STD-3, CHAPTER-8: FOOD, EXTRA QUESTION ANSWERS

 1.      Why the living things need food?

Ans:i) Living things need food to live, grow and remain healthy.

ii) Food also gives us energy to do work.

2.      Name the two sources of our food.

Ans: The two sources of our food are, plants and animals.

3.      Who is a vegetarian?

Ans: The person who eats only plant products like vegetables, fruits and milk (animal product) is called a vegetarian.

4.      Who is a non-vegetarian?

Ans: The person who loves to eat fish, meat, chicken, eggs, is called as non-vegetarian.

5.      Which one is better- to be a vegetarian or nonvegetarian.

Ans: It is always better to be a vegetarian.

6.       Name the parts of plants which are used as food.

Ans: We eat seeds, fruits, roots, stems, leaves of the plants.

7.      Name the plants whose seeds are taken as food.

Ans: Seeds of Wheat plant, Rice plant, Corn plant, maize plant, are taken as food.

8.      How wheat flour is obtained?

Ans: Wheat flour is obtained by grinding the seeds (grains) of wheat.

9.      Name the food items prepared from wheat flour.

Ans: Chappatis and bread, are prepared from wheat flour.

10.  Name the food products obtained from the seeds of wheat.

Ans: We obtain wheat flour, Dalia, sooji (rawa) and maida, from the seeds of wheat.

11.  How are dosas and idlis prepared?

Ans: Dosas and idlis are prepared from a paste of ground rice and dal.

12.  Name some cereals.

Ans: Wheat, rice and corn are some of the cereals.

13.  How do cereals help us?

Ans: Cereals give us energy to do work.

14.  Name some pulses.

Ans: Different kinds of dal, peas, grams, are the pulses.

15.  Why should we eat pulses?

Ans: We should eat pulses, as they help us to grow.

16.  The seeds which are generally eaten raw, are the ______.

Ans: Nuts

17.  Name some nuts.

Ans: Peanuts, walnuts, cashewnuts and almonds are some nuts.

18.  Why do we need to eat nuts?

Ans: Nuts can provide a lot of energy to us and keep our body warm. So, we should eat nuts.

19.  What are green vegetables?

Ans: Leaves, which are cooked and taken as food, are called green vegetables.

20.  Name some leaves which are cooked before eating.

Ans: Spinach, fenugreek (methi), cabbage and mustard are cooked before eating.

21.  Name the leaves which are used for garnishing and flavouring our food.

Ans: Leaves of coriander, mint and curry plant are used for garnishing and flavouring our food.

22.  Why are leaves important for us?

Ans: Leaves protect us from diseases. So, they are important for us.

23.  Name the stems which are used as food.

Ans: Potato, onion, ginger and stem of lotus (kamal kakri) are taken as food.

24.  Potato is an ________ stem.

Ans: Potato is an underground stem.

25.  Name the roots which are eaten as food.

Ans: The roots which are taken as food are, carrot, radish, turnip and beetroot.

26.  Name some sweet and juicy fruits. (OR)  Name some fruits which are eaten raw.

Ans: Mangoes, oranges, grapes, muskmelons and watermelons are some juicy fruits which are eaten raw.

27.  Name some fruits which are eaten as vegetables (after cooking).

Ans: Brinjal, ladyfinger are eaten after cooking as vegetables.

28.  Name the fruit which can be eaten raw as well as cooked.

Ans: Tomatoes

29.   Why are green vegetables and fruits important for us?

Ans:i) Green vegetables protect us from diseases.

ii) Fruits keep us fit and healthy. They also protect us from diseases.

So, green vegetables and fruits are important for us.

30.  List some animal products that we eat.

Ans: Animal products like milk, eggs, meat and fish, are some of the animal products that we eat.

31.  Name the animals who give us milk.

Ans: Cow, buffalo and goat provide us milk.

32.  Name some food products where milk is used.

Ans: Curd, cheese, ice cream, kheer, etc., are the food products where milk is used.

33.  _____ is considered to be a complete food.

Ans: Milk

34.  Why is milk considered to be complete food?

(OR) Why are milk and milk products, regarded as ‘good food’ for one and all?

(OR) Why is milk important for growing children?

