3

Q1. Which of the following correctly denotes the order of stages in the life history of a silkmoth?

• 1) Egg → Larva → Pupa → Adult
• 2) Egg → Pupa → Larva → Adult
• 3) Larva → Egg → Pupa → Adult
• 4) Pupa → Larva → Egg → Adult

Solution

Stages in the life history of a silkmoth are egg followed by larva, pupa and adult.

Q2. Silkworms feed on the leaves of

• 1) Neem tree
• 2) Mango tree
• 3) Oak tree
• 4) Mulberry tree

Solution

Silkworms feed on the fresh leaves of mulberry tree which not only provides them with food but also moisture. 

Q3. After caterpillar stage, next stage is _______.

Solution

After caterpillar stage, next stage is pupa.

Q4. The pupa stage is an intermediate stage between _______ stage and adult stage.

Solution

The pupa stage is an intermediate stage between larva stage and adult stage.

Q5. Silk fibres are made of fat.

• 1) False
• 2) True

Solution

False Silk fibres are made of protein. 

Q6. The removal of silk thread from the cocoons is called reeling.

• 1) False
• 2) True

Solution

True

Q7. The process of removal of fleece from the body of sheep is called

• 1) Shaving
• 2) Shearing
• 3) Scouring
• 4) Sorting

Solution

The process of removal of hair in the form of fleece from the body of sheep is called shearing.

Q8. The process of taking out silk fibres from the cocoon for use as silk is called

• 1) Reeling
• 2) Shearing
• 3) Molting
• 4) Combing

Solution

The process of taking out silk fibres from the cocoon for use as silk is called reeling. It is carried out in special machines which unwind the fibres of silk from the cocoons.

Q9. Which of the following is the most common silk moth?

• 1) Tassar silk moth
• 2) Mooga silk moth
• 3) Mulberry silk moth
• 4) Eri silk moth

Solution

Mulberry silk moth is the most common variety of silk moth. The silk obtained from this variety is called mulberry silk.

Q10. Silk threads are woven into silk cloth by sorters.

• 1) True
• 2) False

Solution

False Silk threads are woven into silk cloth by weavers.

Q11. The fleece of sheep is removed only once a year before the beginning of 

• 1) Summer season
• 2) Rainy season
• 3) Spring season
• 4) Winter season

Solution

Shearing of sheep or removal of fleece from the body of sheep is done in the hot weather of summer so that the sheep may survive without their protective coat of hair on the body.

Q12. Silk is obtained from silk moth by breaking the cocoon in 

• 1) Pupal stage
• 2) Egg stage
• 3) Larval stage
• 4) Adult stage       

Solution

Silk is obtained from silk moth by breaking the cocoon at the end of the pupal stage.

Q13. Describe the various steps involved in obtaining wool.

Solution

The steps involved in obtaining wool are: Step I. The fleece of the sheep along with a thin layer of skin is removed from its body, this process is called as shearing. Step II. The sheared skin with hair is thoroughly washed in tanks to remove grease, dust and dirt and this process is called scouring. Step III. After scouring, sorting is done. The hairy skin is sent to a factory where hair of different textures are separated or sorted. Step IV. Then the small fluffy fibres, called burrs are picked out from the hair. The fibres are scoured again and then dried. This gives us the wool ready to be drawn into fibres. Step V. The fibres are dyed in various colours, as the natural fleece of sheep and goats is black, brown or white. Step VI. Finally, fibres are straightened, combed and rolled into yarn. The longer fibres are made into wool for sweaters and the shorter fibres are spun and woven into woollen cloth.

Q14. The caterpillar completely covers itself by silk fibres and forms a covering called 

• 1) Pupa
• 2) Reel
• 3) Cocoon
• 4) Yarn

Solution

During its life cycle, the silkworm spins a covering of silk fibres called cocoon around itself. The silkworm continues to develop in the form of pupa inside the cocoon to form the silk moth.

Q15. Shearing hurts the sheep.

• 1) True
• 2) False

Solution

False Shearing does not hurt the sheep.

Q16. Take an artificial (synthetic) silk thread and a pure silk thread. Burn these threads carefully. In a tabular column, write the difference in the smell while burning?

Solution

Type of fibre Smell Artificial silk Smell of burning paper Natural silk Smell of burning hair

Q17. The primary use of silk worms is in the production of _______.

Solution

The primary use of silk worms is in the production of silk.

Q18. The sheared skin with hair is thoroughly washed in tanks to remove grease, dust and dirt.

• 1) True
• 2) False

Solution

True

Q19. Sorting of fibres according to different textures is done after ______.

Solution

Sorting of fibres according to different textures is done after scouring.

Q20. Woollen fibres are processed to obtain woollen  ______ .

Solution

Woollen fibres are processed to obtain woollen yarn.

Q21. (i) When is the shearing of fleece of sheeps done? (ii) Why shearing does not hurt the sheep?

Solution

(i) Shearing is done only once in a year generally in spring or early summer. (ii) Shearing does not hurt the sheep because the uppermost thin layer of their skin is dead.

Q22. The most common variety of silk is

• 1) Tassar silk
• 2) Mulberry silk
• 3) Kosa silk
• 4) Mooga silk

Solution

The most common silk moth is the mulberry silk moth and therefore, the most common variety of silk is mulberry silk.

