(b) rearing of silkworm. When the color of their heads turns darker, it indicates they are about to molt. The breeding process of this type takes place twice annually, a feat made possible through the slightly warmer climates and the resulting two life cycles. Explain in brief. She was drinking tea under a tree when a silk cocoon fell into her tea. (c) The rearing of silkworms for obtaining silk is called silviculture. This is the wool ready to be drawn into fibres. 10. They are covered with tiny black hairs. Cotton fibre is the purest source of cellulose and the most significant natural fibre. In an instant, she realized this caterpillar larva was the source of the silk. The eggs of this type hibernate during winter due to the cold climate, and cross-fertilize only by spring, generating silk only once annually. Sarah Underhill Wisseman, Wendell S. Williams. Required fields are marked *, Frequently Asked Questions NCERT Exemplar for Class 7 Science Chapter 3 Fibre to fabric. The domestic silk moths cannot fly, so the males need human assistance in finding a mate, and it lacks fear of potential predators. 16. Step I: The fleece of the sheep along with a thin layer of skin is removed from its body [Fig. 3. [citation needed]. In commercial use, silk is almost entirely limited to filaments from the cocoons of domesticated silkworms (caterpillars of several moth species belonging to the genus Bombyx ). In September 2010, the effort was announced as successful. Similarly, the thread which is burnt with the smell of burning hair is silk because silk, as well as hair, are proteins hence they burn with a similar characteristic smell. To prevent this, silkworm cocoons are boiled. It is the closest relative of Bombyx mandarina, the wild silk moth. If the animal is allowed to survive after spinning its cocoon and through the pupal phase of its lifecycle, it releases proteolytic enzymes to make a hole in the cocoon so it can emerge as an adult moth. Silkworms secrete fibre made of (a) fat (b) cellulose (c) protein (d) nylon. Production of sarees. Bio-wash/Enzyme wash fabric 10. This is called scouring. 10.Silkworms secrete fibre made of (a) fat (b) cellulose (c) protein ... NCERT Exemplar for Class 7 Science Chapter 3 Fibre to fabric Explanation: Salivary gland of silkworm releases a protein which is used as silk. It has gained tolerance to human presence and handling, and also to living in crowded conditions. These questions help you in practising different kinds of questions that can be asked on a specific topic. There are about 20 sets of MCQ tests, each test containing 5 questions with answers and explanation of answers updated for new academy session 2020-21. (c) making silk fabric from silk yarn. The Chinese guarded their knowledge of silk, but, according to one story, a Chinese princess given in marriage to a Khotan prince brought to the oasis the secret of silk manufacture, "hiding silkworms in her hair as part of her dowry", probably in the first half of the first century AD. Your email address will not be published. History of silk: Around 3500 BC, silk was discovered in China during the reign of emperor Huang-ti. The domesticated B. mori and the wild B. mandarina can still breed and sometimes produce hybrids. (b) spinning of silk fibres. 5. Milk fibre 9. Hair are of bad conductors of heat, hence they will not allow the escape of heat from the body, which ensures their bodies stay warm. #manufacturing #fabric #eco #silkworms. Answer: Pure and Artificial Silk. Silk is a natural protein fiber, some forms of which can be woven into textiles.The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. Bombyx mori, the domestic silk moth, is an insect from the moth family Bombycidae.It is the closest relative of Bombyx mandarina, the wild silk moth.The silkworm is the larva or caterpillar of a silk moth. Your email address will not be published. Silkworms eat mulberry leaves, and are native to northern China.. For more information visit BYJU’S website or download BYJU’S learning App. A process of making silk reels. The a) female silk moth lays b) eggs, from which hatch c) larvae called d) caterpillars or e) silkworms. "Molecular phylogeny of silkmoths reveals the origin of domesticated silkmoth, https://phys.org/news/2013-11-captive-thousands-years-impaired-olfactory.html, "Cocoon Silk: A Natural Silk Architecture", "Advantages of the silkworm as an animal model for developing novel antimicrobial agents", "A novel spiro-heterocyclic compound identified by the silkworm infection model inhibits transcription in, "Evidence of selection at melanin synthesis pathway loci during silkworm domestication", "Mountage: Meaning and Types | Sericulture", "Silkworm School Science Project Instruction", "Complete resequencing of 40 genomes reveals domestication events and genes in silkworm (, https://doi.org/10.1016/j.ibmb.2008.11.004, WormSpit, a site about silkworms, silk moths, and silk, Information about silkworms for classroom teachers with many photos, SilkBase Silkworm full length cDNA Database, Silkworm School Science Project Instruction, https://en.wikipedia.org/w/index.php?title=Bombyx_mori&oldid=993006627, Articles with dead external links from December 2017, Articles with permanently dead external links, Short description is different from Wikidata, Articles containing Chinese-language text, Articles containing Japanese-language text, Articles with unsourced statements from November 2010, Articles with unsourced statements from December 2017, Articles with unsourced statements from August 2014, Articles containing Vietnamese-language text, Articles needing additional references from September 2020, All articles needing additional references, Creative Commons Attribution-ShareAlike License, Silkworms have also been