AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics

SCERT AP 7th Class Science Study Material Pdf 11th Lesson Fibres and Fabrics Textbook Questions and Answers.

AP State Syllabus 7th Class Science 11th Lesson Questions and Answers Fibres and Fabrics

7th Class Science 11th Lesson Fibres and Fabrics Textbook Questions and Answers

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I. Fill in the blanks.

1. Fleece pulled through the metal teeth of a machine in order to remove short fibres is known as _______ .
2. Rearing of silkworms to obtain silk is known as _______ .
3. Artificial fibre that resembles silk _______ .
4. Protein present in silk _______ .
5. Inner layer of soft, short, fine hairs of wool-yielding animal is known as _______.
Answer:
1. Shearing
2. Sericulture
3. Rayon
4. Fibroin
5. Fleece

II. Choose the correct answer.

1. Which of the following does not yield wool?
a) Yak
b) Goat
c) Silkmoth
d) Camel
Answer:
c) Silkmoth

2. The silk worm is _______ .
a) Pupa
b) Cocoon
c) Larva
d) Adult
Answer:
c) Larva

3. Shearing means _______ .
a) Selecting fleece basing on its quality
b) Dyeing the fleece
c) Removing wool with a thin outer layer of skin
d) Washing of fleece in hot water
Answer:
c) Removing wool with a thin outer layer of skin

4. Silk production is involved in the cultivation of _______ .
a) Oak trees
b) Sal tree
c) Thellamaddi tree
d) Mulberry tree
Answer:
d) Mulberry tree

AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics

5. The most common type of silk produced in India _______ .
a) Eri
b) Tasar
c) Mulberry
d) Muga
Answer:
c) Mulberry

III. Matching.

A) Pupa 1. Wool
B) Silk moth 2. Goat
C) Animal fibre 3. Cocoon
D) Angora 4. Wild silk
E) Tasar 5. Bombyxmori
6. Rayon

Answer:

A) Pupa 3. Cocoon
B) Silk moth 5. Bombyxmori
C) Animal fibre 1. Wool
D) Angora 2. Goat
E) Tasar 4. Wild silk

IV. Answer the following questions.

Question 1.
Explain how stifling is done. What is the purpose of stifling of cocoons?
Answer:

  1. When the eggs are hatched the larvae come out, these are kept in chandrikalu.
  2. Chandrikalu are specialized cane structures where mulberry leaves are also kept for larval feeding.
  3. This larva forms the cocoon. These are used for obtaining silk fibres.
  4. After 2 – 3 days cocoons formation, farmers remove them from chandrikalu and treat them under steam for 10 to 15 minutes.
  5. The process of killing larvae inside the cocoon by putting them in steam is called stifling.

Importance of stifling:
The larvae in the cocoons have to be killed by stifling otherwise larvae inside cocoons will come out by breaking open the cocoons.

  1. Hence, we can not derive continuous thread of silk. This will reduce the quality of silk fibre.
  2. Stiffled cocoons can be stored for a long time and can be sold in market.

Question 2.
Differentiate between Animal fibres and Plant fibres based on their properties.
Answer:

Animal fibres Plant fibres
1) They burn slowly but not continuously when compared to plant fibres. 1) They burn fast and continuous when compared to animal fibres.
2) These are protein based fibres. 2) They contain cellulose. So, they are cellulosic fibres.
3) They can’t absorb more water. 3) These fibres absorb more water.
4) Stretching capacity is more. 4) Stretching capacity is less.
5) They release fumes emitting the smell of burning hair or meat. 5) They release fumes emitting normal, smell of burning paper.
6) The ashes formed are black in colour and appear as beads and can be made as powder. 6) The ashes formed are not black in colour and is in the form of powder.
7) They dissolve in sodium hypochlorite (bleach). 7) They do not dissolve in sodium hypochlorite (bleach).

Question 3.
Analyse the advantages and disadvantages in usage of clothes made of synthetic fibres. Which type of fabric you prefer to use? Why?
Answer:
I prefer to use jute fabric because it is environmentally friendly.

Advantages of using synthetic fibres :

  1. Synthetic fibres are light, soft and smooth.
  2. They are more durable when compared to natural fibres.
  3. Maintenance of dresses made of synthetic fibres is relatively easier.
  4. These are available at a cheaper price as their production is quite abundant and economical.

Disadvantages of using synthetic fibres :

  1. Except Rayon, all other synthetic fibres are made of chemicals. So, their production leads to Environmental pollution.
  2. Even after their disposal they won’t mix in soils for years and they release harmful chemicals into the soil.

AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics

Question 4.
What happens if stifling is not done to silk moth cocoons?
(OR)
What will happen if cocoon is not boileicl?
(OR)
Generally larvae of silk moth are killed by a process of stiffling to collect silk from cocoon. What will happen if cocoon is not boiled?
Answer:

  1. If cocoon is not boiled, the larva inside the cocoon grows and cuts its way out after growing into a moth and spoil the cocoon.
  2. We cannot derive continuous thread of silk.
  3. This will reduce the quality of silk fabric.

