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.

STD-4, CHAPTER-5: BIRDS-BEAKS AND CLAWS, EXTRA QUESTION ANSWERS

 

1.      Birds do not have ______ to eat their food.

Ans: Teeth

2.      How birds use their beaks and claws?

Ans: i) Birds use their beaks and claws to catch and eat food.

ii) They also use their beaks and claws to protect themselves.

3.      What do birds eat?

Ans: Birds eat flesh, seeds, fruits etc.

4.      Write the uses of a beak of a bird.

Ans: i) Birds use their beaks to tear, bite, chisel or crush the food.

ii) Some birds use their beaks to fight the enemy or catch the prey.

iii) Birds also use their beaks for preening their feathers.

5.      What is preening?

Ans: Preening means to clean the feathers and set them right.

6.      What do birds use for preening their feathers?

Ans: Birds use their beaks for preening their feathers.

7.      How preening is done?

Ans: i) Birds use their beaks for preening.

ii) The birds spread the wax, secreted at the base of the feathers, during this process.

8.      Name the different types of beak.

Ans: Different types of beaks are, i) Crushing beak

                                                            ii) curved beak

                                                            iii) piercing and tearing beak

                                                            iv) Chiselling beak

                                                            v) Probing beak

                                                            vi) Sifting beak

                                                            vii) Sticky beak

9.      Name some birds who have crushing beak. 

Ans: Sparrow and pigeon have crushing beak.

10.  How is a crushing beak helpful to a pigeon?

Ans: The crushing beak helps in crushing seeds and grains, thereby, make it soft before eating.

11.  Name a bird who can imitate our voice.

Ans: Parrot can imitate our voice.

12.  Name the bird who has curved beak.

Ans: Parrot has a curved beak.

13.  How is a curved beak helpful to a parrot?

Ans: The curved beak helps in cracking nuts and fruits.

14.  Name some birds who have piercing beak and tearing beak.

Ans: Eagles and vultures have piercing and tearing beaks.

15.  How is a piercing beak helpful to an eagle?

Ans: The piercing and tearing beak helps an eagle, to tear their flesh.

16.  Name the bird who has chiselling beak.

Ans: Woodpeckers have chiselling beak.

17.  How is a chiselling beak helpful to a woodpecker?

Ans: The chiselling beak helps the woodpecker to peck at the wood and eat insects present in the wood.

18.  Name some birds who have probing beak.

Ans: Humming birds, sunbird and hoopoe, have probing beaks.

19.  How is a probing beak helpful to hoopoe and sunbird?

Ans: i) Sunbird sucks nectar from flowers, with the help of its probing beak.

ii) Hoopoe takes out insects and worms from the holes in the ground, with its probing beak.

20.  A humming bird can flap its wings ____ times in just one second.

Ans: 90 times

21.  Name the bird who has sifting beak.

Ans: Duck has sifting beak.

22.  How is a sifting beak helpful to a duck?

Ans: i) The beak of the duck pushes out the mud and water from the holes leaving the food behind.

ii) Its beak thus, helps it to sift food from mud and water.

23.  Name the bird who has sticky beak.

Ans: A swallow has a sticky beak.

24.  How is a sticky beak helpful to a Swallow?

Ans: The swallow catches flies while flying with the help of its sticky beak.

25.  Give a sure sign of summer. (OR) which bird gives us a sign that summer is coming?

Ans: The arrival of flocks of swallows is a sure sign that summer is on its way.

 

26.  What are claws?

Ans: Claws are the long curved nails present on the feet.

27.  How are claws helpful to a bird?

Ans: Claws can be used for climbing, protecting, holding food, swimming and perching.

28.  What are birds of prey?

Ans: Birds, which kill other smaller animals and eat them as food, are called birds of prey.

29.  Name some birds of prey.

Ans: Eagle, vulture, and hawk are some birds of prey.

30.  What type of claws do eagles and vultures have?

Ans: Eagles and vultures have strong and sharp claws.

31.  How the claws help an eagle?

Ans: Eagle/ vulture firmly hold their prey while flying, with the help of their claws.

32.  Name some perching birds.

Ans: Sparrows, pigeons and crows are some perching birds.

33.  What type of feet do the perching birds have?

Ans: Perching birds have long and slender claws with three toes in front and one at the back.

