1. OUR EARTH AND OUR SOLAR SYSTEM
Exercise
⚫ Look at the picture of the solar system and answer
the following questions :
(1) Which planet is nearest to the sun?
Ans. Mercury.
(2) At what position is the earth from the sun?
Ans. 3rd
position.
(3) Which planet is placed between the Earth and
Mercury?
Ans. Venus.
(4) Name the planets beyond the orbit of Mars in
serial order.
Ans. Jupiter,
Saturn, Uranus, Neptune.
(5) Which planet in the solar system is furthest
from the sun?
Ans. Neptune.
⚫ Can you Tell?
In which direction do these things fall?
(1) Leaves, flowers, fruits from a tree
(2) Rocks that come loose from a hillside
(3) Rain falling from the sky.
Ans. Due to the
force of gravity, all the things fall towards the earth's surface.
1. What's
the solution?
One of the
asteroids has fallen out of its place in the asteroid belt and is hurtling
towards the sun. Our earth is in its way and there is all likelihood of a
collision. What can be done to prevent this collision?
Ans. The first act to save the earth can be attacking the asteroid with the help
of missile. A missile can break an asteroid into smaller pieces.
The second
way is to change the path of an advancing asteroid.
For
changing the path of the asteroid, spaceship or missile can be used to push the
asteroid aside.
Space
shuttle fitted with mirrors can be used, so that the reflected sunrays from
such mirror can be bombarded on the asteroid. This will create the pressure
on the asteroid and its advancing path can be changed.
By use of
laser rays, the surface of asteroid can be subjected to evaporation. This will
create change in the mass of asteroid. We can also send extra material on the
asteroid from the earth. Such change in the mass of asteroid changes the orbit
and the path of the asteroid.
By placing
a space shuttle in the vicinity of this asteroid, the gravitational force could
be created. This can also change the speed and path of the asteroid.
Astronomy
and astrophysics are so much advanced now that even if such a threat exists in
future, we can easily protect our earth inhabitants well in advance.
2. Use your
brain power!
(1) What
will happen to our solar system if the sun was to suddenly disappear?
Ans. If the sun suddenly disappears -
(1) There
would be darkness everywhere.
(2) All the
plants will die as they will not be able to perform photosynthesis.
(3) All the
planets would stop revolving.
(4) The
cycle of day and night would come to a halt.
(5) There
will not be weeks or months any more.
(6) There
will be uniformly only one season, seasonal changes will come to an end.
(7) All the
equipment which work on solar energy will not work anymore.
(8) There
will not be any heat and the entire earth will be cold.
(9) The
water cycle would stop as the water bodies will not evaporate forming water
vapours and then clouds, and thus there re will be no rains.
(10) Germs
would grow at a rapid pace everywhere on the earth and this will result into
outbreak of many diseases.
(2) Suppose
you want to give your address to a friend you have on the planet Mars. How will
you write your address if you want them to understand exactly where you live?
Ans.
Kum. Rajesh
Patil,
`Shiv
Niwas`, M.G. Road,
Latur -
413512,
State of
Maharashtra, India, Continent of Asia, Earth, (3rd planet)
Solar
system, Milky way.
4. Who am
I?
(a) You can see me from the earth but the lighted part of me that you see changes every day. - Moon
(b) I have my own light. It is only from me that the planets get light and heat. - Sun
(c) I turn around myself, around a planet and also around a star. - Satellite
(d) I turn around myself and revolve around the sun. - Planet
(e) No other planet has a living world like mine. - Earth
(f) I am the nearest star to the earth. - Sun
5. (a) For what purpose are rockets used in space travel?
Ans. Space launch technology is used to send the spacecraft in outer space
against the force of gravity. It requires tremendous amount of energy to launch
the spacecraft which is thousands of tons in weight. This energy is obtained
through burning of ample quantity of fuel present in the rocket. Thus, rockets
are used to launch the spacecraft in space travel.
(b) What
information do man-made satellites provide?
Ans. Man-made satellites provide useful information on agriculture, environment,
weather forecasting, searching for water and minerals from the earth. Such
information can be used to make maps. Man-made satellites are also used for
telecommunications.
------- The End -----
2. MOTIONS OF THE EARTH
Exercise
⚫ Try this:
Take a top.
Spin it and observe its movement.
Ans. The tops
spins around an imaginary line. The turning of this top is called rotation.
