Forests Our Lifeline Science

Question 1

Explain how animals dwelling in the forest help it grow and regenerate.AnswerAnimals dwelling in the forest help in various way for growth and regenerate. Some of them are:

i) Animals helps in the seed dispersal and pollination

ii) Dead and decaying bodies of animals convert to humus after decomposition which increase the fertility of the soil of the forest.

iii) Dungs of animals provide nutrient to various types of seedling to grow. 

iv) Herbivores animals clear the land by eating grass for the new growth of vegetation.

Question 2

Explain how forests prevent floods.AnswerForest acts as a natural absorber of rainwater and allows it to seep. It helps in controlling the flow of water and slows it down which helps in preventing flood. Also, the trees present in the forest prevents the rain from directly hitting the ground and bind the soil together which helps in absorption of the rain water and thus prevent flood.

Question 3

What are decomposers? Name any two of them. What do they do in the forest?Answer

The micro-organisms which convert the dead plants and animals to humus are known as decomposers.Bacteria and fungi are the two examples of decomposers.They play an important role in the decomposition of dead remains of the plants and animals and converting them to humus which add nutrient to the soil.

Question 4

Explain the role of forest in maintaining the balance between oxygen and carbon dioxide in the atmosphere.AnswerForest play an important role in maintaining the balance between oxygen and carbon dioxide in the atmosphere. The animals during respiration inhale oxygen and release Carbon dioxide in the atmosphere. The green plants and trees present in the forest take in carbon dioxide and release oxygen through the process of photosynthesis. So plant help to provide oxygen for animal

respiration. Thus it maintains the balance between oxygen and carbon dioxide in the atmosphere.

Question 5

Explain why there is no waste in a forest.AnswerThere is no waste in a forest because whatever produced here are utilized by the other organisms or plants for sustainability. Even the waste materials and dead remains which are produced are biodegradable and converted into humus which returns back the nutrient back to the soil.

Question 6

List five products we get from forests?AnswerFive products we get from forests are:(i) Wood(ii) Resins, gums(iii) Fruits and Vegetables(iv) Honey(v) Medicines (Tulse,Neem,alovera etc.)

Question 7

Fill in the blank:(a) The insects, butterflies, honeybees and birds help flowering plants in ___________ .(b) A forest is a purifier of _____________ and _______________ .(c) Herbs form the ______________ layer in the forest.(d) The decaying leaves and animal droppings in a forest enrich the ______________ .

Answer(a) pollination .(b) water, air .(c) lowest.(d) soil .

Question 8

Why should we worry about the conditions and issues related to forests far from us?AnswerWe should worry about the conditions and issues related to forests far from us because more or less we are dependent on it because

i) As we know from the process of photosynthesis, The amount of carbon dioxide in air will increase if forest will disappear and thus less oxygen in atmosphere to breathe in.

ii) Increase in the percentage of carbon dioxide will also leads to global warming.

iii) There is also imbalance in nature and thus causing climate changes and less rainfall.

iv)

Forests are the dwelling of many animals, so Deforestation will endanger our life and environment and also there will be no shelter for animals. 

v) There will be more soil erosion and thus increase in floods as soil will not able to hold water 

Question 9

Explain why there is a need of variety of animals and plants in a forest.AnswerThere is a need of variety of animals (Herbivores, Carnivores) and plants in a forest as each of them contribute for maintaining the ecosystem of the forest. This biodiversity helps forest in regeneration and growth. Herbivores are needed to eat green plants and to provide food for the carnivores and Carnivores are needed to eat herbivores and check their population. If there are no Carnivores, herbivores population will grow and they will eat all plant and thus shortage of food. Also, decomposers (The micro-organisms which convert the dead plants and animals to humus ) are needed to maintain the supply of nutrients to the soil and to the growing plants else dead remains would pollute the forest.

Question 10

In below figure the artist has forgotten to put the labels and directions on the arrows. Mark the directions on the arrows and label the diagram using the following labels:         clouds, rain, atmosphere, carbon dioxide, oxygen, plants, animals, soil, roots, water table.

Answer

Question 11

Which of the following is not a forest product?(i) Gum(ii) Plywood(iii) Sealing wax(iv) KeroseneAnswer

(iv) Kerosene

Question 12

Which of the following statements is not correct?(i) Forests protect the soil from erosion.(ii) Plants and animals in a forest are not dependent on one another.(iii) Forests influence the climate and water cycle.

(iv) Soil helps forests to grow and regenerate.Answer

(ii) Plants and animals in a forest are not dependent on one another.