Question 5.
Draw a well labelled diagram to explain life cycle of silk moth. Which stage in life of silk moth is important for making silk? Why?
Answer:
AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics 1 AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics 2

  1. Among the four stages of silk moth, larva stage is important for obtaining silk.
  2. In this stage, silk worm secrets a ghee like substance containing protein. This protein dries up on exposure to air to form silk fibre.
  3. Like this way, silk worm completely covers its body with silk fibre. This looks like a capsule known as cocoon (pattukaya).
  4. After stiffling process we get silk from cocoons.

Question 6.
What precautions do you suggest a shearer to take while shearing an animal to prevent hurting them?
Answer:

  1. Cutters and combs should be sharp and they should be cleaned, resharpened and lubricated after each job of shearing.
  2. The shearing floor should be clean and free of straw and debris.
  3. Sheep must be dry before shearing.
  4. Shearing must be done in shade to prevent heat stress.
  5. Prevent cuts to the animal’s skin by taking time while shearing and carefully clipping the wool so as to not get too close to the sheep’s skin.

Question 7.
Describe your views on preparation of silk by killing the larvae. What ways do you suggest to prevent this activity towards silk moth?
Answer:

  1. I feel very unhappy on the methods used for producing silk by killing the larvae of silk moths.
  2. I feel ashamed as a human being, for killing the innocent larvae in the boiled water for getting silk.
  3. It is better to avoid these practices for getting silk.
  4. We should encourage Ahimsa silk which is obtained in non – violent way. In this method, the pupa of silk worm is allowed to hatch and the left over cocoon is then used to derive silk. This method of silk production is introduced by Kusuma Rajaiah, a handloom technologist and a former employee in AP Handloom department.
  5. We should encourage the trails executing to find sources of silk other than silk worms.
  6. A Manipuri silk inventor named Tongbran Bijay Santhi, introduced to draw silk like threads from Lotus stem. We should welcome this type of inventors to pave new ways for getting silk.

7th Class Science 11th Lesson Fibres and Fabrics InText Questions and Answers

7th Class Science Textbook Page No. 68

Observe the given figures and answer the following questions.
AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics 10

Question 1.
Which clothes do people wear in cold regions?
Answer:
Woolen clothes.

Question 2.
Which fabrics are used to make these clothes?
Answer:
Wool is used to make these woolen fabrics.

AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics

Question 3.
Which fabric do you choose to wear in an important celebrations like Sankranthi?
Answer:
I choose silk or cotton fabric to wear in an important celebrations like Sankranthi.

7th Class Science Textbook Page No. 69

Question 4.
Why do people in our area rear sheep and goats in large farms?
Answer:
People in our area rear goats and sheep for meat and wool.

7th Class Science Textbook Page No. 71

Question 5.
Have you seen, Sheep’s hair with dirt and twings attached to them?
Answer:
Yes. As the skin of sheep secrete grease like oily substance, fleece is generally attracted with much dust and dirt.

7th Class Science Textbook Page No. 73

Question 6.
How many stages does the silk moth undergo to complete its life cycle?
Answer:
4 stages.

Question 7.
What are the stages involved in the life cycle of a silk moth?
Answer:
1) Eggs 2) Larvae 3) Pupa 4) Imago

7th Class Science Textbook Page No. 77

Question 8.
With which type of fibres the chunni fabric is made?
Answer:
The chunni is smooth, soft, thin and light weight. Synthetic or artificial fibres are used to make this chunni.

7th Class Science Textbook Page No. 78

Question 9.
Why do we wash clothes?
Answer:
It is necessary to wash clothes every time after wearing them to avoid skin diseases.

7th Class Science Textbook Page No. 79

Question 10.
Think why fabrics made of natural fibres get faded on washing?
Answer:
Natural fibres are mixed with dyes only after they are made as fabrics.

AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics

Question 11.
Which cloth looks fine without shrinkage and wrinkles?
Answer:
The cloth that is wrapped around the rod looks fine without shrinkage and wrinkles.

Think & Respond

7th Class Science Textbook Page No. 70

Question 1.
Sharp razor/scissors like tools are used to shear fleece of an animal. Does it hurt tjie animal? Remember how we tonsure our heads. Does it hurt? If the shearer shaves carefully by preventing cuts and bruises, shearing won’t hurt the animal.
Answer:

  1. The shearer should take all precautions before shearing.
  2. Cutters and combs should be sharp enough for clean shearing.
  3. Sheep must be dry before shearing.
  4. Clipping of wool on sheep should be carefully done before shearing in order to avoid cuts and bruises.