Rotation is performed around an axis.
⚫ Try this:
Perform the experiment showing rotation of the earth.
If a plumb-line is held close to the globe, the plumb-line and earth's axis
make an angle with each other.
⚫ Try this:
Draw a big circle on a paper placed on the table. Keep a lighted candle at
the centre of this circle. Place a globe on any point of this circle. Let the
room be dark. The light falls on that side of the part of the globe which is
facing to the candle is well lit, while the other part which is away from the
candle is in darkness.
⚫ Try this:
Place a red coloured bindi on the globe. Set up the experiment in the same
manner as the previous one. Using the light of the candle perform the rotation
of the globe. We can understand sunrise, noon and sunset by this experiment.
⚫ Try this:
Slowly move the globe along the circle drawn in the
previous experiments. Keep rotating the earth globe and take care that you do
not change the direction of the axis. The globe comes back to its original
position on the circle.
⚫ Can you Tell?
(1) What is the name given to the changing shapes
of the moon that we see?
Ans. The changing shapes of the
moon that we see are called the phases of the moon.
(2) What are the names of the days on which we see
a round moon and on which we see no moon at all?
Ans. The day on which we see a
complete and round moon is called the full moon day. The day on which we cannot
see the moon from the earth is called the new moon day.
1. What's
the solution?
Amit wants
to take his granny to Australia which is in the Southern hemisphere. But she
cannot bear very cold weather. When should they make this trip?
Ans. Australia is located in Southern hemisphere. During the time period of 23rd
September to 22nd March, there is summer. So, Amit's granny could be taken to
Australia during this period. During the period of 22nd March to 23rd September
there is winter so she should avoid going to Australia as she cannot bear the
cold weather.
2. Use your
brain power!
(a) How
many rotations does the earth complete during one revolution around the sun?
Ans. The earth takes one co complete rotation in one day. It takes complete 365
days 1/4 th day for one complete revolution. This means that in one
revolution, the earth shows 365 and 1/4 th rotations.
(b) It is
the sunrise at Itanagar in Arunachal Pradesh. Write the names of the following
cities in the order in which the sun will rise there.
Mumbai
(Maharashtra), Kolkata (West Bengal), Bhopal (Madhya Pradesh), Nagpur
(Maharashtra).
Ans. The earth rotates from west to east. Therefore, there would be sunrise in
the eastern states earlier. Later gradually the sunrise can be seen from the
western states of India. The order in which the sunrise would be seen is as
follows:
(1) Itanagar in Arunachal Pradesh (2) Kolkata (West
Bengal) (3) Bhopal (Madhya Pradesh) (4) Nagpur (Maharashtra) (5) Mumbai
(Maharashtra)
3. Fill in
the blanks:
(a) The motion of the earth around itself is called rotation.
(b) The motion of the earth around the sun is called revolution.
(c) The rotation of the earth gives rise to day and night.
4. What is
meant by each of the following terms?
(a) Full
moon: When the complete and round moon is seen in the sky, it is known as full
moon.
(b) New
moon: When the moon is not visible in the sky, it is known as new moon.
(c) Lunar
month: The period of 28 to 30 days from one new moon day to the next new moon day
is called a lunar month.
(d) Tithi: Every day in the lunar month is called tithi.
5. Answer
the following questions:
(a) What is
the equator?
Ans. An
imaginary circle present between the North and the South pole is called the
equator.
(b) What are
the two parts of the earth made by the equator?
Ans. The Northern hemisphere and the Southern hemisphere are the two parts of
the earth made by the equator.
----- The End -----
3. THE EARTH AND ITS LIVING WORLD
⚫ Can you Tell?
(1) Where do you get water from?
Ans. Water is
obtained from different sources at different places. In cities we get it from
taps and pipes. In villages we get it from wells or rivers, lakes, ponds,
rains, dams, etc.
(2) Where do you lay the foundation of buildings?
Ans. The foundation of buildings is
laid on land.
(3) What need do we meet through breathing? How is
this need met?
Ans. The need of
oxygen to survive is met through breathing. For this purpose, we breathe in air
through our nose.
(4) From where does the earth get light and heat?
Ans. The earth
gets light and heat from the sun.
⚫ Use your brain power!
(1) In which layer of the atmosphere do we see the
rainbow?
