the ocean evaporates by the sun’s heat. This process of conversion of water from

liquid state to vapour state is called evaporation. The sun warms up the surrounding air as well. Evaporation takes place

faster in direct sunlight, than in a shady area.

Evaporation also takes place from wet clothes, fields, ponds, lakes and rivers. Plants take in water to grow as well as to

prepare their food.

Transpiration

They retain the water they need and release the excess water into the air as water vapour through the stomata of the

leaves and the stem. This process is called transpiration. Thus, water is mainly evapo-transpirated to the air from land,

water bodies and plants.

Condensation

The evaporated water is carried away by warm air.As the warm air moves higher from the surface of the Earth, it starts

to cool down. It is because the water vapour present starts to condense to form tiny water droplets. These droplets

float in the air and form cloud and fog.

Precipitation

All these droplets collect to form bigger drops of water. Some of them may become too heavy to remain in the sky and

fall down as rain. This process is known as precipitation. If the air is too cold, the water drops can become snow or hail

and may settle on the top of a mountain. When these snow or hail melts, they can become part of a river or a stream.

Thus, the water that is evaporated from the oceans or seas is again condensed to form water and fills up the rivers and

seas. Rain water also seeps into the ground to form ground water. This circulation of water is called the water cycle.

Effects of Rainfall - Draughts and Floods

Uses of Water

Water is used in our day to day life. Water is used for everyday needs such as brushing, bathing, washing, cleaning etc.

Farmers use ground water to water their fields.

Many industries use ground water to produce everything from paints and fabric to leather and chemicals. So ground

water is used for many purposes. Moreover the decline in the number of trees, excess usage of water and the presence

of concrete in the areas does not allow the rain water to seep into the ground which is the reason for the shortage of

water.

Droughts

Due to lack of rains the wells, lakes, ponds get dried up and thereby creating water scarcity and as result droughts are

possible. If there are no rains, then the soil becomes more dry and patchy.



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Droughts occur when there are no rains for a longer period of time. There is less rainfall because trees are cut

down.Droughts results in drying up of the crops and vegetation and this effects the availability of food for villages and

food for the other animals. Finally this leads to malnutrition in humans.

Floods

Due to heavy rainfall the water levels in ponds, lakes rises to a greater extend and the rise in the water level of these

water bodies causes the excess water to spread across causing floods.

Floods wash out the living beings such as fish and other animals etc. and they create great havoc to the mankind. Once

the rains stops the flood water receded, fish, cattle and other animals were left dead. Floods cause lot of harm to the

living beings and there will be loss in property also.

Rain Harvesting

Harvesting is a method to collect rain water and store the rain water. The purpose of harvesting rain water is that two

thirds of the earth is covered with water. Ocean and sea water contains many dissolved salts and cannot be used for

drinking, agriculture and domestic purposes.

So constant use of ground water results in scarcity of groundwater. So rain harvesting clears the problem of depleting

the ground water.

Technique involved in rain harvesting

First collect the rain water at the rooftop and then allow the rain water to travels through the pipes or drains and then

attach a wire mesh to the mouth pipe which filters large fragments such as leaves etc.

This water is transported to the water tanks. These tanks contain layers of sand, gravel, charcoal that will filter the dirt

and other impurities from rain water. The water stored in the tank will then be transported to an underground pit

which will help water to seep back into the ground. Rain harvesting solves the problem of depleting the ground water

and droughts.

SOLVED QUESTIONS

Question 1:

Fill in the blanks:

(a) The process of changing water into its vapour state is called _______ __.

(b) The process of changing water vapour into water is called _______ __.

(c) No rainfall for a year or more may lead to _______ __ in the region.

(d) Excessive rains may cause _______ __.

Answer:

(a) The process of changing water into its vapour state is called evaporation.

(b) The process of changing water vapour into water is called condensation.

(c) No rainfall for a year or more may lead to drought in the region.

(d) Excessive rains may cause floods.

Question 2:

State for each of the following whether it is due to evaporation or condensation:

(a) Water drops appear on the outer surface of a glass containing cold water.



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(b) Steam rising from wet clothes while they are ironed.

(c) Fog appearing on a cold winter morning.

(d) Blackboard dries up after wiping it.

(e) Steam rising from a hot girdle when water is sprinkled on it.

Answer:

(a) Water drops appear on the outer surface of a glass containing cold water. (Condensation)

(b) Steam rising from wet clothes while they are ironed. (Evaporation)

(c) Fog appearing on a cold winter morning. (Condensation)

(d) Blackboard dries up after wiping it. (Evaporation)

(e) Steam rising from a hot girdle when water is sprinkled on it. (Evaporation)

Question 3:

Which of the following statements are ‘True’?