7th Class Science Textbook Page No. 77

Question 2.
Think about the dresses we prefer to wear ip winter or when we are going to visit cooler places. Which natural fibre are they made of? Why do we choose woolen dresses like sweaters, shawls, scarfs etc. Wool is a bad conductor of heat. It won’t allow our body to lose heat.
Answer:

  1. Wool is a poor conductor of heat. Air trapped in between the woolen fibres and our body prevents the flow of heat from our body to our surroundings.
  2. So we feel hot and are protected from cold.
  3. Woolen cloth also helps to do use fire.
  4. That is why it is good to wrap a person, who is caught in fire, with a blanket.

7th Class Science Textbook Page No. 78

Question 3.
Parachute ropes are made of silk in olden days. It’s strength and elasticity helps in retaining the weight of a person when he is flying in air. Water resistance capacity included along the characters of silk, made parachute manufacturers use Nylon now a days. What will happen if we use cotton or wool fibres for this purpose?
Answer:

  1. If we use fibres like cotton or wool in the manufacturing of parachutes, accidents will take place while flying.
  2. It is because cotton and wool fibres are not strong enough to carry such huge weight against the wind currents.
  3. More over, they are less tensile, water absorbants and heavy in weight, so, they are not suitable for the manufacturing of parachutes.

Activities and Projects

Question 1.
Take an India map and mark the regions where various wool yielding animals are found and mention their names there.
Answer:
AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics 3

Question 2.
Make a scrap book with various wool yielding animals.
Answer:
AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics 4

Activities

Activity – 1

Question 1.
Prepare a flow chart showing stages in the preparation of woolen fabric with the name “From Fibres to woolen fabrics”.
(OR)
Make a flow chart showing various stages of production of woolen fabric.
Answer:
From fibres to woolen fabric :
AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics 5

Activity – 2

Question 2.
Collect pieces of different types of fabrics and paste them in your scrap book.
Answer:
AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics 6

Activity – 3

Question 3.
How do you know the purify of animal fibres basing on their properties ?
Answer:

  1. Get some threads of wool, silk and cotton from a textile or tailor shop.
  2. Burn them on candle flame.
  3. Observe the flame and fumes coming from burning fibres.

Note down them in the following table.
AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics 7

Activity – 4

Question 4.
How do you prove that animal fibres dissolve in chlorine based bleach?
Answer:

  1. Take some toilet cleaner or disinfectant or cloth whitener containing sodium hypochlorite in a beaker or ceramic bowl.
  2. Keep woolen and silk fibres in the toilet cleaner and observe for 20 minutes.
  3. Repeat the same experiment with plant and synthetic fibres.

Observations :

  1. Woolen and silk fibres dissolved in sodium hypochlorite. If not they are not pure woolen or silk fibres.
  2. Plant and synthetic fibres do not dissolved in bleach.

AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics 8

Inference :
Animal fibres dissolve in bleach plant and synthetic fibres do not dissolve in bleach (sodium hypochlorite).

Activity – 5

Question 5.
Observe the manufacturer’s is care label given in the figure and answer the following questions.
AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics 9
a. Which garment the dress is made of?
Answer:
Polyester cotton.

b. Which type of wash is suitable for the dress/garment.
Answer:
Hand wash or Machine wash using only cold water, use only mild detergent.

c. What are the measures to be taken for long durability of the garment?
Answer:

  1. Woolen clothes are washed after 4-5 wearings only because frequent washes may loosen the firmness of knitting resulting in loss of shape of fabric.
  2. After washing also woolen clothes should not be squeezed. It is advised to wrap them in a towel to remove extra moisture before drying off.
  3. Mild detergent should be used to wash wool and silk clothes.
  4. Cotton and silk clothes readily shrink on washing. So, starching and ironing of cotton and rolling of silk can unshrink the garments.
  5. Silk and wool clothes should be stored carefully. Because insects attack these clothes to feed on protein substances present in fibres. (Fibroin, Keratin)
  6. Strong fragrance of phenophthalene balls, boric acid, fragrant oils like sandal oil and lavender oils can successfully repel the insects.
  7. By keeping these substances between the clothes, we can protect silk and woolen clothes from insects.
  8. Shrinkage of silk sarees can be removed by a process called “Rolling”.

AP Board 7th Class Science Solutions 11th Lesson Fibres and Fabrics

Activity – 6

Question 6.
How do you removed the wrinkles of silk fabrics?
Answer:

  1. Collect two long pieces of silk fabric of ribbon width from a tailor.
  2. Dip them in water and observe the wrinkles that formed on the clothes.
  3. Dry off one cloth simply and wrap the second one around a wooden or a metal rod tightly without foldings.
  4. Allow it to be dried off in the same state. Observe the two clothes after two to three hours.

Observations:
The cloth that is wrapped around the rod has lost its wrinkles. This process of removal of shrinkage from silk clothes is called rolling.