Question 13

Micro-organisms act upon the dead plants to produce(i) sand (ii) mushrooms(iii) humus(iv) woodAnswer

(iii) humus

Soil

Question 1

In addition to the rock particles, the soil contains  (i) air and water  (ii) water and plants  (iii) minerals, organic matter, air and water  (iv) water, air and plantsAnswer(iii) minerals, organic matter, air and water

Question 2

The water holding capacity is the highest in  (i) sandy soil  (ii) clayey soil  (iii) loamy soil  (iv) mixture of sand and loamAnswer(ii) clayey soil

Question 3

Match the items in Column I with those in Column II:

Column I Column II

(i) A home for living organisms (a) Large particles

(ii) Upper layer of the soil (b) All kinds of soil

(iii) Sandy soil (c) Dark in colour

(iv) Middle layer of the soil (d) Small particles and packed tight

(v) Clayey soil (e) Lesser amount of humus

Answer

Column I Column II

(i) A home for living organisms (b) All kinds of soil

(ii) Upper layer of the soil (c) Dark in colour

(iii) Sandy soil (a) Large particles

(iv) Middle layer of the soil (e) Lesser amount of humus

(v) Clayey soil (d) Small particles and packed tight

Question 4

Explain how soil is formed.AnswerThe soil is formed by the process of weathering. Weathering is the process of physical breakdown and chemical decomposition of the rocks and minerals at the surface of the earth. It happened by the action of wind, water and climate. It is a very slow process and big rocks get converted into soil.

Question 5

How is clayey soil useful for crops?AnswerClayey soil is very useful for crops because:(i) It has very good water retaining capacity due to very small size particle which are packed tightly(ii) This soil is rich in humus and is very fertile.

(iii) It contains useful organic minerals.These properties of clayey soil are very suitable for growing crops like wheat, paddy, gram etc.

Question 6

List the differences between clayey soil and sandy soil.Answer

Clayey Soil Sandy Soil

(i) It has much smaller particles. (i) It has much larger particles.

(ii) It can retain good amount of water. (ii) It cannot retain water.

(iii) It is fertile and rich in humus (iii) It is not fertile.

(iv) less air is trapped in it (iv) Air get trapped between the particles.

(iv) Particles are tightly packed (iv) Particles are loosely packed

(iv) Good for growing various crops. (iv) Not suitable for growing crops.

Question 7

Sketch the cross section of soil and label the various layers.Answer

Question 8

Razia conducted an experiment in the field related to the rate of percolation. She observed that it took 40 min for 200 mL of water to percolate through the soil sample. Calculate the rate of percolation.

Answer

Amount of water taken = 200 mL

Time taken by water to percolate = 40 min

 So Rate of percolation = Amount of water taken/Time taken by water to percolate

                                    = 200 mL/40 min = 5 mL/min

Question 9

Explain how soil pollution and soil erosion could be prevented.

Answer

Soil Pollution is the persistent buildup pf toxic substance in the soil

Steps for preventing soil pollution:

 i) Plastic bags should be banned and it doesn't decompose and destroy the fertility of the soil and gives rise to soil pollution. It should be should properly and disposed correctly

ii) Use of organic fertilizers and manure instead of synthetic.

iii) Pesticides and insecticides should be used in limited quantity and find natural way to prevent it.

(vi)Industrial waste shouldn't be dumped directly as it kills necessary microorganisms of soil. It should be treated to make it harmless before dumping.

Soil Erosion is the removal of top layer of soil by strong wind and running water

Steps for preventing soil Erosion:

(i) Plantation should be encouraged because plant roots firmly bind the soil and help in preventing erosion.

ii) proper drainage should be present

Question 10

Solve the following crossword puzzle with the clues given:

Across2. Plantation prevents it.5. Use should be banned to avoid soil pollution.6. Type of soil used for making pottery.7. Living organism in the soil.

Down1. In desert soil erosion occurs through.3. Clay and loam are suitable for cereals like.4. This type of soil can hold very little water.5. Collective name for layers of soil.

AnswerAcross2. Erosion5. Polythene6. Clay7. Earthworm

Down1. Wind3. Wheat

4. Sandy5. Profiled to the ocean.

Transportation in Animals and Plants NCERT SolutionsQuestion 1

Match structures given in Column I with functions given in Column II. 

Column I Column II

(i) Stomata (a) Absorption of water

(ii) Xylem (b) Transpiration

(iii) Root hairs (c) Transport of food

(iv) Phloem (d) Transport of water

- (e) Synthesis of carbohydrates

Answer

Column I Column II

(i) Stomata (b) Transpiration

(ii) Xylem (d) Transport of water

(iii) Root hairs

(a) Absorption of water

(iv) Phloem (c) Transport of food

Question 2

Fill in the blanks.

(i) The blood from the heart is transported to all parts of the body by the __________.(ii) Hemoglobin is present in __________ cells.(iii) Arteries and veins are joined by a network of __________.(iv) The rhythmic expansion and contraction of the heart is called __________.(v) The main excretory product in human beings is __________.(vi) Sweat contains water and __________.(vii) Kidneys eliminate the waste materials in the liquid form called __________.(viii) Water reaches great heights in the trees because of suction pull caused by __________.

Answer(i) arteries.(ii) red blood(iii) capillaries.(iv) heartbeat.(v) urea.(vi) salts.(vii) urine.(viii transpiration.

Question 3

Choose the correct option:(a) In plants, water is transported through (i) xylem           

(ii) phloem          

(iii) stomata               

(iv) root hairAnswer

(i) xylem

(b) Water absorption through roots can be increased by keeping the plants (i) in the shade          

(ii) in dim light             

(iii) under the fan            

(iv) covered with a polythene bag Answer

 (iii) under the fan

Question 4

Why is transport of materials necessary in a plant or in an animal? Explain.Answer(i) All animals and plants required food, water, oxygen for their survival. Transport of these materials in a plant or in animal is necessary for carrying out metabolic activities.(ii) Transportation of these materials help in the supply of nutrients and energy to every parts of

animals and plants need energy which they get from the transported materials.(iii) The waste materials produced during metabolic activities are toxic and hence need to be removed from the body by transportation. They need to be transported to excretory organs

Question 5

What will happen if there are no platelets in the blood?AnswerPlatelets help in the clotting of blood at the time of injury. If there would be no platelets, then there would be no clotting of blood and person may die due to excess flow of blood from the body.

Question 6

What are stomata? Give two functions of stomata.AnswerThe tiny holes or openings present under the leaves of the plants is called stomata.Two functions of stomata:(i) It helps in breathing of the plants.(ii) It helps in exchange of gases takes place inside the plants cells.

Question 7

Does transpiration serve any useful function in the plants? Explain.Answer(i) The excess water absorbed by the root system of the plants lost in the form of water vapour to their surroundings by the process of transpiration.(ii) It also help in transport of absorbed water to the leaves of plants from the roots for photosynthesis and helping the plants keeping erect.(iii) Transpiration also produces cooling effect for the plants.

Question 8

What are the components of blood?AnswerThe main components of blood are:(i) Plasma(ii) Red blood cells (RBC)- It carries oxygen(iii) White blood cells (WBC)- fight again germs(iv) Platelets-It help in clotting of blood

Question 9

Why is blood needed by all the parts of a body?AnswerBlood is needy by all the parts of a body and it plays a important role. Here are some of the reason’s

(i) It carries oxygen to all the parts of the body and also carries carbon dioxide back to the lungs.(ii) It carries digested food to various parts of the body for absorption.(iii) It contains platelets which help in the clotting of blood.(iv) It helps in maintaining constant body temperature.(v) It transports hormones and help in fighting the body with germs and bacteria.

Question 10

What makes the blood look red?AnswerThe presence of red pigment called hemoglobin in red blood cells (RBC) makes the blood look red.

Question 11

Describe the function of the heart.AnswerFunctions of the heart:(i) It helps in the circulation of oxygen rich blood throughout the body by the pumping.(ii) The heart has four chambers. The top chambers are called auricles (or atria) and the lower two chambers are called ventricles.

(iii) The right auricle receives carbon-dioxide rich blood from various parts of the body. The right ventricle pumps the blood to the lungs. Inside lungs, carbon-dioxide is exchanged with oxygen.

iv) The left auricle receives oxygen-rich blood from the lungs. The left ventricle pumps this blood to the rest of the body.

(v) It shows rhythmic contraction and relaxation for movement of blood.

Question 12

Why is it necessary to excrete waste products?AnswerThe waste materials produced during the metabolic activities are toxic to the body and must not be accumulated inside and therefore it has to be excreted out from the body by the process of excretion.

Question 13

Draw a diagram of the human excretory system and label the various parts.

