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

 

D.     ANSWER THE FOLLOWING QUESTIONS IN BRIEF.

 

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

Ans: dust and smoke can make rain water impure.

2.      Name any two human activities which can cause water pollution.

Ans: Throwing wastes and bathing cattle in water bodies can cause water pollution.     

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

Ans: Waste materials and harmful chemicals are often dumped by the factories into the rivers.

4.      Name any two diseases that may be caused by drinking polluted water.

Ans: Two diseases that may be caused by drinking polluted water are typhoid and cholera.

5.      Write the names of two types of materials, used by farmers, to increase the production of crops.

Ans: The two types of materials, used by farmers, to increase the production of crops are, pesticides and chemical fertilisers.

 

E.      ANSWER THE FOLLOWING QUESTIONS.

 

1.      How do wastes, from factories and fields, affect the aquatic animals?

Ans: Wastes, from factories and fields, increase the growth of micro-organisms in water. This reduces the supply of oxygen for the aquatic animals.

2.      How can polluted water affect the crops?

Ans: When polluted water is used for irrigation, the fertility of the soil gets reduced and crops can get damaged.

3.      Why are oil spills harmful for marine life?

Ans:  Oil spills form a cover on the surface of water. This cuts off the oxygen supply to the animals living under water.

4.      State any four effects of water pollution.

Ans: (i)  Water pollution leads to the death of marine animals.

(ii) It decreases the fertility of the soil.

(iii) It causes diseases like jaundice, cholera etc.

(iv) It reduces the oxygen supply to the aquatic plants and animals.

5.      State four ways of reducing water pollution.

Ans: Four ways to reduce water pollution are,

(i) wastes from factories and power houses should not be allowed to flow into rivers directly.

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

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

(iv) The use of chemical fertilisers should be minimised.

STD-4, CHAPTER-9: SAFE HANDLING AND STORAGE OF WATER, EXERCISE QUESTION ANSWERS

A.     FILL IN THE BLANKS.

1.      Water, which is fit for drinking, is called ______.

Ans: potable water

2.      Ground water is not fit for drinking because it contains ______ and _______.

Ans: dirt and germs

3.      _____ removes dust from water.

Ans: filtration

4.      ______ and _____ kill germs present in water.

Ans: boiling and chlorination

5.      Water should always be stored in ____ and ____ utensils.

Ans: clean and covered

B.      WRITE TRUE OR FALSE FOR THE FOLLOWING STATEMENTS.

 

1.      We should always store drinking water in covered clean containers.    True

2.      We can drink water that has been stored for many days.                        False

3.      We need to purify water before drinking it.                                                True

4.      We can allow water to stagnate around our house.                                  False

5.      We should use a ladle to take out water from a container.                     True

 

C.      TICK THE CORRECT OPTION.

 

1.      Germs, present in water, may be killed by-

(a)   Simple filtration

(b)   Storing it in covered containers

(c)    Storing it for many days

(d)   Chlorination

      Ans: chlorination

2.      By drinking unclean water, one may get a disease like-

(a)   malaria

(b)   dengue

(c)    chikungunya

(d)   jaundice    

      Ans: jaundice

3.      Dust and other suspended particles present in unclean water can be removed-

(a)   boiling

(b)   keeping it in a fridge

(c)    filtration

(d)   chlorination 

       Ans: filtration

4.      Our body requires, and uses, water for-

(a)   breathing

(b)   digestion of food

(c)    preparation of food

(d)   transpiration           

      Ans: digestion of food

D.     ANSWER THE FOLLOWING QUESTIONS IN BRIEF.

 

1.      State the meaning of the term ‘potable water’.

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

2.      Name any two diseases that can be caused by drinking unclean water.

Ans: The two diseases that can be caused by drinking unclean water are, jaundice, diarrhea, dysentery and cholera.     

3.      Name the diseases which are spread by mosquitoes.

Ans: The diseases which are spread by mosquitoes are, malaria, dengue and chikungunya.

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

Ans: Boiling kills the germs present in water, making it safer for drinking.

5.      Name two methods of purification of water.

Ans: Two methods of purification of water are, boiling and filtration.

6.      State any two ways of safe handling of drinking water.

Ans: Two ways of safe handling of drinking water are,

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

(ii) We should use a ladle to take out water from a container

E.      ANSWER THE FOLLOWING QUESTIONS.

 

1.      Why should water be purified before drinking?

Ans: Water from all sources is not fit for drinking. Drinking unclean water can cause diseases like jaundice, diarrhea, dysentery and cholera. Thus, we should purify water before drinking it.

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

Ans: (i) Chlorination is a method to purify water by adding a correct small amount of chlorine in it.