(a) Water vapour is present in air only during the monsoon. ( )

(b) Water evaporates into air from the oceans, rivers, and lakes, but not from soil. ( )

(c) The process of water changing into its vapour is called evaporation. ( )

(d) The evaporation of water takes place only in sunlight. ( )

(e) Water vapour condenses to form tiny droplets of water in the upper layer of air, where it is cooler. ( )

Answer:

(a) Water vapour is present in air only during the monsoon. (False)

(b) Water evaporates into air from the oceans, rivers, and lakes, but not from soil. (False)

(c) The process of water changing into its vapour is called evaporation. (True)

(d) The evaporation of water takes place only in sunlight. (True)

(e) Water vapour condenses to form tiny droplets of water in the upper layer of air, where it is cooler. (True)

Question 4:

Suppose you want to dry your school uniform quickly. Would spreading it near an anghiti or heater help? If yes, how?

Answer:

Yes, spreading of clothes near an angithi or a heater would help dry the clothes quicker. This is because heat generated from an

angithi or a heater causes the water to evaporate at a faster rate.

Question 5:

Take out a cold bottle of water from the refrigerator and keep it on the table. After some time, you will notice a puddle of water

around it. Why?

Answer:



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This is because water vapour near the cold bottle collides with it, becomes cool, and condenses into water droplets. These water

droplets collect and form a puddle of water around the bottle.

Question 6:

To clean their spectacles, people often breathe out on glasses to make them wet. Explain why the glasses become wet.

Answer:

During exhalation (or breathing out), carbon dioxide is released along with water vapours. If one breathes out onto glass, the

released water vapours collide with the surface of the glass, thereby making it cooler. As a result, the water vapours present in

the air surrounding the glass condense and get attached to the glass surface. Consequently, the glass becomes wet.

Question 7:

How are clouds formed?

Answer:

Clouds are formed by the process of evaporation and condensation. Water from the oceans, rivers, lakes, ponds, plants, fields,

and other land surfaces evaporates, gets into air, and rises up in the atmosphere. At a certain height when the air becomes

cooler, water vapour contained in air condenses. On condensation, these form water droplets. These water droplets collect and

float in air as clouds.

Question 8:

When does a drought occur?

Answer:

A drought occurs if there is no rainfall for a long time. Usually, water lost by soil due to evaporation is returned to it by rains. But

no rainfall occurs for a long time, it leads to a decrease in the water level of various ponds and wells. This leads to the condition

of drought.



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7. AIR AROUND US All about Air

Air is essential for all living beings. It supports life on earth. It is utilized by all the living organisms like plants, animals

and microorganisms.Air is present everywhere on earth.

Atmosphere :

Atmosphere is a thin layer of air surrounding the earth. The atmosphere is dense at the surface of the earth and

becomes thinner as one moves up.The movement of air is called breeze or wind depending on its velocity or speed.

Properties of air:

Transparent

Colourless

Occupies space

Components of air:

Nitrogen

Oxygen

Carbon dioxide

Water vapour

Smoke and dust particles

Nitrogen

Is the major component of air

Does not support burning

Oxygen:

Is the second largest component present in air

Supports burning

Helps in respiration process.

Smoke and Dust:

Present in minute amounts

Harmful to living organisms.

Oxygen is used by all living organisms in the process of respiration. They give out carbon dioxide to the environment.

Carbon dioxide present in air is used by plants in the process of photosynthesis. They give out oxygen as a by-product.

SOLVED QUESTIONS

Question 1:

What is the composition of air?

Answer:

Air is a mixture of 79% nitrogen, 20% oxygen, 1% carbon dioxide, water vapours and some other gases. Air also contains dust

particles.

Question 2:

Which gas in the atmosphere is essential for respiration?

Answer:

Oxygen is essential for respiration.



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Question 3:

How will you prove that air supports burning?

Answer:

Take a candle. Place it in a tub. Light the candle and also fill the tub with some water. Cover the candle with an inverted glass.

You will find that the candle blows out after burning for some time, and the water level inside the inverted glass rises up to

some extent.

The component, oxygen, of air inside the glass is used up in burning. Therefore, water occupies that space. This shows that air

supports burning.

Question 4:

How will you show that air is dissolved in water?

Answer:

To show that air is dissolved in water we take water in a pan and heat it. Just before it boils, you will notice some bubbles at the

inner surface of the pan. These bubbles are formed because of air dissolved in water.

Question 5:

Why does a lump of cotton wool shrink in water?

Answer:

A lump of cotton wool shrinks when immersed in water. This is because air present in the cotton wool escapes. Thus, the volume

of the cotton wool decreases.

Question 6:

The layer of air around the Earth is known as __________.

