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Subject:

science-chemistry

Class:

class VII

Key Concepts

natural fibre, man made fibre,selective breeding, cocoon, life cycle of silkworm, soritng, reeling, sericulture, silk moth, shearing, scouring

essential questions

1. Have you ever wondered why man chose to rear wool bearing animals and how he was inspired to get wool from them?
2. How has man been inspired by nature to get different type of fiber for his own requirements?

Remembering:

  1. Consider the following statements and tell true or false:

a) Silk is a cellulosic fibre

b) The hair on a sheep’s body is called fleece

c) Silk fabric was first developed in ancient China

d)Cashmere is an extremely soft wool obtained from Cashmere sheep

e) Fibroin is the gummy substance that holds the two strand of sericin together of a silk fibre together

f) Asbestos is the only naturally occurring long mineral fibre

g) Merino is an exotic breed of sheep

 

  1. Fill in the blanks:

a) Silk is made of two proteins-_____________ and ___________

b) ____________ and __________ are two breeds of camel, whose wool is used to obtain quality wool.

c) _________ is the process in which fibres are straightened by passing them through metal teeth.

d) The factory where silk fibres are unwound from the cocoons into bundles of yarn or thread is called ___________

e) The fatal blood disease caused due to anthrax bacterium infecting the blood stream is called___________

3. Match the columns

Column A                            Column B

a) Clothing material         i)   Nylon

b)Twisted fibre                 ii) Fabric

c) Synthetic Fibre             iii) Yarn

d) Animal Fibre                 iv) Jute

e) Plant fibre                       v) Wool

4. Fill in the blanks:

  1. Silk when burnt will smell as_______
  2. Wool when burnt will smell as_______
  3. Nylon when burnt will smell as____________

5.The given table enlists types of Silk (P) and plants on the leaves of which the related silkworm feeds(Q) in. Fill in the table with right answers

P    Silk Q plant leaves it feeds on
Mulberry  
Muga  
Eri  
Tussar  
  1. Read the following statements and fill in the blanks:

a) The plant fibres are made up of ________________ which is structural material in the plant world.

b) The process of taking out threads from the cocoon to use as silk is called as______________

c) The sheared hair of sheep is moved through tubes filled wth soapy water to remove dust, dirt and grease. This is known as_________

d) Mohair, spun from the fleece of the Angora__________________ is extremely light weight.

 

 

understanding:

  1. What is sericulture? What are the hazards attached with this industry?
  2. Write the complete life cycle of a silkworm and show it with a labelled diagram.
  3. What are the hazards associated with woolen industry?
  4. How is rayon different from Nylon? Which of the two is environment friendly?
  5. What do you understand by biodegradable and non biodegradable?
  6. Following is the random sequence of steps in the processing of wool. Arrange these steps in the processing of wool.
  7. a)scouring   b) sorting   c) shearing    d) removing burrs   e) dyeing    f) yarn    g) spinning   h) weaving  i) fabric  j)carding

Application:

1.Rani takes X fabric and burns it. She observes following properties of the fabric:

a) It burns but does not melt.

b) It shrinks from flame

c)It gives the odour of charred meat while buring.

d) It left residue after burning which is black, hollow, irregular bead that can be easily crushed to a gritty black powder.

e) It is self extinguishing.

According to her observation X will be_________

Analysis:

1.Pick the odd one out from the series below and give the reasons for the same:

a) Muga, Kosa, Cashemere, Tussar

b) Larva, Pupa, silk moth, tadpole

c) Patanwadi, Marwari, pashmina, Lohi

Evaluation:

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