(ii) This kills the germs and makes water fit for drinking.

 

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

Ans: Traditional method of filtration can remove dust and other suspended particles from water. However, this method does not remove germs. Thus, the traditional method of filtration is not completely sufficient for making water fit for drinking.

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

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

(ii) It becomes a breeding place for mosquitoes.

(iii) Diseases like malaria, dengue and chikungunya will be spread.

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

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

Ans: Two ways to prevent breeding of mosquitoes in room coolers are,

(i) Change water in the room coolers after every 3-4 days.

      (ii) If the water cannot be changed, two spoons of kerosene should be put in it.

STD-4, CHAPTER-2: PLANTS, EXTRA QUESTION ANSWERS

 1.      Name the different parts of the plant.

Ans: The different parts of the plant are, leaf, fruit, bud, flower, stem and root.

2.      _______ fixes a plant in the soil.

Ans: Root

3.      _____ supports a plant and keeps it upright.

Ans: Stem

4.      Leaf has _____ in it to prepare food and to give it its green colour.

Ans: Chlorophyll

5.      Fruits have ______ in them which germinate to form plants.

Ans: seeds

6.      Name the underground part of the plant.

Ans: Root is underground part of the plant.

7.      What happens to the roots when the plant grows?

Ans: As the plant grows, its roots become thick and woody with a corky outer layer.

8.      Name the two types of root.

Ans: Roots are of two types, i) Tap roots

                                                   ii) Fibrous roots

9.      In what way(s) is the tap root different from the fibrous root?

Ans: i) Tap root is a single, long root with thin roots arising from it.

ii) Fibrous roots are those in which many roots arise from the base of the stem.

10.  Name some plants which have tap root.

Ans: Some plants which have tap root are, beans, rose, lady finger, neem and peepal.

11.  Name some plants having fibrous roots.

Ans: Some plants having fibrous roots are, cereals, grasses and banana.

12.  How do plants help in soil conservation?

Ans: Roots bind the soil and protect it from getting washed away. Thus, roots help in soil conservation.

13.  State the two main functions of roots.

Ans: The two main functions of roots are,

i) Absorption – Roots absorb water and minerals from the soil.

ii) Fixation – It holds the plant upright in the soil.

14.  Name the substances that are absorbed by the roots.

Ans: Water and minerals are absorbed by the roots.

15.  What are edible roots?

Ans: Those roots which store food for the plant, are called edible roots.

16.  Name some edible roots.

Ans: Some edible roots are, carrot, radish, beetroot.

17.  In what way are the roots of banyan tree and maize ‘special’?

Ans: i) In case of banyan tree, roots grow downwards from the branches. They provide extra support to the banyan tree.

ii) In maize plants also, roots arise from the base of their stem and support the plant.

Thus, roots of banyan tree and maize perform special functions. So, they are special.

18.  Where do mangrove plants appear?

Ans: Mangrove plants are found in marshy areas.

19.  Define atmosphere.

Ans: The air surrounding the earth, makes the atmosphere.

20.  What are aerial roots?

Ans: Those roots which perform the special function of breathing, are called aerial roots. They come out of the soil to get oxygen.

21.  Why do aerial roots need to come out of the soil?

Ans: Aerial roots need to come out of the soil to get fresh air from the atmosphere.

22.  Name some plants having aerial roots.

Ans: Banyan, maize and mangrove plants, have aerial roots.

23.  What should be kept in mind, before cutting trees?

Ans: A written permission from the appropriate authorities is required before cutting trees.

STD-4, CHAPTER-1: MY BODY, EXTRA QUESTION ANSWERS

 1.      Name the sense organs of human body.

Ans: The sense organs of human body are, tongue, ears, skin, nose and eyes.

2.      What are external organs?

Ans: Those organs which can be seen from outside, are known as external organs.

3.      What are internal organs?

Ans: Those organs which are present inside our body and cannot be seen from outside, are called internal organs.

4.      How our body works?

Ans: Our body works with the help of various organs present in it.

5.      Name the components of food.

Ans: The different components of food are, carbohydrates, proteins, fats and other nutrients.

6.      Define ‘digestion’.

Ans: The process by which complex food materials are broken down into simpler forms, is called digestion.

7.      Define ‘digestive system’.

Ans: The system which is responsible for digestion, is called the digestive system.

8.      Name the organs that make up the digestive system.

Ans: The mouth, food pipe, stomach and intestines are the different organs that make up our digestive system.

9.      Name the first part of the digestive system.

Ans: Mouth is the first part of the digestive system.

10.  Name the organ through which food enters the stomach.

Ans: Food enters through our mouth.

