SCIENCE NOTES, CLASS – 6 LESSON1:

SOURCES OF FOOD SECTION; B Very Short Answer Questions. 1. What are the materials needed to prepare food items called? Ans: Ingredients 2. What are the animals that eat only plants called? Ans: Herbivores 3. Name two edible underground stems. Ans: Potato and onion/ginger 4. Why do we need food? Ans: We need food to get energy, to work and to get nutrients that help in the repair, growth and maintenance of our body cells and protect from diseases. Short Answer Questions. 1. What is apiculture? Ans: The rearing of honeybees on a large scale is called apiculture. 2. What are decomposers? Give two examples of decomposers. Ans: The organisms that feed on dead animals and plants and decompose them are called decomposers. Some of the fungi and bacteria are examples of decomposers. 3. How are scavengers and decomposers useful to us? Ans: Scavengers eat the dead bodies of plants and animals. Decomposers decompose the remains. In this way, they help to keep the earth clean. Without these organisms, our planet would be a heap of dead plants and animals. 4. How do the parasites living inside the host's body get their food? Ans: The parasites like tapeworms and roundworms that live inside the bodies of animals, absorb the food digested by the host. 5. Define carnivores. Ans: Animals that eat only the flesh of other animals are called carnivores. E.g., Lions, tigers, eagles, wolves, etc. 6. Honeybees work hard to collect nectar from flowers. (a) Why do honeybees collect nectar? Ans: Honeybees collect nectar to prepare honey. (b) What value do you learn from honeybees? Ans: We learn team work i.e., working hard together from honeybees. D. Long Answer Questions. 1. How will you sprout seeds? Ans: To sprout seeds, take some seeds like moong or gram in a container filled with water and leave it for a day. Next day, drain out the water completely. Wrap the seeds in a piece of cotton cloth and keep them

aside. After a day, we observe small white structures growing out of the seeds. These seeds are called sprouted seeds. 2. Distinguish between (a) Herbivores and Carnivores. Ans: Animals that eat only plants and plant products are called herbivores. Cow, goat, sheep, etc., are examples of herbivores. Animals that eat only the flesh of other animals are called carnivores. Lion, tiger, leopard, etc., are examples of carnivores. (b) Scavengers and Decomposers. Ans: Scavengers are animals that eat the flesh of dead animals. Jackals, hyenas and vultures are examples of scavengers. Some living organisms in nature like some of the fungi and bacteria feed on dead plants and animals and decompose them. These are called decomposers. 3. What is a food chain? Explain. Ans: Food chain is a series of organisms linked together by the process of eating and being eaten for food. All food chains start with green plants. Plants are the only organisms on the Earth that trap solar energy and make their food through photosynthesis. Plant-eating animals (Herbivores) get energy by eating the green plants which in turn are eaten by flesh-eating animals (carnivores). This feeding relationship among animals is shown by a food chain. Thus, a food chain consists of a series of animals through which energy flows. A simple food chain is given below. Producer Primary Secondary Tertiary

Consumer Consumer Consumer (Plant) (Herbivore) (Carnivore) (Top carnivore) E.g., grass—> grasshopper —> frog —>eagle E. HOTS (Higher Order Thinking Skill) Questions. 1. Radhika loves to eat chicken biryani at her favorite restaurant but she could not resist eating special Paneer stuffed chholebhature from the same restaurant. What type of food habit does Radhika have? Ans: Radhika is an omnivore. 2. Deer are herbivores but bears are omnivores. Why? Ans: Deer eat only plants and plant products thus are herbivores, while bear seat both plant products and flesh of other animals. Thus, they are called omnivores. 3. Can a food chain start from ‘deer’? Why? Ans: No, a food chain always starts from plants because plants are the only organisms on the Earth that can trap and utilize solar energy to make their own food. This energy gets transmitted to the animals directly or indirectly as food.

SCIENCE NOTES, CLASS – 6 4. Your mother makes food in the kitchen .Is she a ‘producer’? Why /Why not? Ans: Producers are the organisms that prepare their own food by trapping solar energy. Green plants are called producers because they trap the energy of the Sun and prepare food from carbon dioxide, water and Chlorophyll through the process of photosynthesis. Your mother is not a producer because she does not make food on her own. She uses many ingredients that are obtained from plants and animals and cooks food. F. Application Based Questions. 1. Look at the delicious pizza shown in Fig. and (a) Identify the sources from which its ingredients are obtained.

ANS: Paneer and cheese — from milk Tomato — from tomato plant Mushroom — from fungi Maida — from wheat grains (plants) 2. Make a food chain in (a) A pond. Ans: Food chain in a pond Phytoplankton —> zooplankton —> small fish —> big fish (b) A desert. Ans: Food chain in a desert Plants/grains —> desert rat —> desert snake —> eagle CROSSWORD PUZZLE: Solve the following crossword puzzle: Across: 1. Animals that eat both plants and flesh of other animals: Omnivores 2. Animals that live on or inside the body of other animals: Parasites 3. A series of organisms linked together by the process of eating and being eaten for food: Food chain 4. A tasty and nutritious food item obtained from beehives: Honey Down: 5. The materials needed to prepare food items: Ingredients 6. Rearing of honeybees on a large scale is called: Apiculture 7. The parts of a plant which can be eaten are called _____ parts: Edible -----------------------------------------------------------------------

LESSON 2: COMPONENTS OF FOOD

SECTION B B. Very Short Answer Questions. 1. Name two food items that are rich in (a) Iron (b) Calcium Ans: (a) green leafy vegetables and groundnuts are rich in iron. (b) Milk and eggs are rich in calcium. 2. Name two sources of roughage. Ans: Raw vegetables and fruits are sources of roughage. 3. Which mineral is vital for bones and teeth? Ans: Calcium and phosphorus 4. Which component of food plays an important role as a solvent in the transport of minerals, digestion of food and excretion of waste products? Ans: Water 5. Why should we avoid fat – rich foods? Ans: We should avoid fat—rich food because overeating of fat—rich food leads to obesity. C. Short Answer Questions. 1. How do we get most of the water needed by our body? Ans: Most of the water needed by our body comes from plain drinking water and beverages like tea and coffee. We also get some water from the food items we eat like fruits, vegetables, meat and fish. 2. Give two cooking practices that lead to the loss of nutrients in food materials. Ans: (i) If cooking is done in excess of water and the water is thrown away after cooking, many water—soluble vitamins and minerals are lost. (ii) If cooking is done at high temperature, many proteins and vitamins are destroyed. (iii) Washing of some peeled and cut vegetables and fruits. (iv) Repeated washing of pulses and rice. 3. Differentiate between the two types of carbohydrates found in our food. Ans: The two types of carbohydrates in our food are sugars and starch. Sugars are simple carbohydrates and found in the form of glucose and fructose. They have a sweet taste. They provide instant energy. E.g., glucose and cane sugar starch is a complex carbohydrate. It is the reserve food material of plants. Pure starch is tasteless and odourless white powder. It provides energy comparatively slowly than sugars. E.g., Rice, wheat and potato. 4. Define balanced diet. Is it the same for every person? Why /Why not? Ans: A balanced diet is a diet that contains adequate amount of all the essential nutrients, roughage and water for the proper growth and development of the

SCIENCE NOTES, CLASS – 6 body. It is not same for every person. It depends on sex and age of the person, occupation (type of work done) and special needs (like during pregnancy). 5. One day, Rohan’s maid brings her 1-year –old son, Monu, with her. Rohan finds that Monu has sunken eyes, dry and wrinkled skin, a very weak and thin body. He requests his mother to give him some milk and eggs. (a) Which disease do you think Monu is suffering from? Ans: Monu is suffering from marasmus. (b) What value is displayed by Rohan's action? Ans: Rohan’s action shows caring, sharing, humanity and kindness for the poor/under privileged people. 6. Why is roughage important for us? Ans: Roughage is fibrous indigestible material present in our body that adds bulk to the food. This helps our body to get rid of undigested food and thereby prevents constipation. Roughage can absorb a great amount of water and helps retain water in the body. 7. Which component of food may be lacking in the diet of following people? (a) A child suffering from kwashiorkor Ans: Protein (b) A person suffering from Scurvy Ans: Vitamin C (c) A person suffering from Rickets Ans: Vitamin D (d) A person suffering from Anaemia Ans: Iron 8. Why do we need to take dietary iodine? Ans: Iodine is essential for the formation of Thyroxine hormone (secreted by thyroid gland) which controls physical, mental and sexual development of body. Lack of iodine in diet causes goiter (abnormal enlargement of the thyroid gland), retarded growth and mental disability. D. Long Answer Questions. 1. What are the symptoms of marasmus? Ans: The symptoms of marasmus are as follows: (i) Body becomes very lean, thin and so weak that the child may not be able to move. (ii) Skin becomes dry, thin and wrinkled. (iii) Ribs become very prominent. (iv) Sunken eyes (V) Unable to digest and absorb food and may suffer from diarrhea. 2. What is obesity? What are its causes? Ans: The overeating of fat-rich foods leads to an overweight condition. This Condition is called obesity. Junk foods like burgers, chips and soft drinks contain large amount of fats and sugars. Due to lack of physical activity, fats get accumulated in the body and causes

obesity. Obesity may cause various cardiovascular diseases like hypertension and arteriosclerosis. 3. What are deficiency diseases? Name three deficiency diseases and also write their causes and symptoms. Ans: Diseases that are caused due to the lack of nutrients (carbohydrates, fats, proteins, minerals and vitamins) in our diet are called deficiency diseases.

Deficiency Diseases

Causes Symptoms

Rickets

lack of vitamin-D

Softened and bent bones, bowed legs due to

malformation of leg bones, pain in bones

Night blindness

lack of vitamin-A

Lack of Poor vision and loss of vision in darkness

(night)

Anemia lack of

iron

Lack of Weakness and fatigue, loss of iron weight, pale skin, loss of appetite

4. (a) Why is water important in our diet ? Ans: Water is the most important constituent of food. Our body contains about 70% of water by weight. Water is needed by our body to perform many vital functions. Some of these are- (i) It regulates the temperature of our body by sweating. (ii) It transports substances and nutrients inside our body. (iii) It acts as an important medium where most chemical reactions occurring in the body take place. (iv) It helps our body absorb nutrients from the food we eat. In rickets, the bones of child are affected. E. HOTS (Higher Order Thinking Skills) Questions. 1. The neck of a person appears to be swollen. Name the deficiency disease he/she is suffering from. What is the cause of this disease? Ans: He/she is suffering from goiter. Lack of iodine in diet causes this disease. 2. If a person has spongy and bleeding gums, general weakness and pain in the muscles, which deficiency disease is he/she is suffering from. What is the cause of this disease? Ans: He is suffering from scurvy. Lack of vitamin C in diet causes this disease. 3. Dietary fibers and water are the food components that do not give us energy but are essential for our diet. Why? Ans: Dietary fibres and water are not food components but they are essential for our diet due to the following reasons. Roughage adds bulk to our diet and helps get rid of undigested food and there by prevents constipation.

SCIENCE NOTES, CLASS – 6 It can also absorb great amount of water and helps retain water in the body. Water is also a most important constituent of food. Our body contains 70% water by weight. Water is needed by our body to perform various vital functions like transportation of nutrients and temperature regulation. The loss of water from the body causes dehydration. F. Application Based Questions. 1. Mrs. Sharma suggested her maid to wash the vegetables before chopping and not after chopping. Does it make a difference? Comment. Ans: Yes, it makes a difference. Washing of vegetables before chopping is a Good practice because washing of cut vegetables and fruits causes a loss of water soluble vitamins. 2. How will you test the presence of protein in milk? Ans: To test the presence of protein in milk. We will take about 10 ml of milk. We will add two drops of copper sulphate solution followed by 10 drops of caustic soda into it. A violet colour appears that indicates the presence of protein in milk. G. Practical Skill Based Question. 1. How will you test the presence of starch in a piece of potato? Ans: We take a piece of raw potato and put a few drops of iodine solution on it, cut surface with the help of a dropper We observe blue-black colour when the iodine drops fall on the cut surface of potato. This shows that the potato contains starch. -----------------------------------------------------------------------

LESSON: 3 FIBRE AND FABRIC

B. Very Short Answer Questions. 1. Name two natural fibers obtained from (a) plants (b) animals Ans: (a) Jute, cotton (b) Wool, silk 2. Name any two mixed fibers. Ans: Terry cot, terry silk/terry wool 3. Name two devices for making fabrics from yarn. Ans: Handloom, power loom 4. What is handloom? Ans: Handloom is a simple machine used to weave on a small scale. It is operated by hand. 5. Define ginning. Ans: Ginning is the process of separation of cotton fibres from their seeds. C. Short Answer Questions. 1. Why do we wear clothes? Ans: We wear clothes to protect our bodies from different weather conditions like heat, cold and rain. We wear different types of clothes according to climate, occupation, culture, tradition and daily needs.

