A Silk: Fibres Obtained from Silkworm, Processing of Silk, Questions (For CBSE, ICSE, IAS, NET, NRA 2022)

Glide to success with Doorsteptutor material for competitive exams : get questions, notes, tests, video lectures and more- for all subjects of your exam.

Silk is a natural protein fibre which can be used as a textile fibre. It is one of the important animals՚ fibres obtained from silkworm.

History of Silk

Around 3500 BC, silk was discovered in China during the reign of emperor Huang-ti. It was considered as one of the most valuable fibre at that time because of its luster and fine quality. It was only used by the emperors and it was kept secret for hundreds of years. Later on, it was spread across the world through trading. The route through which it used to travel was known as the ‘Silkroute’ .

Silk was made in India as well. During the Indus valley civilization, its uses were noticed.

Types

The different types of silk are produced by different types of silkworms. It can be differentiated on the basis of luster and texture. Few examples are kosa, tassar, mooga, etc. They are produced by various types of silk moths. One of the common types is the mulberry silk moth.

Life Cycle of Silk Moth

  • Silkworms are not actually born as worms rather as larvae and caterpillar hatched from the eggs of silk moth. In the beginning, the female silk moth lays eggs and then the larvae are hatched out of the eggs and are known as the caterpillars. They grow up in size and before they enter in the second stage which is called as pupa the caterpillar swings their head from sides and makes the shape of eight every time.
  • During all these times they secrete fibre made up of protein which when comes in contact of air and it hardens to become a silk fibre. After this the caterpillar completely covers itself by the fibre and turns into pupa. This covering is known as the cocoon. The silk moth further develops in the covering called cocoon. The silk fibre is obtained from this silkmoth՚s cocoon.

Silkworm

  • A material which is composed of thin and continuous strands is known as fibre. Fibre can be of two types: natural fibre and synthetic fibre. The fibres which are obtained from plants and animals are known as natural fibres whereas synthetic fibres are man-made fibres.
  • Examples of natural fibres are cotton and silk whereas examples of synthetic fibres are: nylon, polyester, etc. Silk is a type of natural fibre or animal fibre. Silkworm is responsible for spinning of silk and it is reared to obtain silk.

History of Silk

  • Silk was discovered around 3500 BC in China. For a long period of time, silk was shipped to other parts of the world through trade. Technological advancement and new developments have enabled manufacturers to produce different types of silk from different silkworms on the basis of lustre and texture.
  • Mulberry silk is the most common silk moth that is used for producing silk. Rearing of the silkworm is known as sericulture.

The Life Cycle of Silkworm

  • The life cycle of silk moth starts when a female silk moth lays egg. The caterpillar or larvae are hatched from the eggs of the silk moth. The silkworms feed on mulberry leaves and give rise to pupa. In the pupa stage, a weave is netted around by the silkworm to hold itself. After that it swings its head, spinning a fibre made of a protein and becomes a silk fibre.
  • Several caterpillars form a protective layer around pupa and this covering is known as the cocoon. The silk thread (yarn) is obtained from the silk moth՚s cocoon. The life cycle of the silkworm is explained below in detail.
The Life Cycle of Silkworm

Stage 1: Egg

An egg is the first stage of the life cycle of the silkworm. The egg is laid by a female moth which is mostly the size of small dots. A female moth lays more than 350 eggs at a time. In the springtime, the eggs hatch due to the warmth in the air. This procedure happens once in every year.

Stage 2: Silkworm

A hairy silkworm arises after the eggs crack. In this stage of silkworms, the growth happens. they feed on mulberry leaves and consume a large amount of these leaves for around 30 days before going to the next stage.

Stage 3: Cocoon

In this stage, silkworms spin a protective cocoon around itself. It is the size of a small cotton ball and is made of a single thread of silk.

Stage 4: Pupa

The pupa stage is a motionless stage. In this stage, people kill the pupa by plunging the cocoon into boiling water and unwind the silk thread.

Stage 5: Moth

In this stage, the pupa changes into an adult moth. The female moth lays eggs after mating and thus the life cycle of silkworm begins again.

Processing of Silk

  • Extracting silk from the cocoon is known as the processing of silk. Silk is separated from the cocoon by exposing it to sunlight.
  • After the reeling of silk is done, the process of unwinding silk from a cocoon takes place. Silk thread is then bleached. The silk fibre is then spun into silk threads.

Questions

How is Silk Fibre Obtained from Silkworm?

Answer:

  • The process of silk production is known as sericulture. Extracting raw silk starts by cultivating the silkworms on mulberry leaves.
  • Once the worms start pupating in their cocoons, these are dissolved in boiling water in order for individual long fibres to be extracted and fed into the spinning reel.

Which of the Following Makes Silk Fibres?

Answer:

Natural silk is obtained from the cocoons of silkworms and it is made up of a protein. Natural silk is an animal fibre. Artificial silk is obtained from wood pulp and it is made up of modified plant material ‘cellulose’ .

What Are the Three Grades of Silk?

Answer:

There are three main grades of silk, categorized as A, B, and C. Grade A Silk is top grade silk that can be unraveled without silk floss breaking.

Which is the Strongest Natural Fibre?

Answer:

Spider silk

Spider silk is famous for its amazing toughness, and until recently a tensile strength of 1.3 gigapascals (GPa) was enough to earn it the title of strongest natural material.

Which is the Most Common Silk?

Answer:

mulberry silk moth

The most common silk moth is mulberry silk moth and its silk fibres are soft, lustrous, and elastic and can be dyed in beautiful colors.

Developed by: