RBSE Solutions for Class 12 Biology

Rajasthan Board RBSE Class 12 Biology Chapter 41 Domestication, Culture & Economic Importance of Animals

RBSE Class 12 Biology Chapter 41 Multiple Choice Questions

Question 1.
Which one of these in indigenous species used for poultry farming?
(a) White Leghorn
(b) Pekin
(c) New Hampshire
(d) Aseel
Answer:
(d) Aseel

Question 2.
The incubation period of eggs of Hen is –
(a) 21 days
(b) 28 days
(c) 30 days
(d) 12 days
Answer:
(a) 21 days

Question 3.
Poultry farming provides –
(a) Eggs and honey
(b) Meat and Lac
(c) Eggs and wax
(d) Meat and eggs
Answer:
(d) Meat and eggs

Question 4.
Which stage of the silkworm, provides silk?
(a) Egg
(b) Caterpillar
(c) Adult
(d) Cocoon
Answer:
(d) Cocoon

Question 5.
The scientific name of Europian honey bee.
(a) Apis welfare
(b) Apis force
(c) Apis Florida
(d) Apis India
Answer:
(a) Apis welfare

Question 6.
The function of the queen honey bee is –
(a) Control on other honey bees
(b) Protect bee-hive
(c) Perform reproduction
(d) Prepare honey
Answer:
(c) Perform reproduction

Question 7.
Which of the following is not a major carp?
(a) Labeo raita
(b) Catla Catla
(c) Cirrhinus regalia
(d) Chanos Chanos
Answer:
(d) Chanos Chanos

Question 8.
Anthrax disease of cattle is –
(a) Viral disease
(b) Helminth disease
(c) Bacterial disease
(d) Protozoan disease
Answer:
(c) Bacterial disease

Question 9.
Nutritive Plant of Kusumi type lac insect.
(a) Kher
(b) Babool
(c) Shisham
(d) Ber
Answer:
(d) Ber

Question 10.
Which silkworm produces “Moonga silk”?
(a) Bombyx mori
(b) Antheraea assassins
(c) Antheraea Bahia
(d) Antheraea recent
Answer:
(b) Antheraea assassins

RBSE Class 12 Biology Chapter 41 Very Short Answer Type Questions

Question 1.
What is Domestication?
Answer:
Raising and breeding of animals for various purposes by man is called domestication.

Question 2.
What you call the hends reared to lay eggs?
Answer:
Layers.

Question 3.
What is the position of India in the world in poultry?
Answer:
Sixth position.

Question 4.
What did you call rearing and management of fishes?
Answer:
Pisciculture.

Question 5.
Give the names of two Research centres in India working in pisciculture.
Answer:

• Central Inland Fisheries Research Centre.
• Central Marine Fisheries Research Centre.

Question 6.
Write the scientific name of lac insect.
Answer:
Lucifer lack.

Question 7.
Name one disease of the silkworm.
Answer:
Pebrine.

Question 8.
The silk glands found in silkworm are a modification of which gland?
Answer:
Salivary glands.

Question 9.
Which precautions are required in Apiculture?
Answer:
Precautions:
Following precautions are necessary for honey bee culture or Apiculture:

• Plants of fruits and flowers should be within one kilometre only from the hives.
• Artificial beehives should be kept in cool & shady area.
• Source of freshwater must be in the nearest vicinity.

Question 10.
What do you mean by fish seed?
Answer:
The fertilized eggs of the fish are called fish seed.

RBSE Class 12 Biology Chapter 41 Short Answer Type Questions

Question 1.
Describe viral diseases found in hens.
Answer:
Viral diseases:
The main viral diseases in poultry birds are Fowlpox, Infectious bronchitis, Lymphoid leukosis and Ranikhet disease. The most common disease of fowl is Ranikhet in which fever, diarrhoea occurs.

Question 2.
Explain in brief the social organization in honey bees.
Answer:
The social organisation of Honey bee:
A colony of honey bee shows of high-grade social organisation and division of labour.

A colony of honey bees consists of three kinds of individuals or Castes –
1. Queen:

• In the whole colony, there is only one adult queen of large size.
• The queen arises from a fertilized egg and when larva especially fed on royal jelly.
• It is only fertile female in the beehive, having huge developed ovaries.
• The function of a queen is only of reproduction i.e it lays eggs.

2. Drones:
Drones developed from Unfertilized eggs i.e., parthenogenetically. The function of drones is only to mate with the queen fertilize the eggs.