34.  How the perching birds use their claws?

Ans: Toes of perching birds curl around the branch or a wire and hold it firmly.

35.  Name the bird which can sleep even while perching on wires.

Ans: Sparrow can sleep while perching on wires.

36.  Name some swimming birds/

Ans: Ducks and penguins are swimming birds.

37.  What type of feet do swimming birds have?

Ans: Swimming birds have webbed feet.

38.  What is meant by webbed feet?

Ans: When the front toes get joined by skin and give them a flat appearance, it forms a webbed feet.

39.  How do webbed feet help a duck to swim?

Ans: The webbed feet of duck is used to paddle and to push the water while swimming.

40.   Name some wading birds.

Ans: Crane and jacana are some wading birds.

41.  What type of feet do wading birds have?

Ans: Wading birds have long legs and wide spreading toes.

42.  What prevents the body of crane and jacana from sinking in water?

Ans: The widely spread out toes prevent the body of crane and jacana from sinking in water.

43.  Give one example of a scratching bird.

Ans: Hen is an example of scratching bird.

44.  What type of feet do the scratching birds have?

Ans: i) Scratching birds have strong feet with three toes in front and one at the back.

ii) Each toe has a sharp claw to scratch the ground in search of seeds and insects present in the soil.

45.  Name two climbing birds.

Ans: Woodpecker and parrot are two climbing birds.

46.  What type of feet do the climbing birds have?

Ans: The climbing birds have two toes pointing upwards and two pointing downwards.

47.  How do the climbing birds use their feet?

Ans: Climbing birds use their feet to cling to trees to catch insects and to hold the fruits.

48.  A person who studies birds is called an _______.

Ans: Ornithologist

49.  Name one Indian ornithologist.

Ans: Dr Salim Ali was an Indian ornithologist.

50.  Dr Salim Ali has been awarded the ______.

Ans: Padma Vibhushan

STD-4, CHAPTER-10: WATER POLLUTION, EXTRA QUESTION ANSWERS

 1.      ‘Water is an important natural resource.’- justify this statement.

Ans: i) Water is essential for all living beings.

ii) It is a habitat for many plants aand animals.

iii) It is essential for the existence and survival of all plants and animals.

Thus, water is an important natural resource.

2.      Name the major source of water?

Ans: Rain is the major source of water.

3.      ______ is the purest form of water.

Ans: Rain water (when just formed)

4.      How does the rain water become impure?

Ans: As the rain water reaches the surface of the earth, it dissolves some harmful gases, dust, smoke particles and germs present in air. Thus, it gets impure.

5.      Name any two materials which can make rain water impure.

Ans: Dust and smoke particles which can make rain water impure.

6.      Define the term polluted water.

Ans: Water containing impurities is called polluted water.

7.      What is pollution of water?

Ans: The processes, which make water impure, result in pollution of water.

8.      State the human activities which can cause water pollution.

Ans: i) People wash their clothes and bathe in river water. Some people bathe their cattle in rivers.

ii) People throw domestic waste in rivers.

iii) Waste materials, and harmful chemicals from factories, are often dumped in river water.

iv) Solid waste material, from power plants, may be thrown into the river water.

v) Water, from drains and sewage, goes into rivers.

vi) The chemical fertilisers flow into lakes or rivers after getting mixed with rain water.

vii) Oil, spilled by tankers and oil wells, pollutes sea water.

9.      Which two pollutants are often dumped by the factories into the rivers?

Ans: Harmful chemicals and waste materials are often dumped by the factories into the rivers.

10.  State the effects of water pollution.

Ans: i) Poisonous chemicals, from factories, kill marine animals.

ii) Industrial, and agricultural, wastes increase the growth of micro-organisms in water. This can reduce the supply of oxygen for the aquatic animals.

iii) Aquatic plants and animals get infected by polluted water. When other animals eat these infected animals or plants, they also become sick.

iv) Drinking polluted water may cause diseases.

v) Using polluted water for irrigation, decreases the fertility of the soil and damages crops.

11.  Suggest some ways to reduce water pollution.

Ans: i) Wastes from factories and power houses should not be allowed to flow into rivers directly.

ii) Pipes, carrying sewage, should not be allowed to enter into wells or rivers.

iii) Water, from drains or sewage, should not be allowed to enter into wells or rivers.

iv) People should not wash clothes, or use soaps if they bathe, in rivers.

v) The use of chemical fertilisers should be minimised. Instead, natural manure should be used.

