Fibre to Fabric
Science Class Seven
NCERT Exercise Solution
Question (1) You must be familiar with 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?
Answer: Body of sheep have wool.
(b) What is meant by the white fleece of the lamb?
Answer: White fleece means hair of the lamb.
Question (2) The silkworm is (a) a caterpillar, (b) a larva. Choose the correct option.
(i) a
(ii) b
(iii) both a and b
(iv) neither a nor b
Answer (b) both a and b
Explanation
The larva of butterfly, silk moth, etc. are called generally Caterpillar. Caterpillar can crawl.
Question (3) Which of the following does not yield wool?
(i) Yak
(ii) Camel
(iii) Goat
(iv) Wooly dog
Answer (iv) Wooly dog
Explanation
Wooly dog also have hair like sheep, but it cannot spun into wool thread. The fleece of wooly dog was used to make blanket.
Now, wooly dog is an extinct breed of dog. Wooly dog was found in Coast Salish.
Question (4) What is meant by the following terms?
(i) Rearing (ii) Shearing (iii) Sericulture
Answer
(i) Rearing
Rearing is the taking care of animals. This includes breeding, feeding, etc.
(ii) Shearing
The shaving off of fleece from sheep and other wool bearing animals is called Shearing.
(iii) Sericulture
The rearing of silkworm is called sericulture. Sericulture is done in order to obtain silk.
Question (5) Given below is a sequence of steps in the processing of wool. Which are the missing steps? Add them.
Shearing, ______, sorting, _____, ______, _______.
Answer
Shearing, Scouring, sorting, Dyeing, Spinning, Weaving.
Question (6) Make sketches of the two stages in the life history of the silk moth which are directly related to the production of silk.
Answer
Question (7) Out of the following, which are the two terms related to silk production?
Sericulture, floriculture, moriculture, apiculture, and silviculture
Hint: (i) Silk production involves cultivation of mulberry leaves and rearing silkworms.
(ii) Scientific name of mulberry is Morus alba.
Answer
Sericulture and moriculture.
Explanation
Sericulture: The rearing of silk worm is called sericulture.
Moriculture: Cultivation of mulberry plant is called moriculture. Since caterpillars hatch from the eggs of silk moth feed mulberry leaves, so it is related to silk production.
Floriculture: Farming of flower is known as Floriculture. Floriculture is a branch of horticulture.
Apiculture: The rearing of honey bee in scientific way is called Apiculture.
Silviculture: The controlling the growth and quality of forests is called Silviculture.
Question (8) Match the words of Colum I with those given in Column II:
| Question table | |
|---|---|
| Column I | Column II |
| 1. Scouring | (a) Yields silk fibres |
| 2. Mulberry leaves | (b) Wool yielding animal |
| 3. Yak | (c) Food of silk worm |
| 4. Coccon | (d) Reeling |
| (e) Cleaning sheared skin | |
Answer
| Answer table | |
|---|---|
| Column I | Column II |
| 1. Scouring | (e) Cleaning sheared skin |
| 2. Mulberry leaves | (c) Food of silk worm |
| 3. Yak | (b) Wool yielding animal |
| 4. Coccon | (a) Yields silk fibres |
| (d) Reeling | |
Question (9) Given below is a crossword puzzle on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Down
(D) 1: Thorough washing
2: Animal fibre
3: Long thread like structure
(A) 1: Keeps warm
2: Its leaves are eaten by silkworm
3: Hatches from egg of moth
Answer
Extra Questions and Answer: Fibre to Fabric
Question (1) Choose the correct answer for the following questions
(a) Wool is made of
(i) Carbohydrates
(ii) Proteins
(iii) Fat
(iv) Lipid
Answer (ii) Proteins
Explanation
Wool is the hair of sheep or other wool yielding animals. Hair is made of protein. So, Wool is a protein.
(b) Sheep are reared to obtain
(i) Cotton
(ii) Wool
(iii) Silk
(iv) Wood
Answer (ii) Wool
Explanation
Wool is obtained from wool yielding animals. These animals are sheep, goat, yak, rabbit, camel, etc.
Sheep are reared to obtain wool mainly.
(c) The process of cutting of the hair of sheep is called
(i) Shaving
(ii) Cutting
(iii) Shearing
(iv) Hoovering
Answer (iii) Shearing
Explanation
The shaving off of fleece from the body of sheep is called shearing.
(d) The person who do the job of shearing is called
(i) Shearer
(ii) Barber
(iii) Cutter
(iv) Sheeper
Answer (i) Shearer
Explanation
The shaving off of fleece from the body of sheep is called shearing. So, person who sheared the fleece from the body of sheep or other wool yielding animals is called a shearer. Shearer means who shear.
