CBSE Class 7 Science Revision Notes Chapter 3

Class 7 Science Chapter 3 Notes

CBSE Class 7 Science Revision Notes Chapter 3 – Fibre to Fabric

Fibre to Fabric Revision Notes are easily accessible from the Extramarks website. This chapter of the Class 7 Science syllabus is focused on fibre and fabric, and the innovation of clothing materials. These notes include how different fibres are grown and obtained from plants and animals. Class 7 Science Chapter 3 Notes help students gain in-depth information as per CBSE guidelines.

Revision Notes for CBSE Class 7 Science Chapter 3

Access CBSE Class 7 Science Chapter 3 – Fibre to Fabric

Fibres are the lengthy, thin, steady threads or filaments which are extracted from plants and animals.

The two most prominent types of fibres that are generally found are:

  • Animal fibres
  • Plant fibres

The most common animal fibres are silk and wool.

Silk is derived from silkworms, whereas wool is extracted from yak (usually discovered in Tibet and Ladakh), Angora goat, camels, Ilama, and alpaca (discovered in South America), etc. Wool is acquired from either the fleece or hair of these animals.

The hair of animals such as camels, llamas, and alpacas can also be processed to attain wool. Wool is usually bred from sheep in India. Sheep’s hair is first cut from the body, then it goes into a series of processes that are scouring, sorting, drying, dying, spinning, and weaving to attain the wool.

Wool:

Wool is made from a variety of animal fibres, including those yaks, sheep, goats, camels, and alpacas.

Obtaining Wool Fibre:

The procedure of removing the fleece of a sheep with a very thin layer of skin is called shearing.

Processing of Wool Fibre:

  • Sheared sheep’s hair is cleaned and washed in tanks to get rid of grease, dust, and other impurities.
  • After the hair is cleansed and shipped to a factory, the hair is segregated into different quality levels. The hair goes through a ‘carding’ machine after it is separated in the sorting process, where a sheet is made by combining these loose wool fibres and further twisted into a rope or sliver.
  • This sliver is then twined and extended into a yarn.
  • The yarn is cut to make big balls of wool.

Silk:

Sericulture is the practice of growing and keeping silkworms to produce silk fibre. An example of natural fibres includes silk. The silk fibre is extracted from the silkworm’s cocoon. Silkworms are the caterpillars of silk moths.

The Life Cycle of Silkworms:

The worms begin spinning cocoons of silk fibres during their life cycle. Silk fibres are a build-up of protein. Silk threads are made from the silk fibres extracted from cocoons. After being sent to the weavers, silk threads are woven into silk fabric. After the silk moth eggs hatch, larvae known as caterpillars or silkworms are created. The next stage of the caterpillar’s life is called a pupa. When the caterpillar turns into a silk moth, it develops an exterior known as a cocoon. The caterpillar wraps itself with silk and converts itself into a pupa.

CBSE Class 7 Science Chapter 3 Notes

Class 7 Science Chapter 3 Notes by Extramarks are written by subject matter experts according to the revised CBSE syllabus. These notes can be accessed by students at any given time from any device.

Fibre to Fabric Class 7 Revision Notes at a Glance

Fibre to Fabric Class 7 Science Chapter 3 Notes includes the following sections according to the NCERT guidelines as mentioned by CBSE:

  1. Definition and Types of Fibres: The section will focus on Fibres and their Types. Fibres are fine strands that are used for preparing the fabric. The fibres are spun to convert into a yarn, which is further transformed into a fabric by weaving on a loom. Wool, cotton, silk, jute, nylon, and polyester are some examples of fibres.

There are majorly two types of fibres that are:

  • Natural Fibres: Natural fibres are fibres derived from natural sources, such as plants and animals. Cotton and jute are common examples of fibres that are derived from plants. Whereas examples of animal fibres are silk and wool.
  • Synthetic Fibres: Synthetic fibres are man-made fibres and cannot be discovered in nature. Rayon and polyester are examples of man-made fibres.

      2.Plant Fibres: This section explains plant fibres, their types, and their production in detail.

