Gujarat Board GSEB Textbook Solutions Class 7 Science Chapter 3 Fibre to Fabric Textbook Questions and Answers, Notes Pdf.
Gujarat Board Textbook Solutions Class 7 Science Chapter 3 Fibre to Fabric
Gujarat Board Class 7 Science Fibre to Fabric Textbook Questions and Answers
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?
(b) What is meant by the white fleece of the lamb?
(a) The hairy skin called fleece has wool in black sheep.
(b) White fleece of the lamb means the white coloured hairy skin.
The silkworm is (a) a caterpillar (b) a larva. Choose the correct option.
(iii) both (a) and (b)
(iv) neither (a) nor (b)
(iii) both (a) and (b).
Which of the following does not yield wool?
(iv) Woolly dog
(iv) Woolly dog
What is meant by the following terms?
(i) Rearing: The process of keeping, feeding, breeding and medical care of useful animals is called rearing of animals. These animals produce one or more useful products for human beings.
(ii) Shearing: The process of removing the fleece of the sheep alongwith thin layer of skin is called shearing.
(iii) Sericulture: The rearing of silk¬worms for obtaining silk is called sericulture.
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 of burrs, colouring, rolling.
Make sketches of the two stages in the life history of the silk moth which are directly related to the production of silk.
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 Morns alba.
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 silkworm|
|4. Cocoon||(d) Reeling|
|(e) Cleaning sheared skin|
|Column I||Column II|
|1. Scouring||(e) Cleaning sheared skin|
|2. Mulberry leaves||(c) Food of silkworm|
|3. Yak||(b) Wool yielding animal|
|4. Cocoon||(a) Yields silk fibres|
Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
1. Thorough washing
2. Animal fibre
3. Long thread like structure
1. Keeps warm
2. Its leaves are eaten by silkworms
3. Hatches from egg of moth
Extended Learning – Activities And Projects
Paheli wants to know the maximum length of continuous silk thread that can be obtained from a cocoon. Find out for her.
More than 1,000 feet (1,000 to 1,500 feet) continous in length.
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?
The caterpillar eats ferociously the leaves of mulberry tree and grows in size whereas its skin does not increase in size, shape or length. So, it sheds skin (moulting).
Larval period lasts about three to five weeks. During this period it attains from about 1/4″ to 3″ in length. During this period moulting occurs about four times.
Boojho wants to know why caterpillars should not be collected with bare hands. Can you help him?
Caterpillar may cause irritation, skin allergy and transfer diseases.
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.
Artificial silk is synthetic and can be prepared at a large scale in factories / mills. So, it is cheap. For obtaining natural silk, we have to rear silk moth, their larvae to get pupa. To get silk thread, which is wrapped over the cocoon, we have to dip cocoon in hot water. The pupa inside the cocoon dies. To obtain silk for commercial purposes a large number of cocoons (containing living pupa) are killed. For example, for about a pound of silk about 25,000 cocoon are killed. As a result natural silk is costly.
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.
Vicuna lives in the Andes from Ecuador to Chile, at an elevation of 12,000 to 18,000 feet.
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.
Do it yourself.
Look for eggs of any moth or butterfly in your garden or park or any other place full of plants. They look like any 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 taken to complete life cycle. Record your observations in your notebook.
(i) Number of days taken for eggs to hatch: The hatching period varies from insect to insect. For example, in houseflies, the eggs hatch out within 10 to 15 hours of copulation.
Eggs of the moth hatch in 10 to 12 days. In Browntail moth, caterpillars hatch in 2-3 weeks. Eggs of some butterflies, e.g. monarch butterfly hatch in less than a week.
(ii) Number of days taken to reach cocoon stage: It also varies:
- In common mulberry silk moth, within 12 to 15 days, the caterpillar completely transforms into pupa.
- Some moths (Browntail moth) take 3 to 4 weeks to develop caterpillar into mature pupa.
(iii) Number of days taken to complete life cycle: Various insects take different time. It depends upon the insect moth or butterfly you are observing.