3. Workers:

• They are sterile females who develop from unfertilized eggs. Their number varies from 3000 to 6000 or more.
• The worker bees are of three types:
  • Sanitary bees – These bees clean the chambers of the hive.
  • Nurse bees – These workers look after the queen & hive.
  • On the basis of ages, they are of 3 types –
    • Foster mother: They are the nurse workers of 4 to 6 days.
    • They feed a mixture of honey & nectar to the infants.
    • The nurse workers of 7 to 11 days.
    • They secrete royal jelly which is secreted by maxillary glands.
    • Nurse workers of 12 to 15 days.
    • They secrete wax from the wax glands during this period of 4 days.
    • This wax is used to repair & reconstruct hive.
    • The wax glands get functional up to 12th day.
    • They secrete propolis which is a gumlike substance.
• These nurse workers are of 4 types –
  • Fanning bees – They fly stationary near the nest to maintain airflow.
  • Sentinel bees – They act as a guard of the nest.
  • Soldier bees – They protect the hive intruders. They also check the honey collected by the bees.
  • Retinue bees – They clean the queen & queen chambers. They also feed royal jelly to the queen & transfer eggs to other chambers.

4. Scout bees:

• They are also called as field or foraging bees.
• They search for new food sources & collect nectar & pollens.
• They collect food 7 to 15 times a day.
• They also collect water.
• The water requirement of a hive is to 2 litres per day.

Question 3.
Give the uses of lac.
Answer:
Lac is used to making bangles, polish, utensils, toys, varnish, electricity devices etc.

Question 4.
Give the names of main species of the silkworm and the silk produced by them.
Answer:
Main species of Silk Worm:

Species of Silk Worm	Types of Silk	Food Plant
Bombyx mori	Mulberry Silk	Morus alba
Antheraea paphia	Tasser silk	Terminalia arjuna
Antheraea assamensis	Muga silk	Machilus bombycina
Attacus Ricinus	Eri silk	rechinii communis
Ethiopia religious	Dev MUGA silk	Fucus and machilus

Question 5.
Give an account of diseases found in silkworm.
Answer:
Diseases of Silk Worm:
Silkworm can have many diseases. Main two diseases are as follows:
1. Pebrine:
It is of two types:

1. Virus Pebrine:
   • It is caused by Borrelia bombycis virus.
   • After 8 – 10 days, larvae start dying.
   • For protection, dead larvae should be separated and instruments are rinsed with 30% solution of Trichloroacetic acid for 15 minutes & then washed with water.
2. Protozoan Pebrine:
   • It is caused by Nosema bombycis protozoa.
   • It affects both the larva and adult.
   • The adult shape gets irregular, shrink and larva get small in size.
   • Death of larvae before the formation of cocoons.
   • For protection, only eggs from healthy worms should be used.

2. Fletcher and Brasserie: These diseases are caused by viruses.

RBSE Class 12 Biology Chapter 41 Essay Type Questions

Question 1.
Write an essay on Pisciculture.
Answer:
Fish Culture or Pisciculture or Fisheries:

1. In developing countries like India, Supply of milk and meat per person is very less. Hence, fish supplement is essential in the diet of such countries.
2. The necessity of fish protein in the country is approximately one crore tonnes per year, while we have only 35 lakh tonnes production of fish annually. Fish culture provides income and employment to the people residing in coastal states of the country.
3. Various techniques are used to increase the production of fish to full-fill the demand. Fish production in India has approximately 2.34% area of inland water, which is approximately 75 lakh hectare.
4. As a result of researches conducted at Central Inland Fisheries Research Institute, the fish culture and production increases up to 85000 kg./hectare/year. It is a revolution in the field of fisheries. Fisheries or fish culture gained much importance in order to encourage young men to take up small scale industries as a carrier.
5. Pisciculture or fish culture involves production and breeding of fishes. Fishes are the best source of protein. Besides proteins, it has mineral salts, Vitamins (Vit-Aand Vit-D) and healthy fats insufficient amount, Fish is a complete food for men.
6. Some fishes e.g. Common carp, Catla, Rohu (freshwater fishes) and Hilsa, Sardine and Prophrate (marine fishes) are edible. Because of high consumption, these fishes are cultured by scientific techniques.
7. Along with the fishes other aquatic animals e.g. Prawns, Lobsters, Molluscs etc. are also cultured and it is considered as aquaculture.

