Showing posts with label TEXT-CBSE-VI BIOLOGY. Show all posts
Showing posts with label TEXT-CBSE-VI BIOLOGY. Show all posts

Tuesday, January 5, 2021

TEXT: GETTING TO KNOW PLANTS CBSE CLASS-VII BIOLOGY



Go outside and observe all the plants around you Do you see that some plants are small, some very big, while some are just patches of green on the soil? Some have green leaves, while some others have reddish ones. Some have huge red flowers, some have tiny blue ones, while some have none. We do see a variety of plants existing all around us near our homes, in the school ground, on the way to the school, in the parks and gardens, isn’t it? Let us get to know the different parts of any plant. This will help us understand the differences between plants of different kinds. Can you label the stem, branch, root, leaf, flower and fruit of the plant. Colour the parts of the plant. 


Based on these characters most plants can be classified into three categories: herbs, shrubs and trees. Plants with green and tender stems are called herbs. They are usually short and may not have many branches. Herbs are small plants which have soft stem. Examples: Wheat, paddy, cabbage, grass, coriander, etc. 
                   

Shrubs: Some plants develop branches near the base of stem. The stem is hard but not very thick. Such plants are called shrubs. These are bushy and medium- sized plants and they are somewhat bigger than herbs. Their branches start from just above the ground. Examples: Lemon, Coriander, Henna, Rose, etc. 
                     

Tree: Some plants are very tall and have hard and thick stem. The stems have branches in the upper part, much above the ground. Such plants are called trees. These are tall and large plants with hard and woody stem. A single main-stem arises from the ground. The main-stem is called trunk. The trunk gives out many branches at certain height. The branches carry leaves, flowers and fruits. Examples: Mango, banyan, acacia, coconut, poplar, willow, etc. 
                    

Climber: Plants with weak stem that needs support is called climber. Examples: Grapevine, money-plant, cucumber, bean, etc. 
                       

Creepers: Plants with weak stem that cannot stand upright and spread on the ground are called creepers. Examples: Pumpkin, Watermelon, sweet potato, etc 
                      

Parts of Plant and their function:Plants are important part of nature. They can live on land and in water. Plants are very useful to us and we get many things from plant such as food, wood, paper etc. Most of our food that we eat comes from plants for example -fruits, vegetables, cereals, pulses etc. We eat roots, leaves, stems, flowers and fruits of plants. 
          

Each part of the plant has its own work to do. All these parts work together to keep the plant alive. There are two main parts of plant. One is shoot and the other is root.  The part of the plant that grows under the soil is called as root. Different plants have different types of roots
                   

The Shoot: The part of plant that grows above the soil is called the shoot. Stem, branches, leaves, flowers and fruits are all the parts of shoot
               

The function of each plant parts is described below. 
Root: The underground part of a plant is called root. It is usually pale in colour.  The root is a very important component of the plant system, as, without the presence of roots the plant ceases to exist. 
                 

Functions of Roots: Roots are responsible for absorbing minerals and water from the soil and transferring them to the stem. And the stem becomes capable of transporting these to all parts of the plant. Another important function of roots helps in holding the plant firmly to the soil. They anchor the plant to the soil. This is essential to support the upright position of the plants. Roots also perform the function of storing important nutrients and food for growth. 
                       

There are two major types of roots: Roots are two types: tap root and fibrous roots
Tap root: This is composed of a main root which grows from the base of the stem. Many branches and sub-branches come out of the main root (tap root). Examples: pea, radish, carrot, mango, marigold, mustard etc. 
                      

Fibrous root: In this type, a cluster of thin fibre-like roots arise from the base of the stem. These roots spread out in the soil. Examples: Maize, grass, wheat, millet, etc. 
                  

Aerial roots: These are roots of plants and trees that grow above the ground instead of under the ground. 
         

We have learnt that roots absorb water and minerals from the soil and the stem conducts these to leaves and other parts of the plant. The leaves prepare food. This food travels through the stem and is stored in different parts of plant. We eat some of these as roots— like carrot, radish, sweet potato, turnip and tapioca. We also eat many other parts of a plant where food is stored. 
                       

Stem: Stem usually grows above the ground. The stem makes the main structural framework of the plant. The stem bears leaves, branches, buds, flowers and fruits. 
                 