2. Classify the following fibers into natural and synthetic: nylon, wool, cotton, silk, polyester, jute. Ans: Natural fibres - wool, cotton, silk, jute Synthetic fibres - nylon, polyester 3. From which parts of the plant, are cotton and jute obtained? Ans: Cotton is obtained from the seeds of cotton plant. Jute is obtained from the stem of jute plant. 4. How are fibers classified? Give two examples of each. Ans: Fibers are classified according to their sources. Fibers are of three types: FIBRES Natural fibres Synthetic fibres Mixed fibres (Examples: nylon, polyester) (Examples: terry silk, terry wool) Plant fibres Animal fibres Cotton, Jute wool, silk 5. Nikitha sees a poor man shivering in the cold outside her house. She takes permission from her mother and gives him an old blanket. (a)Name the fibers used for making blanket. Ans: Wool (b)Which value is shown by Nikitha? Ans: Kindness, caring and sharing D. Long Answer Questions. 1. Discuss the advantages and disadvantages of natural fabrics. Ans: Advantages of natural fabrics are (i) These fabrics absorb more water and sweat. (ii) They allow air to pass through them. (iii) They are biodegradable and do not affect the environment. Disadvantages of natural fabrics are i) They do not retain their creases for long. ii) They may shrink on ordinary washing. iii) They can easily be attacked by moths and moulds. iv) They do not dry rapidly. (v) Natural silk is very expensive and not affordable. 2. How do you obtain jute fibers from their plants? Explain. Ans: Jute is a plant fibre obtained from the stems of the jute plant. For obtaining jute, the plants are cut during the flowering stage. This is because good quality jute is obtained from young stem otherwise the stem becomes very hard and it is difficult to remove fibres from it. After harvesting, the stalks of the plant are tied into bundles and left in stagnant water.

SCIENCE NOTES, CLASS – 6 In stagnant water, bacteria grow easily and they eat the sticky matter that holds the fibres. This process is called retting. When the stems rot, the fibres are separated by hands and then dried under the Sun. After drying, they are tied into small bundles and sent to the mills. These fibres are then spun and woven into fabrics at the mills. 3. Discuss the uses of jute. Ans: Jute is the second most important fibre after cotton. It is used in following ways- (i) It is used for making gunny bags or sacks. (ii) High quality jute is woven into curtains, carpets, chair coverings and packing for linoleum. (iii) Shopping bags, table mats, jute beads and jewellery are also made up of jute. (iv) Jute bags are extensively used in packing cereals like wheat, jowar and maize. E. HOTS (Higher Order Thinking Skills) Questions. 1. Radhika on a very cold day, took 3 blankets to keep her warm whereas her brother, Raghav, took only thick blanket with thickness equal to 3 blankets. Who will get more warmth and why? Ans: Radhika will get more warmth. The three blankets contain layers of air between them. Air is a poor conductor of heat which prevents the easy conduction of heat as compared to single thick blanket. 2. Mansi is planning to visit Jaipur and Jodhpur during her summer vacation. What should she keep with her nylon leggings or cotton pants with kurtas? Why? Ans: She should keep cotton pants with kurtas because the weather of Jaipur and Jodhpur is hot and she will feel comfortable in cotton pants with kurtas. F. Application Based Questions. 1. Which fabric will you wear while working in the kitchen – cotton or polyester? Why? Ans: Cotton fabric is preferred while working in kitchen because on burning cotton fabric do not stick to the skin. The synthetic fabrics catch fire easily and on burning melt, shrink and become sticky. They stick to the skin and worsen the burn injuries. 2. Aman’s mom is a working woman who leaves for her office early in the morning. She takes a metro to the office and returns late in the evening. What type of fabrics should she use for her dress? Ans: She should use synthetic fabrics for her dress because they are more durable and easy to maintain. They dry up fast and are wrinkle-free.

LESSON: 4 SORTING MATERIALS INTO GROUP

A. Oral questions: 1. On what basis do we classify objects? Ans: We classify objects on the basis of certain similarities and dissimilarities.

2. What is the importance of oxygen dissolved in water? Ans: The oxygen dissolved in water is used by aquatic plants and animals for their survival. 3. Gold and silver are used to make jewellery. Give reason. Ans: Gold and silver are used to make jewellery due to their luster or shine. 4. Why is a tumbler not made with a piece of cloth? Ans: Tumbler is not made with cloth because it is used to contain water and a cloth tumbler cannot retain water. B. Science quiz: 1. Name two natural and human made materials. Ans: Natural materials — wood, gold, cotton, coal, iron Human-made materials -plastic, steel, aluminum, glass 2. Name two translucent materials. Ans: Grounded glass/ tissue paper/ butter paper/ frosted glass/ fog/ mist. 3. Name two liquids which are miscible in water. Ans: Glycerin and vinegar/ alcohol Very Short Answer Questions. 1. Name two transparent objects. Ans: Water and glass/ alcohol/ air/ cellophane paper 2. Name two materials which do not luster. Ans: Wood and plastic rocks/ wood/ aluminum/stones 3. Name two hard and two soft objects. Ans: Iron and copper are hard objects while foam, sponge and melted wax are soft objects. C. Short Answer Questions. 1. (a) What are the three physical states of materials? The three physical states of matter are solid, liquid and gas. (b)Give any two differences between these states. Differences in solid, liquid and gas Parameters Solid Liquid Gas

Shape and Volume

Solids have definite

shape and fixed

volume

Liquids do not definite shape but have fixed

volume

Gases do not have definite

shape and volume

Packing

The molecules are closely

packed

The molecules are loosely

packed

The molecules are freely

packed

Compressibility

Solids can’t be

compressed

Liquids can be

compressible

Gases are highly

compressible

2. (a)What are materials? Materials are substances that are used in making different objects. All the objects are made of one or more kinds of materials. E.g., a chair is made of wood and a steel spoon is made of steel.

SCIENCE NOTES, CLASS – 6 (b)What are the different types of materials? Materials are of two types— natural and human-made. The materials that are obtained from nature are called natural materials, e.g., wood, iron whereas the materials which do not occur in nature but are made by humans in factories by combining two or more materials are called human-made materials. E.g., plastic, aluminum. 3. Classify the following into lustrous and non-lustrous materials: gold chain, plastic bottle, cotton shirt and aluminum rod. Lustrous materials- gold chain, aluminum rod Non-lustrous materials- plastic bottle, cotton shirt 4. Classify the following into hard and soft materials: diamond, wax, brick and tomato. Hard materials-diamond, brick, Soft materials-tomato, wax. 5. We put some sugar in a glass of water and stir. After some time, it disappears. (a)Why did sugar disappear in water? Sugar disappeared in water because it is soluble in water. The particles of sugar have become very small and have spread uniformly in water. (b)What do we learn from this property of sugar which gets mixed in water? We learn to mix, i.e., live in harmony with the people around us irrespective of their religion, caste and social status. D. Long Answer Questions. 1. What are the advantages of classification of objects? We classify objects around us because it has the following advantages: (i) Classification helps in systematic study of objects. (ii) It helps in identifying and locating things. (iii) It helps to study the properties of objects of one category and also observe any pattern in these properties. (iv) It helps us to know how the members of a group different from those of the other groups. 2. How can you find whether a material is lustrous or non-lustrous? In Science, the special shiny appearance is indicated by the term luster. If you observe a gold chain, it has a shiny appearance. So, gold is said to have luster (chamak). On the other hand, if we look at a piece of plastic, it does not have a shiny appearance, thus it does not have luster, and so plastic is non-lustrous material. All the metals like gold, silver, copper, aluminum and iron have shiny appearance and they are lustrous materials. Some metals lose their shine and appear dull due to the action of air and moisture. We can check the lustrous and non-lustrous materials

by observing their freshly cut surfaces and by rubbing the surface with sandpaper 3. (a) What are translucent materials? Give two examples. The materials through which we can see the objects partially are called translucent materials. Frosted glass, fog, mist, grounded glass and tissue paper are translucent materials. (b) What is meant by opaqueness? Explain with examples. The materials through which we cannot see the objects are called opaque materials and this property of materials is called opaqueness. Metals, cardboard, books and wood are examples of opaque substances. 4. (a)What are miscible and immiscible liquids ? The liquid substances that get completely mixed with water are called miscible substances, e.g., vinegar, alcohol, glycerin and the liquid substances that do not mix with water and form a separate layer are called immiscible substances. E.g., kerosene oil, petrol. (b)Is it possible to dissolve gases in water? If yes, give an example. Yes, some gases like oxygen and carbon dioxide can be dissolved in water. These are called soluble gases. E.g., Cold drinks are a mixture of carbon dioxide gas in water. E. HOTS (Higher Order Thinking Skills) Questions. 1. Why are the glasses of the car sometimes coloured? Coloured glass is a translucent material through which we can see the objects partially. The coloured glass of car does not allow the person standing outside to see the person sitting inside clearly. 2. Why are the handles of cooking utensils made up of hard plastic or wood? The handles of cooking utensils are made up of hard plastic or wood because these materials are good insulators of heat. The hard plastic cannot melt easily by heat. 3. Why do solids, liquids and gases have different properties? Solids, liquids and gases are the three physical states of materials where the arrangement of atoms is different. So, they have different properties. 4. What will happen when you pour mustard oil and vinegar on water kept in two separate glasses? Write your observation. When we pour mustard oil on water kept in a glass, it forms a separate layer on water as both water and mustard oil are immiscible liquids. When we pour vinegar on water kept in another glass, it dissolves completely in water and forms a homogeneous solution as both water and vinegar. -----------------------------------------------------------------------

SCIENCE NOTES, CLASS – 6 LESSON: 5

SEPARATION OF SUBSTANCES A. Oral questions. 1. Why do we need to separate different components of a mixture? Ans: We need to separate different components from a mixture to remove undesirable and harmful substances and obtain useful components. 2. What are immiscible liquids? Give two examples. Ans: Liquids which do not mix or dissolve in one another and form separate layers are called immiscible liquids. Examples — (a) Water and kerosene (b) Water and mustard oil 3. What is meant by filtrate? Ans: The clear liquid obtained after filtration is called filtrate. 4. What is meant by residue? Ans: The insoluble solids that cannot pass through the filter paper and Remain on the filter paper during filtration is called residue. B. Science quiz. 1. Name the method which is used to obtain a solid substance that is dissolved in a liquid. Ans: Evaporation 2. How do we get water from a salt solution? Ans: We get water from salt solution through evaporation followed by condensation or through distillation. 3. Give the name of the chemical substance which used for settling down of fine particles of impurities. Ans: Alum 4. Mixture of water and oil and mixture of chalk in water are examples of heterogeneous mixture. B. Circle the odd ones. Give reasons for your choice. 1. Evaporation —> It is used to separate soluble solids dissolved in a liquid. Whereas others are methods of separation of solid substances. 2. Winnowing —> It is used to separate the desired substance (food grains) from a mixture of food grains and husk. Whereas others are the methods of separation of Insoluble solids. 3. Water —> It is a solvent. Others are solid substances. 4. Sand —> It is not a part of solution. Others are used together to form a mixture or solution. B. Very Short Answer Questions. 1. Which method is used to separate grains from stalk? Ans: Threshing 2. Give an example from our daily life where the processes of sedimentation and decantation are used. Ans: Cleaning of muddy water