Ans. We see rainbow in the layer of
troposphere of the atmosphere.
(2) Mountaineers carry oxygen in cylinders when
they climb mountains that are more than 5000 m high. What could be the he
reasons for that?
Ans. As we climb
up the heights, the air at the top becomes rare. At the height of 5000 m or
more the air is very rare. The oxygen may be limited here. Therefore, the
mountaineers carry oxygen in cylinders when they climb mountains that are 5000
m high.
1. What's
the solution?
⚫ Dark patches appear on the skin after exposure to
the sun.
Ans. The harmful
radiation of the sun can cause burning sensation to our skin. In order to avoid
this, we should not roam in the harsh sunlight. If it is necessary to leave the
house, we should use an umbrella or cap. Wear cotton clothes that would the
hands and leg cover the skin of hands and legs. Use of sun-screen cream is
advisable. Covering the face with handkerchief can protect the delicate skin.
After returning from outside, splash cold water on the face. This will help to
reduce the temperature of the skin.
2. Use your
brain power!
(a) Why are
microorganisms important?
Ans. In every
envelope of the earth there are microorganisms. These microorganisms perform
important function of degradation. They also occupy important place in the food
chain. The dead and decaying plant and animal matter is converted into soil and
minerals by these microorganisms. If there were no microorganisms, huge piles
of debris could have piled up everywhere on the earth. Therefore,
microorganisms are very important organisms on the earth.
(b)
Think about all the food stuffs obtained from the sea. Find more information
and write ten lines about them.
Ans. (1) Many marine organisms inhabit seas. Some of these forms our food. (2)
Various edible varieties of fish are caught from the seas. (3) There are good
quality proteins and fatty acids in the fish. Therefore, it is a nutritive
food. (4) Shell fish varieties such as crabs, prawns, lobsters are favourite
food items worldwide. Prawns are abundantly available in the Indian waters; therefore,
we get lots of foreign exchange through export of prawns. (5) Bivalves, squids,
oysters are also eaten as delicacies. (6) Algae from the seas are also eaten in
the Asian countries, though not in India. (7) Agar is the substance made from
marine algae which is used in jellies and puddings. (8) Salt is made from the
sea water. (9) In some countries potable water is made from the sea water by
special processes. (10) Young ones of prawns and fishes are used for the
aquaculture.
3. Answer
the following questions:
(a) What
are clouds made up of?
Ans. Clouds are
made up of fine droplets of water. The sun's heat evaporates the water to form
vapours from the earth's surface. This water vapour rises high up in the
sphere. At cool heights, it condenses forming fine droplets of water which in
turn the clouds.
(b) What is
meant by 'biosphere'?
Ans. Living things are seen in all the envelopes of the earth such as
lithosphere, sphere and atmosphere. All the living things together in these
three envelopes forms a biosphere. Thus, the plants, animals and microorganisms
together make a biosphere.
(c) Where
do all the weather-related phenomena take place?
Ans. All the weather-related phenomena take place in the troposphere. Almost all
water vapour found in the atmosphere is in the troposphere. Therefore,
formation of clouds, rains, storms and winds and all other weather-related
phenomena take place here.
4. In the
following sentences, underline the words that refer to landforms:
(a) Anil lives at the foot of a hill.
(b) Ria lives in a plateau region.
Ans. (1) Anil lives at the foot of a hill.
(2) Ria lives in a plateau region.
5. Write
short notes on:
(a)
Evaporation.
Ans. The heat changes water into vapour. This action is called evaporation. The
sun's heat converts the water present on the earth's surface into water vapour. The water that has percolated into
the soil also evaporates due to heat. All such vapour enters the atmosphere.
This vapour condenses and comes in the form of rain back to the surface of the
earth. Thus, evaporation is necessary for rainfall. The water cycle keeps on
functioning due to evaporation.
(b)
Condensation.
Ans. Condensation
is the process in which vapour is changed into water. In nature due to
condensation, there is rainfall. The water vapour that reaches the upper layers
atmosphere, gets condensed and forms fine droplets of water.
(c) Water
cycle.