Types of Cultivable Fishes:
Cultivable fishes are of three types –

1. Indigenous or naturally occurring freshwater fishes.
   Example: Major carps.
2. Some marine fishes which get adapted to freshwater
   Example: Chanos, Mullets etc.
3. Exotic fishes: Those fishes which brought from foreign countries in India Examples: Mirror Carp, Chinese carp, Crucian carp and Common carp.

Question 2.
Give the salient features of lac insect and plant names on which it is cultivated.
Answer:
Salient features of Lac Insects:

• In lac insect, males & females are separate i.e. it shows sexual polymorphism. Male length is 1.2 – 1.5 mm and red in colour.
• They are small in comparison to female. Female has a soft body and oval in shape. Females are big and 5 mm in length.
• The body is indistinctly divided into head, thorax and abdomen. It is dark red in colour and does not have wings. Female lives in the resinous sac.
• Female gives 200 – 500 eggs in the resinous sac After 6-week first Instar larva comes out. It is called Nymph.
• They are active and accumulate at the small soft twig of a succulent tree. They secrets lac from their skin gland Nymph which gets dry when coming in the contact with air.
• Present on the skin takes sap as a nutrient from succulent plants. After 6 to 8 weeks due to metamorphosis nymph change into 70% wingless females and 30 % males with wings.
• In every year 2 times they complete their life cycle (Oct Nov and June – July). On nutritious plant.

Host Plants for Lac Insect:
In India, there are many plants on which lac insects complete their life cycle. Some of the plants are followed –

Common Name of Plant providing Nutrition	Botanical Name
Kusum	Schleicher oleos
Khair	Acacia catechu
Ber	Zizyphus mauritiana
Babul	Acacia ilotica
Fig	Ficus carica
Palas	Beta monosperm
Shisham	Dalbergia siss

Lac insect sucks sap using its appendages. Quality of Lac depends on the type of plants. Kusumic lac is the best lac which is obtained from Ber & Palas plants.

Question 3.
Explain in detail the poultry.
Answer:
Poultry Farming:

• Fowl is in use by man since ancient time. In the 20th century, the need for nutritive and tasty food has given a rank of a significant cottage industry to poultry. Fowl (Hen) yields nutritional food in the form of eggs and meat.
• This Beneficial use of fowl attracts human to search scientific technique for their reproduction, hatching, rearing and maintenance. For the success of the poultry industry, knowledge of habits of fowl, breed and their reproduction is essential.
• For the country like India, which is heavily populated it is necessary to increase the use to get healthy & nutritious food.
• Some breeds of poultry are more suitable for meat production which are called Broilers e.g. Plymouth rock. Other breeds of hens have high-quality hen gives 240 eggs per year and are called Layers. While other normal hens give only 60 eggs per year. Man has developed many species of hens for high-quality egg and meat producing by artificial selection.

(1) Bids useful in Poultry:
Many species of birds are used in poultry. Some important species are given below –
1. Fowl (Hen):

• In India domestic fowl, Gallus domestic is the main species in poultry. Two types of fowl breeds are used for poultry viz.,
• Indigenous or Desi Breed – These are Aseel, Kakarnath, Brahma, Busara, Ghagus, Chittagong etc. Aseel variety is used in cock-fighting and it is reared like a game bird.
• Exotic Breeds – Mostly European hens are included as exotic birds. Important foreign breeds are White Leghorn, Plymouth Rock, Rhode island red, New Hampshire etc. These breeds are considered as super breed variety.

2. Ducks:

• Duck, Anas platyrhynchos is also a source of eggs and meat. In India, 6% of the poultry population is contributed by ducks. These are found in southern and eastern states of India. Indian runner, Sylhet meta and Nageshwari are main Indian breeds, while foreign breeds are Muscari, Pekin, Campbell and Aylesbury.

3. Turkey:

• Meleagris gallopavo (Meleagris) is domesticated in recent years. Some main breeds are British white, Narfold, Broad breasted bronze, Beltsville small. white etc.

(2) Selection of fowls for breeding:
Following points are to be considered in the selection of good quality hens for reproduction.

1. Selection of male fowl for reproduction:

• Body of Cock must be shining, broad and strong. Eyes should be attractive, beak small and curved, wide back, skin thin and elastic, long tail with the upward position.

2. Selection of female fowl for reproduction:

• Size of hens should be large and in good shape. Good shape head and protruded eyes are the characters of good quality of hens. Mature hens of below one year are to be selected.
• A hen of good health, fast-growing, mature at an early age and producing more eggs are suitable for selection. The look looks active and always ready for the defence of a female. His roosting strike also is good. Such a bird will produce healthy chicks.

