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  CBSE Class 8 Science Chapter 3 Notes: Synthetic Fibres And Plastics Clothes that we wear on a daily basis are made of fabrics. Fabrics are made of fibres which are obtained from natural and artificial sources. Wool, silk, and cotton are a few examples of natural fibres and fibres like polyesters and terylene are a few examples of synthetic fibres. In class 8 science chapter 3, the various types of synthetic fibres along with their characteristics are mentioned. Let’s Build Fibre The clothes, which we wear are made of fabrics. Fabrics are made from fibres obtained from natural or artificial sources. Fibres are also used for making a large variety of household articles. To know more about Fibre,  visit here . Polymer The word ‘polymer’ comes from two Greek words; poly meaning many and mer meaning part/unit. A polymer is a substance composed of many repeated similar subunits. To know more about Polymer,  visit here . Synthetic Fibre Fibres that are made or created by humans are known as

 Important Terms For Class 7 Science Chapter 3 Youtube channel 1. Wool Class 7 Science Chapter 3 describes the rearing and breeding of different animals and learns fibre production and its management. You have learnt about some fibres obtained from animals. You also learnt that wool and silk fibres are obtained from animals. Do you know where do we get wool? Wool is obtained from the fleece or hair of sheep. The hairy skin of the sheep has two types of fibres that form its fleece – the coarse type of beard hair and the fine soft hair close to the skin. 2. Animals That Yield Wool Remember, fine hair provides the fibres for making wool. There are several breeds of sheep found in different parts of our country. However, the fleece of sleep is not the only source of wool. As Yak wool, Angora wool and Kashmiri wool is found in Tibet, Jammu and Kashmir respectively. The hair on the body of camels is also used as wool. 3. From Fibres To Wool In this part of the content gives an idea about rea

 Important Questions For 7th Science Chapter 2 1. The enzymes present in the saliva convert (a) fats into fatty acids and glycerol. (b) starch into simple sugars. (c) proteins into amino acids. (d) complex sugars into simple sugars. 2. Given below from (i) to (iv) are some food items. (i) Boiled and mashed potato (ii) Glucose solution (iii) A slice of bread (iv) Mustard oil Which of the above will give blue-black colour when tested with iodine? (a) (i) and (ii) (b) (i) and (iii) (c) (ii) and (iii) (d) (iii) and (iv) 3. Cud is the name given to the food of ruminants which is (a) swallowed and undigested. (b) swallowed and partially digested. (c) properly chewed and partially digested. (d) properly chewed and completely digested. 4. The acid present in the stomach (a) kills the harmful bacteria that may enter along with the food. (b) protects the stomach lining from harmful substances. (c) digests starch into simpler sugars. (d) makes the medium alkaline. 5. Which of the following pair o

Hiiii Important Main Point In Class 7 Science Chapter 2 1. Different Ways Of Taking Food We have already studied about the nutrition in plants. This part of the content describes the nutritional needs and digestive system in human beings, along with other living beings. As we know that food is needed for every living organism. Plants can prepare their own food but animals cannot. But we know nutrition is required for every organism for energy. The food contains some nutrients like carbohydrate, protein, fat, vitamin and minerals which are required by our body for growth and development, called ‘Nutrition’. Generally, in the process of nutrition, food is taken as a complex substance and break down in simpler substances, called ‘Digestion’. After that, it is utilised by our body. You may have observed that different types of animals show different modes of nutrition. Such as, eagle tear flesh of prey, hummingbirds suck the nectar from the flower, mosquito and lice suck blood from other

 Q.1. Why do organisms need to take food? Ans. Food is needed by all organisms for many purposes: (a) The main function of food is to help in growth. (b) Food provides energy for movements such as running, walking or raising our arm. (c) Food is also needed for replacement and repairing damaged parts of body. (d) Food gives us resistance to fight against diseases and protects us from infections   Q.3. How would you test the presence of starch in leaves? Ans. The presence of starch in leaves can be tested by Iodine test. When we remove chlorophyll from leaf by boiling it in alcohol and then put 2 drops of iodine solution, its colour change to blue indicates the presence of starch. Q.4. Give a brief description of the process of synthesis of food in green plants. Ans. The green plants have chlorophyll in the leaves. The leaves use C02 and water to make food in presence of sunlight.   Q.5. Show with the help of a sketch that the plants are the ultimate source of food.   Q.6. Fill in the b

 Microorganisms: Friend and Foe Class 8 Science NCERT Textbook Questions Question 1. Fill in the blanks. (a) Microorganisms can be seen with the help of a _____ (b) Blue-green algae fix ______ directly from the air to enhance the fertility of soil. (c) Alcohol is produced with the help of _____ (d) Cholera is caused by ______ Answer: (a) microscope (b) nitrogen (c) yeast (d) bacteria Question 2. Tick the correct answer. (a) Yeast is used in the production of (i) sugar (ii) alcohol (iii) hydrochloric acid (iv) oxygen Answer: (ii) alcohol (b) The following is an antibiotic: (i) sodium bicarbonate (ii) streptomycin (iii) alcohol (iv) yeast Answer: (ii) streptomycin (c) Carrier of malaria-causing protozoan is: (i) female Anopheles mosquito (ii) cockroach (iii) housefly (iv) butterfly Answer: (i) female Anopheles mosquito (d) The most common carrier of communicable diseases is (i) ant (ii) housefly (iii) dragonfly (iv) spider Answer: (ii) housefly (e) The bread or idli dough rises because o

 NCERT Solutions for Class 8 Science, Chapter 1 - Crop Production & Management: 1. Select the correct word from the following list and fill in the blanks. float, water, crop, nutrients, preparation (a) The same kind of plants grown and cultivated on a large scale at a place is called _____________. Answer (a): Crop. (b) The first step before growing crops is _____________ of the soil. Answer (b): Preparation. (c) Damaged seeds would _____________ on top of water. Answer (c): Float. (d) For growing a crop, sufficient sunlight and _____________ and _____________ from the soil are essential. Answer (d): Water, nutrients 2. Match items in column A with those in column B. A                                     B (i) Kharif crops             (a) Food for cattle (ii) Rabi crops               (b) Urea and super phosphate (iii) Chemical fertilisers    (c) Animal excreta, cow dung urine and plant waste (iv) Organic manure        (d) Wheat, gram, pea Solution (2):        A