Class-7 Chapter-3 Fibre to Fabric

 

Fibre to Fabric

Cloth is one of our basic needs. Cloth protects us from heat, cold, rain, dust, insects, etc. Clothes also make one civilized and smart. Clothes are made of cloth. Cloth is also known as fabric. Fabric is made of fiber.

Types of Fibre 

There are two types of fibre, viz. natural and man-made.

Natural fibers: Natural fibers are obtained from plants and animals; such as jute, cotton, wool, silk, etc.

Man-made fibers/ artificial/synthetic : Fibers that are synthesized in laboratory are called man- made fiber, such as terrylene, terry-cotton, acrylic, etc.

Types of Natural fiber:

Natural fibers can be classified into two types – Plant fiber and Animal fiber.

Plant Fiber: Fiber obtained from plants is called plant fiber. For example – cotton, jute, flex, etc.

Animal Fiber: Fiber obtained from animals is called animal fiber. For example: wool and silk.

WOOL

·  There are many animals that bear a thick coat of hair on their body. Such animals generally live-in cold climates.

·  Thick coat of hair over the body of such animals’ traps lot of air and keeps them warm as air is a bad conductor of heat.

·   It prevents the warmth of the body from escaping and also prevents the coldness of the surroundings from entering. Thus, thick layer of hair over their body protects them from harsh cold.

·  Angora wool is obtained from Angora Goats. Angora Goats are found in hilly regions, such as Jammu and Kashmir.

·   Pashmina wool is obtained  from Pashmina Goats.

·   Yak wool is obtained commonly in Tibet and Laddakh.

·   Alpaca and Llama are other animals that give wool. Selective breeding and rearing of sheep: Some breeds of sheep bear only a coat of fine hair. Such animals are reared by selective breeding.

·   Selective breeding is the process to obtain animals or plants having special characteristics.

    In India, sheep are reared generally in the sates of Jammu and Kashmir, Himachal Pradesh, Uttaranchal, Arunachal Pradesh and Sikkim, or the plains of Haryana, Punjab, Rajasthan and Gujarat.

 Process to obtain wool from sheep:There are some steps are followed to obtain wool from sheep or other wool bearing animals:-

Step 1: Shearing: Sheep shearing is the process by which the woollen fleece of a sheep is cut off. 

Step 2: Scouring: Fleece, after shearing, is washed properly to remove dirt and grease. The washing of fleece; after shearing; is called scouring.

 Step 3: Sorting: After scouring, fleece is sorted according to texture. This process is called sorting.

 Step 4: After sorting, fluffy fibers called burr are picked out from hair. Burr is the fiber that gives wool.

 Step 5: Dyeing: After sorting and picking out of burrs, these are dyed in desired colors.

Step 6: Spinning: The fibers are then straightened, combed and rolled into yarn. this process is called spinning.

Types of silk- Tassar silk, munga silk, kosa silk are the most commonly known silk varieties. 

The most common silk moth among all is the mulberry silk moth which is soft, lustrous, and elastic and can be dyed in to beautiful colours.

 

The Process of obtaining Silk from the Silkworms- 

Seri-culture -Rearing of Silkworms to obtain silk from them. in order to get silk 

·    Rearing: the silkworm farmers buy the eggs of the Silk moth and looking after to raise them

·   
These eggs are generally large in numbers as a single silk about 100 eggs at a time. moth can lay these   eggs   are    stored   in   an environment  having  an  appropriate temperature, humidity and hygienic conditions.

·  In order to hatch the larvae ( also known as caterpillar) out of the eggs are heated.

·  They are then kept in a bamboo tray.

·   This process is conducted generally when the fresh leaves appear on the Mulberry trees so that the Caterpillar can get enough feed.

·  The Caterpillar feeds for around 25 to 30 days and then moves into a chamber in the tray to build a cocoon.

Processing of Silk

·   Firstly, as the cocoons are acquired they are kept under the sun or boiled so that the Silk fibres can separate out from them.