Ans. The
movement of water is continuously taking place from earth's surface to earth's
atmosphere. The process of evaporation, condensation and rainfall is a
continuous process. Due to the sun's heat, the water on the earth's surface is
continuously evaporated. Since the water vapour is lighter than air, it rises
high in the atmosphere. Due to cool temperatures at the heights, the water
vapour condenses forming fine droplets of water. These droplets later form
clouds. When small droplets of water become heavier and bigger, they descend
down on the earth in the form of rain. Rainwater mixes with different water
bodies. The snowbound regions also show melting of ice and glaciers. This water
also eventually mixes with ocean waters. In this way water moves in the cyclic
manner, which is known as water cycle.
6. Give any
two examples of each:
(a) Weather
related events.
Ans. (1) Formation of clouds (2) Rainfall (3) Fog (4) Winds (5) Storms.
(b) Sources
of water.
Ans. (1) Rills and brooks (2) Streams (3) Wells and rivers (4) Lakes and ponds
(5) Glaciers.
----- The End -----
4.
ENVIRONMENTAL BALANCE
Exercises
⚫ Can you Tell?
Look at the pictures below:
Food Chain
The plants
prepare their food with the help of sunlight. This food is eaten by a
caterpillar or worm. The caterpillar is eaten by the grasshopper. Birds in turn
eat grasshoppers.
(1) Who eats birds?
Ans. Smaller birds are killed and eaten by bigger birds. Cats and snakes may
also hunt the smaller birds. Man, also kills birds for food.
(2) What is the food of plants?
Ans. Water and minerals present in the soil is food for plants. Plants take up
water and minerals from soil with the help of their roots. With the help of the
sunlight, they use carbon dioxide from the air and prepare their own food.
Through their leaves they absorb carbon dioxide. The green coloured pigment,
chlorophyll present in the leaves helps in this process of photosynthesis to
prepare their own food.
⚫ Can you Tell?
(1) What is the deer's food?
Ans. Deer is a herbivorous animal. It eats grass. In search of green grass, they
move about in the jungles. It also feeds on leaves and smaller herbs and
shrubs.
(2) What is the food of the tiger?
Ans. Tiger is a carnivorous animal. It feeds by hunting on small prey. Flesh of
these animals is food for the tiger.
1. What's
the solution?
We have to
remove insects from the grain without using insecticides.
Ans. (1)
Let the grain dry in the sunlight. The harsh sunlight does not allow eggs and
caterpillars to grow in the grain.
(2) Keep
dried Neem leaves in the container in which the grains are stored. The Neem
acts as a repellent for insects.
(3) Grains
like beans are smeared with mud. The mud particles keep the weevils away from
infesting the grains.
(4) The
place where grain is stored should be cool and dry. It should be airy. The
chances of insect infestations are less in such storage places.
2. Use
your brain power!
Make up a
food chain:
Frog, kite,
worm, snake, grass.
Grass → worm → frog → snake → kite
3. Answer
the following questions:
(a) What is
a food chain? Give an example of it?
Ans. (1) One living thing is dependent on other living thing for the purpose of
feeding.
Therefore,
they are interconnected with each other like a chain. This relationship is
called a food chain. (2) Plants prepare food with the help of sunlight. Leaves
of this plant are nibbled by a caterpillar. Grasshoppers eat these
caterpillars. Grasshoppers are eaten by sparrows. This is a food chain,
Sunlight→
Plants → Caterpillar → Grasshopper → Sparrow
(b) How is
the balance in the environment maintained?
Ans. (1) In any environment, the food chains and food webs are present. (2) Due
to his there are interactions among different types of living things. (3)
Similarly, the non- living things too move in a cyclic manner in this
environment. (4) Living and non-living things give and take different materials
in water cycle, carbon dioxide-oxygen cycle, etc. 5) Microorganisms bring about
decomposition in the soil and add required substances in the soil. (6) When all
these cycles and interactions take place in an environment without any check,
then there is balance in that environment.
4. What
substances in the soil are useful for the growth of plants?
Ans. (1) Plants require water, minerals and other substances in the soil for
their growth. (2) The substances formed due to decomposition of dead and
decaying plant and animal material are very useful for plants. (3) These
substances help in the rapid growth of plants.
5. True or
False?
(a)
Microorganisms form a part of the environment. -True
(b) It is
necessary to maintain biodiversity. -True
(c) A
grasshopper eats birds. -False
-----The
End -----
12. FOOD
FOR ALL
Exercises
⚫ Can you Tell?
(1) Which vegetables do we get around the time of
Diwali ? Which fruits? Which grains?
