NCERT Exemplar Problem Class 7 Science Fibre to Fabric

Here in this post we provided NCERT Exemplar Problem Class 7 Science Fibre to Fabric Chapter 3 Full Explanation by group of Science Experts. We have provided here each questions answer with reason behind the answer.

Hope it help you!

Fibre to Fabric Class 7 Exemplar full Explanation:

1.) The rearing of silkworms for obtaining silk is called

A) Cocoon

B) Silk

C) Sericulture

D) Silviculture

Answer:-  c) sericulture

Sericulture is the obtaining silk from rearing the Silkworms.

2.) Which of the following is not a type of silk ?

A) Mulberry silk

B) Tassar silk

C) Mooga silk

D) Moth silk

Answer:- d) moth silk

Mulberry silk, Tassar silk and mooga silk are types of silk . But moth silk is not type of silk. Female Moth silk lay eggs after which the process of silk starts.

3.) Paheli wanted to buy a gift made of animal fibre obtained without killing the animal. Which of the following would be the right gift for her to buy ?

A) Woollen shawl

B) Silk scarf

C) Animal fur cap

D) Leather jacket

Answer:- a) woollen shawl

Wool is obtained form the hair of the sheep. This doesn’t need to kill the animals. Thus woollen shawl would be right gift for her to buy.

4.) Silk fibre is obtained from

A) Fleece of sheep

B) Cotton ball

C) Cocoon

D) Shiny jute

Answer:- c) Cocoon

Silk fibre are obtained from cocoon. Fleece of sheep used for making woollen , cotton balls and shiny jute makes other fibres.

5.) Wool fibre cannot be obtained from which of the following ?

A) Goat

B) Llama

C) Alpaca

D) Moth

Answer:- d) moth

Moth silk is used to make the silk fibres , not the wool fibre. From the hairs of goats, Llama , and Alpaca woollen fibres are formed.

6.) Selective breeding is a process of

A) Selecting the offspring with desired properties

B) Selecting the parents with desired properties

C) Selecting an area for breeding

D) Selecting fine hair for good quality wool.

Answer:- b) selecting the parents with desired properties.

Selective breeding is the process in which two parents with desired properties are selected for the good breed and quality offspring.

7.) The general process that takes place at a sheep shearing shed is

A) Removal of fleece.

B) Separating hair of different textures.

C) Washing of sheep fibre to remove grease.

D) Rolling of sheep fibre into yarn.

Answer:- a) Removal of fleece.

Removal of fleece is the general process that takes place at a sheep shearing shed After that all the process are carried out to form the woollen fibres.

8.) The term sericulture is used for

A) Culture of bacteria

B) Rearing of silkworm

C) Making silk fabric frim silk yarn.

D) Production of sarees.

Answer:- b) rearing of Silkworm.

Rearing of Silkworms is the process for obtaining silk known as sericulture.

9.) Reeling of silk is

A) A process of making silk reels.

B) Spinning of silk fibres.

C) Weaving of silk cloth.

D) The process of taking silk threads from cocoon.

Answer:- d) the process of taking silk threads from cocoon.

Silk moth forms the cocoon by its proteinous substances which is converted into thin threads which we known as silk.  The process of taking out this threads from the cocoon is the reeling of silk.

10.) Silkworms secrete fibre made of

A) Fat

B) Cellulose

C) Protein

D) Nylon

Answer:-  c) protein

Silkworms caterpillars Secrets protein. This protein when get in contact with sunlight and air get Harden and converted into thin fibre. This fibre is thin and really smooth which is known as silk.

  • Very Short Answer Questions

11.) Fill in the blanks in the following statements.

A) ____________ and _________ fibres are obtained from animals.

B) Silk fibres come from __________ and __________.

C) Wool yielding animals bear ____________ on their body.

D) Hair trap a lot of ___________, which is a poor __________ of heat.

Answers:-

A) Silk and wool fibres are obtained from Animals.

B) Silk fibres come from cocoons and moth.

C) Wool yielding animals bear hairon their body.

D) Hair trap a lot of air which is a poor conductor of heat.

12.) State whether the following statements are true or false. If false, correct them.

A) Silkworms are caterpillars of silk moth.

Answer:- True

B) In India , camels and goats are generally reared for obtaining wool.

Answer:- False , In India generally sheeps are reared.

C) The rearing of Silkworms for obtaining silk is called silviculture.

