Saturday 18 June 2011

Fibre to Fabric : Lesson 3 : Class VII (7th) Science Exercise

Questions & Answers

1.Question  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?
Answer : The black sheep in the poem seems to  have wool on almost  all the parts as it in the poem it offers wool,  enough to fill three bags full.

(b) What is meant by the white fleece of the lamb?
Answer : Here the white fleece of the lamb refers to pure white woolen coat that it wears.

2. Question : he 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.

Answer : (iii) both a and b

3. Question :  Which of the following does not yield wool?
 (i) Yak (ii) Camel (iii) Goat (iv) Woolly dog

Answer : (iv) Woolly dog

4.Question : What is meant by the following terms?

(i) Rearing (ii) Shearing (iii) Sericulture

(i) Rearing : Rearing is raising livestock like goat, cows, sheep etc for commercial purpose by taking them out in herds for grazing ,  feeding them on a mixture of pulses, corn, jowar, oil cakes (material left after taking out oil from seeds) and minerals for better growth and yield of produce like meat, milk, wool. Beside this in extreme climatic condition like winter these are also provided shelter and fed on leaves, grain and dry fodder.

ii) Shearing: Shearing is the process in which  fleece of the sheep along with a thin layer of skin is removed from its body.  Machines similar to those used by barbers are used to shave off hair. Generally, the hair are removed during the hot weather which enables the sheep to survive without their protective coat of hair. The hair provide woolen fibres. Woolen fibres are then processed to obtain woolen yarn. Shearing does not hurt the sheep as the uppermost layer of the skin is dead..

(iii) Sericulture : Sericulture, or silk farming, is the rearing of silkworms for the production of raw silk. For obtaining silk, silk worm moths are reared and their cocoons are collected to get silk threads. Silk yarns come from the cocoon of the silkworm. The caterpillar hatches from a very small egg and is an eating machine. Their diet of continually eating mulberry leaves results in a semi-liquid protein called fibroin. When the silkworms start its spinning process in the cocoon, the worm's head is coated with a gummy protein called sericin. The silkworm rotates its body thousands of times extruding one continuous strand of silk the length of 12 football fields. The silk adheres to itself, forming the cocoon. 

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

Shearing, __________, sorting,________ , _____________

Answer : Shearing, scouring, Sorting,  fiber spinning,  fiber  dying, rolling into Silk yarn

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.
(i) Silk production involves cultivation of mulberry leaves and rearing silkworms.
(ii) Scientific name of mulberry is Morus alba.

 Answer : Sericulture, Moriculture

8. Question :  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 : 
Column I                                   Column II
1. Scouring                              (e) Cleaning sheared skin
2. Mulberry leaves                   (c) Food of silk worm
3. Yak                                    (b) Wool yielding animal
4. Cocoon                               (a) 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                                        Across
(D)                                            (A)
1 : Thorough washing                 1 : Keeps warm
2 : Animal fibre                          2 : Its leaves are eaten by silkworms
3 : Long thread like structure     3 : Hatches from egg of moth

Extended Learning — Activities and Projects

1. Paheli wants to know the maximum length of continuous silk thread that can be obtained from a coco
Find out for  her

2. Boojho wants to know why caterpillars need to shed their skin when they grow bigger but we humans do not.
Do you have any idea?

3. Boojho wants to know why caterpillars should not be collected with bare hands.
Can you help him?

4. Paheli wanted to buy a silk frock and went to the market with her mother.
There they found that the artificial (synthetic) silk was much cheaper and wanted to know why.
Do you know why? Find out.
5. Someone told Paheli that an animal called ‘Vicuna’ also gives wool. Can you tell her where this animal is found? Look for this in a dictionary or an encyclopaedia.
6. When handloom and textile exhibitions are held, certain stalls display real moths of various varieties of silk and their life histories. Try and visit these stalls with elders or teachers and see these moths and stages
of their life history.
7. Look for eggs of any moth or butterfly in your garden or park or any other place full of plants. They look like tiny specks (dots) laid in a cluster on the leaves. Pull out the leaves containing eggs and place them in a cardboard box. Take some leaves of the same plant or another plant of the same variety, chop them and put them in the box. Eggs will hatch into caterpillars, which are busy eating day and night. Add leaves
everyday for them to feed upon. Sometimes you may be able to collect the caterpillars. But be careful. Use a paper napkin or a paper to hold a caterpillar.
Observe everyday. Note the 
(i) number of days taken for eggs to hatch,
(ii) number of days taken to reach the cocoon stage, and 
(iii) number of days to complete life cycle. Record your observations in your notebook.
You can read more on the following website:
Did you know?
In terms of the number of sheep, India ranks third in the world, behind
China and Australia. However, the New Zealand sheep are known to yield
the best wool.