Answer:

The layer of air around the Earth is known as atmosphere.

Question 7:

The component of air used by green plants to make their food is __________.

Answer:

The component of air used by green plants to make their food is carbon dioxide.

List five activities that are possible due to the presence of air.

Answer:

(i) Respiration

(ii) Photosynthesis

(iii) Burning

(iv) Movement of sailing yachts, gliders, parachutes, airplanes

(v) Generation of electricity by windmills

Question 9:



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How do plants and animals help each other in exchange of gases in the atmosphere?

Answer:

Plants utilize carbon dioxide present in the atmosphere for the process of photosynthesis. They release oxygen in the

atmosphere. This oxygen is inhaled by humans and in turn, carbon dioxide is exhaled.

In this way, plants and animals help each other in exchange of gases in the atmosphere.



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8. GARBAGE IN, GARBAGE OUT Garbage Disposal and Vermicomposting

Garbage Disposal:

A large, low-lying area used to dispose garbage is known as a dump. A garbage dump is also used as landfill. Garbage

collectors collect waste and then dispose it at garbage disposals. Garbage dumps have flies, cockroaches and

mosquitoes, and later turn into breeding grounds for micro-organisms that may cause diseases. That is why these

garbage dumps are usually located on the outskirts of a city. When garbage mixes with soil, it takes a longer time to

decay. The soil becomes loose and a building cannot be constructed on such a landfill. Moreover, it takes 20 to 30 years

for the soil to get ready for construction.

Components of garbage:

Garbage has useful and non-useful components.

1: Useful garbage components are those that can be decayed easily. The process of decaying is known as composting.

Useful garbage components are fruit and vegetable waste, plant and animal waste, tea leaves, coffee grounds and

paper. These useful components of garbage are converted into manure in the soil.

2:Non-useful garbage components include polythene bags, plastics, glass and aluminium foils. These take longer to

decay. Decaying of these non-useful components is known as decomposition. When non-useful components decay,

they release harmful gases that damage the environment. To avoid the adverse impact, these garbage items are sent

for recycling.

For example, when leaves burn, they release harmful gases and causes air pollution. Moreover, they lead to asthma

and lung diseases. That is why leaves should be buried so as to convert them into manure.

Vermicomposting

The process of preparing compost with the help of red worms is called vermicomposting. The red worm is a type of

earthworm that lives in the soil rich in organic matter, which is a combination of nitrogen-rich and carbon-rich material

with plenty of moisture and microbes.

Method of Vermicomposting

A vermicomposting pit is made with a wooden box or big cement rings.

A mesh is spread at the bottom of the pit.

Vegetable waste, fruit waste, waste paper which is not shiny or coated with plastic, is spread over the mesh.

Water is sprinkled to create moisture so that the red worms can live.

A vermicomposting pit takes nearly two to four weeks to completely convert waste into manure.

Red Worms:

Waste material that is rich in oils, salt, meat and vinegar stops the growth of red worms. These red worms have a

special structure called gizzards with which they grind food material. A red worm eats food equal to its weight every

day. Red worms do not survive in too hot or too cold conditions.

Recycling Paper and Plastics

it is important to reuse things than discarding them as waste. Many nice articles can be made out of waste.

Industries use recycled or waste paper to regenerate paper. Paper that is suitable for recycling is called "scrap paper".

You can recycle old newspapers, magazines, notebooks and used envelopes, but not waxed paper, oil-soaked paper,

paper contaminated with food, carbon paper, thermal fax paper, plastic laminated paper, stickers, and sanitary

products or tissues.

Steps involved in recycling paper

Tear paper into small pieces.

Soak these pieces in water for a day.

Make a thick paste and spread it on a net or sieve.



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Let water drain off completely.

Use an old cloth or newspaper to remove the extra water from the paste and dry it.

Use this paste to get beautiful patterns.

Disadvantages of using of polythene bags

We use many plastic items such as tooth brush, combs, containers, bottles, shoes, toys, wires, frames and bags every

day. Certain parts of vehicles like cars and buses, and electronic goods like radios, televisions and refrigerators, are all

made of plastic. All these are useful to us in many ways, but using plastic is very harmful in terms of health and as well

as the environment.

Plastics are not suitable for storing cooked food because they emit harmful chemicals when they are exposed to high

temperatures. Using plastics causes health problems such as heart disease, diabetes and reproductive dysfunction.

Harmful gases are emitted from burning plastics, which cause cancer and they kill living beings.

That is why plastics should be disposed in the right way.

Plastics that do not contain the chemical, BPA, are usually licensed for storing food items.

Plastics thrown casually get into drains and sewages, often blocking the way and causing water-logging. A major cause

of the floods in Mumbai, India, in August 2005 was the choking of the drainage system by plastic waste. So polythene

bags should not be used for garbage disposal.