Ans. (A) Vegetables that we get around the time of Diwali: Spiny gourd
(Kantoli), Ridge gourd (Shirali), Ghosali, Kohala
(B) Fruits
that we get around the time of Diwali: Sweet lime, Oranges, Apples, Musk
melons
(C) Grains
that we get around the time of Diwali: Ragi, Rice.
(2) What are the seasons for jowar, bajra, rice,
mangoes, oranges and jackfruit?
Ans. Jowar and Bajra: During winter
Mango and Jackfruit: In
summer
Rice: In monsoon/rainy season
Oranges: Beginning of winter
(3) Which parts of plants do we use as food?
Ans.
Roots: Carrot, Beet root, Radish, Sweet potato
Stem: Potato, Elephant's foot (Suran), Ginger,
Onion 900
Leaves: Arum, Colocasia, Cabbage, all leafy green
vegetables
Fruits: Pumpkin, Tamarind, Bitter gourd, Snake gourd
Flower: Cauliflower, Banana flowers
Seeds: Beans, Lentil, Cow pea, Gram
⚫ Can you
Tell?
Which is the season for growing rice?
Ans. Rice is grown in the kharif season.
⚫ Find out:
(1) Names of two varieties of improved seeds of
Jowar.
Ans. CSH4 and SSV-84,
Phule Yashoda, Phule Mauli, Swati are the names of improved seed varieties of
Jowar.
(2) Who helps the farmer to drive the 'mot’?
Ans. A pair of
oxen help the farmer to drive the 'mot'.
(3) How is groundwater lifted these days?
Ans. The groundwater
was taken out with the help of hand pumps and by digging bore wells. Even now
at many places hand pumps are used. However, in majority cases, now electric
motor is fitted to draw water from the underground level.
⚫ Use your brain power!
What is the advantage of storing grain in wattle
and daub baskets?
Ans. Wattle and
daub baskets have holes on their surface. This keeps air circulating around the
stored grains. The grains do not become moist and thus do not catch fungus.
Moreover, there is less chance of insect attacks due to dry and airy
conditions. The grains stored like this can remain in better condition for a
longer period of time. Therefore, grains are stored in wattle and daub baskets.
(1)
What's the solution?
The plant
in the pot is not growing well.
Ans. (1) Keep the potted plant in such a way so that it gets maximum sunlight.
(2) Add
manure and organic fertilizer to the pot. If chemical fertilizers are to be
added, ask the expert about the dosage.
(3) Water
the plant daily and preferably in the morning.
(4) Loosen
the soil near the roots.
(5) Trim
the plant occasionally to enhance the growth.
(6) Take
care of the plant so that parasitic pests and insects do not harm the plant. If
all the above care is taken the plant in the pot will start growing well again.
(2) Use
your brain power!
What is the
purpose of storing food grains in our house?
Ans. (1) In order to avoid daily commuting to market, we store the food grains
in our house.
(2) Some
food stuff is seasonal. It is available only during certain season. This needs
to be bought and suitably preserved for storage.
(3)
Sometimes the shops and markets may be closed causing inconvenience at the last
minute. So, we need to store the food stuff in our house.
(4)
Sometimes guests may also drop in and we may need more supplies.
(5) There
may be parties, celebrations or similar occasions when we need more food stuff.
(6) Some
food grains may be sold only at a particular period of time. So that we need to
bring them home and store.
3. Find and
correct the wrong statements:
(a) There
is only one way of farming.
False. (There are many ways of farming.)
(b) India
is an agricultural country. - True.
(c) Use of
improved seeds does not lead to higher yields.
False. (Use of improved seeds leads to higher yields.)
4. Answer
the following questions:
(a) What
are the advantages of using improved seeds?
Ans. (1) Improved seeds have higher yield.
(2) These
seeds resist pest attacks.
(3) They
grow well and become ripe for harvest in a shorter period of time.
(4) Some
seeds can give high yield in low water supply too.
(b) Which
are the modern methods of irrigation? What are their advantages?
Ans. (1) Drip irrigation and sprinkle irrigation are modern methods of
irrigation.
(2) Due to
modern methods of irrigation, roots of the crops get enough water.
(3) One can
save a lot of water by these methods.
(4) In
modern methods of irrigation, full use is made of the available water.
(5) There
is danger of land becoming saline and fallow when there is overwatering. This
can be avoided due to the modern irrigation methods.