The point from where branches or leaves grow is called as node. The portion of a stem between two consecutive nodes is called the internodes
Functions of stem: 
The stem gives structural support to the plant. It bears branches, leaves, flowers and fruits. The stem carries water and minerals from the roots to different parts of the plant. Stem gets modified for food storage in some plants, e.g. potato, ginger, turmeric, etc. 
                           

Leaf: 
Observe the leaves of some plants around you. Are all the leaves of same size, shape and colour? How are leaves attached to the stem? The part of leaf by which it is attached to the stem is called petiole. The broad, green part of the leaf is called lamina. Can you identify these parts of the leaves in plants around you? Do all the leaves have petioles? names of some plants having reticulate and parallel venation.The leaves of plants are majorly responsible for performing two essential functions for the plant’s survival and growth. These two functions are called transpiration and photosynthesis. Leaves and stem together form the shoot. 
                       

Parts of a leaf: 
The leaf is a thin, flat and green structure which arises from the node of the stem. The green colour of leaves is due to the presence of chlorophyll. Chlorophyll is a green-coloured pigment. The flat green portion of the leaf is called leaf-blade or lamina. The leaf is attached to the stem by a short stalk; called petiole. Small lines present on a leaf are called its vein. These gives support and transport water and mineral through the leaf. A thick vein in the middle of the leaf is called midrib
                               

Let us discuss about: 
Venation: Arrangement of veins in a leaf is called venation. We distinguish between two major types of leaf venation. 
                           

Reticulate venation: When the veins make a network like structure, it is called reticulate venation,. This type of venation is seen in dicots like guava, mango, jackfruit, etc.
  

Parallel venation: When the veins run parallel to each other, it is called parallel venation.This type of venation is in monocots like banana, wheat, coconut, leaves of paddy, wheat, grass, etc. 
                            

Functions of leaf: 
Photosynthesis: Green leaves prepare food for plants by using water and carbon dioxide in the presence of sunlight. This process is called as photosynthesis. . Leaves prepare their food in the presence of sunlight and a green coloured substance present in them. For this, they also use water and carbon dioxide. Oxygen is given out in this process. The food prepared by leaves ultimately gets stored in different parts of plant. 
                             

Transpiration: Loss of water vapour from plants through the stomata is as called transpiration. Plants release a lot of water into the air through this process. A major portion of transpiration happens through stomata. 
                

Stomata: There are many small openings on the lower surface of a leaf. These are called stomata. Stomata allow gases to enter or exit the leaf. Unwanted water is also removed through stomata; in the form of water vapour
                          

Reproduction: Leaves of some plants helps in reproduction also. For e.g. leaves of Bryophyllum give rise to a new Bryophyllum plant. 

Children in next session we will learn about parts and function of the flower. 

FLOWER 
Which colour did you use for the flower ? Are all flowers colourful? Have you ever seen flowers on grass, wheat, maize, mango or guava? Are those brightly coloured? Let us study a few flowers. 
             

 Flower: Flower is the most beautiful and colourful part of a flowering plant. It is the reproductive part of a plant. Following are the main parts of a flower: 


Sepal: The outer green leafy structure in a flower is called sepal. Petals make the first whorl of a flower. This whorl is called calyx. It protects the flower at bud stage. Different flowers have petals of different colours. 
                       

Petals: The coloured leaf-like structures; next to the sepals; are called petals. The bright colours of the petals, attracts insects. This helps the plants in reproduction. The whorl formed by the petals is called corolla. 
                          

Stamens: Around the centre of the flower there are many little stalks with swollen tops. These are called Stamen. It is the male part of the flower. Each stamen consists of a green stalk called filament. The capsule-like structure; called anther is at the top of the stamen. The anther produces pollen grains. Pollen grains are powder like particles and take part in reproduction.      
  
Pistil: It is the female part of the flower. It is a flask- shaped structure in the middle of the flower. It is divided into three parts.   


Ovary: The lower broader portion of the pistil is called ovary. It contains the ovules which take part in reproduction. 
Style: The narrow middle portion of the pistil is called style. 
Stigma: The sticky end at the top of the style is called stigma.
                          