  • Cotton: Cotton is an example of plant fibre that we get from the cotton plant. It is produced in regions with black soil and a warm climate. Cotton bolls are the fruits of the cotton plant through which cotton is derived. The cotton fibres are segregated from the seeds through a method named  Ginning.
  • Jute: Jute fibre is derived from the stem of the jute plant. It is mostly produced during the rainy seasons in the regions of Assam, West Bengal, and Bihar. Jute plants are generally gathered at the flowering stage, and the stems are submerged in water to decay. The jute fibres are segregated from the rotten stems using a hand.

      3. Animal Fibres: This section of Class 7 Science Chapter 3 Notes discusses animal fibres and  how they are produced.

  • Silk: Silk is one of the most common examples of animal fibre that is derived from an insect named the silk moth. Sericulture is the procedure of producing silk. A silkworm discharges fibres of proteins during its lifecycle that harden when exposed to the air and convert to silk fibres. The coating of silk fibres around the pupa is known as a cocoon. These silk fibres are then segregated from the silk moths and made into silk thread.
  • Wool: Wool is extracted from several animals like goats, sheep, yak, etc. Shearing is the process by which the fleece of the sheep or yak is detached to attain wool fibre. Shearing, grading, carding, and spinning are the distinct steps that are included in the processing of wool fibre.

      4.Yarn: This section covers the details of the creation of yarn from different fibres and how to transform the yarn into a fibre.

  • The spinning of cotton yarn: The process of producing yarn from fibre is called spinning. The takli and charkha are the significant tools that are utilised for spinning cotton yarn from cotton fibres. Spinning machines are used to produce yarn on a large scale.
  • Processes that are used to make fabrics from yarn: Weaving and knitting are the two most prominent methods by which fabrics are produced from yarn. Two sets of yarn are involved in producing fabric and are involved in the process of weaving, whereas in knitting, a single yarn is utilised to make a fabric. Looms are used to do the weaving, and machines are used to get the knitting done.

FAQs (Frequently Asked Questions)

Cotton plants are typically grown in areas where black soil and warm climates are found. Cotton is cultivated in a few states in the nation. The cotton plant’s fruit, called a cotton boll, is nearly the size of a lemon. After it blooms, the cotton bolls split open and the seeds coated in cotton fibres are visible. When cotton is ready for picking, the fields appear to be covered in snow. Typically, cotton is selected by hand and removed from cotton bolls. To remove the fibres from the seeds, combing is used. Cotton ginning is the name given to the entire procedure.

A piece of cotton fabric is taken. Then, a loose thread or yarn is selected at one of the edges and pulled out. If no loose yarns are visible, one is gently pulled with a pin or a needle. Fabric is made up of yarns arranged together. The process of arranging two sets of yarns together to make a fabric is called weaving.

The end of the thread is split up into some thin strands. That makes it tough to move the thread through the tiny hole of the needle. The thin strands of thread that can be seen are made up of even thinner strands called fibres. Fabrics are made from yarns, which are made from fibres. The fibres of a few fabrics, such as cotton, jute, silk, and wool, are derived from plants and animals. These are termed natural fibres. Examples of natural fibres are cotton and jute. Examples of animal fibres are wool and silk fibres.

  • The fleece of sheep or goats is used to attain wool. It is also derived from the hair of yaks, rabbits, and camels. The cocoon of the silkworm is used to extract the silk fibre. Natural fibres were the only available material for making fabrics for a long time.
  • For about the last hundred years, fibres have also been made from chemical substances that are not extracted from plant or animal sources. These are called synthetic fibres. Polyester and nylon are some examples of synthetic fibres.

In ancient times, people used the bark and large leaves from trees or animal skins and furs as clothing to cover their bodies.

  • People learned to knit twigs and grass into mats and baskets after people started to settle in agricultural communities.
  • Vines, animal fleece, or hair were braided together into long strands. Those were further knitted into fabrics.
  • The fabrics were created using the cotton that grew, especially in the region near the river Ganga, and were worn by the early Indians. Natural fibres are derived from the flax plant. Cotton and flax were grown near the river Nile and were used for making fabrics in prehistoric Egypt. Stitching was not widely used back then. People used fabrics to cover different parts of their bodies. They also invented different styles of draping fabrics.
  • People started stitching fabrics after the invention of the sewing needle to make clothes. But, there are certain fabrics such as sarees, dhotis, lungis, or turbans that are used as an un-stitched piece of fabric.