Question

what is the importance of cocoon stage in a life cycle of silk?
silk gives us a lustrous appearance ? give reasons
what do you mean by upper and lower standard time?
explain the symbiotic association between fungus and alga in lichens?

Answer 1

cocoon stage is important in a life cycle of silk because it gives thin thread of silk when boiling and thread of single silk fibre is too fine so upto ten cocoons are wound together onto a reel by hand . each cocoon is made from a single silk fibre around 1km long.

Answer 2

The fibres are triangular prism like structure. so the silk cloth refracts the light falling on it at different angles and gives a shimmering appearance.The cocoon of the silkworm is produced by the animal in a trianglular shape, so that for the length of the strand, light is reflected from most any angle.