3. Name any two processes used to separate soluble components from a mixture. Ans: Evaporation and condensation 4. Name the method by which we can separate seeds and pulp from the fruit juice. Ans: Filtration. 5. What is meant by condensation? Ans: The process of changing vapour into its liquid state on cooling is called condensation. E.g., it is used to get water from salt solution. 6. What are the two types of mixtures? Ans: Homogeneous and heterogeneous mixtures C. Short Answer Questions. 1. (a)Why water is called the universal solvent? Ans: Water is called universal solvent because it can dissolve many substances like sugar and salt. (b) Define solubility. How can it be increased in water? Ans: The extent to which a substance gets dissolved in a liquid is called its solubility. The solubility of a solid solute in water can be increased with the rise in temperature. The solubility of gases get affected by changes in temperature and pressure. 2. Define the terms: (a) Sedimentation. Ans: The process of settling down of heavier insoluble particles at the bottom of a liquid is called sedimentation. The heavier insoluble particles at the bottom of the liquid are called sediments. (b)Decantation. Ans: The process of pouring out a clear liquid from a vessel (after sedimentation) without disturbing the sediment (heavy, insoluble settled particles) is called decantation. 3. Can water dissolve any amount of a substance? Explain. Ans: No, water cannot dissolve any amount of a substance. Different substances dissolve to different extent in water at a given temperature. Water can dissolve any substance only up to a limited amount. 4. What is loading? Ans: The process of increasing the rate of sedimentation in a suspension by adding some chemicals to it is called loading. E.g., a piece of alum is used to increase the rate of sedimentation in muddy water. 5. What is the difference between filtrate and residue? Ans; After filtration, the clear liquid that passes through the filter paper and collects in the beaker kept below the funnel is called a filtrate. The particles that cannot pass through the filter paper and remain behind on the filter paper is called residue.

SCIENCE NOTES, CLASS – 6 6. Soni is helping her mother and accidentally she mixes the arhal dal with gram seeds and rice flour. Her brother helps her in separating the things from each other. (a) Which method they would have to separate things? Ans: Sieving and hand picking. Sieving to separate dal and gram seeds from rice flour and then hand picking to separate gram seeds. (b) What value do you learn from Soni’s brother? Ans; From Soni’s brother we learn to be helpful and caring. D. Long Answer Questions. 1. (a)How will you separate the following: mustard seeds and common salt, chalk powder and water, sand and water, grains and stones? Ans: Mustard seeds and powdered common salt are separated by sieving. Chalk powder and water are separated by sedimentation and decantation. Sand and water are separated by sedimentation and decantation. Grains and stones are separated by hand picking. (b)How is fine sand separated from larger particles? Explain. Ans: Fine sand is separated from larger particles through sieving. When the components of a mixture are of different sizes, a sieve can be used to separate them. A sieve is a shallow vessel that has small holes. The size of the holes in the sieve depends on the size of components to be separated. 2. How will you obtain clear water from a sample of muddy water? Ans: We can obtain clean water from muddy water by filtration. Things needed: Muddy water, filter paper, glass rod, iron stand, funnel, and two beakers. Method: Take some muddy water in a beaker. Now, take a circular piece of filter paper and fold it twice. Open it out to make a cone. Place this filter paper cone in a funnel. Water liter funnel. Clamp the funnel containing the filter paper on an iron stand. Keep an empty beaker below the funnel. Pour the muddy water slowly into the cone, using a glass rod. The clear water passes through the filter paper and collects in the beaker kept below the funnel. The clear liquid obtained is called filtrate. Take out the filter paper cone and open it out. Mud particles can be seen on the filter paper this is called residue. In filtration, the mud particles (bigger in size) cannot pass through the filter paper and remain behind on the filter paper.

Diagram:

3. What happens if a saturated solution of a substance and water is (a) heated and (b) cooled? (a) The solubility of a saturated solution increases with the rise in temperature. It means, by heating we can dissolve more solute in a saturated solution. (b) When the saturated solution of a substance is cooled, the solubility of the substance decreases and some of the dissolved substances separates in the form of crystals. 4. (a)Why do we need to separate substances from a mixture? Ans: Separation of substances from a mixture is often necessary for the removal of harmful and undesirable substances and to obtain useful components. (b)Differentiate between homogeneous and heterogeneous mixtures with examples. Ans: Homogeneous mixture is a mixture in which the constituents are uniformly distributed and each part of the mixture has the same properties. For example, salt dissolves in water to form a homogeneous mixture. Particles of salt and water are uniformly distributed and each part of the mixture has the same properties. Heterogeneous mixture is a mixture in which the constituents do not get mixed uniformly and each part of the mixture has different properties. For example, sand and sawdust form a heterogeneous mixture. Each part of the mixture has different properties. E. HOTS (Higher Order Thinking Skills) Questions. 1. How will you separate a mixture of sugar and sand? Ans: Sieving 2. Can a farmer use a pedestal fan to do winnowing? Comment. Ans: Yes, a farmer can use a pedestal fan to do winnowing as it increases the rate of winnowing. Winnowing is used to separate heavier and lighter components of a mixture by moving air or wind. F. Application Based Questions.

SCIENCE NOTES, CLASS – 6 1. Your mother wants to remove pieces of wheat grains from a large quantity of flour .Find out, how she can do that quickly. Ans: By sieving, she can easily remove the wheat grains from wheat flour. 2. Ruchika’s mother went to market to buy fruits and vegetables. Which method did she use to select the best vegetables and fruits in the market? Ans: Hand picking is the best method to select the best vegetables and fruits in the market. -----------------------------------------------------------------------

LESSON: 6 CHANGES AROUND US

B. Circle the odd ones. Give reasons for your choice. 1. Boiling water —> It is a reversible change whereas others are irreversible changes. 2. Hammering of metals —> It is a reversible change, whereas others are natural changes. 3. Tearing of paper —> It is a physical change, whereas others are chemical changes. B. Very Short Answer Questions. 1. What kind of change is burning of paper? Ans: Chemical change 2. What happens when an aluminum rod is heated? Ans: On heating, aluminum rod expands. 3. What happens on cooling of steam? Ans: On cooling, steam changes into water. 4. What type of change is melting of wax? Ans: Physical change/reversible change 5. Is the formation of day and night, a natural or human made changes? Ans: Formation of day and night is a natural change. 6. What change do you observe on applying pressure on brittle substance? Ans: On applying pressure, a brittle object breaks. It is an irreversible change. C. Short Answer Questions. 1. What are reversible changes? Ans: The changes that can be reversed easily by reversing the conditions to obtain a substance in its original form are called reversible changes. E.g., stretching of a rubber band. 2. What are irreversible changes? Ans: The changes that cannot be reversed even by changing the conditions to obtain a substance back in its original form are called irreversible changes. E.g., burning of wood, crackers, ageing of living beings. 3. Neha’s mother is sick. Neha makes vegetable soup for her mother and serves it to her. (a)Can we get the vegetables back from the soup? What type of change does it represent? Ans: No, we cannot get the vegetables back from the soup. It represents an irreversible change.

(b)What value does Neha’s action show? Ans: It is our duty to take care of our parents. Neha's action shows concern and affection for her mother. 4. What are the different ways to bring about changes? Ans: The ways to bring about changes are heating, cooling, applying pressure and mixing of substances. 5. What change do you observe on keeping milk in refrigerator? Ans: The milk kept in refrigerator becomes cold after some time. If milk is kept in the freezer of the refrigerator, then it is converted into frozen milk (solid). In both the cases, the changes are physical. In the first case, the change occurs due to change in temperature. In second case the changes occurs due to change in temperature as well as matter. 6. Classify the following as reversible or irreversible changes: burning of coal, freezing of water, digestion of food, ironing of shirt, baking of chapatti, knitting of a sweater, folding of water and rusting of iron. Ans: Burning of coal, digestion of food, baking of a chapathi and rusting of iron are irreversible changes. Freezing of water, ironing of a shirt, knitting of a sweater and folding of paper are reversible changes. D. Long Answer Questions. 1. Explain how heating or cooling of water brings changes in the state of matter. Ans: Heating and cooling of water brings change in its states. On heating, water changes to steam (water vapour) i.e., water (liquid) changes to gaseous state. This process is called evaporation. On heating, the kinetic energy of water molecules increases. Due to increase in kinetic energy, the particles start moving with greater speed. As the temperature is further increased, the energy supplied in form of heat overcomes the force of attraction between the particles. At this stage, the particles leave their original position and start moving fast and thus, water changes into water vapour. On cooling, water changes into ice, i.e., water (liquid) changes to solid state. This process is called freezing. On cooling, the kinetic energy of water molecules decreases. Due to decrease in the kinetic energy, the water molecules start moving slowly. As the temperature is further lowered, the force of attraction pulls the particles close together and water changes into ice (solid). 2. Explain how a metal rim is fixed around the wooden wheel of a cart. Ans: A metal rim is fixed around the wooden wheel in the following way- The iron rim is made slightly smaller in size than the wooden wheel. The ironsmith heats this iron rim uniformly over fire. On heating, the iron rim expands and becomes somewhat bigger in size.

SCIENCE NOTES, CLASS – 6 This hot iron rim is now easily put around the wooden wheel. Water is then poured over the hot iron rim to cool it. On cooling, the hot iron rim contracts (shrinks) and fits tightly around the wooden wheel. 3. How are physical changes different from chemical changes?

4. Is the burning of a candle, a chemical change or physical change? Explain with reasons. Ans: Burning of candle is a chemical change. On burning a candle, wax burns to produce wax vapors and carbon dioxide. It produces heat and light. Candle becomes smaller on burning. New substances are formed and energy is released during the burning of candle. It cannot be reversed. It is a permanent change. Thus, burning of candle is a chemical change. E. HOTS (Higher Order Thinking Skills) Questions. 1. Why is a gap left between the rails in railway tracks? Ans: In summer, the rail tracks that are made from iron, expand. To allow this expansion, space is left between two sections of the rail tracks. If this is not done, expansion of tracks can cause them to bend that may lead to serious accidents. 2. Why is mercury used in thermometers? Ans: Mercury is a metal and expands on heating. When it comes in contact with heat, the mercury inside it expands and reaches at a certain level according to the temperature. The shining thread of mercury can be easily seen from the outside of a thermometer. 3. What is the difference between the following changes? (a) Rolling of roti from dough— It is an example of a reversible change as we can change the roti into the dough. It requires kinetic energy. (b) Baking of roti— It is an example of irreversible change as on baking, the roti cannot be changed into dough. It requires heat energy. -----------------------------------------------------------------------

LESSON: 7 THE LIVING AND THE NON-LIVING

A. Oral questions. 1. How is the growth of a crystal different from the growth of a baby bird? Ans: The growth of the crystal is external, i.e., due to addition of substances from outside. The growth of baby bird is internal, i.e., from inside due to multiplication and growth of cells. 2. Why do living things respire? Ans: All the living things respire to get energy. 3. How is a lion different from a peepal plant? Ans: (i) A peepal plant can make its food through photosynthesis whereas a lion does not make its own food and gets its food from other animals. (ii) A peepal tree cannot move, whereas the lion can move. (iii) A peepal tree continues to grow throughout its life while the lion grows only up to a certain age. B. Science quiz. 1. Name the structural and functional unit of a living things. Ans: A cell 2. Name a microscopic organism. Ans: Amoeba/Paramecium/bacteria 3. Name the two waste products produced each in animals and plants. Ans: Wastes of plants —gums, resins and latex, carbon dioxide Wastes of animals —urea, carbon dioxide, uric acid, faeces, urine B. Circle the odd ones. Give reasons for your choice. 1. Kitten — It is a living thing. Others are non-living things. 2. Stomata — It is found in plants for gaseous exchange. Others are respiratory organs of different animals. 3. Bird — It is a multicellular organism. Others are unicellular organisms. B. Very Short Answer Questions. 1. Name the process by which living things obtain energy from food. Ans: Respiration 2. Which part of the leaf takes part in exchange of gases? Ans: Stomata 3. Name any two animals which reproduce by (a) Giving birth to babies Ans: Dog/cow/elephant/giraffe/horse (b)Through hatching of their eggs. Ans: Hen/lizard/cockroach/duck/ostrich C. Short Answer Questions.