Answer

Respiration in Organisms Science

Question 1

Why does an athlete breathe faster and deeper than usual after finishing the race?AnswerDuring the running, the demand of energy is high but the supply of oxygen to produce energy is limited. Therefore, anaerobic respiration takes places in the muscle cells to fulfill the demand of energy. After finishing the race, an athlete breathes faster and deeper than usual so that more oxygen is supplied to the cells. Extra oxygen is required to burn this lactic acid into carbon dioxide.

Question 2

List the similarities and differences between aerobic and anaerobic respiration.

Answer

Similarities

(i) In both aerobic and anaerobic respiration, food is broken down to release energy.(ii) Both takes place inside cells.(iii) Both produces byproducts

Differences:

Aerobic Respiration Anaerobic Respiration

(i) It breaks down food in the presence of oxygen. (i) It breaks down food   in the absence of oxygen.

(ii) Energy is released in higher amount. (ii) Energy is released in lesser amount.

(iii) CO2 and H20 are it ends product (iii) It end product are Lactic acid, CO2 and alcohol

(iv) It is a slow process and takes longer time to release energy (iv) It is a fast process.

(v) Examples: Animals and plants cells. (iv) Examples: Human cells, yeast, Bacteria etc.

Question 3

Why do we often sneeze when we inhale a lot of dust-laden air?AnswerWhen we inhale dust laden air, these particles get past the hair in the nasal cavity and irritate the lining of the cavity which results in sneezing. We often sneeze when we inhale a lot of dust-laden air to expel out these foreign particles

Question 4

Take three test-tubes. Fill each of them with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2 ?AnswerTest-tube A will have the highest concentration of CO2 because snail inhales dissolved oxygen from water during breathing and releases carbon dioxide(CO2)In test-tubes B and C, the CO2 will be utilized by the water plant for synthesizing food(photosynthesis) and hence there will be less concentration of CO2 in these.

Question 5

Tick the correct answer:(a) In cockroaches, air enters the body through (i) lungs            

(ii) gills             

(iii) spiracles            

(iv) skin

Answer

(iii) spiracles

(b) During heavy exercise, we get cramps in the legs due to the accumulation of  (i) carbon dioxide             

  (ii) lactic acid               

   (iii) alcohol          

   (iv) water

Answer

(ii) lactic acid

(c) Normal range of breathing rate per minute in an average adult person at rest is:  (i) 9 - 12              

  (ii) 15 - 18            

  (iii) 21 - 24              

  (iv) 30 - 33Answer

(ii) 15 - 18(d) During exhalation, the ribs  (i) move outwards            

  (ii) move downwards        

 (iii) move upwards        

(iv) do not move at allAnswer

(ii) move downwards

Question 6

Match the items in Column I with those in Column II:

Column I Column II

(a) Yeast (i) Earthworm

(b) Diaphragm (ii) Gills

(c) Skin (iii) Alcohol

(d) Leaves (iv) Chest cavity

(e) Fish (v) Stomata

(f) Frog (vi) Lungs and skin

- (vii) Tracheae

Answer

Column I Column II

(a) Yeast (iii) Alcohol

(b) Diaphragm (iv) Chest cavity

(c) Skin (i) Earthworm

(d) Leaves (v) Stomata

(e) Fish (ii) Gills

(f) Frog (vi) Lungs and skin

Question 7

Mark T if the statement is true and F if it is false:(i) During heavy exercise the breathing rate of a person slows down. (T/ F)(ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/ F)(iii) Frogs breathe through their skins as well as their lungs. (T/ F)(iv) The fishes have lungs for respiration. (T/ F)(v) The size of the chest cavity increases during inhalation. (T/ F)

Answer

(i) F(ii) F

(iii) T(iv) F(v) T

Question 8

Given below is a square of letters in which are hidden different words related to respiration in organisms. These words may be present in any direction - upwards, downwards, or along the diagonals. Find the words for your respiratory system. Clues about those words are given below the square.

(i) The air tubes of insects(ii) Skeletal structures surrounding chest cavity(iii) Muscular floor of chest cavity(iv) Tiny pores on the surface of leaf(v) Small openings on the sides of the body of an insect(vi) The respiratory organs of human beings(vii) The openings through which we inhale(viii) An anaerobic organism(ix) An organism with tracheal system

Answer

(i) Trachea(ii) Ribs(iii) Diaphragm(iv) Stomata(v) Spiracles(vi) Lungs(vii) Nostrils(viii) Yeast(ix) Ant

Question 9

The mountaineers carry oxygen with them because:(a) At an altitude of more than 5 km there is no air.(b) The amount of air available to a person is less than that available on the ground.(c) The temperature of air is higher than that on the ground.(d) The pressure of air is higher than that on the ground.