(c)
Describe the 'drip irrigation' method.
Ans. (1) In Drip irrigation method, pipes with holes are used for giving water
to the plants.
(2) Only
required amount of water drips near the plants in this method.
(3) Full
use of available water can be done by drip irrigation method.
(d) What
are the causes of damage to crops in the fields?
Ans. (1) Growing crops in the field can be attacked by diseases and pest
attacks.
(2) If the
fertility of soil is reduced the productivity of fields is also reduced. (3) If
enough water is not available for growing crops, their growth is stunted. All
these factors can cause damage to the crops in the fields.
(e) What is
done to avoid damage to the crops?
Ans. (1) To avoid damage to the crops, modern irrigation methods are used to
water the crops.
(2) To
reduce the pest and disease attacks, the crops are sprayed with insecticides
and pesticides.
(3) Seeds
used are also of improved quality and they are rubbed with certain chemicals
before sowing.
(4) Proper
amount of fertilizers are used to enhance the growth of the crops.
(f) What
causes the fertility of soil to diminish?
Ans. Overuse of chemical fertilizers leads to accumulation of excessive
chemicals in soil. This reduces the fertility of soil. Overwatering also turns
the soil saline and fallow.
(g) What
changes has modern technology brought about in the methods of farming?
Ans. (1) Modern technology of agriculture uses improved seeds that give higher
yield.
(2) Modern
methods of irrigation such as drip irrigation and sprinkle irrigation are used.
(3) Organic
fertilizers and manures are used to increase the fertility and productivity of
soil.
(4)
Pesticides and insecticides are used to protect the crops against diseases and
pest attacks.
(5) Through
agricultural assistance programmes farmers are given information and weather
forecasts. All these changes have brought about a better yield of farm produce.
(h) What
are the methods used to preserve food grains?
Ans. In order to preserve the stored food grains the following methods are used:
(1) The
grain is dried well in the sun and stored in sacks.
(2) The chemicals
are sprayed on the places where the sacks are stacked.
(3) Neem
leaves are mixed with the grain to avoid insect attacks.
(4)
Protective chemicals are mixed with the grains. The smell of these chemicals
repels the insect pests.
(5) The
place where grains are stored is kept dry and airy to prevent it from catching
fungus.
(i) How
is water made available to farming?
Ans. (1) In India, most of the agriculture is dependent upon monsoon.
(2) Along
with this rainwater, water from rivers, lakes and wells are used for irrigation
purposes.
(3) Dams
are built on rivers for holding huge quantities of water.
(4) Small
bunds are also made downstream on the rivers.
(5)
Traditionally, 'mot' and canal water were used for watering the crops.
(6) Now
modern methods of irrigation are used for farming.
3. Match
the following:
'A'
Group
Answer
'B' Group
(1) Grain
stored in damp place
( ) (a) Prevents growth
of fungus
(2) Grain
stored in dry
air
( ) (b) P Preserves insect infestations
(3) Adding
proper chemicals to the stored grains. ( ) (c) Fungus attack
Ans. (1) Grain
stored in damp place - Fungus attack
(2) Grain stored in dry air - Prevents growth of
fungus
(3) Adding proper chemicals to the stored grains - Preserves
insect infestations.
------ The End -----
13. METHODS
OF PRESERVING FOOD
Exercises
⚫ Can you Tell:
Talk to the
elderly people in your family to find the answers to the following questions,
with reference to the foodstuffs mentioned below:
Milk,
vegetables, grains, flours, sugar, jaggery.
(1) When do we say that the foodstuff is
spoiled? What changes are seen in it?
Ans. The foodstuff that is smelling foul and with unpleasant appearance is a
spoilt food. Sometimes there is growth of fungus on the foodstuff. The spoilt
food undergoes chemical changes. The colour and taste of such food is changed.
There is growth of fungus and microorganisms in such food. Such foodstuff
develops hazardous substances in it. This food is bad for health.
(2) Is the time in which foodstuffs get spoilt
different in different seasons?
Ans. Spoiling of
foodstuff is dependent on the temperature and humidity of the surrounding. Food
spoilage is rapid when the surrounding temperature and humidity is more. If the
surrounding air is dry and cool, the food spoilage is not immediate. Thus, the
foodstuffs take different time for spoilage in different seasons. In summer
season, food may get spoilt rapidly but not so during winter.