Physical change Chemical change

i) A change in which no new substance is formed

is called a physical change.

A change in which a new substance is formed is

called a chemical change.

ii) In physical change the state, size and shape of a

substance change. The properties the substance

remain same.

The properties of new substances formed in chemical changes are

entirely the different from those of the original

substances.

iii) Most of the physical changes are temporary

and reversible.

Most of the chemical changes are permanent

and irreversible

iv) Melting of ice and tearing of paper are

physical changes.

Burning of paper and charring Of sugar are

chemical changes

SCIENCE NOTES, CLASS – 6 1. What is meant by lifespan? What is the average lifespan of humans? Ans: The time period for which a living organism remains alive is called its lifespan. The average lifespan of humans is 65-80 years. 2. Which of the following were once a part of living things? Leather, wool, electric bulb, salt, mango, wooden table, metallic bucket. Ans: Leather, wool, mango and wooden table were once a part of living things. 3. What is meant by respiration? Why is respiration essential for living organisms? Ans: Respiration is the process of breakdown of food in the body of an organism with the help of oxygen to release carbon dioxide, water and energy. Respiration is essential for all living things because it provides energy to living things to do work, move and stay alive. 4. Monoj sees a dog in his garden. He picks up a stone and throws it at the dog. The dog gets hurt and within no time bites Manoj’s leg. Manoj’s friend, Arjun, takes him to the doctor. The doctor immediately gives him first aid and injections. Manoj promises his parents and friends that he will not repeat this in future. (a) Name the ‘stimulus’ and ‘response’ in this case. Ans: Throwing stone on dog is a stimulus and biting of dog is a response. (b) What values do you learn from Arjun and Manoj? Ans: From Manoj, we learn to be helpful and kind to others and from the actions of Arjun we learn that we should not harm other animals or plants unnecessarily. D. Long Answer Questions. 1. Explain how different organisms carry out exchange of gases. Give one example of each. Ans: Different organisms carry out exchange of gases the rough different organs. Animals like tigers, cats, dogs and human beings breathe through lungs. Insects like cockroaches, flies, mosquitoes and grasshoppers breathe through air holes (spiracles) present on the surface of their bodies. The fish has special organs of breathing called gills. The gills absorb oxygen dissolved in water. The earthworm breathes through its skin. The skin of an earthworm is quite thin and moist and has a good blood supply. Like animals, exchange of gases also takes place in plants through tiny pores called stomata, present on the surface of the leaves. 2. Animals grow only till a particular age whereas plants grow throughout their life. Justify. Ans: All the living things grow, they become taller and bigger on their own. Growth is actually an increase in size of the body. All the animals grow up to a certain age only. After attaining certain size and shape, they

stop growing. Humans also grow for a few years and then they stop growing. For example, in humans we observe that there is no growth in arms and limbs after a certain age. But in case of plants, a tiny seed grows into a baby plant and after some time it grows into a big plant or tree. Unlike animals, plants continue to grow throughout their life. After attaining a certain height, the plants do not grow in height but only in width. New branches grow. They produce seeds, flowers and fruits. E.g., a peepal tree and a banyan tree lives for 200 years. 3. (a) A plant grows towards sunlight . Mention the stimulus and the response. Ans: Sunlight is stimulus and bending of plant towards sunlight is response. (b) What is meant by ‘stimulus‘ and ‘sensitivity’? Ans: Stimulus is any change in the surroundings of an organism to which it responds. Some examples of stimuli are light, sound, smell and touch. The ability to respond to any external change is called sensitivity. 4. (a)Which characteristic of living things is shown in the Fig.(a) given alongside? Ans: The given picture shows the growth of a tiny seed into a big plant. (b)Distinguish between ‘tissues’ and ‘organs’. Ans: A group of similar cells that perform a particular function is called a tissue. A group of tissues that work together to perform a particular function in the body is called an organ. E.g., heart, lungs, etc. 5. (a)What is the common feature in living things and non-living things? Ans: The common feature in living and non-living things is that they are made up of matter. I.e. they have mass and occupy space. (b)Give any four differences between living things and non-living things.

Living things Non-living things

i) Living things are made

up of cells.

Non-living things are

not made up of cells.

ii) Living things can move

on their own.

Non-living things cannot

move

iii) Living things have a

definite lifespan.

Non-living things do not

have a definite lifespan.

iv) Living things

reproduce.

Non-living things do not

reproduce.

v) Living things need

food to live

Non-living things do not

need food

E. HOTS (Higher Order Thinking Skills) Questions.

SCIENCE NOTES, CLASS – 6 1. While walking, Ibrahim hears a dog barking. He starts running immediately, Mention the stimulus and the response. Give another example mentioning the stimulus and the response. Ans: Barking of dog is a stimulus and running of Ibrahim is response. When we touch the leaves of Mimosa pudica (touch-me-not) plant, it quickly folds its leaves. Here, touching is the stimulus and folding of leaves is the response. 2. A seed is put inside the soil. In which direction, will the stem and roots grow? Ans: The shoot or stem always grows upwards while the roots always grow downwards. 3. Are wheat grains stored in the gunny bags living? Why/Why not? Ans: The wheat grains stored in gunny bags are non-living, but when they were attached to the plant, they were living. -----------------------------------------------------------------------

LESSON: 8 GETTING TO KNOW PLANTS

Very Short Answer Questions. 1. What is male reproductive part of a flower called? Ans: Stamen 2. Name two plants that have reticulate venation. Ans: Peepal and mango/ China rose/ mustard/ cabbage/ lemon/ Neem 3. What is the function of stem in a potato plant? Ans: The stem of a potato plant that is present above the ground, makes food by photosynthesis. The underground stem that is fleshy, stores food and is edible. 4. What is the differences between node and internode? Ans: The part of a stem where a leaf arises is called node and the region of the stem between the two adjacent nodes is called internode. 5. What happens when pollen grains falls on the stigma – fertilization or pollination? Ans: When pollen grains fall on the stigma, they germinate and move down through the tube called style and reach the ovary. Inside the ovary, the male sex cells present in the pollen grains fuse with the female sex cells present in ovules. This is called fertilisation. Short Answer Questions. 1. What is venation? Name two plants that have parallel venation. Ans: The arrangement of veins on leaf blade or lamina is called venation. The leaves of banana, palm, bamboo and sugar cane have parallel venation.

2. What are fibrous roots? Draw a sketch of fibrous roots.

Ans: In some plants, a bunch of thin, fibre-like roots stem arise from the base of the stem. These are called fibrous roots. E.g., onion, rice, grass, maize and wheat are plants that have fibrous roots. 3. What happens to the voule and ovary after fertilization? Ans: After fertilisation, the ovules grow and become seed. The ovary of a flower grows and becomes fruit. The fruit protects the seeds. 4. Shalini sees an uprooted pea plant. She notices some swellings on the roots called root nodules. (a)What do these root nodules contain? Ans: These root nodules contain a nitrogen-fixing bacteria called Rhizobium. (b)What does the relation between the roots of leguminous plants and bacteria teach us? Ans: The relationship between the roots and bacteria teach us to help each other to survive and live in harmony in the society. 5. What is pistil? Draw its labelled diagram. Ans: A pistil is a flask-shaped organ present at the centre stigma of a flower. The pistil is the female reproductive part of the flower. Each pistil consists of stigma, style and ovary

6. Classify the following plants into herbs, shrubs and trees – sunflower, China rose, lemon, tomato, mango, gulmohar, rose plant, mustard. Ans: Herbs—sunflower, tomato, mustard Shrubs—China rose, lemon, rose plant Trees—gulmohar, mango 7. How can you say that ginger is a modified stem? Ans: Ginger is a stem because like stems it also has nodes, internodes, buds and scaly leaves. It is modified to store food.

SCIENCE NOTES, CLASS – 6 D. Long Answer Questions. 1. Write an activity to show that roots absorb water for the plant. Ans: To show that roots absorb water and minerals from the soil Things needed: Two pots, two weed plants, khurpi, some water, soil, a pair of scissors Method: Take two pots (A and B) and fill them with soil. Select two weed plants from an open ground. With the help of a khurpi, dig these plants without breaking their roots. Plant one plant in pot A. With the help of scissors, cut off the roots of the other plant and plant it in pot B. Provide water to both the pots regularly and observe the plants after a week. Observation: The plant in pot A remains healthy, while the plant in pot B wilts and eventually, dries. Result: This activity shows that roots are essential for the absorption of water and minerals from the soil. 2. What are the advantages of transpiration in plants? Ans: The advantages of transpiration are as follows: (i) It helps in cooling the plant body just as loss of water during sweating helps us to keep cool. (ii) When leaves lose water during transpiration, more water and minerals are pulled upwards from the roots to make up for the lost water. Thus, transpiration helps in the conduction of water and minerals in the plant. 3. Describe the structure of flower with a well – labelled diagram. DIAGRAM:

Flowers are the most beautiful part of a plant. Different plants have different types of flowers. The flower is attached to the stem by a stalk called pedicel. The uppermost part of the stalk is somewhat swollen. This swollen part of the pedicel is known as thalamus. Parts of a flower: The main parts of a flower are sepals, petals, stamens and pistil. Sepals - The green, leaf - like parts in the outermost circle of a flower are called sepals. They protect the flower during the bud stage.

Petals — these are usually brightly coloured due to the presence of coloured pigments. The brightly - coloured petals serve to attract insects which help in pollination. Stamens — they are found just inside the petals. The stamen is the male reproductive part of a flower. Each stamen consists of a thin stalk called filament and a two-lobed head called the anther. Each anther lobe has two pollen sacs that are filled with pollen grains. Pollen grains are yellow fine dust—like particles which contain the male sex cells of the flowering plant. Pistil — at the centre of the flower, there is a flask-shaped organ called pistil. The pistil is the female reproductive part of a flower. Each pistil consists of stigma, style and ovary. 4. What is the differences between tap root and fibrous root? Explain the relationship between types of roots and leaf venation. Ans: Tap root is a single straight root which grows vertically down into the soil and gives out many branches on all the sides. Tap root is the main root and the smaller side roots are called lateral roots. E.g., mango, Neem, carrot and radish. The fibrous roots consist of many thin, fibres-like roots of same size. The fibrous roots spread out in the soil and give a firm support to the plant. E.g., grass and wheat. The leaf venation and the types of root system in a plant are related. Plants with reticulate venation in their leaves have tap roots whereas those with parallel venation have fibrous roots. E.g., sugarcane and banana leaves. E. HOTS (Higher Order Thinking Skill) Questions. 1. What is the difference between making of food by leaves and making of food in the kitchen? Ans: Plants prepare their food in the presence of sunlight and chlorophyll with the help of water, minerals and carbon dioxide. The plant food is a kind of simple sugar called glucose. The food in the kitchen is made from one or more than one type of plant and animals products by cooking. 2. Tomato, brinjal and lemon are fruits. Comment. Ans: Tomato, brinjal and lemon are fruits because they are formed from maturation of ovary. They contain seeds. 3. If you remove the stamens of all the pea flowers in a garden, which phenomenon will be affected fruit formation, pollination or fertilization? Ans: Pollination 4. You find more climbers in a thick forest. Why? Ans: Climbers are plants with weak stems that take the support to climb. |n thick forests, there are more climbers because trees provide support to the climbers.