(e) We get silk from
(i) Cow
(ii) Sheep
(iii) Silk-worm
(iv) Rabbit
Answer (iii) Silk Worm
Explanation
Eggs of silk moth hatch into caterpillars. Caterpillars spin cocoon in order to develop into silk month. While making in cocoon, caterpillar secrets protein to get it covered. We get silk from these cocoons. So, we can say that we get silk from silk worm.
Question (2) Fill in the blanks
(i) Silk worm is __________ to get silk fiber.
Answer: Silk worm is reared to get silk fiber.
(ii) The silk worm feed _________.
Answer: The silk worm feed mulberry leaves.
(iii) The rearing of silk worm is called ________
Answer: The rearing of silk worm is called sericulture
(iv) Silk was discovered in ____________
Answer: Silk was discovered in China.
Question (3) Very short answer type question
(i) What is the larva of silk worm called?
Answer The larva of silk worm are called caterpillars.
(ii) What is a cocoon?
Answer : Caterpillar spin a cover by secreting a liquid to cover it up in order to develop into silk month. These covers are called cocoons.
(iii) What is called scouring?
Answer : The cleaning of the dirt, greese, etc. from the sheared fleece of sheep is called Scouring.
(iv) After how many days caterpillar does start spinning the cocoon?
Answer : About after 25 to 30 days, caterpillar stop eating and starts spinning the cocoon.
(v) Silk fibre is made of which material?
Answer : Silk fibre is made of protein.
Question (4) Short answer type questions
(i) How many types of fibres found in nature?
Answer There are two types of fibres found in nature. Plant fibres and animal fibres. Silk and wool are animal fibres while cotton, jute, etc. are plant fibres.
(ii) What is the difference in Animal and plant fibre?
Answer: Fibres which obtained from animals are called animal fibres, wool and silk are animal fibres.
And fibres obtained from plants are called plant fibres, e.g. cotton, jute, etc.
(iii) What is the use of wool?
Answer: Wool is used in making of warm cloths, knitting of sweaters, making of shawls, socks etc.
(iv) What is the use of silk?
Answer : Silk is used in making of different types of clothes, such as sarees, kurta, shalwal suit, neck tie etc.
(v) Why scouring is done?
Answer: Sheared fleece contains dirt, grease, etc. These dirt are needed to be washed out to obtain clean wool. The cleaning or washing of fleece is called scouring.
Question (5) Long answer type question
(i) Write the life cycle of silk worm.
Answer
Silk month lays eggs. Eggs hatches in about 14 days into larva called caterpillars. Caterpillars feed mulberry leaves. After about 25 days caterpillar stops eating and starts spinning of silk thread to enclose itself in order to develop into silk moth in about 10 to 14 days.
Silk moth ⇒ Eggs ⇒ caterpillar ⇒ cocoon ⇒ Silk moth
(ii) Write process of separating out of wool from a sheep.
Answer :
(a) Fleece is shaved off from the body of sheep. This is called shearing.
(b) Sheared fleece is washed thoroughly in hot water and chemicals. This process is called scouring.
(c) After scoring, sorting is done to separate out different texture of fleece.
(d) After sorting scouring is done again.
(e) After that dyeing is done to get desired colour of wool.
(d) After dyeing, wool is spun into threads.
(e) After getting of wool thread, weaving and/or knitting is done to get desired fabrics.
(iii) How was silk introduced to the world?
Answer: Silk was discovered into China. Chinese kept it secret for hundreds of years. Travelers and traders introduced silk to other countries.
(iv) What is Sericulture.
Answer: The rearing of silk worm in order to obtain silk is called Sericulture.
Steps of sericulture:
Silk moth lays eggs.
Eggs hatches into larva. Larva, which is called caterpillars are kept into bamboo trays and fed mulberry leaves.
After about 25 days caterpillars start spinning cocoon. It takes about 3 to 4 days.
Cocoon is then kept into sun or steam or boiled into hot water.
Boiling soften the cocoons and silk thread is separated out from cocoons.
Separating out of silk thread from cocoon is called reeling of silk.
Question (6) Match the following
| Question table | |
|---|---|
| Column A | Column B |
| 1. Sorting | (a) Winter |
| 2. Caterpillar | (b) Pashmina shawl |
| 3. Angora | (c) Shaving off of fleece |
| 4. Shearing | (d) Cocoon |
| 5. Wool | (e) Separating out of different texture of fleece |
| 6. Cocoon | (f) Silk thread |
Answer
| Answer table | |
|---|---|
| Column A | Column B |
| 1. Sorting | (e) Separating out of different texture of fleece |
| 2. Caterpillar | (d) Cocoon |
| 3. Angora | (b) Pashmina shawl |
| 4. Shearing | (c) Shaving off of fleece |
| 5. Wool | (a) Winter |
| 6. Cocoon | (f) Silk thread |
Reference: