Fibre To Fabric - Class 7 Chemistry - Extra Questions

What were the materials used by people in ancient times in place of clothes?

It appears that in those days people used the bark and big leaves of trees or animal skin and furs in place of clothes.


When we burn wool why do we get the smell of hair burn?

Wool is obtained from the fleece (hair) of sheep, goats, yak etc. This is the reason why burning of wool resembles the burning of hair.


 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. 
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In the innermost ring, the name of animal is YAK. In the middle ring, the name of animal is CAMEL. In the outermost ring, the name of animal is SHEEP. 


______________ is a thread or filament from which cloth is made.

Fiber is a thread or filament from which cloth is made. Plants and animals are two of the most common sources of fibre. Natural Fibres are the name given to these fibres. Natural fibres include cotton, wool, and silk.

Synthetic fibres are artificially created by humans with the help of machinery and technologies in the textile industries, in addition to natural fibres. These fibres are also known as synthetic fibres. Synthetic fibres include Rayon, Nylon, and Polyester.


What are yarns made of?

Yarns are made up of thin strands called fibers.


Name some fabrics in your surroundings.

Bed sheets, blankets, curtains, table cloths, towels, and dusters are examples of fabrics in our surroundings.


Which part of sheep has fibres that are used to make wool?

Answer-

The hairy skin of the sheep has two types of fibres namely the coarse beard hair and the fine soft under- hair close to the skin. These fibres are called fleece and are used to make wool. 


What is meant by the white fleece of the lamb?

Answer-

White fleece of lamb refers to the pure whitish colour hair of the lamb which is used to make wool. 


Out of the following, which are the two terms related to silk production? Sericulture, floriculture, moriculture, apiculture and silviculture.

  1. Silk production involves the cultivation of mulberry leaves and rearing silkworms, known as sericulture.
  2. Moriculture can be defined as the process of cultivating mulberry plants in order to feed silkworms.


What is meant by the following terms?
  1. Rearing 
  2. Shearing 
  3. Sericulture

  1. Rearing: The process of keeping, feeding, breeding, and medical care of useful animals is called the rearing of animals. These animals produce one or more useful products for human beings.
  2. Shearing: The process of removing the fleece of the sheep along with a thin layer of skin is called shearing.
  3. Sericulture: The rearing of silkworms for obtaining silk is called sericulture.


Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Down: (i) Thorough washing
(ii) Animal fibre
(iii) Long thread like structure
Across:
(1): Keeps warm
(2): Its leaves are eaten by silkworms
(3): Hatches from egg of moth.

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Some words related with silk are jumbled up. Write them in their correct form. 
a) TURECULRISE
b)WILSMORK
c) BELMURRY
d) RINGLEE 

The correct form of given words are:
a) SERICULTURE
b) SILKWORM
c) MULBERRY
d) REELING 


How do the hairs of certain animals help in keeping their bodies warm ?

On the animal body, there is a thick coat of hair. These hairs trap a lot of air in them which helps to keep their body warm. 


Match the items of Columns I with the items given in Column II 
$$Column\ I$$$$Column\ II$$
Yak woolSheared hair
Angora goatsSilkworm
Mulberry leaves Tibet and Ladakh
ScouringJammu and Kashmir

Correct match of given table:
$$Column\ I$$         $$Column\ II$$
Yak wool         Tibet and Ladakh
Angora goats         Jammu and kashmir
Mulberry leaves         Silkworm
Scouring         Sheared hair


Fill in the blanks in the following statements.
a) ______ and _______ fibres are obtained from animals.
b) Silk fibres come from ______ of silk ______ .
c) Wool yielding animals bear _______ on their body.
d) Hair traps a lot of _______, which is poor ________ of heat.

Fill up for above statements are:
a) Fill up is silk, wool.
b) Fill up is cocoons, moth.
c) Fill up is hair.
d) Fill up is air, conductor.


Write a caption for each of the figures from (a) to (d).
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Figure (a) : Eggs of silk moth on mulberry leaf.

Figure (b) : Silkworm

Figure (c) : Cocoon

Figure (d) : Cocoon with developing moth.


State whether the following statements are true or false. If false, correct them.
a) Silkworms are caterpillars of silk moths.
b) In India, camels and goats are generally reared for obtaining wool.
c) The rearing of silkworms for obtaining silk is called silviculture.
d) In the process of obtaining wool from fleece, sorting is done after scouring.
e) Yak hair is not used to make woollen fabric.

In the given statements: 
a) The given statement is true.
b) The given statement is false. In India, sheep are reared for obtaining wool and not camels.
c) The given statement is false. The rearing of silkworms for obtaining silk is called sericulture.
d) The given statement is true.
e) The given statement is false. Yak hairs are used to make woollen fabric.


