Make sketches of the two stages in the life history of the silk moth which are directly related to the production of silk.
The two stages in the life history of the silk moth are: Caterpillar and Cocoon.
1. Caterpillar: Bombyx mori, the domestic silk moth which helps in making warm clothes, is an insect from the moth family Bombycidae. The silkworm is the larva or caterpillar of a silk moth which is developed by the eggs that lays by female silkmoth. Silkworm is reared at the commercial level for obtaining silk. Silkworm feeds on mulberry leaves.
2. Cocoon: When the caterpillar is ready to enter the next stage of its life history called pupa. firstly it weaves the net to hold itself. during this, the caterpillar secretes a fibre that is made up of proteins which hardens on the exposure of air and becomes silk fibre. Soon the caterpillar completely coveres itself by silk fibre by making it and turns into the pupa. This covering is known as cocoon. The further development of pupa into moth continues inside the cocoon.
The silf yarn (thread) is obtained from the cocoon of the silkmoth.
Popular Questions of Class 7 Science
- Q:-
Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food - Q:-
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) 1 : Thorough washing (A) 1 : Keeps warm
2 : Animal fibre 2 : Its leaves are eaten by silkworms
3 : Long thread like structure 3 : Hatches from egg of moth
- Q:-
Sketch the cross section of soil and label the various layers.
- Q:-
Here is a crossword puzzle: Good luck!
Across
3. Liquid waste products
4. Solid waste extracted in sewage treatment
6. A word related to hygiene
8. Waste matter discharged from human bodyDown
1. Used water
2. A pipe carrying sewage
5. Micro-organisms which causes cholera
7. A chemical to disinfect water - Q:-
Take three test-tubes. Fill æth of each with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2?
- Q:-
Sketch the reproductive parts of a flower.
- Q:-
Solve the following crossword puzzle with the clues given:
Across
2. Plantation prevents it.
5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.Down
1. In desert soil erosion occurs through.
3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil. - Q:-
Describe how crystals of copper sulphate are prepared.
- Q:-
Match the items in Column I with those in Column II:
Column I Column II
(i) A home for living organisms (a) Large particles
(ii) Upper layer of the soil (b) All kinds of soil
(iii) Sandy soil (c) Dark in colour
(iv) Middle layer of the soil (d) Small particles and packed tight (v) Clayey soil (e) Lesser amount of humus - Q:-
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
Recently Viewed Questions of Class 7 Science
- Q:-
Explain how forests prevent floods.
- Q:-
Match structures given in Column I with functions given in Column II.
Column I Column II
(i) Stomata (a) Absorption of water
(ii) Xylem (b) Transpiration
(iii) Root hairs (c) Transport of food
(iv) Phloem (d) Transport of water
(e) Synthesis of carbohydrates - Q:-
Look at Fig. 4.13. Mark where the heat is being transferred by conduction, by convection and by radiation.
- Q:-
Which type of mirror can form a real image?
- Q:-
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? - Q:-
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) 1 : Thorough washing (A) 1 : Keeps warm
2 : Animal fibre 2 : Its leaves are eaten by silkworms
3 : Long thread like structure 3 : Hatches from egg of moth - Q:-
List five products we get from forests?
- Q:-
An iron ball at 40°C is dropped in a mug containing water at 40°C. The heat will
(a) flow from iron ball to water.
(b) not flow from iron ball to water or from water to iron ball.
(c) flow from water to iron ball.
(d) increase the temperature of both. - Q:-
Tick the correct answer:
(a) Amarbel is an example of:
(i) autotroph (ii) parasite (iii) saprotroph (iv) host(b) The plant which traps and feeds on insects is:
(i) Cuscuta (ii) china rose (iv) pitcher plant (iv) rose - Q:-
The mountaineers carry oxygen with them because:
(a) At an altitude of more than 5 km there is no air.
(b) The amount of air available to a person is less than that available on the ground.
(c) The temperature of air is higher than that on the ground.
(d) The pressure of air is higher than that on the ground.
- NCERT Chapter