Ans: i) Milk is a very good source of nutrients for one and all.

ii) It helps us to grow, gives us energy and protects us from diseases.

So, it is regarded as ‘good food’ for one and all and is very important for growing children.

35.  Name the birds who give us eggs.

Ans: Poultry birds like hen, goose and duck give us eggs.

36.   List the factors on which the intake of food of different persons depend.

Ans: The factors on which intake of food depends are,

i)       Age of the person

ii)     Occupation of the person

iii)   Type of physical activity

iv)   Gender of the person

37.  Ramesh is a labour, working at the construction sites. Suresh, is a bank officer. Who do you think needs more food to eat? And why?

Ans:i) Ramesh needs more food to eat.

ii) As Ramesh is doing more physical activity than Suresh, so he needs more energy.

38.  How the food habits of a person depends on his/her age?

Ans: i) From birth, till about four months of age, small babies take milk only.

ii) When a child is nearly six months of age, he/she is given soft pieces of fruit and semi-solid foods. The child continues to take milk also.

iii)Growing children and young persons, need to eat proper amounts of a balanced diet.

iv)In old ages, people prefer easily digestible simple food.

39.  Name the food items which are included in a balanced diet?

Ans: The balanced diet include rice, vegetables, chappatis, dal, dosa, idli, uttapam, sambhar, fruits, nuts, milk and milk products.

40.  What is over eating? How it affects our body?

Ans:i) Eating too much is called over eating.

ii) Over eating makes us fat or obese.

iii)We will not be very active and healthy.

STD-5, CHAPTER- 11: OUR SOLAR SYSTEM, EXTRA QUESTION-ANSWERS

 1.      Define solar system.

Ans: The family of sun and its eight planets constitute the solar system.

2.      ______ is the central part of the solar syatem.

Ans: The sun

3.      Why is the sun called a luminous body?

Ans: The sun produces light of its own. So, the sun is said to be a luminous body.

4.      Why the sun appears small to us?

Ans: The sun appears small to us due to its very large distance from the earth.

5.      Name the source of energy for Earth.

Ans: Sun is the source of energy for the Earth.

6.      The sun gives out energy in the form of ______ and _____.

Ans: Heat and light

7.      Define solar energy.

Ans: The energy received from the Sun, is called as solar Energy.

8.      How is the sun useful to us?

Ans: i) The sun is essential for growth, and maintainence, of all forms of life on the earth.

ii)  All living beings, whether plants or animals, depend on the sun for their food.

iii) Plants make their food in the presence of sunlight. All other animals get their food, directly or indirectly, from plants.

9.      Name the devices which use solar energy.

Ans: Solar cookers, Solar geysers and solar cells work through solar energy.

10.  What are the ways in which we use solar energy?

Ans: i) Solar cookers and solar geysers are used for cooking food and getting hot water in our homes.

ii) We also have solar cells that work through solar energy. These are used in devices like the calculators and wrist watches.

iii) Solar cells are also used in man-made satellites and space vehicles.

iv) Solar cells also provide electricity in many remote areas.

11.  Why has the Sun been worshipped as a God?

Ans: The sun is the source of energy for all of us. Being so essential for evolution and propagation of life on earth, it has been worshipped as a God by almost all the ancient civilisations.

12.  What are planets?

Ans: Planets are almost spherical celestial bodies, which move around the sun.

13.  Define revolution.

Ans: When one object moves around another object, it is called as revolution.

14.  Define an Orbit.

Ans: The definite path along which the planets revolve around the sun, is called an orbit.

15.  Name the planets of our solar system in the increasing order of their distances from the sun.

Ans: The planets of the solar system in the increasing order of their distances from the sun, are – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

16.  Name the closest planet to the sun.

Ans: Mercury is the closest planet to the sun.

17.  Name the smallest planet in our solar system.

Ans: Mercury is the smallest planet in our solar system.

18.  Write four lines about Mercury.

Ans: i) Mercury (Budh) is a dry, hot and almost airless planet.

ii) It is the closest planet to the sun.

iii) There is no atmosphere, around this planet.

iv) The light and heat of the sun, therefore, reach the side of mercury, facing the sun, directly. This side becomes hot and the other side remains comparatively cold.