Measures taken to prevent from the dangerous effects of plastics:

Adopt healthy practices such as:

Reduce, reuse and recycle plastics.

Carry jute or cloth bags for shopping

Do not store food items in plastic bags.

Do not burn plastic items.

Recycle plastics so that new plastic items can be made.

Waste that does not decompose should be put in blue dustbins, while waste that decomposes easily should be put in

green dustbins.

Vermicomposting

Conversion of the waste generated in the kitchen into organic matter with the combined action of earthworms and

micro-organisms is called vermicomposting. The organic matter so formed is used as manure for plants.

SOLVED QUESTIONS

Question 1:

(a) Which kind of garbage is not converted into compost by redworms?

(b) Have you seen any other organism besides redworms in your pit? If yes, try to find out their names. Draw pictures of them.

Answer:

(a) The garbage which contains pieces of cloth, broken glass, aluminium wrappers, polythene bags, nails, broken toys, and old

shoes cannot be converted into compost by red worms.

(b) Yes. A pit might contain other soil microbes such as bacteria, other species of earthworms such as brandling worm and red

wiggler worm.

Question 2:

Discuss:

(a) Is garbage disposal the responsibility only of the government?



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(b) Is it possible to reduce problems relating to the disposal of garbage?

Answer:

(a) Proper disposal of garbage should be a concern of every citizen, and not just of the government. Each and every individual

must reduce activities that pollute the environment. A lot of waste is generated from homes, offices, schools, hospitals, etc. It

includes food waste, paper, plastic, glass, metal, etc. Therefore, it is required that every individual must reduce the production

of wastes and must help in the proper disposal of these wastes.

(b) Yes, it is possible to reduce problems related to disposal of garbage. Here are some steps that can be observed by every

individual to reduce the problem of garbage disposal.

(i) Avoid using plastic bags. Encourage shopkeepers to use paper bags or always carry a cloth or jute bag while shopping.

(ii) Save paper. Use both sides of paper to write.

(iii) Use separate bins for recyclable and non-recyclable waste.

(iv) Kitchen waste that includes fruit and vegetable peels, waste food, tea leaves, etc. can be used to make manure.

(v) Encourage your family, friends, and others to follow proper disposal practices.

Question 3:

(a) What do you do with left over food at home?

(b) If you and your friends are given the choice of eating in a plastic plate or a banana leaf platter at a party, which one would

you prefer and why?

Answer:

(a) Left over food can be collected and used to make compost. Compost provides nutrients essential for the growth and

development of plants.

(b) We would prefer to eat food in a banana leaf platter. This is because a leaf platter is a harmless substance that can be used

to make manure by the process of composting, whereas plastic plates cannot be converted into harmless substances by

composting. They remain in the environment and create many problems.

Question 4:

(a) Collect pieces of different kinds of paper. Find out which of these can be recycled.

(b) With the help of a lens look at the pieces of paper you collected for the above question. Do you see any difference in the

material of a recycled paper and a new sheet of paper?

Answer:

(a) All type of paper can be recycled.

(b) It is impossible to find out the difference between a recycled and a new sheet of paper. However, it is believed that recycled

paper is usually of low quality.

Question 5:

(a) Collect different kinds of packaging material. What was the purpose for which each one was used? Discuss in groups.

(b) Give an example in which packaging could have been reduced?

(c) Write a story on how packaging increases the amount of garbage.

Answer:



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(a) The different kinds of packaging materials commonly used includes:

(i) plastic bags for carrying eatables or other household things (ii) cloth or jute bags for carrying fruits, vegetables, or other

groceries

(iii) paper bags for carrying small groceries, packing of food, etc.

(b) The usage of plastic bags must be reduced as packaging of cooked food items in plastic bags might affect our health. Also,

plastic bags are non-recyclable and burning of plastic bags may release harmful gases that can cause many health diseases.

(c) Packaging increases the amount of garbage as we keep on throwing the packaging materials carelessly on roads and other

places. Also, since these packaging materials (mainly plastic covers) are non-recyclable, they keep lying on the roads and cannot

be properly disposed off. Sometimes, they get into drains and sewer systems and block them, creating more problems.

Question 6:

Do you think that it is better to use compost instead of chemical fertilizers? Why?

Answer:

Yes, it is better to use compost instead of chemical fertilizers. This is because compost is prepared from plant and animal wastes,

therefore, it easily gets decomposed. It does not add any harmful chemicals to the soil, whereas an excessive use of chemical

fertilizers causes soil and water pollution.



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“your success,your way,to build a nation” the wisdom academy · 2018-10-22 · “your...

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