(3) Systems of Mating of Birds:

• Pen mating: Pen mating is a system in which one cock is kept with many hens i.e. one male for 10 females in captivity for mating.
• Flock mating: Many males in a flock of females. In such group fighting between male birds usually seen and the strongest cock will not allow the weaker to mate. Hence this process may be allowed where no record of mating is required.
• Stud mating: Cock and hen kept in separate cages and as per requirement females are left with males for mating.
• Alternating males: In this mating, two cocks are used. one cock for one day and the other cock for the next day left for mating. There is difficulty in keeping the record with this technique.

(4) Systems of Breeding:
1. Inbreeding:

• It is mating between a close relative of a species, for example between brother and sister, father and daughter, mother and son etc. This method of breeding is not preferred because the progeny becomes weak.

2. Linebreeding:

• Sometimes one bird is used for breeding again and again, because of its good quality. It is known as line breeding. In this type of breeding, close relatives are not allowed for a cross between them.

3. Out Crossing:

• It is a kind of mating, where birds of a species with different strains allowed for breeding. For example, one species of white leghorn is capable to produce more eggs but of small size, while other strain which is producing eggs of large size even in small numbers should be crossed.

4. Crossing:

• Cross between different bird species is called a hybrid, or hybrid vigour.

5. Grading:

• Mating between a pure male of a species with females of other species. Today’s poultry farming from a commercial point of view hence hybrid species is mostly reared.

(5) Incubation and Hatching:
1. Incubation Period:

• The period between fertilization and hatching of an embryo is called an incubation period.
• The incubation period of eggs is different for each bird species e.g. hen 21 days, turkey 28 days, ducks 28 days and Japanese bate 17-18 days.
• During the incubation period, extra-embryonic membranes of developing embryo perform various biological activities such as nutrition respiration, excretion and protection of the embryo. Extra-embryonic membranes, never participate in the formation of organs of the embryo.

2. Various stages of embryonic development:

• Before egg-laying: Fertilization
• Between egg-laying and Incubation: No growth
  • During Incubation:
  • 16 Hours – First sign of chick embryo
  • 20 Hours – Appearance of Vertebral Column
  • 22 Hours – Head formation starts
  • 24 Hours – Eye formation starts
  • 42 Hours – Heartbeat starts
  • 62 Hours – Leg formation Initiates
  • 64 Hours – Feathers formation starts
  • 5th Day – Formation of sex organs and sex differentiation begins
  • 6th Day – Beak formation starts
  • 17th Day – Beak turns towards air space
  • 19th Day – Entering of the yolk sac into the coelom
  • 20th Day – Yolk sac enters into coelom completely.
  • 21st Day – Hatching of a chick from the egg.

3. Selection of eggs for hatching:

• Selection of eggs for incubation should be done carefully because any type of abnormality in eggs cause an adverse effect on hatchability.
• Selection of eggs is done on the basis of shape, colour, quality of shell etc.

4. Artificial Incubation:

• The incubator is used for artificial incubation of eggs, which is essential for eggs to hatch out within 21 days. Eggs are kept for 18 days in an incubator and rest 3 days in other apparatus known as a hatcher.

Benefits of Artificial Incubation:

• Benefits of artificial incubation are given below:
  • Many young ones can be produced at a time.
  • Egg hatching can be performed as per requirement.
  • Developing young can be protected from infectious diseases.
  • Expenditure is less on artificial hatching.
  • Percentage of young one formation is more.

(6) Brooding and Rearing:
Incubation of eggs is called Brooding and after egg hatching, the caring of young chick is called Rearing. Rearing can be done in two ways –
1. Natural brooding:

• Hen itself acts as a brooder and incubator. Generally, a hen can brood 8 – 10 eggs at a time. It means hen incubate eggs by providing body heat.

2. Artificial brooding:

• The eggs are incubated artificially in an incubator and reared without hen is called artificial brooding. It has the following advantage over natural brooding –
  • This can be performed in any month of the year.
  • Chick can be reared in large numbers at a time.
  • Cleanliness and management to save from diseases can be managed.
  • Temperature can be controlled.
  • Food to developing chick is given as their requirement.
  • Hens are not required for brooding and rearing the young ones.

(7) Brooder House:
1. General:

• Before egg hatching, it is essential to prepare a proper brooder house. Proper airflow, temperature regulation, safety from outer factors (animals), safety from storm, cold or heat waves etc. are required in the brooder house. Large brooder house should be partitioned so that chicks of different ages can be kept separately.