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

Column IColumn II
a) Pashmina shawli) Camel wool
b) Woolen Carpetii) Angora wool
c) Baby blanketiii) Kashmiri goat 
d) Woolen sweateriv) Sheep wool

Pashmina shawls are made from the under fur of Kashmiri goats, as it is very soft. It is woven into fine shawls. Woolen carpets are made from camel wool, which coarse and durable. Baby blankets are made from soft angora wool and woolen sweaters are made from sheep wool, which is thick and warm.
So, the correct pairs are:

Column IColumn II
a) Pashmina shawl i) Kashmiri goat
b) Woolen Carpetii) Camel wool
c) Baby Blanketiii) Angora wool
d) Woolen sweater iv) Sheep wool


Fill in the blank:
The ............ get wrapped in silk fibre and form cocoon.

The $$\underline{caterpillars}$$ get wrapped in silk fibre and form cocoon.

Caterpillars or silkworms weave a net to hold themselves and then secrete a fibre made of a protein that hardens on exposure to air. This fibre becomes silk fibre. Caterpillars cover themselves in silk fibres and the covering is called cocoon.


Write various steps for processing fibres into wool. 

The various steps for processing fibres into wool:
a) Shearing: The procedure of removing fleece of sheep is termed as a shearing.
b) Scouring: The procedure of cleaning removed fleeces is termed as a scouring.
c) Sorting: After the procedure of scouring, next step is sorting. In this procedure washed hairs are sent to the various factories. In the factories separation of different texture of hairs takes place.
d) Picking out blurrs: The tiny fluffy fibres that were picked out from fleece are known as blurrs. After collecting all the blurrs they were cleaned and dried again.
e) Dyeing: In this process fibres are dyed into different colours.
f) Rolling into yarn: The fibres are straightened, combed, and also, rolled into yarn. 


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. 

The proper sequence of the given statements are given below: 
a) Female silk moths lay eggs.
b) Eggs are warmed to a suitable temperature for the larvae to hatch from eggs.
c) The larvae/caterpillars or silkworms are kept in clean trays along with freshly chopped mulberry leaves. 
d) After $$25$$ to $$30$$ days, the caterpillars stop eating and start spinning cocoons.
e) Cocoons are kept under the sun or boiled in water. 
f) Fibres are taken out from the cocoon.


Which natural materials are used to obtain fibers?

Natural materials obtained from plants and animals are used to obtain fibres. For example, wool and silk are natural materials of animal origin which are used for obtaining fibers. Wool is obtained from the fleece (hair) of sheep or yak and silk is obtained from the cocoons of a silk moth. Cotton and jute are examples of natural materials of plant origin which are used for obtaining fibers.


Complete the paragraph related to the life history of the 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)___, it first weaves a covering to hold itself, which is known as ______(g)____.

(a) female (b) eggs, (c) larvae (d) caterpillars (e) silkworms. (f) pupa (g) cocoon.


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

To identify the purity of silk, you have to burn a thread of silk. If the burning smell of that thread is similar to the burning smell of hair then the thread will be pure silk. Silk and hairs are protein fibers, thus, they generate the same smell.
To identify the purity of cotton, you have to burn a thread of cotton. If the burning smell of that thread is similar to the burning smell of paper then the thread will be pure cotton. Cotton and paper are carbohydrates, thus, they generate the same smell. 


How is lac obtained from nature?

Lac is a natural resin and is a product of animal origin. It is secreted by an insect, known as lac-insect. In order to obtain lac, these insects are cultured and the technique is called lac-culture. Lac culture requires proper care of host plants, regular pruning of host plants, propagation, collection and processing of lac. The lac insect lives as a parasite, feeding on the sap of certain trees and shrubs. Lac secretion begins as soon as the larva of the insect settles on the plant. Initially, lac has a shining appearance but later on it turns harder on coming in contact with air.
This lac is then collected and used for making jewellery etc.


What are the uses of wood?

Wood is used in:
  • making table, chair, door, bed,etc
  • as a source of fuel
  • wooden toys



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

The life history of silk moth with the help of figures of various stages: 
The female 'silk moth' lays eggs. From these eggs, the larvae come out. These larvae are termed 'caterpillars/ silkworms'. These caterpillars/silkworms feed fresh leaves of mulberry. After this, the silkworm changes in size or shape and then becomes a "pupa". 
Pupa first weaves a covering to hold itself, which is termed a cocoon. It develops inside the cocoon into a moth. After this, it comes out as an adult female or male silk moth.
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What is meant by sericulture?

