NCERT Solutions Std 7 Science Fibre to Fabric

Fibre To Fabric

Exercise:

1). You must be familiar with the following nursery rhymes:

(i) ‘Baa baa black sheep, have you any wool.’

(ii) ‘Mary had a little lamb, whose fleece was white as snow.’

Answer the following:

(a) Which parts of the black sheep have wool?

 Ans: Fleece – the hairy skin of the black sheep has wool.

(b) What is meant by the white fleece of the lamb?

Ans: White fleece is the white hairy skin of the lamb.

2). The silkworm is (a) a caterpillar, (b) a larva. Choose the correct option.

(i) a (ii) b (iii) both a and b (iv) neither a nor b.

Ans: Both a and b

3). Which of the following does not yield wool?

(i) Yak (ii) Camel (iii) Goat (iv) Woolly dog

Ans: Woolly dog.

4). What is meant by the following terms?

(i) Rearing

       Rearing of animals taking care of economically useful animals by managing their breeding, feeding and medical care. 

(ii) Shearing

       The fleece of the sheep along with a thin layer of skin is removed from its body. This process is called shearing.

(iii) Sericulture

      The rearing of silkworms for obtaining silk is called sericulture

5). Given below is a sequence of steps in the processing of wool. Which are the missing steps? Add them.

Shearing, __________, sorting, __________, __________, _________.

Shearing, scouring, sorting, picking out burrs, colouring, rolling.

 

6). Make sketches of the two stages in the life history of the silk moth which are directly related to the production of silk.

7). Out of the following, which are the two terms related to silk production?

Sericulture, floriculture, moriculture, apiculture and silviculture.

Hints: (i) Silk production involves the cultivation of mulberry leaves and rearing silkworms.

(ii) Scientific name of mulberry is Morus alba.

Ans: Sericulture, moriculture

8). Match the words of Column I with those given in Column II:

Column I                                                                       Column II

1). Scouring                                                  (a) Yields silk fibres

2). Mulberry leaves                                        (b) Wool-yielding animal

3). Yak                                                         (c) Food of silk worm

4). Cocoon                                                    (d) Reeling

                                                                   (e) Cleaning sheared skin

Answer

1). Scouring – Cleaning sheared skin

2). Mulberry leaves –   Food of silkworm

3). Yak Wool-yielding animal

4). Cocoon – Yields silk fibres

 

9). Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.

Down                                                 

(D) 1: Thorough washing         

2: Animal fibre                     

3: Long thread-like structure      

Across

1: Keeps warm

2: Its leaves are eaten by silkworms

3: Hatches from the egg of a moth

Answer:

Additional Questions:

True or false

1). Nowadays scouring is done by machines.

true.

2). Silk fibres are plant fibres.

False

3). Silk fibres are natural fibres

True.

4). A female silk moth lays hundreds of eggs at a time.

true.

5). Silk fibres come from cocoons of the silk moth

True.

Fill in the blanks

1). The silk yarn is obtained from the cocoon of the silk moth.

2). The most common silk moth is the mulberry silk

moth.

3). Wool is obtained from the fleece (hair) of sheep or yak.

4). Llama and Alpaca, found in South America, also yield wool.

5). Sheep are reared in many parts of our country for wool.

 

Answer in short

1). Name the animals that give wool?

      The wool comes from sheep, goats, yak and some other animals.

2) Write the types of fibres found in sheep?

      Sheep have two types of fibres that form its fleece:

(i) the coarse beard hair, and

(ii) the fine soft under-hair close to the skin.

3). Name any two animal fibres.

     Wool and silk.

4). What is the scientific name of mulberry tree?

     Morus alba.

Define the following.

1). Selective breeding

        This process of selecting parents for obtaining special characters in their offspring, such as soft under hair in sheep, is termed ‘selective breeding’.

2). Shearing

       The fleece of the sheep along with a thin layer of skin is removed from its body. This process is called shearing.

3). Scouring

       The sheared skin with hair is thoroughly washed in tanks to remove grease, dust, and dirt. This is called scouring.

4). Sericulture

       The rearing of silkworms for obtaining silk is called sericulture.

5). Reeling of silk.

       The process of taking out threads from the cocoon for use as silk is called reeling the silk.

Click here for the solutions of

1). Nutrition in Plants

2). Nutrition in Animals

3). Fibre to Fabric

4). Heat

5). Acids, Bases and Salts

6). Physical and Chemical Changes

7). Weather, Climate and Adaptations of Animals to Climate

8). Winds, Storms and Cyclones

9). Soil

10). Respiration in Organisms

11). Transportation in Animals and Plants

12). Reproduction in Plants

13). Motion and Time

14). Electric Currents and its Effects

15). Light

16). Water: A Precious Resource

17). Forests: Our Lifeline

18). Wastewater Story

 

 

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