19.  ‘Venus is the brightest object seen in the sky after the sun and the moon.’- comment.

Ans: Venus reflects back a very large amount of solar energy that falls on it. Venus is, therefore, the brightest object seen in the sky after the sun and the moon.

20.  ‘Venus is hotter than mercury’- Justify.

Ans: Venus has a very thick atmosphere. Its thick atmosphere traps a large amount of solar energy reaching its surface. It is because of this trapping that it is hotter than mercury.

21.  Name the hottest planet of the Solar system.

Ans: Venus

22.  Name the third planet in terms of increasing distance from the sun.

Ans: Earth

23.  Why the surface of earth, appears flat to us?

Ans; The surface of earth, appears to be flat because of its large size.

24.  Why the earth is referred to as the Blue planet?

Ans: The earth reflects sunlight from the water and landmass present on its surface. So, the Earth is referred to as the blue planet.

25.  Define ‘time period of revolution’ or ‘a year’.

Ans: The time taken by a planet to complete one revolution is called its time period of revolution or a year.

26.  How does the time period of revolution change with the distance of planet from the sun/

Ans: The time period of revolution increases as the distance of planet from the sun increases.

27.  Why do the planets not collide among themselves or with the sun?

Ans: Planets do not collide among themselves or with the sun, because the planets are in constant motion around the sun and move in the same direction in orbits that are widely far apart.

28.  What is the time period of revolution for Earth?

Ans: Nearly 365 days.

29.  Different seasons appear on different places on the earth due the _____ of earth around the sun.

Ans: Revolution of Earth.

30.  What is the time period of rotation for earth?

Ans: Nearly 24 hours

31.  ‘Days and nights are due to the rotation of the earth.’- Justify the statement.

Ans: i) During the rotation of Earth, the side facing the sun, receives light and appears bright. This side is said to have day.

ii) The other half then does not receive light from the sun and is said to have night.

iii) The two halves reverse their roles after every half rotation i.e. every 12 hours nearly.

32.  In what ways, the earth is unique?

(OR) State the conditions necessary for existence of life on a planet.

Ans: The conditions necessary for existence of life on a planet are,

i)      Presence of atmosphere

ii)    Presence of (liquid) water on the surface.

iii)  Right size and right distance from the sun

         All these conditions are fulfilled by our earth. It is the only planet that can sustain life on it. This makes earth, a unique planet.

33.  What is the difference between a day and a year?

Ans: i) A day for a planet equals the time taken by it to complete one rotation about its own axis.

ii) A year, on the other hand, equals the time taken by it to complete one revolution around the sun.

34.  Which planet is called as the red planet?

Ans: Mars

35.  Name the planets which have structures similar to that of the earth.

Ans:  Mercury, Venus and Mars have structures similar to that of the earth.

36.  What are terrestrial planets?

Ans: Those planets, which are mostly made up of rocks and metals, are called terrestrial planets.

37.  Name the terrestrial planets.

Ans:  Mercury, Venus, Earth and Mars are the terrestrial planets.

38.  Name the fifth planet of the solar system in terms of the distance from the sun.

Ans: Jupiter is the fifth planet in terms of distance from the sun.

39.  Name the largest planet of the solar system.

Ans: Jupiter

40.  What are planetoids?

Ans: The collection of a large number of very small planets is called as planetoids.

41.  Where does the asteroid belt lie?

Ans: The asteroid belt lies between the orbits of Mars and Jupiter.

42.  Name the second largest planet of the solar system.

Ans: Saturn

43.  Saturn is known as the Ringed planet. Why?

Ans: Saturn has a system of beautiful rings surrounding it. It is therefore, known as the ringed planet.

44.  Name the third largest planet in the solar system.

Ans: Uranus is the third largest planet in the solar system.

45.  Uranus is a _______ without any solid surface.

Ans: Gas giant

46.  Neptune is known as a windy planet. Why?

Ans: Neptune is known as a windy planet, as very strong winds blow on its surface.

47.  Name the Jovian planets. Why are they named so?

Ans: i) Jupiter, Saturn, Uranus and Neptune are the Jovian planets.

ii) Because they are mostly made up of gases and ice.