·  Then, the reeling of the silk takes place. It is a process in which the cocoon’s threads are processed to be used as silk.

·  The silk fibres thus obtained are drawn and rolled into thread

Science Quiz- 3 important mcq for class 10

Science

Quiz

 

1. The most poisonous product formed by incomplete combustion of fossil fuels is
   1.   Carbon dioxide
   2.   Nitrogen dioxide
   3.   Carbon monoxide
   4.   Sulphur dioxide
2. Identify ‘x’, ‘y’ and ‘z’ in the following reaction:
   2KClO3(x) ---------> 2KCl(x) + O2 (z)
   This reaction take place in presence of (y).
   1.   x = gas; y = reaction condition, z = gas
   2.   x = solid; y = liquid; z = gas
   3.   x = number of moles of KClO3; y = reaction condition; z = no. of molecules of oxygen.
   4.   x = physical state of KClO3 and KCl; y = reaction condition; z = physical state of O2.
3. An element ‘X’ with atomic number 11 forms a compound with element ‘Y’ with atomic number 8. The formula of the compound formed is
   1.   XY
   2.   X2Y
   3.   XY2
   4.   X2Y3
4. A compound ‘A’ is used in the manufacture of cement. When dissolved in water, it evolves a large amount of heat and forms compound ‘B’. Identify A and B.
   1.   A= CaO,B= Ca(OH)2
   2.   A=Ca(OH)2, B=CaO
   3.   A=MgO, B= Mg(OH)2
   4.   A=Mg(OH)2, B= MgO
5. A visually challenged student, has to perform a lab test to detect the presence of acid in a given solution. The acid-base indicator preferred by him will be:
   1.   Blue litmus
   2.   Clove oil
   3.   Red cabbage extract
   4.   Hibiscus extract
6. An aqueous solution ‘A’ turns phenolphthalein solution pink. On addition of an aqueous solution ‘B’ to ‘A’, the pink colour disappears. Which of the following statement is true for solution ‘A’ and ‘B’?
   
   1.   A is strongly basic and B is a weak base.
   2.   A is strongly acidic and B is a weak acid.
   3.   A has pH greater than 7 and B has pH less than 7.
   4.   A has pH less than 7 and B has pH greater than 7.
7. In which of the following the identity of initial substance remains unchanged?
   1.   Curdling of milk
   2.   Formation of crystals by process of crystallisation
   3.   Fermentation of grapes
   4.   Digestion of food
8. Several factories were pouring their wastes in rivers A and B. Water samples were collected from these two rivers. It was observed that sample collected from river A was acidic while that of river
   B was basic. The factories located near A and B are
   1.   soaps and detergents factories near A and alcohol distillery near B
   2.   soaps and detergents factories near B and alcohol distillery near A
   3.   lead storage battery manufacturing factories near A and soaps and detergents factories
      near B
   4.   lead storage battery manufacturing factories near B and soaps and detergents factories
      near A
9. An element ‘X’ is forming an acidic oxide. Its position in Modern Periodic Table will be
   
   1.   Group 1 and Period 3 (b)
   2.   Group 2 and Period 3
   3.   Group 13 and Period 3
   4.   Group 16 and Period 3
10. Isotopes are
    1.   Atoms of an element with similar chemical properties but different atomic masses.
    2.   Atoms of different elements with similar chemical properties but different atomic masses.
    3.   Atoms of an element with different chemical properties but same atomic masses.
    4.   Atoms of different elements with different chemical properties but same atomic masses.

Class 7 Chapter -2 Notes on Nutrition in Animals

Notes on Nutrition in Animals

·   The animals depend upon other plants and animals for their food.

·    Animal nutrition comprises the mode of taking in the food in the body, nutritional requirements of the body and how animals can utilize their food.

·    Digestion - it is a process by which animals break down complex food substances in simpler substances.

Different ways of taking the food

Digestion in Humans

·       The food that we eat passes through a Canal inside our body.