2. Floor brooder:

• Bomboos basket with clay on both sides are prepared and it can be used as a good brooder floor for the development of the chick. Wooden brooder, tin or aluminium brooder is also in practice.

3. Battery Brooder:

• In a small area, a maximum number of young ones can be reared up to 4 weeks after hatching in the battery brooder.
• However, this method is not cheaper and hence not very common.
• In battery brooder, there may be many tiers and such brooder also has a cold place where young can go if necessary.
• In Battery Brooder, a bird with least age is kept on the top floor. Water & food arrangement is outside and there is no mixing of faecal matter with it. There are fewer chances of infection/disease.

(8) Poultry Farming using Cage system:
1. General:

• Before this method came in practice, dip litter method was in practice. In this method, many hens cannot be reared together as each hen requires three square feet area and for a large number of hen big house or poultry farm is required.
• In dip litter method, each hen requires three square feet space. So instead of dip litter method, the cage method is more convenient and in use nowadays because of the increase in the cost of hen houses. In dip litter method, each hen requires three square feet space. So instead of dip litter method, the cage method is more convenient and in use nowadays because of the increase in the cost of hen houses.

2. Benefits of Cage system:

• More birds in small space: Less space is required as compared to dip litter method. If a one poultry house rearing one thousand birds and if the cage system is followed than up to 2500 birds can be reared easily.
• Protection from diseases: Fowls are kept in the cages, hence any disease can not infect the whole group at a time. Hence, it is very useful.
• The scientist is of this opinion, that less food is consumed by a hen in a cage system.
• In a cage system, an animal can be sorted out easily if required, while in dip litter system it is not so easy.
• Labour saving: It is believed that less human labour is required in a cage system, as one person can look after large hens.

3. Management Tips for Cage Layers:

• Cage system requires different management than dip litter system. Some important points are as given below –
  • Food management: Food is to be supplied at the proper time in cages. If food supply delays even by one hour, it will reduce production. It is necessary to provide food three times a day (morning, afternoon & evening) one shall monitor food pipe for any problem.
  • Water Management: Fresh water must be available at every time and the water pots and drainage should be cleaned properly and regularly.
  • Fowl manure Management: The faecal matter accumulate in the cage and develops foul odour. Hence regular timely cleanliness of cage is essential.
  • Light Arrangement: Light must be proper and everywhere in the cage so food can be ingested properly.
  • Egg collection: Egg collection should be done at least thrice in a day.
  • Building construction: The building in cage system depends on our requirement. The height of the building depends on the layers of cages required. If two-tier cages are required then roof must be at at least 12 feet.
    If three-tier cages are to be kept than 14 feet height of the building is required. A flat roof is best. If hut roof is required then the height should be 9 – 10 feet. A building should be made in a dry area. The moisture of land will provide moisture to faecal matter, as a result, Insects will increase in number & faecal matter will not dry.

(9) Poultry Food:
1. General Poultry food is prepared in view of the following objectives:

• To fulfil fowls nutritional requirements.
• For growth, development and reproduction.
• Provide energy for voluntary and involuntary functions.
• Non-edible poultry food into edible food.

2. Different Poultry Feeds:
I. Carbohydrate Feeds –

• It is 70 – 80% part of poultry food. Carbohydrate is used for energy, heat and fat production. It is cheaper in comparison to other food and easily available. Some of the important major sources are:
  • Maize: It is maximally used in Poultry feed. It has starch and fat content in more amount.
  • Wheat: It is just second to Maize. It contains less calcium but more amount of phosphorus. It also contains vitamin B & E. It can be used in many ways as poultry feed such as wheat fibres (Chapter).
  • Oats: It contains 12% protein, 10.6% fibre and 4.7% fat. It can be given either as a whole or broken into smaller pieces.
  • Barley: It can also be used in poultry feed just as oat.
  • Sorghum: Its shape & structure is like maize but doesn’t contain vitamin A. It is beneficial only when its cost is lower than wheat, maize or oats.
  • Rice: It is also used in place of other cereals but its price normally remains higher than other cereals so used very less.
  • Molasses: It is remaining part after sugar is formed from sugarcane juice. It can be used as a 5 – 10% replacement of cereals.
  • Potatoes: Those potatoes which cannot be consumed by a human being small in size, can be boiled and given to hen.