Answer(b) The amount of air available to a person is less than that available on the ground.

Physical and Chemical change

Question 1Classify the changes involved in the following processes as physical or chemical changes:(a) Photosynthesis(b) Dissolving sugar in water(c) Burning of coal(d) Melting of wax(e) Beating aluminium to make aluminium foil(f) Digestion of food

Answer

Photosynthesis Chemical change

Dissolving sugar in water Physical change

Burning of coal Chemical change

Melting of wax Physical change

Beating aluminium to make aluminium foil Physical change 

Digestion of food Chemical change

Question 2State whether the following statements are true or false. In case a statement is false, write the corrected statement in your notebook.(a) Cutting a log of wood into pieces is a chemical change. (True/False)(b) Formation of manure from leaves is a physical change. (True/False)(c) Iron pipes coated with zinc do not get rusted easily. (True/False)(d) Iron and rust are the same substances. (True/False)(e) Condensation of steam is not a chemical change. (True/False)

Answer

S.no

Answer Correct sentence

a) False Cutting a log of wood into pieces is a physical change

b) False Formation of manure from leaves is a chemical change.

c) True  

d) False Iron and rust are different substances. Rust is oxide of iron (Fe2O3) 

e) True  

Question 3

Fill in the blanks in the following statements:

(a) When carbon dioxide is passed through lime water, it turns milky due to the formation of _________.(b) The chemical name of baking soda is _________.(c) Two methods by which rusting of iron can be prevented are _________ and _________.(d) Changes in which only _________ properties of a substance change are called physical

changes.(e) Changes in which new substances are formed are called _________ changes.

Answer

(a) calcium carbonate (CaCO3).(b) sodium hydrogen carbonate (NaHCO3).(c) galvanization , painting.(d) physical(e) chemical

Question 4When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.

AnswerWhen baking soda (Sodium Hydrogen carbonate) is mixed with lemon juice, the bubbles which are formed with the evolution of a gas is due to the evolution of carbon dioxide gas.

Baking Soda + Lemon Juice ---à Carbon dioxide + Other substances

Since, there is formation of a new substance in this reaction, it is a chemical change.

 Question 5When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.

AnswerWhen a candle burns, both physical and chemical changes take place.

The melting of wax is physical change as there is no formation of new product.

The burning of wax is chemical change as light is lit up by consuming the energy from wax.

Another example would be eating of food which  is both physical and chemical because  food get digested which is a chemical change and the larger food particles is converted  into smaller food particles which is a physical change.

Question 6 How would you show that setting of curd is a chemical change?AnswerThe curd is formed from milk. Both curd and milk have different properties. Also, once the curd is formed it cannot be reversed back into milk. So, there is formation of new substance with different properties and also an irreversible process, setting of curd is a chemical change.

Question 7 Explain why burning of wood and cutting it into small pieces are considered as two different types of changes.Answer

When we burn wood, it turns into ashes which is a new substance and process is irreversible one, hence is a chemical change. While cutting the wood into small pieces, we get no new substance, hence is a physical change.

Question 8 Describe how crystals of copper sulphate are prepared.AnswerCrystals of copper sulphate are prepared by the method of crystallization.

The procedure followed is given below

1) A cupful of water in a beaker is taken.

2) Few drops of dilute sulphuric acid is added to it.

3)Water is heated and when it starts boiling copper sulphate powder is added slowly while    stirring till no more copper sulphate powder dissolved in it i.e., it becomes saturated

4) Solution is filtered into china dish and allowed to cool without disturbance. After some time, the crystals of copper can be observed in it.

Question 9 Explain how painting of an iron gate prevents it from rusting.AnswerPainting of an iron gate prevents it from rusting because it prevents the direct contact of iron from the environment and hence there is no further exposure of iron to oxygen in moisture which causes rusting.

Question 10Explain why rusting of iron objects is faster in coastal areas than in deserts.AnswerIron objects get rusted because of the reaction with oxygen present in moist air. In coastal areas, the presence of moisture is more because of sea or ocean while in deserts the air is dry and hot. Therefore, rusting of iron objects is faster in coastal areas than in deserts due to presence of moisture.

Question 11 The gas we use in the kitchen is called liquefied petroleum gas (LPG). In the cylinder it exists as a liquid. When it comes out from the cylinder it becomes a gas (Change–A) then it burns (Change–B). The following statements pertain to these changes. Choose the correct one.(i) Process – A is a chemical change.(ii) Process – B is a chemical change.(iii) Both processes A and B are chemical changes.(iv) None of these processes is a chemical change.Answer(ii) Process – B is a chemical change.