SCIENCE NOTES, CLASS – 6 5. Rahul finds a plant with no leaves. It has tap root. He wants to know the venation in the leaves. Help him. Ans: The leaf venation and the type of root system in a plant are related. Since, the plant has taproot, the venation of leaf will be reticulate. -----------------------------------------------------------------------

LESSON: 9 BODY MOVEMENTS

Very Short Answer Questions. 1. How many types of girdles are found in human body? Name them. Ans: There are two types of girdles found in human body (i) A pair of shoulder girdles (ii) A pair of hip girdles 2. What kind of arrangement is found in the ball and socket joint? Ans: In ball and socket joint, the ball-shaped end of one bone fits into the hollow cup-shaped socket of the other bone. 3. How many legs does a cockroach have? Ans: A cockroach has three pairs of jointed legs. 4. Where do you find a hinge joint in your body? Ans: The joints of elbows, knees, fingers and toes have hinge Joints. Short Answer Questions. 1. What is ribcage? What is the function of the ribcage? Ans: The twelve pairs of thin and curved bones called the ribs form a cage-like structure called ribcage. The function of ribcage is to protect the heart and lungs. 2. What are fixed joints? Give an example. Ans: The joints that do not allow any movement between the bones are called fixed joints. Example, bones of the skull (except lower jaw) are interlocked with each other which do not allow any movement. 3. Why do animals move from one place to another? Ans: Animals move from one place to another to find food, water, shelter, favorable environment, partner, suitable place for laying or rearing eggs and protection from enemies. 4. Why can’t we bend our elbows backwards? Ans; Our elbows have hinge joints that allow movement of bones in one direction (upwards) only. So, we cannot move our elbows backwards. 5. Why is mucus secreted by a snail’s foot? Ans: A slimy substance called mucus is secreted by a snail's foot which reduces the friction between the foot and the ground surface and helps the muscles of foot to move forward. A trail of mucus is left behind when the snail crawls. 6. Shreya’s grandmother is very old. She has pain in her knee joint and thus, she finds it very difficult to

move from one place to another .Shreya always helps her grandmother, when she walks. (a) Name the type of joint found in the knee. Ans: Hinge joint is found in the knee. (b) What value do you learn from Shreya? Ans: From Shreya we learn that it is our duty to take care of our grandparents in their old age and when they need us. D. Long Answer Questions. 1. Explain in brief the different types of movable joints in the human body. Ans; Most of the joints in the human body are freely movable. Freely movable joints are of four types, depending on the type and extent of movement they allow: (i) Ball and socket joint (ii) Hinge joint (iii) Pivot joint (iv) Gliding joint (i) Ball and socket joint: In this type of joint, the ball-shaped end of one bone fits into the hollow—cup shaped socket of another bone. This joint allows maximum movement in all directions. The joint of the shoulder and the hip are examples of ball and socket joint. (ii) Hinge joint: A hinge joint is like the hinges in a door. This joint allows movement of bones in one direction only. i.e., up and down or back and forth movement. The joint of elbows, fingers, knees and toes are examples of hinge joint. (iii) Pivot joint: The joint where our neck joins the head is a pivot joint. It allows us to bend our head forward and backward and turn the head to our right or left. (iv) Gliding joint: This kind of joint allows bones to glide over each other to provide little movement in all directions. It is found between the wrist and the carpals and between the ankle and the tarsals. 2. How do the muscles attached to bones bring about movements? Ans: Muscles are the fibrous tissues in the body that have the ability to contract. Muscles are attached to the bones of our skeleton (through strong fibres called tendons). So, when the muscles attached to a bone contracts, it pulls the bone and makes the bone move at the joint. A muscle can only pull a bone, it cannot push a bone. So, another muscle attached to the same bone has to contract to pull it in the opposite direction. This means that two muscles work together to move a bone. The movement of body parts as well as locomotion in human beings is brought about by the alternate contraction and stretching of muscles attached to the bones of the skeleton. When muscles pull on the bones, they produce movements such as moving of head, bending of arm, straightening of arm, walking or running, etc.

SCIENCE NOTES, CLASS – 6 3. How does a bird fly? List the features that help a bird to fly. Ans: The bird’s fly with the help of strong chest muscles and wings. Birds can fly because of the following reasons: (i) The forelimbs are modified into wings which help them fly. Hind limbs are used for walking and perching. (ii) They have streamlined bodies that cut the air current while flying. (iii) Their bones are hollow which makes their body light. (iv) They have powerful chest muscles which help them in flapping their wings during flight. 4. Describe the structure and function of the ribcage with the help of a labelled diagram.

There are twelve pairs of thin and curved bones called the ribs. These bones form a ribcage. All the 12 pairs of the ribs are joined to the backbone at the back and the first ten pairs are joined with the chest bone or breastbone in the front. The last two pairs of ribs are free at the front end and are called floating ribs. The ribcage protects the heart and the lungs. Ribcage also takes part in our breathing movements. E. HOTS (Higher Order Thinking Skills) Questions. 1. Why does a child have 300 bones whereas an adult who has grown up bigger in size has only 206 bones? Ans: A child has about 300 bones but an adult person has only 206 bones. The reason is that as the child grows, some of the bones fuse together and thus, the number of bones is reduced in adults. 2. Imagine yourself with a vertebral column with a long single bone or with fixed joints. How will such a change affect your life? Ans: If our vertebral column is with a long single bone or with fixed joints, we will not be able to bend or twist our backbone in different directions. -----------------------------------------------------------------------

LESSON 10 THE LIVING ORGANISMS AND THEIRSURROUNDINGS B. Very Short Answer Questions. 1. Name two free – floating plants. Water hyacinth and lotus/water lily 2. Write two characteristics of pine tree that help it adapt in mountain regions. Pine tree has leaves reduced to needle-like structures that help to conserve water. The pine trees are normally cone-shaped and have sloping branches. This helps the rainwater and the snow to slide off easily. 3. Name two biotic components of a habitat. Plants and animals/ human beings/ microorganisms 4. Name two scavengers. Vulture, hyena C. Short Answer Questions. 1. Differentiate between adaptation and acclimatization. Ans: Adaptation refers to changes that take place in plants and animals that help them to survive in a particular type of habitat over a long time period. But acclimatization refers to changes in the body of organisms that take place over a short period of time to adjust in their surroundings. 2. What is camouflage? Ans: Some animals protect themselves from their enemies by changing their skin colour according to surroundings, therefore they get unnoticed by their enemies. This is called camouflage. E.g., the stripes of a tiger help it to hide in tall grasses. 3. How is yak able to survive in water? Ans: Yaks are able to survive on mountains because they have thick fur to protect them from cold. They also have a layer of fat under their skin that keep them warm. 4. A fish adapts itself to live in water. Likewise, different animals adapt themselves to their surroundings. (a) How do animals adapt themselves to their surroundings? Ans: Animals adapt themselves to their surroundings by developing certain favorable features like modifications in their body shape, body organs, colour, behaviour, location and eating habits. (b) What value do we learn from the animals that easily adapt themselves? Ans: From the animals we learn to adapt, i.e., adjust in all types of circumstances. 5. Why do animals like yak, bear and snow leopard have thick fur? Ans: The thick fur of the animals like yak, bear and snow leopard protect them from cold weather conditions of the mountains where they live.

SCIENCE NOTES, CLASS – 6 6. Why does a cactus plant have long roots and leaves reduced to spines? Ans: The long roots of cactus plant go very deep into the soil to absorb water. The leaves of cactus are reduced to spines because that helps in reducing the loss of water through transpiration. 7. How do aquatic animals breathe in water? Ans: Some aquatic animals like fishes breathe through gills. The gills absorb the dissolved oxygen of water. Some other aquatic animals like dolphins and whales do not have gills. They breathe through lungs. They inhale air through the nostrils that are located in the upper parts of their heads. This allows them to breathe in the air when they swim near the surface of water. Amphibians like frogs and toads breathe in water through their moist skin and on land through their lungs. D. Long Answer Questions. 1. How do lions and deer adapt themselves to live in a forest habitat? Ans: Lions adapt themselves in the forest habitat in the following ways: (i) Lions have eyes in front that help them to see from a greater distance. (ii) Lions have sharp teeth and long claws in their front legs to catch and tear flesh of the prey. (iii) Lion have light-brown coloured skin which helps them to hide in dry grasslands. (iv) Lions run very fast that allows them to catch their prey. Deer adapt themselves in the forest habitat in the following ways: (i) They have eyes on the sides of the head, which give them a wide range of vision. (ii) They have long ears to hear the movement of predators. (iii) They can run very fast to save themselves from predators. 2. Explain how desert plants and animals are able to survive in a hot dry climate. Ans: Desert plants and animals show various adaptations to survive in hot climate. Adaptations in plants (i) The leaves in desert plants are either absent, very small or present in the form of spines (thorns). This helps in reducing the loss of water from the leaves. (ii) The stems of desert plants are thick and fleshy due to storage of water. The stems also have a thick waxy coating that prevents the loss of water from it. (iii) The roots of desert plants are long and go very deep into the soil to absorb water. Adaptations in animals: Desert animals like desert rats and desert snakes live in deep burrows that have cool and moist environment during daytime when the

desert is hot and dry. At night, when the desert is cool, the animals come out of their burrows and holes and become active. These desert animals pass out very little amount of urine and hence, conserve water in their body. Camel, the main animal of desert, adapt in the hot dry climate in the following ways— (i) The camel has long legs that keep its body away from the hot sand. (ii) A camel can drink a large amount of water and store it in the body. (iii) A camel's hump has fat stored in it. It acts as a food reserve. (iv) A camel has large and flat feet that help it to walk easily on sand. (v) Its long eyelashes protect the eyes from sand. 3. How is a frog adapted to live both on land and in water? Ans: Frogs have the following adaptations to live both on land and in water. (i) They have webbed feet that help them swim in water. (ii) They have long and strong back legs that help them in hopping on the land for catching their prey. (iii) They breathe through lungs on land and through moist skin in water. 4. Discuss about plants that adapt themselves to survive in an aquatic habitat. Ans: Different plants adapt themselves to live in aquatic habitat in different ways. The two common types of aquatic plants are— (i) Free-floating plants— These plants float freely on water. In these plants, leaves are large and flat. The leaves are covered with waxy coating which makes them waterproof and protects them from the decaying effects of water. Stems have air spaces which enable the plants to float. For example, lotus, water lily (ii) Submerged plants— These plants remain completely submerged in water. In submerged plants, the leaves are thin and ribbon-like. Such type of leaves allow water currents to pass through without damaging the leaves. For example, Hydrilla, Vallisneria E. HOTS (Higher Order Thinking Skills) Questions. 1. Camel is called the ‘ship of the desert’. Justify. Ans: A camel is the most common animal found in desert habitat. It is used in deserts for various purposes like riding, transportation and entertainment. It has some special features to adapt in the environment of deserts like long eyelashes to protect eyes from sand, nostrils can be closed to keep away sand, hump to store water and long and broad feet to walk easily on sand. Due to all these features and utility of camels in deserts, they are known as the ship of the desert.

SCIENCE NOTES, CLASS – 6 2. How does a sea animal, like dolphin, survive in water without gills? Ans: Dolphins do not have gills. They breathe through lungs. They inhale air through the nostrils that are located in the upper part of their heads. This allows them to breathe in the air when they swim near the surface of water. They can stay inside the water for a long time without breathing. They come out to the surface from time to time to breathe in air. -----------------------------------------------------------------------

LESSON: 11 MOTION AND MEASUREMENT OF DISTANCES

Very Short Answer Questions. 1. The distance between two bus stops is 3540m. Express this distance in (a) km (b) cm. Ans: (a) 3.54 km (b) 3, 54, 000 cm 2. Give two means of transport developed with the invention of the steam engine. Ans: Motor—ships, electric trains, aeroplanes, automobiles etc., have developed with the invention of the steam engine. 3. Give the SI unit of the following: (a) length (b) time (c) mass (d) temperature. Ans: (a) Metre (b) Seconds (c) Kilogram (d) Kelvin C. Short Answer Questions. 1. How is circular motion different from rotator motion? Give an example to support your answer. Ans: When an object moves along a circular path, it is said to be in circular motion. For example, the Earth moves around the Sun in a circular path, minute hand of a watch. An object is said to be in rotatory motion if it moves about a fixed axis without changing its position. Example: the motion of the blades of a fan, a giant wheel. 2. Define rectilinear motion. Ans: When an object moves along a straight line, its motion is called rectilinear motion. Example: the movement of the drawer of a table, a car moving in a straight line. 3. When is an object said to be in motion? Ans: An object is said to be in motion if it changes its position with respect to a stationary object in its surroundings. For example, when the position of a car changes with time, we say that the car is moving or that the car is in motion. 4. Measuring the length of a paper clip on a scale, the reading at one end is 1.0 cm and at the other is 4.3 cm what is the total length of a paper clip? Ans: The total length of the paper clip is 4.3 cm -1.0 cm = 3.3 cm 5. Which two kinds of motion does the earth have? Ans: The Earth rotates about its axis, it is rotatory motion. The Earth also revolves around the Sun in circular path, it is an example of circular motion.