·       The food is processed and utilized in the body and unused food is collected inside the canal only.

·       This Canal is often called as the Alimentary Canal or the Digestive Tract.

·       The canal is divided into different parts:

o    The Mouth or Buccal Cavity

o    Food Pipe or Oesophagus

o    Stomach

o    Small Intestine

o    Large Intestine

o    Anus

 

There are three glands associated with the alimentary canal that secrete digestive juices that are used to convert the complex food substances into simpler substances.

·       liver

·       pancreas

·       salivary glands

The Digestive System - The alimentary canal and the digestive glands together form a system in the human body which is responsible for the digestion of food in the body. This system is called     the Digestive System.

Ingestion - the process of taking in the food through the mouth is called ingestion.

·   The food is chewed with the help of teeth, saliva and the tongue present in the mouth.

·  The salivary glands present in our mouth secrete saliva which mixes with the food, moist it and breaks the starch present in the food into sugar.

·       The tongue present in the mouth helps in mixing the food with the saliva and helps in swallowing it inside the mouth. It also has taste buds which help in identifying the taste of anything that we eat. Besides this, the tongue also helps in talking.

The Teeth

Milk Teeth - In the early childhood a set of teeth growth in children that then fall off after certain age 6 to 8 years. These teeth are called Milk Teeth.

Permanent Teeth - The teeth that grow after milk teeth fall off are called Permanent Teeth. They generally remain during the lifetime of a person or at least until old a

Tooth Decay –

·       A gradual damage of teeth is often called tooth decay.

·       The main cause of tooth decay is the presence of bacteria in the mouth that grow if we do not keep our mouth and teeth clean.

·       Any leftover food present inside our teeth is broken down by such bacteria.

·       As a result, an acid is released which damages the teeth slowly.

·       Tooth decay can cause severe pain and even toothless.

·       Tooth decay is caused mainly because of eating food with high sugar content, soft drinks and choc

How can we prevent tooth decay?

·       Clean your teeth with a brush or dental floss at least twice a day

·       Rinse your mouth after every meal you eat

·       Do not put a dirty finger or any unwashed food items in your mouth

Food Pipe or Oesophagus

·       The food pipe starts from the neck region and runs until the chest area in animals.

·       The food, when the chewed, moves through the food pipe and reach the stomach through this path.

·       The food moves in download direction in the food pipe.

The Stomach

·       It is the widest part of the alimentary canal.

·       It's a bag like structure in a flat U shape.

·       The stomach is connected with the food pipe and the small intestine.

·       The stomach’s inner lining produces three things:

     o    Mucous: It protects the stomach lining

o    Hydrochloric Acid: It kills the bacteria present inside the stomach and activates the digestive juices

o    Digestive Juices: They help in digestion of the food by breaking down the proteins present in the food into simple substances.

Small Intestine

·       It is a highly coiled structure.

·       The length of the small intestine is almost 7.5m.

·       The liver and pancreas release digestive juices into the small intestine.

·       The inner lining of the intestine also secretes some digestive juices on its own.

·       The small intestine breaks the carbohydrates into glucose, fats into fatty acids and proteins into amino acids.

The Liver

·       It is a gland reddish brown in colour.

·       It is known as the largest gland of the human body.

·       It secretes a digestive juice called bile juice.

·       The bile juice is stored in the gallbladder.

·       The bile juice makes it possible for the body to digest the fats.

The Pancreas

·       It is a cream coloured gland present in the human body.

·       It secretes pancreatic juice that helps in digestion of fats, carbohydrates and proteins.

How small intestine absorbs food?

·    Absorption: it is a process by which the digested food enters the blood vessels of the small intestine.

·    Villi in the intestine: the small intestine contains small finger-like structures called Villi. They increase the surface area of the intestine thereby increasing the amount of absorption. The digested food gets into the blood vessels through villi and then reaches the whole body.

Summary of digestion 

Link of Chapter -1 Nutrition in plants