Fruits are the fleshy substances that usually surround seeds. Some of the fruits that we eat are orange, mango, apple, grapes, etc. They protect the seeds and attract animals to eat them. This helps in seed dispersal. ` 
                     

Seeds contain plant material that can develop into another plant. This plant material is called an embryo. Seeds are covered with a protective seed coat and have one or two cotyledons. Cotyledons are the food for the baby plant until it can make its own food from light and are often the first embryonic leaves of the plant. 
The number of sepals, petals, stamens and pistils may also be different in different flowers. Some of these parts may even be absent at times! We have studied some features and functions of leaves, stems and roots. We studied the structure of different flowers. We will learn about the function of flowers in higher classes. We will also learn about fruits in higher classes.
THANK YOU

Sunday, January 3, 2021

TEXT: FIBRE TO FARIC - CLASSVI & VII (CBSE)

FIBRE TO FARIC 
CHAPTER-3
CBSE CLASS-VI

A Material which is available in the form of thin and continuous stand is called Fibre. The thin strands of thread that we see are made up of still thinner strands called Fibres. 


The cloth produced by weaving or knitting textile fibre is called Fabric. There are two types of fibres,
1. Natural Fibre
2. Man – Made fibre or Synthetic Fibre            
      

TYPES OF FIBRES
Natural Fibre: The fibres which are obtained from pland and animals are called Natural Fibres. Example: cotton wool, jute & silk.


Man-Made or Synthetic Fibres: The fibres that are synthesized in laboratory are called Man-Made or Synthetic Fibres.  Example: Nylon, Polyester, Makmal, Fur etc.  


Natural Fibres
COTTON:  Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus Gossypium in the mallow family Malvaceae. The fiber is almost pure cellulose. Under natural conditions, the cotton bolls will increase the dispersal of the seeds.   
      

The fiber is most often spun into yarn or thread and used to make a soft, breathable textile. The use of cotton for fabric is known to date to prehistoric times; fragments of cotton fabric dated to the fifth millennium BC have been found in the Indus Valley Civilization. 


Process of Making Cotton: From field to fabric
The process of making cotton transforms the raw fibers into threads, yarn and fabric in three steps: Preparation, Spinning, and Weaving. 


Preparation: To be used for thread or fabric, raw seed cotton must cleaned and free of debris. Seeds, burrs, dirt, stems and leaf material are removed from the cotton during ginning (The process of separating cotton from seed).


Spinning: A Yarn is usually of substantial length & of small cross section. In the cross section of a yarn there are usually a multiple number of Staple fibers (short fibers) or Filaments (long fibers) of unlimited length.


Yarn made out of Staple fiber is known as Spun Yarn, because the staple fibers should undergo number of process stages so that a yarn can be made out of them. This procedure or process stages in correct sequence is called “Spinning”


Spinning is the twisting together of drawn-out strands of fibers to form yarn, and is a major part of the textile industry.  The yarn is then used to create textiles, which are then used to make clothing and many other products.


There are several industrial processes available to spin yarn, as well as hand-spinning techniques where the fiber is drawn out, twisted, and wound onto a bobbin. 
Staple Spun YarnThose are made by Twisting Staple Fibres together into a Strand. The length of the Fibre is limited. Given are some of the spun yarns.        


1. Mono Yarn: Solid, Single Strand of Unlimited Length. 
2. Multi Filament: Many continuous filaments with some twist
3. Staple Yarn: Many short fibers twisted together tightly. 
4. Two Plied Yarn: Two single yarn twisted together. 
5. Multi Plied Yarn: Plied Yarns twisted together. 
6. Thread: Hard, Fine, Plied Yarn. 
7. Cord or Cable: Many plied yarns twisted into a course structure. 
Weaving: Weaving is a method of textile production in which two distinct sets of yarns or threads are interlaced at right angles to form a fabric or cloth. Other methods are knitting, crocheting, felting, and braiding or plaiting. The longitudinal threads are called the warp and the lateral threads are the weft or filling.



SLIK: Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. 


There are different types of silk worm produce different silks in terms of luster and textile. Example: tassar silk, mooga silk, kosa silk etc. are produced by different types of silk moth. Mulbery silk is the most common silk moth.  


