This PSEB 7th Class Science Notes Chapter 3 Fibre to Fabric will help you in revision during exams.
PSEB 7th Class Science Notes Chapter 3 Fibre to Fabric
→ Fibre of wool and silk is derived from animals in nature.
→ The fibre of wool is obtained from sheep, goats, or yaks.
→ The thin skin of a sheep has two types of fibres:
- Coarse beard hair
- Fine soft hair under the hair close to the skin.
→ Some breeds of sheep possess only fine under hair, their parents are specially chosen to give birth to sheep which have only soft under hair, such selection of parents for the specific characters is called ‘selective breeding’.
→ There are different types of wool, such as sheep’s wool, Angora, and cashmere wool.
→ Sheep are reared to obtain wool.
→ Sorters disease is spread by the bacterium Anthrax.
→ Raising silkworms to get silk is called Sericulture.
→ Female silkworms lay hundreds of eggs.
→ The larvae that hatch out from eggs are called caterpillars.
→ Caterpillars grow in size and become pupae (adult).
→ Then pupa swings its head from side to side in the form of a figure of eight(8).
→ During this movement, caterpillar secret fibre is made up of a protein that hardens on exposure to air and becomes silk fibre.
→ Caterpillar also covers itself completely with these silk fibers and this covering is known as Cocoon.
→ The most common silk moth is a mulberry silk moth. Other types of silk are Tassar silk, Mooga silk, and Kosa silk, etc.
→ The process by which cocoons are boiled or given steam to extract silk fibres is called Reeling of silk.
→ Reeling is done with special machines.
→ Silk thread is used to weave silk fabric.
→ Tuft: A cluster of sheep’s body hair.
→ Reeling: The process of extracting silk fibres by boiling or steaming silk cocoons.
→ Scouring: The sheared skin with hair is washed thoroughly to remove grease, dust, and sweat, which is called scouring.
→ Cocoon: A layer of silk fibres that covers the caterpillar is called a cocoon.
→ Sericulture (rearing silkworms): Rearing of silkworms to get silk, is called Sericulture.
→ Shearing or shaving: The process of removing a thin layer of sheep’s hair and skin from a sheep’s body is called shearing.
→ Throwing: Raw silk is spun to make raw silk stronger (thick). This process is called throwing. This protects the fibres from breaking down.
→ Combing: The process of removing small swollen fibres called burrs is called combing.
→ Dyeing or colouring: Sheep wool can be dyed in different colours as the natural color is only black, brown or white.
→ Selective Breeding: Two sheep with special required traits are selected as parents for breeding and reproducing a sheep of required traits. This process is said selective reproduction.