48.  Name the gaseous planets.

Ans: Jupiter, Saturn, Uranus and Neptune, taken together, are known as gaseous planets.

49.  What is a satellite?

Ans: A satellite is an object that revolves around a much larger object.

50.  Name the two types of satellites?

Ans: The two types of satellites are, i) Natural Satellites and ii) Artificial (man-made) satellites.

51.  What are natural satellites?

Ans: Celestial bodies, which revolve around a planet, are known as the natural satellites of that planet.

52.  Name the natural satellite of the Earth.

Ans: Moon is the natural satellite of the earth.

53.  Name the planets which have a very large number of satellites.

Ans: Saturn and Jupiter

54.  Name the nearest neighbour of earth in space.

Ans: Moon

55.  Why is the moon called a non-luminous object?

Ans: Moon does not have its own light. It only reflects a part of sunlight falling on it. So, it is a non-luminous object.

56.  What is the time period of revolution of moon around the earth?

Ans: Nearly 28 days

57.  Why do we observe phases of moon?

Ans: Because of the changes in the relative position of the earth and the moon, with respect to the sun, we observe the gradual change of shape and size of the moon everyday, which we call as the phases of the moon.

58.  Name the different phases of the moon.

Ans: The phases of the moon include, i) Completely dark phase-amavas or new moon day

ii) a complete bright phase- poornima or full moon day

59.  What is the time gap between amavas and poornima?

Ans: Nearly 15 days

60.  Write the meaning of the term ‘Artificial satellites’.

Ans: Artificial satellites are man-made objects, which can be made to revolve around the earth.

61.  State the uses of artificial satellites.

Ans: i) Artificial satellites are used in communication for transmitting radio, telephone and television signals.

ii) They are also used for weather forecasting and remote sensing.

iii) Artificial satellites are also being used to collect information about the other planets and the stars.

62.  Name the first satellite launched by India.

Ans: Aryabhatta (in 1975)

63.  Name some artificial satellites launched by India.

Ans: Rohini, Apple, INSAT, EDUSAT, CARTOSAT, IMS-1, Chandrayan-1, GSAT-4, Jugnu and SARAL are some satellites launched by India.

64.  In which year, India launched chandrayan-1?

Ans: October 2008 (by ISRO)

65.  What are geo-stationary satellites?

Ans: Those satellites which take as much time to complete one orbit around the earth as the time taken by the earth to complete one rotation on its axis, are called as geo-stationary satellites.

STD-5, CHAPTER-10: AIR, EXTRA QUESTION ANSWERSS

 1.      Why cannot we see air?

Ans: Pure air is colourless. So, we cannot see air.

2.      We feel air only when it _____.

Ans: Blows

3.      Name the main components of air.

Ans: The main components of air are, nitrogen (nearly 78%), oxygen (nearly 21%), water vapour and small amounts (1%) of other gases like carbon dioxide, ozone, helium and hydrogen.

4.      Define Humidity.

Ans: The amount of water vapour present in air determines the humidity of air.

5.      Why is air necessary for animals?

Ans: i) All the animals, including human beings, need oxygen to live.

ii) They take oxygen from air through the process of breathing.

iii) The oxygen, present in air, is used to produce energy from the food that is eaten.

iv) Oxygen is also required for burning.

6.      _______ gas is breathed out by animals.

Ans: Carbon dioxide

7.      _______ gas is required for burning..

Ans: Oxygen

8.      ______ gas is used by plants during photosynthesis.

Ans:  Carbon dioxide

9.       Define photosynthesis.

Ans: Photosynthesis is the process by which green plants prepare their food in the presence of sunlight.

10.  How is the balance of oxygen and carbon dioxide in air, maintained in nature?

Ans: i) Animals and human beings use oxygen present in the air and give out carbon dioxide gas.

ii) Plants, on the other hand, consume carbon dioxide during photosynthesis in day time. They then give out oxygen.

iii) In this way, a balance of carbon dioxide and oxygen is maintained in the air.

11.  How is nitrogen important for plants?

Ans: i) Nitrogen helps in the rapid growth of plants.

ii) It also helps them to develop their fruits and seeds.

iii) It also increases the size and quality of their leaves.

Therefore, plants require nitrogen in large amounts.

12.  How do plants utilise atmospheric nitrogen?

Ans: i) Bacterias, present in the soil, help to convert the atmospheric nitrogen into nitrate or ammonium salts.

ii) These salts are taken in by plants to get the nitrogen needed by them.

13.  Plants use nitrogen to form ______ essential for their growth.

Ans: Proteins

14.  Define atmosphere.

Ans: The blanket of air surrounding us, which acts as a shield to protect us, is called as the atmosphere.

15.  State the two possible harmful effects of ultraviolet rays.

Ans: The ultraviolet rays can cause skin and eye diseases in animals and affect the growth of plants.

16.  Which layer protects us from the harmful ultraviolet rays of sunlight?

Ans: The ozone layer protects us from the harmful ultraviolet rays of sunlight.

17.  When is air said to be polluted?

Ans: When air contains impurities like dust, soot, germs or other harmful gases like carbon monoxide, oxides of nitrogen and sulphur, it is said to be polluted.

18.  Define the term ‘air pollutants’.

Ans: The impurities present in air, are called as pollutants.

19.  Name the two basic forms of air pollutants.

Ans: The two basic forms of air pollutants are, gaseous pollutants and solid pollutants.

20.  Name the gaseous pollutants.

Ans: Carbon monoxide, ozone, oxides of nitrogen and sulphur, are gaseous pollutants.

21.  Name some solid pollutants.

Ans: Smoke, dust and germs are solid pollutants.

22.  What are the causes of air pollution?

Ans: i) Dust raised from the ground during dust storms.

ii) Stone dust raised by crushing of stones in quarries.

iii) Smoke emitted by vehicles.

iv) Smoke from forest fires.

v) Smoke raised by burning of coal in powerhouses.

vi) Burning of wood, cowdung cakes, garbage, etc., in households and open places.

vii) Germs from coughing and sneezing.

23.  What are the effects of air pollution?

Ans: i) By breathing polluted air, we may suffer from various problems like suffocation, cough, headache and so on. Polluted air may also cause skin and eye diseases.

ii) Air pollution may also lead to acid rain.

iii) Presence of carbon dioxide and some other gases, in air, causes greenhouse effect.

24.  How acid rain is caused?

Ans: Gases, like oxides of nitrogen and sulphur, present in automobile exhausts, mix with rain water and forms acid rain.

25.  Why is ‘acid rain’ harmful?

Ans: i) Acid rain damages crops and reduces the fertility of soil.

ii) It can also damage monuments made of marbles.

26.  How greenhouse effect is helpful to us?

Ans: Greenhouse effect helps the earth to stay ‘suitably warm’.

27.  What leads to global warming?

Ans: If carbon dioxide and some other gases present in excess in air, their ‘increased greenhouse effect’ can cause an ‘extra increase’ in the average temperature of the earth, which leads to global warming.

28.  Why should we feel ‘worried’ about ‘global warming’?

Ans: global warming can result in an increase in the melting of polar ice-caps which can cause wide-spread damage and destruction.

29.  Suggest some ways of reducing air pollution.

Ans: i) We should plant more trees.

ii) We should use less vehicles.

iii) Regular check-up of vehicles.

iv) Use of cleaner fuels.

v) Dumping the garbage in a pit.

vi) We should construct tall chimneys.

vii) We should cover our nose and mouth while sneezing or coughing.

30.  How does planting of trees help in making air cleaner?

Ans: i) Plants use up carbon dioxide gas, present in the air, during the process of photosynthesis.

ii) This helps to reduce the greenhouse effect and maintain the earth’s temperature at a desirable level.

31.  Name some cleaner fuels.

Ans: LPG or biogas, CNG

32.  Why constructing tall chimneys is important for powerhouses and factories?

Ans: Powerhouses, and factories, should construct tall chimneys so that smoke coming out of them goes higher up in the atmosphere and is not inhaled by us.

33.  How can we minimise the use of vehicles?

Ans: i) We should use a bus or metro, if available, for going to the office instead of using a personal vehicle.

ii) We can also share, or ‘pool’, vehicles for going to the office.

This will reduce the number of vehicles on the road. As a result, the amount of smoke emission will also get reduced.