The breeding and management of silkworms for the production of silk is known as sericulture. Different types of silk (eg. mulberry silk, Tassar silk etc.) with different textures are obtained from different varieties of silk moths.


Draw a neat diagrams of life-history of silk moth.

Life history of silk moth
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What is sericulture ? Explain the life - cycle of silk worm.

Sericulture is the process of rearing silkworms for obtaining silk.
Life Cycle of silkworm:
  • Female silkworm lays eggs on the leaves of the mulberry tree. 
  • These eggs hatch into caterpillars or larvae.
  •  They develop by eating the leaves of this plant. 
  • They have a silk gland that secretes a substance, which helps them to form a thread-like structure. 
  • Later, this thread-like structure takes a round shape which is called a cocoon. In the cocoon, the caterpillar changes to a pupa. 
  • Then the pupa changes into an adult silkworm and completes its life-cycle.

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What are sources of wool ?

Several breeds of sheep are found in different parts of our country. Sheep wool is very common. 
Yak wool is common in Tibet and Ladakh.
Mohair is obtained from angora goats, found in hilly regions such as Jammu and Kashmir.
Wool is also obtained from goat hair. The underfur of Kashmiri goat is soft. It is woven into fine shawls called Pashmina shawls.
The fur on the body of camels is also used as wool. Llama and Alpaca, found in South America also yield wool.


Where and how the sheep are reasred in India ?

In Jammu and Kashmir, Himachal Pradesh, Uttaranchal, Arunachal Pradesh, Sikkim, the plains of Haryana, Punjab, Rajasthan, Gujarat etc., the shepherds taking their herds of sheep for grazing. Sheep are herbivores and prefer grass and leaves. 

Apart from grazing, rearers also feed them on a mixture of pulses, corn, Jowar, oil cakes etc., In winter Sheep are kept indoors and fed on leaves grain and dry fodder.


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'. 
What is meant by the white fleece of the lamb ?

White fleece refers to the white hair of lamb that is used to make wool.


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'. 
Which parts of the black sheep have wool?

The fine and soft under-hair that grows close to the skin of the sheep has fibres that are used as wool.


Fill in the blanks:
___________ are woven from the soft wool of Kashmiri goat.

Pashmina shawls are woven from the soft wool of Kashmiri goat.


What are the various types of silk?

The types of silks are mulberry silk, tasar silk, eri silk, and muga silk etc.


What is sericulture?

Sericulture, the production of raw silk by means of raising caterpillars (larvae), particularly those of the domesticated silkworm (Bombyx mori).


Fill in the blanks:
The soft silk yarn (thread) is as strong as the thread of _______.

The soft silk yarn (thread) is as strong as the thread of steel.


Fill in the blank:

The rearing of silkworms for obtaining silk is called ________.

The rearing of silkworms for obtaining silk is called sericulture or silk farming.


Fill in the blanks:
The most common silk moth is the ________ silk moth.

Answer: mulberry 
The most common silk moth is the mulberry silk moth.


Fill in the blank:
________ and ________ found in South America, yields wool.

Llama and Alpaca found in South America, yields wool.


Fill in the blanks:

Yak wool is common in ______ and ________.

Yak wool in is common in Tibet and Ladakh.


Fill in the blank:
_________ leads the world in silk production.

China leads the world in silk production.


Give two examples of animals fibres.

$$\text{Silk}$$(obtained from silkworm) and $$\text{wool}$$(obtained from sheep) are two examples of animal fibres.


Fill in the blank:

The risks faced by workers in any industry are called ___________ hazards.

The risks faced by workers in any industry are called occupational hazards. Occupational hazards can encompass many types of hazards, including chemical hazards, biological hazards, psychosocial hazards, and physical hazards.


Fill in the blanks:
The process of taking out threads from the cocoon is known as __________.

The process of taking out threads from the cocoon is known as reeling the silk.
Reeling is done in special machines, which unwind the threads or fibers of silk from the cocoon. Silk fibers are then spun into silk threads, which are woven into silk cloth by weavers.


What is a fibre?

Fibre is a natural or man-made substance that is significantly longer than it is wide. Fibers are often used to make yarns which are in turn used to make fabrics.


___ is an example of dietary fibre.

$$\text{Cellulose}$$ is an example of dietary fibre.


Fill in the blanks:
The scientific name of mulberry is ________.

The scientific name of mulberry is $$Morus \ alba$$.


___ and ___ are animals fibres.

Silk and wool are animals fibres. Silk is obtained from silkworm and wool from sheep.


Fill in the blanks:
Silk fibres are made of a________.

Silk fiber is made of a $$protein$$.


Class 7 Chemistry Extra Questions