6. Give two precautions to be taken while measuring the length of a pencil using a scale. Ans: (i) The scale should be placed with the pencil (an object) along its length. If we place it at an angle, our reading will not be correct. (ii) The correct position of the eye is also important for taking measurement. Our eyes must be focused exactly above the end point on which we are taking measurement. 7. Mohan goes to see the Republic Day parade with his father. He is very happy to see the soldiers marching in harmony. He tells his father of his desire to be a soldier. (a) Which type of motion do soldiers in a parade show? Ans: Soldiers in a parade show rectilinear motion. (b) What value do we learn from the marching soldiers? Ans: We learn to be disciplined from the marching soldiers. D. Long Answer Questions. 1. Why is it necessary to have a standard unit of measurement? Ans: In our daily life, we use a variety of objects as units of measurement. For example, we can measure the length of an object by using hand span, cubit (forearm length) or foot step (pace). In this case, the length of each one of these objects becomes a unit of measurement of length. But hand span, cubit and pace cannot be used as standard units of measurements because their length is not the same for all the persons. The length of hand span, cubit and pace are different for different persons as the length of the body parts varies from person to person. A unit of measurement which has a fixed value and does not change from person to person or place to place is called a standard unit of measurement. For example 'metre' is a standard unit of measuring length. It represents exactly the same length whether used by one person or another person or used in one country or other country. Thus, a ’metre' means the same length to everyone. So, it is a standard unit of measuring length. It is necessary to have standard units of measurements for the sake of uniformity and convenience in measurement. 2. (a) What is Rotational motion? Ans: Rotational motion is the movement of an object about a fixed axis without changing its position. (b) Give two examples of Rotational motion. Ans: Motion of the wheel of a sewing machine, a spinning wheel, a merry-go-round. Motion of blades of a fan and motion of a spinning top are examples of rotational motion.

SCIENCE NOTES, CLASS – 6 3. What is meant by periodic motion? Give examples of periodic motion. Ans: A motion that repeats itself after regular intervals of time is called periodic motion. The swinging pendulum of a wall clock, heartbeat of a normal person and the needle of a sewing machine are examples of periodic motion. E. HOTS (Higher Order Thinking Skills) Questions. 1. Name the types of motion in (a) A person drawing water from a well. Ans: Rectilinear motion (b)A bullet fired from a gun (up to some distance). Ans: Rectilinear motion 2. You are given a metre rod and a measuring tape. Which device will you use for measuring each of the following and Why? (a) The girth of your ball. Ans: The girth of ball is measured by measuring tape because the tape is flexible. (b) The length of your pencil box. Ans: The length of pencil box is measured by metre rod because pencil box has small length. 3. Why do scientists and researches use SI units in their work? Ans: Scientists and researchers use SI units in their work because these units are accepted by every person and every country. F. Application Based Questions. 1. How is the motion of a bicycle and a ceiling fan (that has been switched ‘ON’) different? Ans: Motion of a bicycle is a combination of rotatory motion and translator motion. So, it is multiple motion. The motion of a ceiling fan is rotator as the blades of a fan move about a fixed axis without changing its position. 2. Why can you not use an elastic measuring tape to measure distance? What problems you may face if you use it? Ans: Elastic measuring tape can be stretched to any extent. Due to this property of elasticity, we cannot get the accurate measurement of distance with it. -----------------------------------------------------------------------

LESSON 12 LIGHT. SHADOWS AND REFLECTIONS

B. Very Short Answer Questions. 1. Name three luminous objects. Ans: Sun, star and firefly 2. Name three opaque materials. Ans: Metal, wood and brick/clay/wall 3. What is the colour of the shadow formed if the colour of the object is blue? Ans: Black C. Short Answer Questions.

1. What is meant by translucent materials? Ans: The materials that allow only some of the light to pass through them are called translucent materials. Grounded glass, butter paper and tissue paper are examples of translucent materials. 2. What is lateral inversion? Ans: The left-right reversal of an object and its mirror image is called lateral inversion. 3. Mention the two factors on which the size of a shadow depends. Ans: The size of a shadow depends on the distance between the source of light and the opaque object and the distance between the opaque object and the screen. 4. How do we get moonlight when the moon is a non- luminous object? Ans: Moon is a non-luminous object but we get moonlight because the moon reflects the sunlight that falls on it. This reflected light is called moonlight. 5. What happens to the shadow formed on a screen when (a) The distance between the source of light and the object increases and. Ans: The size of a shadow on the screen decreases when the distance between source of light and the object increases. (b) The distance between the object and the screen decreases? Ans: The size of a shadow on the screen decreases when the distance between the object and the screen decreases. 6. We can see through a glass. (a) How can we see through a glass? Ans: We see through a glass because it is a transparent material. (b) In our daily activities, what value can we learn from this property of glass? Ans: We should also be transparent in all our dealings and actions in our daily life. We should never hide anything from the people around us. D. Long Answer Questions. 1. (a) How is a shadow formed ? Ans: When an object is placed in front of a source of light it stops the light from passing through it and it produces a shade behind it. The shade cast by an object is called its shadow. Shadows are formed when light is blocked by an opaque object. (b) What are the characteristics of a shadow? Ans: The characteristics of a shadow are: (i) A shadow is always dark regardless of the colour of the object or the colour of the light used to make the shadow. (ii) A shadow only shows the dark outline of an object and does not provide the details of the object.

SCIENCE NOTES, CLASS – 6 (iii) A shadow is formed in the direction opposite to the source of light. (iv) The size of a shadow varies depending on the distance between the object and the screen and the distance between the object and the source of light. (V) The shape and size of the shadow also varies with the position of the source of light. 2. Differentiate between an image and a shadow.

PARAMETER IMAGE SHADOW

Colour The image of

the same color as the object

The shadow is always dark regardless of the

color of the object

details

The image gives all the

details of the object.

The shadows no details of the object. It tells only the shape of

the object

Lateral inversion

The image undergo lateral

inversion

The shadow does not undergo lateral

inversion

Formation

The image is formed when light from the object reaches

our eyes

The shadow is formed when the path of light

is obstructed by an opaque object

size Size of the

image is same as the object

The size of the shadow depends on the

distance of the object and the source the source of light and

distance of the object and screen

3. What is meant by reflection of light? What type of objects reflect more light? Ans :(a)The process of sending back the light rays that fall on the surface of an object is called reflection of light. The reflection of light depends upon the nature of surface. Reflection of light on a rough or irregular surface— a rough or irregular surface reflects light in all the directions. This is called Irregular reflection (or diffuse reflection). For example, a piece of white paper has a rough surface, so it reflects the light falling on it in all directions. It is due to the irregular reflection of light Produced by the rough surface of a piece of white paper that we cannot see the image of our face on looking into the piece of paper. (b)Reflection of light on a smooth and shiny surface— a mirror has smooth and shiny surface. A mirror reflects all the light falling on it in the same direction. In fact, a mirror reflects a ray of light at the same angle at which it strikes the mirror. This is called regular reflection. Regular reflection of light can form an image. In fact, all the smooth and shiny surfaces reflect light in a regular way forming images. Regular reflection occurs only at very smooth surfaces. E. HOTS (Higher Order Thinking Skills) question.

1. Juhi was sitting in her drawing room enjoying the activities of the squirrels in her garden. The doors and windows of the room were closed. Can you tell the material from which the door is made of? Ans: The door is made up of glass. Glass is a transparent material. 2. Can we always recognize the object by observing its shadow? Explain giving an example. Ans: Yes, we can identify the objects from their shadows because the shadows of objects are usually similar in outline to the objects. For example, the shadow of a ceiling fan hung in the centre of a room will fall on the side opposite to the lighted electric bulb. By seeing the shadow of ceiling fan, we can recognize it. However, it is not necessary that we always recognize the object with the shadow. 3. Can you see your image in the water of your swimming pool? How? Ans: We can see our image in the water of swimming pool because the smooth surface of still water of swimming pool causes regular reflection of light that produces image. The smooth surface of still water in a swimming pool or lake acts like a mirror. 4. Why does the image of red rose look red whereas its shadow is black? Ans: The image of red rose looks red because the image of an object is always of same color as the object is. The shadow of red rose is black because shadow is always black regardless of the color of object or color of light. 5. Can shadow of an astronaut form on moon? Why/Why not? Ans: Yes, the shadow of an astronaut can form on moon whenever an astronaut gets in front of a source of light (Sun). -----------------------------------------------------------------------

LESSON: 13 ELECTRICITY AND CIRCUITS

CLASS RESPONSE Oral questions. 1. Name any five appliances used at home that work with electricity. Ans: Microwave oven, refrigerator, television, washing machine, computer/ geysers/ juicer/ grinder/ air conditioners/ electric fans/ bulbs 2. What are insulator? Give two examples. Ans: The materials that do not allow electric current to pass through them are called insulators. Wood, glass, rubber and plastic are examples of insulators. 3. How does a bulb get fused? Ans: If the filament is broken, the bulb is said to be fused and it no longer glows as there is a break in the path of the electric current.

SCIENCE NOTES, CLASS – 6 4. Why should we wear rubber – soled shoes or chappals while operating electrical appliances? Ans: We should wear rubber-soled shoes or chappals while operating the electrical appliances because rubber is a good insulator and protect us from electric shocks. B. Very Short Answer Questions. 1. Name any two gadgets that use electric cells for their working. Ans: Watch and calculator 2. What is an electric circuit? Ans: The path along which an electric current can flow is called an electric circuit. 3. In which direction does the electric current flow? Ans: Electric current flows from the positive terminal towards the negative terminal of a cell. C. Short Answer Questions. 1. Why we should not operate electrical switches with wet hands? Ans: We should not operate electrical switches with wet hands because water is a good conductor of electricity. If a person operates an electric switch with wet hands, he/she can get electric shock because water present on the wet hand can conduct some electricity from the switch into his/her body. 2. What is meant by an open circuit? Ans: The circuit in which the path from one terminal of cell to another terminal of cell is incomplete and electric current does not flow through the circuit, as a result the bulb cannot glow, is called an incomplete or open circuit. 3. Define insulators. Ans: The materials that do not allow electric current to pass through them are called insulators. Eg. Rubber, plastic, wood and glass are the examples of insulators. 4. Sahil’s hands are wet, but still he goes to switch on the fan. Monika immediately stops him from doing so. (a)Why does Monika stop Sahil? Ans: Monika stops Sahil because it is not safe to touch an electric switch with wet hands, he may get an electric shock. (b)What value do you learn from Monika? Ans: From Monika we learn to care for others 5. What happens when the switch is in the (a) ‘On’ position Ans: When the switch is in the ’ON' position, the circuit is complete or closed and current will flow through it. (b) ‘Off’ position? Ans: When the switch is in ’OFF’ position the circuit is incomplete or open and current will not flow through it. D. Long Answer Questions.

1. Draw a labelled diagram of an electric bulb. Explain its parts. Ans: Electric bulb diagram

An electric bulb has an outer case made of glass that is fixed on a metallic base. A bulb consists of a tiny thin wire called a filament. The filament is made up of tungsten and is fixed to two thick wires that provide support to it. One of these thick wires is connected to the metal case at the base of the bulb. The other thick wire is connected to the metal tip at the centre of the base. The metal tip at the centre of the base and the metal casing at its lower end acts as terminals of the bulb. These two terminals of bulb are fixed in such a way that they do not touch each other. When electric current is passed through the filament, the bulb glows. 2. Differentiate between conductors and insulators. Give one example of each. Ans: The materials that allow electric current to pass through them are called conductors (of electricity). All the metals are good conductors of electricity. The materials which do not allow electric current to pass through them are called insulators. Insulators are usually the non-conductors of electricity. Plastic, wood, glass and rubber are all insulators. 3. How does electricity flow in a circuit? Draw an open circuit.