STD-4: CHAPTER-9: METHODS OF SAFE-HANDLING OF WATER: EXTRA QUESTION-ANSWERS

 1.      Why does our body need water?

Ans: i) Water is needed for proper functioning of our body.

ii) Our body needs water for digestion of food and for removal of wastes from the body.

2.      We need to drink _______ glasses of water everyday.

Ans: We need to drink eight to ten glasses of water everyday.

3.      Define potable water.

Ans: Water, which is clean and fit for drinking, is called potable water.

4.      State two methods of drawing ground water.

Ans: Ground water can be drawn from wells or by using hand pumps.

5.      What are germs?

Ans: Germs are extremely small living beings which can cause diseases.

6.      Name the diseases that can be caused by drinking unclean water.

Ans: Jaundice, diarrhea, dysentery and cholera can be caused by drinking unclean water.

7.      Why should water be purified before drinking?

Ans: Drinking unclean water can cause diseases, as they contain dirt and germs. So, water should be purified before drinking.

8.      State three methods of purifying water.

Ans: Three methods to purify water are, i) Boiling,  ii) Filtration,  iii) Chlorination

9.      How does boiling help in making water safer for drinking?

Ans: Boiling kills the germs present in water. Thus, boiling helps in making water safer for drinking.

10.  What is filtration?

Ans: Filtration is a method for removing dust and other suspended particles from water.

11.  How can traditionally water be purified?

Ans:i) We can filter water through a clean, thin cloth.

ii) We can also use a traditional filter containing sand and gravel.

12.  How filtration method is useful?

Ans: Filtration removes dust and other suspended particles from water.

13.  What is drawback (demerit) of filtration method?

Ans: Filtration method does not remove germs.

14.  Why is the traditional method of filtration not completely sufficient for making water fit for drinking?

Ans: i) Traditional method of filtration removes dust and other suspended particles from water.

ii) But, this method does not remove germs.

So, traditional method of filtration is not completely sufficient for making water fit for drinking.

15.  What is the difference between traditional filters and modern filters?

(OR) How modern filters are more useful than traditional filters?

(OR) What is the advantage of modern filters over traditional filters?

       Ans: i) Traditional filters does not remove germs. For removing germs, water should be boiled after filtration.

ii) But, modern filters remove germs along with dirt and dust. Water filtered by such filters can be directly used for drinking.

So, modern filters are more useful than traditional filters.

16.  What is chlorination? How does it purify water?

Ans: i) Adding a correct small amount of chlorine in filtered water, is called chlorination.

ii) Chlorination kills germs and makes it fit for drinking.

17.  What is stagnant water?

Ans: Standing water or still water is called as stagnant water.

18.  Why should we not allow water to stagnate around our houses?

Ans: i) Dirty and stagnant water is a major cause of diseases.

ii) Stagnant water is a breeding place for mosquitoes.

So, we should not allow water to stagnate around our houses.

19.  Name some places where water can stagnate.

Ans: Water can stagnate in old or broken containers, in room coolers, in flower pots etc.

20.  Name the diseases which are spread by mosquitoes.

Ans: Malaria, dengue and chikungunya are spread by mosquitoes.

21.  State two ways that can be used to prevent breeding of mosquitoes in room coolers.

Ans: We can adopt the following measures to prevent the breeding of mosquitoes in room coolers,        i) We should change water in room coolers after every 3-4 days.

ii) When water in room coolers cannot be changed, two spoons of kerosene should be put in it.

22.  Which substances are used for making containers of water?

Ans: Copper, brass, steel and plastics are used for making water containers.

23.  Why proper storage and safe handling of water is important?

Ans: Proper storage, and safe handling, of purified water is very important to keep the germs away.

24.  State the ways of safe handling of drinking water.

Ans: Some ways of proper storage and safe handling of water are,

i) Water should always be stored in clean and covered containers.

ii) We should never dip our hands in water stored for drinking purpose.

iii) We should use a ‘ladle’, or some other clean utensil, to take out water from a container.

iv) We should not drink water that has been stored for many days.