Answer:- False , the rearing of Silkworms for obtaining silk is called sericulture.

D) In the process of obtaining wool from fleece, sorting is done after scouring .

Answer:- true.

E) Yak hair are not used to make woollen fabric

Answer:- False , yak hair are used to make woollen fabric.

13.) How do the hair of certain animals help in keeping their bodies warm?

Answer:- Some animals like sheep, Yak,  camels, Kashmiri goats , have lots of hair on their bodies. The hair present on their body trap a lot of air. heat transfer from the process of conduction. Poor conductor are known as insulator. hair is a poor conductor of heat. Therefore Hair are insulator.so, hair keeps these animals Warm. The air do not transfer form thishairy coat and thus they don’t feel cold. Simultaneously their body gets warm due to that. Wool is derived from these hairy fibres.

  • Short Answer Questions

14.) Match the items of Column I with the items given in Column II

Column I Column II
A)          Yak wool I)                           Sheared hair
B)           Angora goats II)                       Silkworm
C)           Mulberry leaves III)                   Tibet and Ladakh
D)         Scouring IV)                  Jammnu and Kashmir

Answer:-

A) Yak wool → III) Tibet &ladakh

B) Angora goats→ IV)Jammu&kashmir

C) Mulberry leaves→II) silkworm

D) Scouring→ I) sheared hair

15.) Various steps involved to obtain wool form fleece are given here.

i) Picking out the burrs

ii) Dyeing in various colours

iii) Shearing

iv) Scouring

v) Sorting

Write the above steps in the correct sequence in which they are carried out.

Answer:-

The correct sequence of various steps involved to obtain wool form fleece are –

1) Shearing

2) Scouring

3) Sorting

4) Picking out the burrs

5) Dying in various colours

16.) Some words related with silk are jumbled up. Write them in their correct form.

a) TURECULRISE

b) WILSMORK

c) BELMURRY

d) RINGLEE

Answer:-  The correct Name of silk are –

A) SERICULTURE

B) SILKWORM

C) MULBERRY

D) REELING

17.) Figure. 3.1 shows three rings of circles with letters in them some of these letters in each ring can form the name of one wool yielding animal. Find the names of these animals.

Answer:- the names of the wool yielding animals are –

1) Yak

2) Camel

3) Sheep

18.) Write a caption for each of the figures given 3.2 (a-d)

Answer:-  the caption for each figure –

A) Eggs of silk moth on mulberry leaves

B)Silkworm

C)Cocoon

D)Cocoon with developing moth

19.) Steps for the production of silk are given below in a jumbled order. Arrange them in their proper sequence.

A) Eggs are warmed to a suitable temperature for the larvae to hatch from eggs.

B) Fibres are taken out from the cocoon.

C) After 25 to 30 days , the caterpillars stop eating and start spinning cocoons.

D) The larvae/caterpillars or Silkworms are kept in clean trays along with freshly chopped Mulberry leaves.

E) Female silk moths lay eggs.

F) Cocoons are kept under the sun or boiled in water.

Answer :-

The proper sequence of steps of production of silk are –

E) Female silk moths lay eggs .

A) Eggs are warmed to a suitable temperature for the larvae to hatch from eggs.

D) the larvae/ caterpillars or Silkworms are kept in clean trays along with freshly chopped mulberry leaves.

C) after 25- 30 days the caterpillars stop eating and start spinning cocoons.

F) cocoons are kept under the sun or boiled in water.

B) fibres are taken out from the cocoon.

20.) A wholesale woollen fibre dealer gets the woollen fibre of different textures sorted for various purposes. Match the items in Column I  with the woollen fibre in Column II.

Column I Column II
a)            Pashmina shawl I)Camel wool
b)           Woollen carpet II) Angora wool
c)            Baby blanket III) Kashmir goat
d)           Woollen sweater IV) sheep wool

Answer:-

A) Pashmina shawl → Kashmir goat

B) Woollen carpet → camel wool

C) Baby blanket → angora wool

D) Woollen sweater → sheep wool

  • Long Answer Questions

21.) Complete the paragraph related to the life history of silk moth by filling in the blanks.

The _____(a)___ silk moth lays ____(b)____ , from which hatch _____(c)_____ called _____(d)_____ or _____(e)_____. They grow in size and when the caterpillar is ready to enter the next stage of its life history called _____(f)_____, if first weaves a covering to hold itself, which is known as _____(g)______.