Q23. Silk is prepared from the leaves of a mulberry plant.

• 1) False
• 2) True

Solution

False Silk is prepared from the fibres of the cocoon of the pupa. 

Q24. Shearing is done during winter season.

• 1) True
• 2) False

Solution

False Shearing is done during the hot weather.

Q25. During sorting, wool of different _______ are separated.

Solution

During sorting, wool of different texture are separated.

Q26. Hair on a sheep's body are _______ conductor of heat.

Solution

Hair on a sheep's body are poor conductor of heat.

Q27. Uppermost layer of skin of animals like sheep, goats etc. is ______.

Solution

Uppermost layer of skin of animals like sheep, goats etc. is  dead.

Q28. Wool is obtained from hairs of sheep, yak, camel, goat, etc.

• 1) True
• 2) False

Solution

True

Q29. The process of separation of fleece of a sheep according to the quality of woollen fibres is called

• 1) Combing
• 2) Shearing
• 3) Sorting
• 4) Scouring

Solution

The process of separation of fleece of a sheep into sections according to the quality of woollen fibres is called sorting.

Q30. Before weaving, the silk threads are printed.

• 1) False
• 2) True

Solution

False Before weaving, the silk fibres are spun into threads.

Q31. (i) What is the purpose of scouring of the sheared skin obtained from sheeps? (ii) How is it done?

Solution

(i) Scouring of sheared skin with hair is done to remove grease, dust and dirt from the hair. (ii) It is done by thoroughly washing the sheared skin and hair in soap solution to remove all the dirt. It can be done by both hands and machines.

Q32. Name the four stages of the silkworm's life cycle?

Solution

The four stages of Silkworm life cycle are: 1. Egg 2. Larva (caterpillar) 3. Pupa 4. Adult

Q33. Hair on sheep's body forms a protective coating and keeps it warm.

• 1) True
• 2) False

Solution

True

Q34. Silkworms require a lot of feeding during the 

• 1) Caterpillar stage
• 2) Egg stage
• 3) Adult stage
• 4) Cocoon stage

Solution

The larvae also known as caterpillars or silkworms feed on cut mulberry leaves. They eat day and night and increase enormously in size.

Q35. Larvae hatched from the eggs are called _______.

Solution

Larvae hatched from the eggs are called caterpillars.

Q36. When the cocoons are dropped in ______ water, they become loose and fibres unwind from the cocoons.

Solution

When the cocoons are dropped in hot water, they become loose and fibres unwind from the cocoons.

Q37. The eggs hatch to give pupa.

• 1) True
• 2) False

Solution

False The eggs hatch to give birth to larvae. 

Q38. Wool obtained from animals can directly be used to knit sweaters.

• 1) True
• 2) False

Solution

False Wool obtained from animals has to be processed before using it to knit sweaters.

Q39. The process of taking out threads from the cocoon for use as silk is called ______.

Solution

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

Q40. Shearing involves removing fleece of sheep along with a thin layer of skin.

• 1) False
• 2) True

Solution

True

Q41. Wool is a __________ fibre.

Solution

Wool is a natural fibre.

Q42. Why is it advised to place twigs in trays while rearing silk moth?

Solution

Twigs in trays are placed for rearing silk moth so that the cocoons find a stable base and get attached to twigs. The caterpillar or silkworm spins the cocoon, inside which the silk moth develops.

Q43. Usually, sheep hair are removed during the _______ weather.

Solution

Usually, sheep hair are removed during the hot weather.

Q44. Explain the formation of cocoon in silkworms?

Solution

The silkworms secretes a very fine filament made of fibroin protein from two glands on its head which solidifies upon exposure to air and becomes silk fibres. Through movement of head from side to side in the form of figure of eight, the silkworm completely covers itself forming the cocoon.

Q45. Reeling of silk involves _______ of silk threads from the cocoon for use as silk.

Solution

Reeling of silk involves unwinding of silk threads from the cocoon for use as silk.

Q46. What happens during the reeling process?

Solution

During reeling, threads or fibres of silk are separated from the cocoons by immersing them in boiling water. The machines unwind the threads or fibres of silk. These fibres are then spun into silk threads. 

Q47. Describe briefly how silk is produced.

Solution

In order to obtain silk, mulberry trees are cultivated, silkworms are reared and their cocoons are collected to get silk fibres. The various steps involved are: (i) Rearing of silkworms: A female silk moth lays hundreds of eggs at a time. The eggs are stored by the farmers at suitable temperature and humidity under hygienic conditions. When the eggs hatch, silkworms come out of the eggs. The silkworms are fed mulberry leaves. After 25-30 days, the silkworms stop eating and get ready to spin cocoons. The silkworms enclose themselves completely inside the silken cocoons in two or three days. (ii) Processing of cocoons to obtain silk fibres: The pile of cocoons is placed in hot water. Hot water makes the silk fibres of cocoons to separate out. The long fibres are obtained by unwinding the threads from cocoons. This process is called reeling. (iii) Converting silk fibres into silk cloth: Silk fibres obtained from cocoons are spun (twisted) to form silk threads called silk yarn. The silk yarn is then woven on looms into silk cloth by the weavers.

Q48. What is done after dyeing of fibre in various colours during the process of making wool?

Solution

The fibres are straightened, combed and rolled into yarn after dyeing in various colours.

Take Another Test