(3) Which foodstuffs spoil most quickly?
Ans. Milk and
milk products, fruits, vegetables, fish, meat, etc. are the foodstuffs that
spoil most quickly.
(4) What measures are taken to keep the foodstuffs
in the house in good condition, for as long as possible?
Ans. We keep certain foodstuffs in the refrigerator. Some foodstuffs are dried
and then stored. Some are processed and kept for a longer time.
1. What's
the solution?
(a) The
papads have become soft and moist.
Ans. Place the moist papads in the sun for drying. If
they are dried for 3 to 4 days continuously, their moisture content will vanish
and they can become crisp again. If there is a microwave oven in the house, we
can also dry them by placing them in the oven for 1 to 2 seconds. Later, these
papads should be stored in an airtight container.
(b) Fruits
like mangoes, amlas, guavas and vegetables like peas, onions, tomatoes,
fenugreek are needed all year around. They are available in plenty only in
certain seasons.
Ans. We can use different methods of food preservation in order to preserve
fruits and vegetables. E.g., Juice and pulp can be extracted from mangoes. One
can make products from mango pulp like amba-polt or dried sheets of mango pulp.
Raw mangoes, amla, or guava can be preserved by making their squash
preparations. Peas can be peeled from pods and then frozen and stored for a
long time. Fenugreek can be used for making theplas, muthiyas and other
eatables. Tomatoes can be preserved by making tomato puree, squash, ketchup or
sauce. Onions can be dried or fried and kept for a long time. If any fruits or
vegetables are available in plenty in certain sea- son, they can be preserved
using suitable method. They can be thus stored for even a year or more.
2. Use your
brain power!
Semolina (Shevaya) do not get spoilt for a long time. But kheer made from
them spoils easily. Why is this so?
Ans. Semolina are made by drying them in the sun. They
do not have moisture in them and hence can be stored for a long time. They do
not get spoilt even after storage. But kheer is made using milk. Milk is highly
perishable, that is, it can get spoilt soon. Therefore, kheer spoils quickly.
3. Find and
correct the wrong statements.
(a) When something is boiled, the microorganisms in it are destroyed. - True.
(b) Our food does not get spoiled when microorganisms begin to grow in it.
False. (Our food gets spoiled when microorganisms begin to grow in it.)
(c) Foodstuffs
dried during summer season cannot be used for the rest of the year.
False. (Foodstuffs dried during summer season can be used for the rest of
the year.)
(d) Foodstuffs
get warmth when put in a fridge.
False. (Foodstuffs get cool temperatures when put in a
fridge.)
4. Answer
the following questions:
(a) What
are the different methods of preserving food?
Ans. Drying, cooling, boiling, placing in airtight
containers and using food preservative substances are the different methods of
preserving food.
(b) Why do
we avoid eating food that has spoiled?
Ans. (1) Microorganisms that spoil the food are harmful for health.
(2) The spoiled food has foul smell and bad
appearance.
(3) Eating such food can cause stomach-ache,
vomiting and diarrhoea.
(4) Sometimes the spoiled food also has fungus
growing on it.
(5) Such food is not nutritious and can be
dangerous for health. Therefore, we must avoid eating spoiled food.
(c) Why do
we make jams from fruits?
Ans. Fruits cannot stay longer in their natural and tasty form.
Microorganisms and fungus can grow on them. For preserving them, food
preservatives like sugar are added in them. Sugar is used to make jams which
can be stored for a longer time. We can have jams even after the season of
fruits is over. Therefore, we make jams from fruits.
(d) What
are preservatives?
Ans. Substances added to foodstuffs to store them for a
longer period are called preservatives. By using preservatives, we can relish
some foodstuffs like fruits even after their season is over.
(e) Find
out the names of different spices. Also find out which part of their plant they
are.
Ans. (1) There are different types of spices such as cinnamon (dalchini),
cardamom (velchi), bell leaves (tamalpatra), cloves (lavang), coriander seeds
(dhana), cumin seeds (jeera), black pepper (kali miri), nutmeg (jaifal), etc.
(2)
Coriander seeds, cumin seeds, black pepper are seeds of a plant.
(3)
Cinnamon is a part of the stem of a plant.
(4)
Cardamom and nutmeg are fruits.