11.    Name the organs present inside our mouth.

Ans: Teeth, tongue, are present inside our mouth.

12.  How do our teeth help us?

Ans: i) Teeth help to bite and chew the food.

ii) They also give shape to our face and help us to speak clearly.

13.  Name the two sets of teeth that are formed during one’s life time.

Ans: The two sets of teeth are, temporary teeth (milk teeth) and permanent teeth.

14.    When do the teeth begin to appear in a human baby?

Ans: When the baby is about six months old, his/her teeth begin to appear.

15.  The number of milk teeth (temporary teeth) in humans is ______

Ans: 20

16.  When do the temporary teeth (milk teeth) start to fall out?

Ans: Between the age of six and twelve years, the milk teeth fall out one by one.

17.  What are permanent teeth?

Ans: The set of teeth which replace the milk teeth, are the permanent teeth.

18.  What is the number of permanent teeth?

Ans: The number of permanent teeth in humans, is 32.

19.  Name the different types of teeth.

Ans: The different types of teeth are,

i)  Flat teeth (Incisors)

ii)Pointed teeth (Canines)

iii) Broad and Grooved teeth (Premolars and molars)

20.  Where the flat teeth are located?

Ans: Flat teeth, are located in the front of the mouth.

21.  What is the shape of incisors?

Ans: Incisors are flat in shape.

22.  What is the total number of incisors (flat teeth) in our mouth?

Ans:  Total 8 incisors are present in our mouth.

23.  How many incisors are present in each jaw?

Ans: 4 incisors are present in each jaw.

24.  What is the function flat teeth (incisors)?

Ans: The incisors are used for biting and cutting the food.

25.  Where the pointed teeth are located?

Ans: The pointed teeth are located on either side of flat teeth.

26.  What is the shape of canines?

Ans: Canines are pointed in shape.

27.  What is the number of canines in each jaw of human mouth?

Ans: 2 canines are present in each jaw of human mouth.

28.  What is the total number of canines in human mouth?

Ans: 4 canines are present in human mouth.

29.  What is the function of canines?

Ans: Canines are used for tearing the food.

30.  What is the shape of pre-molars and molars?

Ans: Pre-molars and molars are broad and grooved.

31.  Where are the pre-molars located?

Ans: Pre-molars are located next to canines.

32.  What is number of pre-molars in each jaw?

Ans: 4 pre-molars are present in each jaw.

33.  What is the total number of pre-molars in humans?

Ans: The total number of premolars in human mouth is 8.

34.  Where are molars located?

Ans: Molars are located next to premolars.

35.  What is the number of molars in each jaw?

Ans: The number of molars in each jaw of human being is 6.

36.  What is the total number of molars in human mouth?

Ans: The total number of molars in human mouth is 12.

37.  What is the function of molars and premolars?

Ans: molars and pre-molars are used for chewing and grinding the food.

38.  Name the different types of teeth present in the mouth. Also mention their numbers, location and functions.

Ans:

Type of teeth	Shape	Location	Number in Each Jaw	Total number in Human Mouth	Function
Incisors	Flat	In the front	4	8	Biting and cutting the food.
Canines	Pointed	On either side of incisors	2	4	Tearing the food
Premolars	Broad and Grooved	Next to canines	4	8	Chewing and grinding the food
Molars	Broad and Grooved	Next to premolars	6	12	Chewing and grinding the food.

 

39.  Why is it important to take care of our teeth?

Ans: If we do not take care of our teeth, they may decay and fall. So, it is important to take care of our teeth.

40.  Describe the ways to protect our teeth.

Ans:We should,

 i) Brush teeth twice a day- in the morning and at night.

ii) Wash our mouth after every meal.

iii) Avoid eating sweets or sugary snacks and taking soft drinks as much as possible.

iv) Visit a dentist for regular dental check ups.

v) Eat fruits, like apple and guava, and vegetables, like radish and carrot.

vi) Clean the tongue to remove germs.

vii) Eat calcium rich food, like eggs, milk and milk products for strong teeth.

41.  We should avoid eating sweets or sugary snacks and taking soft drinks, as they can cause ___.

Ans: Tooth decay

42.  Why should we eat fruits, like apple and guava?

Ans: We should eat fruits, like apple and guava as these foods give exercise to our gums.

43.  Why should we clean the tongue?

Ans: We should clean the tongue to remove germs.

44.  Eggs, milk and milk products are rich in _____.

Ans: Calcium

45.  A doctor for teeth is called a ______.

Ans: Dentist

46.  Describe the correct way to brush our teeth.

Ans: i) Brush up and down in front.

ii) Then brush up and down the back.

iii) Always brush the teeth with a circular movement.