The rearing of silkworms for obtaining silk is called Sericulture. silk was discovered in chinna around 3500 BC. Silkworms are reared on mulberry leaves as they feed on mulberry leaves.


Life cycle of silkworm: There are four stages in the life cycle of silk moth. Egg, larva, pupa & adult.
Female silk moth- lays eggs- After about 14 days eggs are hatched into larva (called caterpillar) – Grow into pupa – Secretes fibres made of protein and weaves the fibres around itself completely- This covering is called cocoon.- Lives in the cocoon for some time- After coming out cocoon grows into silk moth. 
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. 
Silk moth to silk: After they are laid by the silk moth; eggs are stored over a clean cloth or paper strips. When larvae are hatched from eggs, they are kept in clean bamboo trays with fresh leaves of mulberry. Larvae feed on mulberry leaves for about 20 to 25 days.


After that, larvae move into tiny chambers of bamboo in which they start spinning cocoon. They do it by secreting liquid protein from their salivary glands.  Finally they enclose themselves in cocoon. Cocoons get hardened because of exposure to air. 


Process of silk:
The process of obtaining silk from silk moth involves- 
1) Rearing of silkworms :The process of keeping, feeding, breeding and medical care of useful animals is called rearing of animals. .
2) Reeling and Dyeing: Cocoons of silk moth are used to obtain the silk fibres. These cocoons are kept under the sun or boiled or exposed to steam. The silk fibres is then separated. This process of obtaining wool from the cocoons is called reeling the silk. This followed by spinning and weaving.


WOOL
Wool is obtained from the fleece (hair) of sheep, sheep, goat, camel, yak, llama, alpaca and other animals. These animals have thick coat hair on their body because the hair traps the air and air is poor conductor of heat. So thick layer of hair keep their body warm and protect them from harsh cold. 


Rearing and breeding of sheep: Sheep are reared in many parts our country like Jammu and Kashmir, Himachal Pradesh, Uttaranchal, Sikkim, Arunachal Pradesh, Haryana, Punjab, Rajasthan, Gujarat etc. Rearing of sheep means to look after the sheep by providing them food, shelter and health care. Breeding is done to obtain animals with desired characters.


Processing of making wool:
The major steps necessary to process wool from the sheep to the fabric are: shearing, cleaning and scouring, grading and sorting, carding, spinning, weaving, and finishing. 
Shearing: Sheep shearing is the process by which the woollen fleece of a sheep is cut off. The person who removes the sheep's wool is called a shearer.


Cleaning and scouring: scouring is a way of cleaning textile fibres. Wool that's been shorn from a sheep is known as greasy, or raw wool. 
Grading and sorting: Grading should not be confused with wool classing: sorting fleeces into various lines according to fineness, length, strength, yield, color, and style. 
Carding: Short-stapled pieces of wool which result from the carding process, spun and woven to make standard-quality fabrics. 
Spinning: Spinning is the twisting together of drawn-out strands of fibers to form yarn, and is a major part of the textile industry. 
Dyeing: After sorting and picking out of burrs, these are dyed in desired colors. 
Weaving: The process of arranging two sets of yarn together to make a fabric is called weaving. 


JUTE: Jute is a long, soft, shiny vegetable fiber that can be spun into coarse, strong threads. It is produced primarily from plants in the genus Corchorus, which was once classified with the family Tiliaceae, and more recently with Malvaceae. Jute was used for making textiles in the Indus valley civilization since the 3rd millennium BC. 


Process of making jute: The jute fiber comes from the stem and ribbon (outer skin) of the jute plant. The fibers are first extracted by retting. The retting process consists of bundling jute stems together and immersing them in slow running water. There are two types of retting: stem and ribbon.  Manufacturing Process of Jute Yarn:   
        