Ans: An electric circuit is a path along which electricity can flow. Electric current flows when one or more electric cells are connected to other components such as a bulb by electric wires in an unbroken (or complete) closed loop. Such an unbroken loop is called electric. Circuit. Thus, the electric circuit provides a complete path for electricity to pass between the two terminals of an electric cell. In an electric circuit, the direction of flow of electricity is taken to be from the

SCIENCE NOTES, CLASS – 6 positive terminal of the cell to the negative terminal of the cell. A simple device that is used to open or close an electric circuit is called an Electric switch. When the key is closed, the electric circuit is complete and the current is allowed to flow through the circuit. The appliance (like a bulb or a fan) which is the part of circuit, works. When the key is open, the circuit is incomplete no current flows and the appliance does not work. 4.(a) Name the source of electricity in a torch . Ans: In the torch, two or three cells are placed in series (it means the positive end of one cell touches the negative end of other cell). These cells are the source of electric current. Diagram of electric torch:

E. HOTS (Higher Order Thinking Skills) Questions. 1. What alternative device can we use if there is a sudden breakdown in electric supply? Ans: We can use generators or invertors at the time when there is a sudden Break down in electricity supply. 2. Give reasons for the following: (a) We remove the plastic coating from ends of an electric wire while using it for connections in an electric circuit. Ans: Plastic covering on wires is used for insulation and it prevents us from electric shocks. While checking the connections in electric circuit, we remove the plastic coating because electric current flows only in metallic wire, not in plastic coating. (b) The handle of tools, like screw drivers and pliers, usually have plastic or rubber covers on them. Ans: The plastic and rubber covers are good insulators and protect us from electric shocks while working with electrical appliances. 3. Can electricity make the bulb glow in the given figure? Ans: Diagram:

Yes, electricity can flow in bulb and make the bulb glow.

4. If a person gets caught by the current, why are we advised not to touch the person directly rather to touch him with a wooden material like stick? Ans: If we touch a person who gets caught by the current we can also feel the electric shock as our body is a good conductor of electricity. The wooden stick is used because wood is an insulator and it prevents us from electric shock. 5. Both copper and silver are conductors of electricity but only copper is used for making electric wires and not silver. Why? Ans: All the electric wires are made up of copper because silver is a costly metal and is used in making of jewelries. -----------------------------------------------------------------------

LESSON: 14 MAGNETISM

CLASS RESPONSE B. Circle the odd ones. Give reasons for your choice. 1. Plastic —> It is a non-magnetic material, whereas others are magnetic materials. 2. Iron —> It is a magnetic material, whereas others are non- magnetic materials. 3. Rubbing —> It is a method to induce magnetism. 4. Television —> Its surface is not coated with magnetic material to store data. B. Very Short Answer Questions. 1. Mention three uses of magnets. Ans: (i) Magnets are used to separate iron and steel from junk materials. (ii) Information is stored in magnetic strips of credit cards and ATM cards. (iii) Data, sound and images are stored on special surface coated with magnetic material in CDs and floppies. (iv) In scrapyards, magnets are used to separate iron and steel from junk materials. 2. Name two objects that are attracted by magnets. Ans: Iron and steel/nickel/cobalt 3. Name a natural magnet. Ans: Magnetite 4. What is the effect of heating on magnets? Ans: On heating, the magnets lose their property of magnetism. C. Short Answer Questions. 1. What are magnetic substances? Ans: The substances that are attracted by the magnets are called magnetic substances. Eg.—Iron, steel, nickel and cobalt are magnetic substances. 2. What are non-magnetic substances? Ans: The substances that are not attracted by the magnets are called non- magnetic substances. Wood,

SCIENCE NOTES, CLASS – 6 stone, leather, plastic, aluminum and copper are non-magnetic substances. 3. Differentiate between natural and artificial magnets. Ans: Natural magnets are found in nature. Magnetite and lodestone are natural magnets. Natural magnets have generally low magnetic power and such magnets are not found at all places. Artificial magnets are prepared by humans which can be used at any time and in any place. These magnets are much stronger than natural magnets. Artificial magnets may be rod shaped, U-shaped or horse shoe shaped. 4. What is meant by directive property of a magnet? Ans: A freely suspended magnet always rests pointing in the north-south direction. This property of a magnet is called directive property. The end of a magnet that points towards north is called North Pole of the magnet, the other end that points towards the south is called the south pole of the magnet. 5. Prove that repulsion is the sure test for magnetism. Ans: We take a magnet and suspend it with the help of a thread. Now, bring one end of a metallic bar near one pole of the suspended magnet at a time. If one end of the metallic bar is attracted and the other end is repelled, the metallic bar is a magnet. If both the ends of the metallic bar are attracted, it is not a magnet. 6. Rashmi is watching her favourite T V show. Her grandmother asks her to look for her sewing needle which has fallen on the ground .Rashmi brings her magnet and searches the needle. (a) Which property of magnet do you think helped Rashmi find the needle? Ans: Attractive property of magnet helped Rashmi to find the needle. (b) Which value is displayed by Rashmi? Ans: Rashmi is caring, helpful and obedient. D. Long Answer Questions. 1. How can you make your own magnetic compass? Ans: To make a magnetic compass Things needed: A sewing needle, a bar magnet, a cork, a cup and a rubber Method: We can magnetize a sewing needle using a bar magnet. Pass the magnetized needle through a small piece of cork or rubber. Place this cork containing the magnetized needle in a cup containing water. Make sure that the needle does not touch water. When the needle comes to rest, it points to the north-south direction. Rotate the cork with the needle inserted in it in different directions. Observation: You observe that the needle always points in the north-south direction, when the cork stops rotating. The magnetic compass is ready for use.

2. What is meant by the poles of a magnet? Where are the poles of a bar magnet located? Ans: The ends of a magnet where the magnetic force is strongest are called its poles. A magnet always has two poles. The two poles of a magnet are near its free ends. The two poles of a magnet are always different. One pole of a magnet is called North Pole and the other pole of a magnet is called South Pole. 3. What happens when the north pole of a magnet is brought near? (a) The north pole of a freely – suspended magnet. Ans: It repels freely – suspended magnet (b) The south pole of a freely suspended magnet. Ans: It attracts the freely—suspended magnet. E. HOTS (Higher Order Thinking Skills) Questions. 1. A long magnet is broken into 10 pieces. How many north poles will be there in (a) 10 or (b) one? 10 pieces 2. How will you find poles of an odd-shaped magnet? We can identify the poles of an odd-shaped magnet by using a bar magnet. On placing the north pole of a bar magnet near one end of odd shaped magnet, if it repels, it is North Pole and if it attracts, it is South Pole. We can check another pole by the same process. 3. How will you find out the North Pole and South Pole of a bar magnet with no marking to indicate poles? If the bar magnet with no marking to indicate poles, is suspended freely, the end that points towards the geographic north is North Pole of magnet. Similarly, the end that points towards geographic south is South Pole of magnet. F. Application Based Questions. 1. It was observed that a pencil sharpener gets attracted by both the poles of a magnet, although it has a plastic body. Name a material that might have been used in some part of its body, responsible for attraction towards magnets. Ans: The blade used in the sharpener may be made of iron or steel that is attracted by the poles of a magnet. 2. A carpenter accidentally mixed iron nails and screws with wood shavings how can you help him in getting back the nails and screws from the wood shavings? Ans: By using a magnet, he can easily get back the nails and screws from the wood shavings. -----------------------------------------------------------------------

LESSON: 15 WATER

C. Short Answer Questions. 1. Define transpiration? Ans: The process of releasing of extra water by plants into the air in the form of water vapour through stomata is called transpiration.

SCIENCE NOTES, CLASS – 6 2. What is drought? Ans: Absence of rain in a particular region for a long time leading to severe shortage of water is called drought. 3. One day, there occurs a shortage of water in Pooja’s colony. She has a hand pump in her house she allows everyone to take water from there. (a)Why do you think the problem of water shortage is increasing day by day? Ans: The problem of water shortage is increasing day by day due to the increasing population. (b)What value is shown by Pooja? Ans: Puja cares for her neighbourhood. She is helpful. The reservoir of water collected over the hard, non-porous rocks below the surface of the Earth is called groundwater or underground water. D. Long Answer Questions. 1. How is rain useful to us? Give any three reasons. Ans: Rain is useful to us because— (i) It brings relief by cooling the environment especially after hot summer days. (ii) It is important for irrigating the crops in fields. (iii) It maintains the supply of water on land by filling streams, lakes, ponds and raising the water table. 2. How do the life of animals living in soil gets affected by heavy rain? Ans: The life of animals living in soil gets affected by heavy rains as the land gets covered with water. The animals like (snake and earthworm) that live in soil come out in search of air and food. 3. What is the advantage of rainwater harvesting? Ans: The main purpose of rainwater harvesting is not only to hold rainwater on the surface of the Earth but also to make rainwater percolate under the ground more efficiently so as to recharge groundwater. This ground water can then be taken out through tube wells, hand-pumps, etc., as and when required. The advantage of rainwater harvesting is that it increases the availability of groundwater and helps in overcoming water shortage. The other advantages of rainwater harvesting are— (i) Soil erosion can be checked by rainwater harvesting. (ii) It helps to control floods. iii) During dry months one can also avail water supply for irrigation and other purposes. iv) It reduces the loss of rainwater. 4. (a) How are trees helpful in the process of water cycle ? Ans: The trees absorb water from the soil through their roots. They release excess water as water vapour by the process of transpiration. This water vapourgoes into the air and forms clouds. The roots of trees also help in deep percolation of rainwater and enriches the water table.

(b) How does flood affect vegetation? Ans: The flood water submerges the standing crops, grasslands and forests. Due to this, the plants do not get sufficient amount of air and nutrients and they die. (c) What are the possible problems faced by people of a country after floods? Ans: The problems faced by people after floods are (i) Flood in city areas leads to water—logged roads and streets. This disrupts the traffic on road and causes inconvenience to the people. (ii) Floods caused extensive damage to crops. This may cause a cute food shortage and deaths due to hunger. (iii) Floods cause serious injuries or death of domestic animals by drowning. (iv) When flood water recedes, it causes the spread of diseases like malaria, dengue, cholera, dysentery and diarrhoea. (v) Floods wash away the top layer of the soil, thus, reduces the Fertility of soil. (vi) Floods also affect the animals living in the soil. Animals like earthworms and snakes are exposed. 5. (A). Why should we conserve water? Ans: With increasing population, the demand of water has also increased. Apart from drinking and using water for different household works water is also used in agriculture for producing food and industries for manufacturing a large variety of products. Since the freshwater is available in limited amount, thus we should conserve water. (B) What are the different methods of water conservation? Ans: The ways to conserve water are— (i) Plant more and more trees. (ii) Use a bucket and a mug instead of shower while taking bath. (iii) Close the taps tightly after using them. (iv) Avoid cleaning utensils under running water. (v) Check over flowing of water tanks. (vi) Recycle waste water. (vii) Adopt rainwater harvesting to store the rainwater. (viii) Repair leaking pipelines and water taps immediately. (c) What are the types of rainwater harvesting? Ans: The two main types of rainwater harvesting are (i) Rooftop rainwater harvesting (ii) Roadside rainwater harvesting E. HOTS (Higher Order Thinking Skills) Questions. 1. Why do prices of food grains, fruits and vegetables rise during floods or drought? Ans: Floods and drought damage the crops and create acute food shortage leading to increased prices of food grains, fruits and vegetables.