47.  What is the cause of tooth decay?

Ans: If sugar and bacteria are left on the teeth for long, they can cause tooth decay.

48.  What is enamel?

Ans: The white outer covering of teeth is called enamel.

49.  Name the hardest substance in the human body. (OR) Name the white outer covering of teeth.

Ans: Enamel

50.  What is the function of tongue?

Ans: i) Tongue is used for tasting, licking and speaking.

ii) Tongue also pushes the food into the food pipe at the time of swallowing.

51.  Name the sensitive sites of tongue and their location.

Ans:i) The back of the tongue is sensitive to bitter taste.

  ii) Its sides are sensitive to sour and salty tastes.

iii) The tip of the tongue is sensitive to sweet taste.

52.  Name the glands present in the mouth.

Ans: Salivary glands are present in the mouth.

53.  How many pairs of salivary glands present in the mouth?

Ans: There are three pairs of salivary glands present in the mouth.

54.  Name the gland that secretes saliva.

Ans: The salivary glands secrete saliva.

55.  Name the part, where the process of digestion starts.

Ans: The process of digestion starts in the mouth.

56.  How the process of digestion is carried out in mouth?

Ans:i) Teeth helps in breaking the food into smaller pieces and chewing it.

ii) Saliva gets mixed with the food and makes it soft.

iii) Saliva converts insoluble starch into soluble sugar.

57.  Why is it important to chew the food properly?

Ans: It is important to chew the food properly for proper digestion of food.

58.  After chewing the chappati for a longer time, it starts tasting a little sweet. Why?

Ans: The saliva acts on the food. It converts the starch into sugar. So, after chewing the chappati for a longer time, it starts tasting a little sweet.

59.   The food from the mouth goes into the _____.

Ans: Food pipe

60.  The food from the food pipe goes into the _______.

Ans: stomach

61.  What happens to the food when it enters the stomach?

Ans: i) The stomach stores the food for a few hours.

ii) The food mixes with the digestive juices secreted by the walls of the stomach.

ii) The food is partially digested here.

62.  The food leaves the stomach and enters into the ______.

Ans: Small intestine

63.  Name the glands that pour their juices into the small intestine.

Ans: Liver and pancreas pour their juices into the small intestine.

64.  Name the largest gland of our body.

Ans: Liver is the largest gland of our body.

65.  What happens to the food when it enters the small intestine?

Ans: i) Juices from liver and pancreas, mixes with the food in the small intestine.

ii) The food gets completely digested.

iii) The walls of the small intestine absorb the digested food and pass it to blood.

66.  How the digested food reaches all parts of the body?

Ans: Blood carries the digested food from the small intestine to all parts of the body.

67.  What happens to the undigested food?

Ans: i) The undigested food passes into the large intestine.

ii) Then it is collected in the rectum and is eliminated through the anus.

68.  Which part of the digestive system absorbs water?

Ans: Large intestine absorbs water.

69.  What are the benefits of cooking food before eating?

Ans:i) Cooking makes the food soft, tasty and digestible.

ii) It also kills the germs that may be present in the food.

70.  Describe the points that should be kept in mind at the time of eating food.

(OR) List some good habits that should be taken care of at the time of eating food.

Ans: One should,

i) wash hands before eating.

ii) chew food properly before swallowing.

iii) not speak while chewing food.

iv) eat green vegetables and fruits everyday.

v) eat a balanced diet.

vi) take food at fixed intervals.

vii) drink about 8-10 glasses of water everyday.

71.  How can cooked as well as uncooked food become the source of many infections?

(OR) Why is it important to eat fresh and clean food?

(OR) Why is washing of fruits and vegetables important for us?

Ans: i) Unwashed fruits and vegetables can carry germs which may cause different diseases.

ii) Unwashed fruits and vegetables can also carry very small eggs of worms. When they reach our stomach, they can produce worms, making the person weak and unhealthy.

iii) Peeled and cut fruits and vegetables, which are exposed to flies and dust, can transfer germs into the body.

iv) Cooked food when left uncovered or unrefrigerated for long, can also cause food poisoning.

So, it is very important to eat fresh and clean food.

72.  Name some diseases that we are likely to suffer, by eating poisoned or unhealthy food.

Ans: We may suffer from, diarrhea, vomiting, jaundice, cholera, etc. by eating unhealthy food.

73.  How food poisoning occurs?

Ans:i) When food is kept uncovered or unrefrigerated for long, germs grow and multiply in the food.

ii) The germs produce harmful substances which results in food poisoning.

74.  What measures should be taken by a person suffering from diarrhea?

Ans: A person suffering from diarrhea and vomiting should take plenty of boiled water containing a small amount of sugar and salt.