Question 12 Anaerobic bacteria digest animal waste and produce biogas (Change –A). The biogas is then burnt as fuel (Change –B). The following statements pertain to these changes. Choose the correct one.(i) Process – A is a chemical change.

(ii) Process – B is a chemical change.(iii) Both processes A and B are chemical changes.(iv) None of these processes is a chemical change.Answer(iii) Both processes A and B are chemical changes.

Waste Water StoryWaterWater is an essential element in daily life. Water is used by all living organisms on earth to perform their life processes. Contaminants are the suspended and dissolved impurities of water. Humans contaminate water by their activities. Drinking contaminated water results in the development of diseases such as cholera, typhoid and arrowhead. Polluted water can sometimes be fatal. Water should be boiled and filtered before it is used for drinking as it contains many impurities that are not visible to naked eye. 

Waste water Waste water is the contaminated water which is often referred to as liquid waste. Liquid waste is mainly released from wash rooms, kitchen and other areas where sewage gets collected. Liquid wastes are usually disposed through closed drains.

Components of waste water There are many components of waste water.

Sewage or liquid waste makes up the main component of waste water. Human excreta in the form of faeces is the main suspended impurity in the sewage. Oil and grease float as layers or froth on the waste water. Industrial liquid wastes are the effluents contaminating water. Agricultural wastes like pesticides, fertilisers do not dissolve in water but remain in the waste water.

Causes for contamination of water

Human activities like bathing and washing clothes in rivers and lakes. Animals bathing in rivers and lakes. Increase in population forms the major cause for water contamination. Untreated sewage. Industrial wastes. Agricultural wastes.

Water scarcityWater scarcity refers to lack of sufficient access to drinking water. Water has become so scarce that many people have to travel several kilometres to fetch drinking water. More than 1.5 billion people all over the world do not get clean drinking water. March 22nd is celebrated as World Water Day. It was on March 22, 2005, that the United Nations declared 2005-2015 as the International Decade for the Action “Water for Life”.Every house releases lot of waste water daily. Waste water should be cleaned before it is drained into water bodies.

SewageSewage is liquid waste containing dissolved impurities called as contaminants. Contaminants are the harmful substances which can cause illness. Sewage comprises dissolved and suspended impurities.

Organic and inorganic impurities: Organic impurities in sewage include animal waste, urine, oil, vegetable and fruit waste, faeces, pesticides and herbicides. Inorganic impurities include phosphates, nitrates and metals.

Disease-causing bacteria: Coliform bacteria and certain Bacilli. Saprotrophic bacteria: Bacteria that feed on dead organisms. Nutrients: Sewage contains some useful nutrients, such as phosphorus and nitrogen. Other microbes: Microbes that cause typhoid, cholera, diarrhoea and dysentery are present in sewage.

Types of SewageThere are various types of sewage, depending upon the colour and odour.

Sullage water: Waste water released from the kitchen is called sullage water. The contaminants in sullage water are mild detergents, oils and food particles.

Foul waste: Waste water released from toilets is termed as foul waste. It consists of human waste and a lot of bacteria that release gases and bad odour. It is highly infectious.

Trade waste: Wastes released from industries and commercial organisations is called as trade waste. It consists of acids and strong chemicals that are toxic in nature.

Agricultural waste: Rain water which runs off from agricultural field carries toxic substances into water resources.

SewerageSmall and big pipes that carry waste water are called sewers. All sewers together form the sewerage. Waste water is carried from home to the point of disposal, that is, the waste water treatment plant through sewerage. After the treatment of waste water, the clean water is released into nearby water bodies. Sewerage has manholes that can be used to clear blockages. Manholes are located at every 50 to 60 metres in the sewerage. Manholes are placed at every junction of pipes forming sewerage.In the absence of sewerage facility, waste water is directly drained into nearby streams and lakes resulting in water contamination.

Questions & Answers

1 . What is rainwater harvesting

Rain water harvesting is to collect and storing rainwater.

2 . Give some examples of organic impurities.

Some organic impurities are urine, faeces, corpses, carcasses, ashes etc.

3 . What is hard and Soft water

Hard water contains a significant quantity of dissolved minerals, such as calcium and magnesium. In general, hard water is not harmful.

4 . Wastewater management

Open drainage system has a access to contaminate with other water pollutants.