II. Fat Feeds:

• Fat is the main source of energy. It is mixed in feed up to 2 5%. Fat improves the size of fowl, it increases hunger so more food is consumed resulted in well physical development and increase egg production. Fat is obtained from these substances –
  • Soyabean oil
  • Ground Nuts oil
  • Cottonseed oil
  • Maize oil
  • Wheat germ oil
  • Animals fat
  • Emulsified oils

III. Protein feeds:

• It is the most important part of nutrition. It is a basic requirement for physical development and egg production. Protein feed is obtained from –
  • Animal protein feed: It includes milk, meat scrap, fish meal etc. It has more mineral elements and vitamins.
  • Vegetable protein feed: Important vegetable feed is soybean meal, corn gluten meal, oil cakes of groundnut, cottonseed and sunflower oil.
  • Milk: It is the best to the source of protein but it is costly so not in practice.
  • Meat scrap: In chicken food, it is used to obtain protein and minerals.
  • Feather meal: It has 86 – 88% protein, but essential amino acids are not found in it. 10 – 20% of the protein part can be used in poultry feed.
  • Poultry blood meal: It has 65% protein, it can be used only up to a small part of the total protein requirement.
  • Soyabean oil meal: It is significantly used in the soybean-producing area. Soybean is a very rich source of protein. In India Groundnut oil cakes are mostly used, now these days soybean cakes are also in use.

IV. Mineral Meals:

• Calcium: Calcium carbonate is the best source of it. It is obtained from oyster shells, marble chips and eggshells.
• Phosphorus: Tricalcium phosphate is chief substance in bone meal. It is given to get phosphorous.
• Manganese: Its requirement is 50 parts per million but it is essential for hatching and bone formation.
• Salt: Salt is essential for taste and digestion 0.5% of Salt. In a similar way Iron, Iodine is also added in Poultry feed is added in food.

(10) Common diseases of Poultry:
Some poultry diseases are as follows –
1. Viral diseases:

• The main viral diseases in poultry birds are Fowlpox, Infectious bronchitis, Lymphoid leukosis and Ranikhet disease. The most common disease of fowl is Ranikhet in which fever, diarrhoea occurs.

2. Bacterial diseases:

• These diseases are Fowl cholera, Pullorum, Coryza, Mycoplasmosis and Spirochaetosis.

3. Fungal diseases

• Aflatoxicosis, Brooder pneumonia and Aspergillosis are main fungal diseases.

Question 4.
Explain various steps of sericulture in detail.
Answer:
Rearing of Silkworm:

• Silkworm rearing is an extensive month-long exercise starting from egg stage, aestivation, hibernation, incubation and finally cocoon formation. For maintaining the systemic culture, Grainage technology is important.

Grainage Management:

• The most important stage of sericulture is the production of healthy and disease-free eggs and egg management and it plays a vital role in which the success of the industry depends. There are the main objectives of Grainage Management.
• This managements keep caterpillars with healthy nutrients, disease-free etc. cocoons are developed from caterpillars.
• After the last selection, cocoons are separated by their sex. This is performed using Naghara instrument. This machine cut 10,000 to 15,000 cocoons. For the industrial purpose of egg production, loose types of cocoons are used. Mass pebrine detecting machine or simple microscope is used for detection of female adult silkworm and Sabrin disease-free worm.

Supply of seed to rearers and commercial rearing:
After grainage management, the second step is to supply eggs to cultivators. On the basis of the knowledge and experience of cultivators, it is of 2 types –

1. Supply of eggs
2. Supply of Instar Caterpillar

• Those who have the experience to culture silkworm, take eggs but those having no experience always take 2 stages instar caterpillar. I, II, and III stages of Caterpillar are carefully handled. IV and V stage instar caterpillar are provided nutrients through a nylon net plate.
• From this technique, high quality of cocoons has been made. To culture 1,2,3,4, and 5 instar caterpillar temperature should be 27°C, 27°C, 25°C, 24°C & 23°C maintained respectively.

Formation of Cocoon:

• This is the time when caterpillar stops taking food and it secretes sticky substance. In this phase, caterpillars are transferred into the spinning tray. These trays are kept sideways in sun. After 3 days cocoons are formed which is the last stage of sericulture.

Method of obtaining silk from Cocoons:

• Firstly, cocoons are kept into a hot oven or hot water to destroy the cocoons shell. This process is called Stiffiling.
• Afterwards, a cocoon is reeled together to produce a single thread. One cocoon makes 1000 to a 15000-meter-long thread. This thread is rolled on the spool (Red silk) and again it is boiled in hot water. It was washed with chemical acids which make it clean and shiny. They are changed into Fiber silk when spun. This process is called spinning.

RBSE Solutions for Class 12 Biology