SCIENCE NOTES, CLASS – 6 2. Give reasons for: (a)Several accidents take place in cold winter mornings. Ans: Fog in the cold winter morning reduces visibility due to which several accidents take place. (b)Our feet become wet while walking on grass in cold winter mornings. Ans: Presence of tiny drops of dew on grass, wets our feet on cold winter mornings. (c)Rain maintains the supply of water on land. Ans: Rain maintains the supply of water on land by filling lakes, ponds, streams and raising the underground water table. (d)Floods cause an extensive damage to human life and property. Ans: Land gets submerged under water during floods which causes extensive damage to human life and property. -----------------------------------------------------------------------

LESSON: 16 AIR AROUND US

Short Answer Questions. 1. What components of air will you find more in? (a) Coastal areas Ans: water vapour (b)Industrial areas Ans: Increased level of dust, smoke and gases especially higher amount of carbon dioxide and oxides of nitrogen and sulphur. 2. Define atmosphere. Name the gases present in the atmosphere. Ans: The blanket of air that surrounds the Earth is called atmosphere. The major components of air are nitrogen, oxygen, carbon dioxide and a few other gases, water vapour, smoke and dust particles. 3. Priyanka with her mother, visits the hospital to meet her sick uncle. While talking, her uncle feels some breathing problem. Priyanka, immediately, calls the doctor, who arranges for oxygen for the patient that saves his life. (a)How the doctor does provides extra oxygen to Priyanka’s uncle? Ans: The doctor provides extra oxygen to Priyanka’s uncle by an oxygen cylinder. (b) Which value is shown by Priyanka? Ans: Care for others and taking quick decisions in case of emergency or critical situation. 4. Why is Nitrogen is needed by living organisms? Ans: Nitrogen is needed by living organisms as it forms various components of the body of living organisms like proteins and nucleic acids. 5. What would happen if there is no air in water? Ans: Air contains oxygen. If there is no air in water then aquatic plants will die due to the absence of oxygen.

6. How is Air helpful in maintaining temperature? Ans: Air helps in maintaining proper temperature on the Earth. During the day, when the Sun rays fall on the Earth, some of them get absorbed by the atmosphere and rest are reflected back. This trapped heat prevents Earth's atmosphere from too much cooling at night and helps to maintain appropriate temperature. 7. Why do we observe water droplets outside the glass containing ice? Ans: The air around the glass with ice contains water vapour. The cold surface of the glass containing ice cools the air around it and when the water vapour of the air comes in contact with a cool surface it condenses on the outer cool surface of the glass. This occurs due to condensation. D. Long Answer Questions. 1. How do plants and animals maintain the balance of oxygen and carbon dioxide in the nature? Ans: Animals inhale oxygen from air and exhale carbon dioxide which goes into the air. Burning of fuels uses oxygen from the air and gives out carbon dioxide. Green plants use carbon dioxide from the air for photosynthesis during the daytime and give out oxygen. The process of respiration in plants takes place during day as well as at night. The oxygen released during photosynthesis is more than the oxygen used in respiration. Therefore, there is a net release of oxygen in the atmosphere. In the above mentioned ways, plants and animals maintain the balance of oxygen and carbon dioxide in the air and remains unchanged. 2. How will you show that air is dissolved in water? Ans: To show that air is dissolved in water Things needed: A beaker, tripod stand, a burner, some water Method: Take some water in a beaker and keep it on a tripod stand Heat the water slowly by using a burner. Observation: You observe that, much before the water begins to boil, tiny bubbles appear on the inner side of the beaker. These bubbles come from the air dissolved in water. Actually, when water is heated, the solubility of air in water decreases. As a result, the air dissolved in water comes out in the form of tiny bubbles. When the dissolved gas is removed through heating and the same water is heated again after a short interval of time, we do not observe bubbles. Conclusion: Air is dissolved in water. 3. (a) Do all organisms do not breathe through lungs? Ans: No, all organisms do not breathe through lungs. Most of the terrestrial organisms breathe through lungs.

SCIENCE NOTES, CLASS – 6 (b) From where do aquatic animals get oxygen? Ans: The aquatic organisms take the oxygen dissolved in water for breathing. The air is useful to us in many ways. The major uses are as follows— 4. How is air helpful for us in different ways? Ans: (i) Oxygen is used by all living organisms for respiration. (ii) Oxygen is necessary for burning of fuels. (iii) Compressed air is used for inflating Tyres of bicycles, scooters, cars and buses. It is also used in balloons and footballs. (iv) Moving air has force. This force helps yachts (sailing boats), parachutes and gliders to move. (v) Moving air (wind) is used to turn the blades of windmills. (vi) Wind helps in the dispersal of seeds of plants. It also helps in pollination. E. HOTS (Higher Order Thinking Skill) Question: 1. Why should breathe only through the nose and not through the mouth? Ans: We should breathe only through the nose because the fine hair and mucus present inside the nose prevents dust particles to enter our lungs. If we breathe through mouth, harmful dust particles and germs may enter our body and affect our health. 2. Explain why some insects living in soil, come out only during heavy rain. Ans: Some insects living in soil, come out of the soil only during heavy rain because rainwater fills up all the spaces occupied by the air in the soil and no air is left in the soil for the insects to breathe. 3. Coastal areas in India are more humid in comparison to the central region. Why? Ans: Coastal areas are surrounded by sea and evaporation of sea water increases the amount of water vapour in the atmosphere (humidity) and makes the weather more humid than the central region which is away from the coast. 4. How can you improve the air quality in our locality? Ans: We can improve the air quality in our locality by the following methods: (i) Planting more and more trees. (ii) Using catalytic converters and cleaner fuels like CNG in vehicles, instead of petrol and diesel. (iii) Reducing the use of vehicles that run on petrol and diesel. (iv) Using pollution-free sources of energy such as tidal energy and solar energy. (v) Walking and using rickshaw or bicycle, for shorter distances. (vi) Building tall chimneys in factories.

5. Why is it advised not to sleep under the trees at night? Ans: During the daytime, the rate of photosynthesis in plants is much more than the rate of respiration. During the daytime, the carbon dioxide produced during respiration is used by the plants for photosynthesis. Thus, carbon dioxide is not released in the environment. But at night, there is no photosynthesis, only respiration takes place. At night carbon dioxide is released by the plants. Thus, it is advised not to sleep under the tree at night, because it can cause suffocation and breathlessness. -----------------------------------------------------------------------

LESSON: 17 GARBAGE IN, GARBAGE OUT

B. Very Short Answer Questions. 1. Name a natural fertilizer. Ans: Compost 2. Name (a) a solid (b) a liquid and (c) a gaseous form of waste. Ans (a) Fruit and vegetable peels b) Water containing detergent c) Smoke released by vehicles 3. Mention at least two benefits of waste management. Ans: i) It reduces air, water and land pollution. ii) It provides healthy and clean environment. iii) It conserves the natural resources. iv) It saves money. 4. What type of worms are used for vermin composting? Ans: Red worms are used for vermicomposting. 5. What type of garbage is collected in blue dustbin and green dustbin? Ans: The blue dustbin is used for collecting non-biodegradable wastes e.g., plastic or metal objects. The green dustbin is used for collecting biodegradable wastes. E.g., fruit and vegetable peels, leftover food Short Answer Questions. 1. Distinguish between biodegradable waste and non-biodegradable waste. Ans: Waste that can be decomposed by the action of microorganisms (like bacteria and fungi) into simple and harmless substances so that they cannot harm the environment are called biodegradable waste. Peels and cuttings of fruits and vegetables, animal dung, agricultural wastes are some examples of biodegradable waste. Waste that cannot be decomposed by the action of microorganisms into harmless substances are called non-biodegradable waste. The objects made from plastic, glass and metals are non-biodegradable waste.

SCIENCE NOTES, CLASS – 6 2. What are the advantages of recycling used paper? Ans: By recycling used paper, we can make new paper from old, used and discarded paper and can save many trees. 3. What is meant by recycling? Ans: Making useful things from waste materials is called recycling. Materials like glass, metal, plastic and paper are recycled to make fresh glass, metal, plastic and paper. 4. Why is composting is better than burning leaves? Ans: Composting is better than burning of leaves because composting results in the production of natural fertilizer (compost) while burning of leaves produces smoke and gases that are harmful for the human health and environment. 5. On the beginning of a new session, Rohan’s mother gives him a new bag. Rohan gives his old bag to his maid’s little daughter, Radha. Radha very happily uses it. (a)Why do you think Rohan gave his bag to Radha? Ans: Rohan gave his bag to Radha as he has a new bag to use and does not need his old bag. Radha needed that bag to carry her books to school (b) Which value is shown here by Rohan? Ans: Caring, sharing, kindness and being ecofriendly by the reuse of the thing. 6. Why is segregation of biodegradable and non-biodegradable waste is necessary? Ans: Segregation or separation of biodegradable and non-biodegradable waste is necessary because biodegradable waste are decomposed through composting and vermicomposting while non-biodegradable waste are disposed by other methods like incineration. Long Answer Questions. 1. What are the harmful effects of wastes? Ans: The harmful effects of wastes are as follows— (i) Wastes make the surroundings dirty and ugly. (ii) Wastes give foul smell and the dumped garbage becomes breeding ground for flies and mosquitoes which spread various diseases. (iii) Drains get choked and overflowing of sewage may contaminate drinking water. (iv) Non-biodegradable wastes can cause various types of pollution. (v) They can block the digestive canals of stray animals, if eaten by them. 2. Explain how plastic a boon is. Ans: Plastic is a boon because plastics have made our life easy and comfortable. Most of the things we use in our daily life are made up of plastic. It will not be wrong to say that we live in plastic age. Plastics are used in a wide range of products from paper clips to spaceships due to their lightweight, relatively low cost

and resistance to water and microorganisms. Plastics can be given any colour, shape and can be used for making anything. Plastics are very durable. All this has made plastic a boon for us. 3. What are the basic approaches towards to the management of wastes? Ans: The basic approaches towards the waste management involves production of minimum wastes by practicing three R’s (reduce, reuse and recycle) and proper disposal of wastes. Reduce—We can reduce the amount of waste by throwing less. For example, carry your own cloth bag when you go for shopping to avoid the use of polythene bags. Reuse—Reuse is to use an item more than once. It is another method of reducing waste production. For example, old furniture and clothes should be donated to the poor so that they can be reused. Recycle—Recycling is making of useful things from waste materials. Materials like glass, plastic, metal and paper are recycled to make fresh glass, metal, and plastic and paper products. 4. List various methods of garbage disposal. Explain any one. Ans: The biodegradable and non-biodegradable wastes need to be disposed of properly. They should first be segregated and then disposed through various methods. The methods of garbage disposal are — (i) Composting (ii) Landfill (iii) Incineration Landfill— Landfill is a large, low lying, open area outside the city or a town where the garbage collected from a city or town is dumped. The garbage is spread out on the landfill and covered with soil. Garbage buried in landfill stays in it for a long time as it decomposes very slowly. When the landfill is completely filled, a park may be developed on it. The Indraprastha Park in Delhi is an example of a landfill park. E. HOTS (Higher Order Thinking Skills) Questions. 1. What is the role of a junk dealer? Do you think junk dealer help in waste management? Ans: A junk dealer separates the items sent for recycling thus helps in waste management. 2. Why is it better to use compost than chemical fertilizers? Ans: Compost is better than chemical fertilizers because compost does not cause any type of pollution while use of chemical fertilizers cause soil pollution as well as water pollution.

SCIENCE NOTES, CLASS – 6 3. Rock garden at Chandigarh has been created from discarded things. What is your view on this? Ans: This is great because these type of activities reduce the wastes and make the environment clean. F. Application Based Question. How can you contribute to control pollution? Ans: We can contribute to reduce pollution by (i) Minimizing the use of plastic bags and other non-biodegradable objects. (ii) Planting more and more tress. (iii) Using public transport instead of our own vehicles. (iv) Using ecofriendly, clean fuels like CNG in vehicles. (v) Avoiding excess use of fertilizers and pesticides. G. Practical Skill Based Questions. Can we add wastes like metal cans and plastic toys in a compost pit to make compost? Why? Ans: No, we cannot add waste like metal cans and plastic toys in a compost pit to make compost because metal cans and plastic toys are non-biodegradable waste. They do not decompose easily. These waste can add various harmful chemicals to a compost and if this compost is used as manure for plants, it can harm the soil as well as the plants grown. -----------------------------------------------------------------------