Answer:-

The female silk moth lays eggs from which hatch larvae called caterpillars or Silkworms. They grow in size and when the caterpillars is ready to enter the next stage of its life history called pupa , if first weaves a covering to hold itself , which is known as cocoon.

22.) Paheli went to the market to buy sarees for her mother. She took out a thread of the two sarees shown by the shopkeeper and burnt them. One thread burnt with the smell of burning paper. Which thread is form a pure cotton saree and which one from a pure silk saree? Give reason for your answer.

Answer:-there were two saree’s thread taken by the paheli to burnt them . The first thread was burntwith a smell of burning hair . These thread was formed by the pure silk. As silk and hairs both are formed by protein. But the second thread burnt was made up of cotton. Thus when it was burnt smelled same as paper, because cotton and paper both are made up of carbohydrates, therefore gives similar smell on burning.

23.) Explain the phrase- “Unity is strength” on the basis of the making of fabric from fibre.

Answer:-“unity is strength” .The term have meaning in itself.One single person needs more energy and more time to do the same work which may be done inless time and less energy when more than one person do it. Sameas that when we take a single thread of any fibre. We can easily break it by applying pressure or stretching.  But when many fibres are hold tightly and weave together to make a fabric it gets almost impossible to tear it. It needs more energy than a single fibre needs. Thus the phrase ‘unity is strength’is explained with fibre and fabric.

24.) Write various steps for processing fibres into wool.

Answer:-  the steps which are involved in the process of making fibres into wool is as below-

A) Shearing–(step – I)

This is the process in which the fleece is removed from sheep’s body, also thin layer of skin with the Hair are removed during the hot weather by machines which is used by barbers. Shearing does not hurt the sheep. The outer layer of the skin is dead also the hair of sheep grow again in few days.

B) Scouring – ( step – II)

Scouring is the process in which the sheared skin with hair is Completely washed in tanks to removedust and dirt . It is also done by machines.

C) Sorting –( step – III)

The next process in the wool formation after the scouring is sorting. In the sorting process the hairy skin is send to factorywhere hair of different types are separated.

D) Burrs picking – ( steps – IV)

Burrs picking is the next process in which the small fluffythreads, known burrs are picked out of the hair. After the picking up of burrs the fibres are washed again and dried. After this the wool is ready for making fibre.

E) Dying the fibres – ( step – V)

The natural hairs of the sheep or goat or yak have only black, brown or white colour. But we can dye the fibres in various colours. As we wear sweater of different shades and different colours these are not natural colour these are dyes which is given to fibres.

F) Separation (Step – VI)

This is the last step in the wool formation process. In this step the dyed fibres are straightened and combed. And then rolled into yarn. The longer fibres and shorter fibres are separated which are then use in different things such as longer fibres are used to make wool for sweaters and the shorter fibres are used for woven into woollen cloth.

This is the whole process of the wool formation from the fibres.

25.) Describe the life history of silk moth with the help of figures of various stages.

Answer:- silk fibre is the natural animal fibre which get from the Silkworms . Silkworms spin the silk fibres.

The rearing of Silkworms for obtaining silk is called “sericulture”.

the life history of the silk moth is as follows :

  1. The female silk moth lays eggs.
  2. Eggs are hatched into larvae which known as“caterpillars”or “Silkworms” .
  3. The next stage of the caterpillars when they grow in size is the pupa.
  4. Caterpillars first weaves a net to hold itself tightly. Then it starts weaving the net around itself by moving the head in the form of the figure 8 in maths.
  5. With these movements of the head , caterpillars secrets the fibre which is made up of a “protein”.
  6. This protein hardens when contacted to air and sunlight and becomes“silk fibre”.
  7. This process continues goes on till the caterpillar totally covers itself by the fibreand turns into
  8. “cocoon” is the covering made up of this silk fibres.
  9. Pupa is getting developed inside the cocoon continually. And after that it is developed into moth.
  10. For obtaining silk fibres, these moths are reared and their cocoons are collected to get silk thread.
  11. After the complete processing on the cocoons the silk fibre gets ready for the weaving silk fabric.
  12. Types of silk fibres are mulberry silk, Tassar silk, mooga silk, eri silk, etc.

This is the complete life history of the silk moth.

Updated: February 28, 2021 — 11:23 pm

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