Raw Jute: Raw jute in the form of bales are processed in jute mills to produce hessian, sacking, jute yarn, bags, and other useful products. 
Selection of Raw Jute: In the selection process, raw jute bales are opened to find out any defect and to remove the defective portion from the mora by experienced workers. Raw jute bales are of two types i.e. 150 kg weight and 180 kg weight with or without top portion cutting. The bales are assorted according to end use like Hessiean weft, Sacking wrap, Sacking weft etc. After selection, jute bales are carried to softning section by workers called Gariwala and Bajawala. 
Softning Process Jute: In softning process jute morahs are made soft and pileable. Two methods are used for softning; use of softening machine and use of jute good spreader. Generally an emulsion plant with jute softner machine is used to lubricate and soften the bark and gummy raw jute. The emulsion plant consists of gear pump, motor, vat, jet sprayer, nozzles, emulsion tank and the jacket. In this softning process jute becomes soft and pileable and suitable for carding. 
Carding: Carding is a combining operation where jute reeds are splitted and extraneous matters are removed. Jute fibres are formed into ribbon called "sliver". There are three different carding sections: 
(i) Breaker carding 
(ii) Inner carding 
(iii) Finisher carding 


In the Breaker carding machine soften jute after piling is feed by hand in suitable weight. The machine by action with different rollers turns out raw jute in the form of jute sliver for finisher carding. In this process root cutting is necessary before feeding the material to the hand feed breaker carding machine.  Finisher carding machine make the sliver more uniform and regular in length and weight obtained from the Breaker carding machine. 
             Finisher carding machine is identical to the Breaker carding machine, having more pair of rollers, staves, pinning arrangement and speed. The material thus obtained is send to drawing section. 
Drawing:  Drawing is a process for reducing sliver width and thickness by simultaneously mixing 4 to 6 sliver together. There are three types of Drawing Frame machine. In most mills 3 Drawing passages are used in Hessian and 2 Drawing passages are used in Sacking.


Spinning: Spinning is the process for producing yarn from sliver obtained from Third drawing. The jute spinning frame machine is fitted with slip draft zone and capable of producing quality yarns at high efficiency with auto-dofting arrangements also. 
           

MAN MADE OR SYNTHETIC FIBRE
These are also known as man-made fibers. Synthetic fibers are obtained by chemical processing of petrochemicals. The synthetic fibers can be woven into a fabric, just like natural fiber.  Synthetic fibers have a wide range of use ranging from household articles like ropes, buckets, furniture, containers, etc. to highly specialized uses in aircrafts, ships, spacecrafts, health care, etc.


Synthetic fibers and plastics are made up of molecules called polymers. A polymer is a large molecule formed by combination of many small molecules, each of which is called a monomer. 
Properties of synthetic fibers:The properties of synthetic fibres are as follows-  They quickly dry up.
1. It means that synthetic fiber dries easily after washing. They are durable. 
2. It means that they can be used for a longer period of time. They are less expensive.
They are readily available.
They are easy to maintain and do not need extra care.

Kinds of Synthetic Fibers: 
There are different kinds of synthetic fibers which are as follows-
Rayon
Polyester
Nylon
Acrylic
Plastic 


Rayon: This is a type of synthetic fibre obtained from wood pulp. Rayon is soft, absorbent and comfortable. It is easy to dye in wide range of colors. Rayon is mixed with cotton to make bedsheets. Rayon is mixed with wool to make carpet.


Nylon: This type of synthetic fibre is obtained from coal, water and air. Nylon is very lustrous, easy to wash and elastic. It dries quickly and retains its shape. It finds its application in seat belts of car, sleeping bags, socks, ropes, etc.  Nylon is also used in ropes for rock climbing, making parachutes and fishing nets. 


Acrylic: Acrylic is warm and lightweight, soft and flexible fibre. It is often used for making sweaters, blankets, cashmere, jackets, shawls, and tracksuits. It is also used as linings for boots and gloves as well as in furnishing fabrics and carpets. It is used in craft yarns, boat sails and vehicle covers. 


Polyester: polyster is obtained from coal, water, air and petroleum. It is made from repeating units of chemical known as esters. It is easy to wash and it remains wrinkle free and it is quite suitable in making dress material. Polyester retains its shape and remains crisp. Polyester is used in making ropes, nets, raincoats, jackets, etc. 


Advantages of synthetic fibres: Synthetic fibres are very durable and do not wrinkle easily They are elastic and can be easily stretched out They are strong and can sustain heavy load. It is soft and hence it is used in clothing material. It is cheaper as compared to natural fibres. 


Disadvantages of synthetic fibres: Most synthetic fibres do not absorb moisture. Synthetic fibre can be affected if washed using hot water. It catches fire easily as compared to natural fibre. 


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