proposed for cultivation by astronauts as, Several diseases caused by a variety of funguses are collectively named, This page was last edited on 8 December 2020, at 08:18. (c) Wool yielding animals bear hair on their body. 7th Standard CBSE Science - Fibre to Fabric Book Back Questions - Complete list of 7th Standard CBSE question papers, syllabus, exam tips, study material, previous year exam question papers, centum tips, formula, answer keys, solutions etc.. The heat kills the silkworms and the water makes the cocoons easier to unravel. When the silkworm (or caterpillar) is ready to enter the next stage of its development called pupa, it first weaves a net to hold itself. The uppermost layer of the skin is dead. [15] Antibiotics such as lysocin E,[16] a non-ribosomal peptide synthesized by Lysobacter sp. This process is called shearing. Using this knowledge they built a silk pavilion with 6,500 silkworms over a number of days. They also created implants made of silk and drug compounds which can be implanted under the skin for steady and gradual time release of medications.[14]. (c) weaving of silk cloth. Silk fibres can be incorporated as reinforcements into thermoplastic matrices to create composite materials with a high strain to failure rate. Step VI: The fibres are straightened, combed and rolled into yarn. Which of the following is not a type of silk? The major groups of silkworms fall under the univoltine ("uni-"=one, "voltine"=brood frequency) and bivoltine categories. This exemplar covers questions on fibres like silk and wool, their source of production, different animals reared for wool production and methods of production of fibres. Before then, the tools to manufacture quantities of silk thread had not been developed. [2][3], Silk moths were unlikely to have been domestically bred before the Neolithic Age. (e) Yak hair is not used to make woollen fabric. [13], Researchers at Tufts developed scaffolds made of spongy silk that feel and look similar to human tissue. False- The rearing of silkworms for obtaining silk is called sericulture. [10] One useful development for the silk industry is silkworms that can feed on food other than mulberry leaves, including an artificial diet. (d) production of sarees. Write them in their correct form. (c) washing of sheep fibre to remove grease. (c) weaving of silk cloth. Selective breeding is the process of the crossing of two selected varieties having different traits to produce a hybrid having good traits of both, e.g., some breeds of sheep possess only soft under-hair. (b) separating the hair of different textures. It is easy to break a fibre thread as it is fragile and easy to break as well. (a) Eggs are warmed to a suitable temperature for the larvae to hatch from eggs. Paheli went to the market to buy sarees for her mother. During these movements of the head te silkworm secretes fibre made of a protein which harden on exposure to air and becomes silk fibre. A thread which burns with the smell of burning paper is of cotton because both paper and cotton are cellulose which is carbohydrate and hence they burn with similar odour. Quality of cocoon and silk depends on a number of factors, including genetics. Very Short Answer Questions. Also, the hair of sheep grows again just as your hair does. In addition, antibiotics with appropriate pharmacokinetic parameters were selected that correlated with therapeutic activity in the silkworm infection model.[19]. Habit and Habitat of Mulberry Silkworm 3. High genetic variability has been found in domestic lines of silk moths, though this is less than that among wild silk moths (about 83 percent of wild genetic variation). (d) production of sarees. Steps for the production of silk are given below in a jumbled order. Fibre to Fabric NCERT – Question: How silkworms are reared? (d) In the process of obtaining wool from fleece, sorting is done after scouring. (a) _________ and _________ fibres are obtained from animals. The general process that takes place at a sheep shearing shed is. Silkworm completely covers itself by silk fibres and this covering is called cocoon which is further processed to … Healthy larvae lead to a healthy cocoon crop. polyester). (b) rearing of silkworm. Step V: The fibres can be dyed in various colours, as the natural fleece of sheep and goats is black, brown or white. This is because their bodies are too big and heavy for their small wings. The girl died in her sleep, and as she wished to continue to help other people, her soul turned into silkworms. [5], Mulberry silkworms can be categorized into three different but connected groups or types. Many hundreds of strains are maintained, and over 400 Mendelian mutations have been described. Woollen fibres are then processed to obtain woollen yarn. 11. The practice of raising silk moths by children as pets has, in non-silk farming South Africa, led to the development of extremely hardy landraces of silk moths, because they are invariably subjected to hardships not encountered by commercially farmed members of the species. After molting, the larval phase of the silkworms emerge white, naked, and with little horns on their backs. They are implanted during reconstructive surgery to support or restructure damaged ligaments, tendons, and other tissue. Write a caption for each of the figures given as Figure 3.2 (a–d). Answer (d) Question 10. If false, correct them. The hair provides woollen fibres. 24. 12. (d) The larvae/caterpillars or silkworms are kept in clean trays along with freshly chopped mulberry leaves. made of cellulose (e.g. Describe the life history of silk moth with the help of figures of various stages. Various steps involved to obtain wool from fleece are given here. 13. 10. 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