Watch Queue Queue Silk fibers have an outstanding toughness, that is, are very extensible while also sustaining large forces. Properties of Silk Silk is an elastic, lustrous protein fibre. This happens usually after 25 to 30 days when the caterpillars stop feeding and move to the twigs to spin cocoons. Reeling is also done in special machines. The simulation is totally image based about each stage of silkworm. Learn all about wool. The characteristics of silk give this elegant fabric a luxuriously soft, yet springy 'handle', resulting in it being one of the most desired fabrics for clothing - including for scarves! The caterpillar covers itself completely with silk fibre and turns into a pupa, this covering is known as the cocoon. Rearing Silkworms China is the largest silk producer and consumer in the world followed by India where Indian sarees made from silk are famous. CBSE Class 7 Videos. Properties and Characteristics of Silk Fabric; Properties and Characteristics of Silk Fabric. The soft looking silk yarn is as strong as a comparable thread of steel. Learn all about silk. Emperor Huang-ti found out that the white worms were eating up the mulberry leaves and spinning shiny cocoons. CBSE Class 7 Sample Papers and Solutions. Ans: Processing Silk: Extracting silk from the cocoon is called processing silk. Other insects can also produce silk. It has a tenacity of 3.5 – 5 gm/den. Silk moth to silk: After they are laid by the silk moth; eggs are stored over a clean cloth or paper strips. Go to Activity, What is cool in summer and warm in winter? The strength is greatly affected by... Elongation at break: 20 -25% at break. Skip to main content; Skip to secondary menu; Skip to primary sidebar ; Class Notes. Silk For Class 7. over here on EduRev! Silk is a natural fibre which is obtained from an insect (called silk moth). Sericulture, or silk farming, is the rearing of silkworms for the production of raw silk. Life Cycle – Silk Moth In the pupa stage, it weaves a net to hold itself. Activity3: Larvae feed on mulberry leaves for about 20 to 25 days. The simulation containes interesting question through the quiz. Some of the worksheets displayed are Refer to the educators guide for, 1 b7b bwork b bclassb vii subject, Lesson plan the bsilkb road, Brilliant public schoolsitamarhi, Vii science practice paper, Question bank bclassb vii science chapter 1 nutrition in plants, Pullout bwork b, International indian school jeddah bclassb vi history bwork b. Insulating Properties: Silk: Silk is not as good as wool in retaining warmth. Extracting silk from the cocoon is called processing silk. Chinese legend has it that empress Si-lung-Chi was worried about the damaged mulberry leaves in her garden. Trivia The simulation is based on images. This video is highly rated by Class 7 students and has been viewed 13 times. CBSE Class 7 Syllabus . Properties of silk include a high tensile strength and good elasticity so that it resists creasing, … Springer.com has developed an interesting simulation regarding life cycle of silkworm through intersingf images and explanation for the each stage of silkworm life cycle. However, it is generally thrown，or twisted, with two or thre… Cultivated silk from the Bombyx mori silkworm, which is and has always been the most common type of silk used, has a number of interesting and desirable properties that have been admired for … Showing top 8 worksheets in the category - Silk For Class 7. NCERT Exemplar solutions for Class 7 Science Chapter 3 cover a variety of questions like MCQS, fill in the blanks, match the following and long answer questions. Let us discuss about the life cycle of silk moth. These woollen clothes are made of wool. The skin of the caterpillar does not grow along with it. This was kept secret for hundreds of years. Pem.org has developed an about silkworm life cycle, silk cultivation and fashioned in silk with interseting images from the ancient times. Apart from being the largest Class 7 community, EduRev has the largest solved Question bank for Class 7. The silk fibre is then spun into silk thread, which is then woven into silk cloth by weavers. Go to Activity The cost of silk varies widely, depending on the nature of the fiber, the method of collection, the country in which it was produced, the quality of the silk, and market conditions. How is Silk Obtained? Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube. The rearing of silkworms for obtaining silk is called (a) cocoon (b) silk (c) sericulture (d) silviculture. This process is known as reeling, The filaments are usually twisted to form a silk yarn of about 6 to 8 denier. Multiple Choice Questions. Class 1-5; Class 6; Class 7; Class 8; Class 9; Class 10; Class 11; Class 12; NCERT Solutions. CBSE Class 7 Tests. Spider silk and B. mori silk feature unique physical properties – such as superior mechanical properties in terms of toughness (the amount of energy absorbed before breakage) (Table 1). So, it sheds its skin, and underneath the old one is a new skin. Naina Nisa. During special occasions or functions, you like to wear silk clothes. Sericulture Activity2: However, only silk from the silkworms is used for textile purposes. When larvae are hatched from eggs, they are kept in clean bamboo trays with fresh leaves of mulberry. Properties of Silk Wool is acquired from the fleece or hair of these animals. It’s Latin name is Bombyx mori. Class-VII . These are stored on strips of cloth or paper. Silk is a durable fabric, has lustre and can be worn in both in summers and winters. Wool is obtained from the fleece (hair) of sheep or yak. The moth continues to develop within the cocoon. The soft silk thread is as strong as a comparable steel thread. You can learn the concept through images which excelently desingned in understanding the concept. Go to Activity To obtain silk, workers stifle the larvae and boil the cocoons in a carefully controlled bath to loosen the sericin coating. Solving For Complementary Supplementary Vertical. NCERT Exemplar for Class 7 Science Chapter 3 Fibre to fabric Explanation: Obtained from wool which does not required killing of animals. The female silk moth lays hundreds of eggs. Thus, tassar silk, kosa silk, mooga silk, etc are obtained from cocoons spun by different types of moths. How is Silk Obtained? These properties of silk make it an attractive fabric. Figure 1: Animals that yield wool The larvae or caterpillars hatched from the eggs of the silk moth. Sources of Wool (image credits: openclipart.org) Q1: You must be familiar with the following nursery rhymes: (i) ‘Baa baa black sheep, have you any wool.’ (ii) ‘Mary had a little lamb, whose fleece was white as snow.’ Answer the following: (a) Which parts of the black sheep have wool? Also you can give online test and analyze your preparation level. thumb_up Like (2) visibility Views (21.7K) edit Answer . So far, the maximum strength of spider dragline silk (dragline of Caerostris darwini ) up to 1.7 GPa, which exceeds that of steel (1.5 GPa), is in the range of high-tech materials [ 1 ]. You can & download or print using the browser document reader options. Different types of silk moths yield different types of silk yarn, such as mulberry silk, tassar silk, eri silk and moonga silk.The most common silk moth is the mulberry silk moth. You can study other questions, MCQs, videos and tests for Class 7 on EduRev and even discuss your questions like Write any two properties of silk.? The rearing of silkworms for obtaining silk is called Sericulture. Keratin also protects epithelial cells from damage or stress. Mulberry leaves are the staple diet of silkworms. They eat day and night, and grow to enormous sizes. The life history of a silk moth starts when a female silk moth lays eggs. One thread of silk contains approximately 50 silk filaments. Class 7 Study Material – Notes, Important Questions, Practice Tests. This silk is then re-boiled in order to improve its luster. These two factors permit many more hydrogen bonds to be formed in a much more regular manner. Image Courtesy: “Green wool texture” By M0tty – Own work (CC BY-SA 3.0) via Commons Wikimedia “white silk 5” By J E Theriot via Flickr. Question 1. Yes! Free Education for All. Physical Properties of Silk Fiber: Tenacity - The silk filament is strong. Showing top 8 worksheets in the category - Silk For Class 7. CBSE Class 7 Textbook Solutions. You also learnt that wool and silk fibres are obtained from animals. Here, we provide a review on structures, mechanical properties and applications of silk fibroin. These solutions for Animal Fibres are extremely popular among Class 7 students for Science Animal Fibres Solutions come handy for quickly completing your homework and preparing for exams.
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