(5) Bell
leaves are leaves of a plant while cloves are dried peduncles of a flower.
----- The End -----
16. WATER
Exercises
⚫ Can you Recall?
(1) What happens when a spoonful sugar, sawdust and
soil are added to a glass of water?
Ans. When sugar is added to the water, it dissolves
completely and disappears in water.
When sawdust is added, it will float on the surface of the water. When soil
is added it will settle at the bottom of the water.
(2) Which are the three states of water?
Ans. Three
states of water are
(1) Solid
form - e.g., Ice
(2) Liquid
form - e.g., Plain water
(3) Gaseous
form- e.g., Vapour
(3) What is done to make drinking water clean and
safe?
Ans. Methods of
settling and filtering will make the water clean. For making it safe it is
boiled for some time.
⚫ Try this:
While it is raining, collect
some of the rainwater directly in a clean container placed in an open. Also
collect some of the rainwater that is flowing over the ground. Observe and
compare the two.
What difference do you see?
What is the reason for this?
Ans. Water collected directly from the falling rain will
appear to be clean. The water that flows over the ground will appear turbid.
Since water flowing over the ground carries a lot of contamination, it will
look turbid and dirty.
⚫ Can you
Tell?
List the substances that are
mixed in the waste water drained out of the kitchen and bathroom in your house.
Ans. Various substances are mixed with the waste water
that drains out of the kitchen and bathroom of our house. This drained water
contains excreta, urine, bathing water, liquid soap, detergents, water
containing leftover food particles, dirty water formed due to washing utensils
and clothes and various other contaminants.
⚫ Can you
Tell?
If, at some place, it did not
rain for a very long period of time, what would be its effect on the life of
the people there?
Ans. If a particular place does not get enough rains
for a long period of time, then there would be scarcity of water. If water is
not available, farming cannot be done. Crops will not grow. People might have
to migrate in search of food and water. Cattle would also die due to lack of
food and water. This complete area will be under drought.
1. What's the solution?
Soil in the garden gets washed away with the
water due to the slope of the land.
Ans. On the slope of the guidue s slope of the garden,
we could plant saplings and smaller shrubs. We can even plant grass rocks of
bricks are on the slope. If rocks or bricks are placed on the side of slope,
then that can also arrest flow of w of soil. While watering the garden, it should
be done gently. Forceful watering can lead to more soil erosion.
2. Use your brain power!
How should roads and footpaths be built to
make rainwater seep into the ground?
Ans. If the entire road and footpaths are made of
concrete, there would be problem for rainwater to seep into the soil.
Therefore, some adjoining part of road footpath should be kept without
concretization so that rainwater could seep inside. Similarly, if a little gap
is maintained between the two adjacent tiles on the footpath, rainwater can
percolate inside.
3. Answer the following
questions:
(a) What conditions prevail
during a famine?
Ans. (1) In drought conditions or during famine, the
levels of water in different reservoirs decrease. Some of the reservoirs become
totally dry. Similarly, the land also becomes barren and dry.
(2) Animals and people face scarcity of water.
(3) Agriculture suffers due to lack of water.
(4) Domestic animals, other animals and people suffer a lot. People are
forced to migrate from drought area as they have to face hardships.
(b) What works are undertaken
to make water available even after the rainy season?
Ans. (1) Different methods are adopted to make water
available even after rainy season.
(2) In places where large dams cannot be constructed, smaller reservoirs
are made.
(3) Counter bunding, stopping water of the streams by building bunds and
similar such works are undertaken by the Government and the local people.
(c) Why is it necessary to
stop rainwater?
Ans. (1) If the rainwater is stopped, from flowing away
and allowed to percolate in soil or stored, this water will be available for us
even after the rainy season.
(2) The ground water level rises due to percolation of rainwater in the
soil.
(3) Trees and agriculture can get water by this method.
(4) Well water rises and more land can be cultivated. By all these efforts,
drought can be avoided.
(d) What is meant by water
management?
Ans. Taking steps to ensure that the rainwater will be
available even after the rainy season is called water management. Saving water
and catching rainwater are some of the ways of water management.
4. Answer whether the
following statements are True or False. If false, rewrite them after
correcting:
(a) We get rainwater throughout the year.
False. (We get rainwater only for four months.)
(b) During a famine, the government moves people and animals temporarily to
safe places.
True.
----- The End -----
